You searched for +publisher:"Texas A&M University" +contributor:("Naraghi, Mohammad").
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Texas A&M University
1.
Baranikumar, Aishwarya.
Imparting Electrical Conductivity into Asphalt Composites Using Graphite.
Degree: MS, Civil Engineering, 2013, Texas A&M University
URL: http://hdl.handle.net/1969.1/151140 
► Electrically conductive asphalt composites have immense potential for various multifunctional applications such as self-healing, self-sensing, snow and ice removal, and energy harvesting, and controlling asphalt…
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▼ Electrically conductive asphalt composites have immense potential for various multifunctional applications such as self-healing, self-sensing, snow and ice removal, and energy harvesting, and controlling asphalt conductivity is the first step to enable such applications. Previous investigators have used conductive fibers as major conductive additive for asphalt composites, and the sudden transition from the insulated phase to the conductive phase, known as the percolation threshold, is commonly observed. Since the percolation threshold hinders precise control of asphalt conductivity, it is imperative to mitigate the sudden transition in the electrical resistivity curve to enable practical applications of asphalt composites. Some recent publications showed the potential of graphite in mitigating the sudden transition. The study presented herein investigates possibility of precisely controlling the electrical conductivity of asphalt concrete only by adding filler size graphite powder. Nine different types of graphite having different particle shapes and sizes are selected to investigate their effect on conductivity control. The volume resistivity of the asphalt mastic specimens containing various concentrations of graphite is evaluated. In addition, scanning electron microscope analysis is conducted for the graphite particles to provide physical explanation for their different effects on imparting conductivity. The results show that the electrical resistivity of asphalt mastic is significantly varied with the types of graphite. The mastics containing natural flake graphite show gradual decrease in volume resistivity as the graphite content increases, and sufficiently low resistivity can be obtained in the specimens with natural flake graphite. On the other hand, amorphous graphite is not efficient in reducing volume resistivity. Graphite with high surface area presents difficulty in mixing. In the next stage of research, two best performing graphite out of the nine different types are selected to be added to asphalt concrete, and the effect of aggregates on electrical resistivity is examined. It is found that flake graphite 516 provides good electrical conductivity along with improved mechanical performance of asphalt concrete. Thus the study provides fundamental information on the selection of graphite type and amount to achieve proper electrical conductivity required for multifunctional applications.
Advisors/Committee Members: Park, Philip (advisor), Gharaibeh, Nasir (committee member), Naraghi, Mohammad (committee member).
Subjects/Keywords: Asphalt mastic; graphite
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APA (6th Edition):
Baranikumar, A. (2013). Imparting Electrical Conductivity into Asphalt Composites Using Graphite. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/151140
Chicago Manual of Style (16th Edition):
Baranikumar, Aishwarya. “Imparting Electrical Conductivity into Asphalt Composites Using Graphite.” 2013. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/151140.
MLA Handbook (7th Edition):
Baranikumar, Aishwarya. “Imparting Electrical Conductivity into Asphalt Composites Using Graphite.” 2013. Web. 13 Apr 2021.
Vancouver:
Baranikumar A. Imparting Electrical Conductivity into Asphalt Composites Using Graphite. [Internet] [Masters thesis]. Texas A&M University; 2013. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/151140.
Council of Science Editors:
Baranikumar A. Imparting Electrical Conductivity into Asphalt Composites Using Graphite. [Masters Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/151140
Texas A&M University
2.
Mayadeo, Nikhil.
Modeling of Downstream Heating in Melt Electrospinning of Polymers.
Degree: MS, Chemical Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/165747
► The current study is driven by the demand for sub-micron fibers with high surface area to volume ratios to be used in applications such as…
(more)
▼ The current study is driven by the demand for sub-micron fibers with high surface area to volume ratios to be used in applications such as high performance filtration, tissue engineering, in-situ wound dressing, drug delivery, thermal management, and energy storage.
Traditionally, industry has been using solution electrospinning for manufacturing sub-micron fibers. However, it is expensive and environmentally unfavorable because a significant quantity of toxic solvent is lost to the surroundings during this process. The alternative approach, melt electrospinning, is inherently limited to the production of micron-sized fibers. This is mainly due to the high viscosity and low electrical conductivity of the melt. In addition, rapid heat loss to the surroundings results in solidification of the polymer melt jet before it has been significantly stretched by the electric field.
In order to address this problem, we propose that a volumetric heat source placed downstream in the melt electrospinning process can lead to markedly decreased fiber diameters. For this purpose, we utilize a model for non-isothermal melt electrospinning in the presence of a downstream volumetric heat source. The model is based on thin filament approximation applied to fully coupled momentum, continuity, charge, and energy equations, along with the non-isothermal Giesekus constitutive model and the electric field equation at steady state.
The simulation results demonstrate that downstream heating does reduce the fiber diameter, and is therefore a feasible solution for resolving the drawbacks of melt electrospinning. In addition, the model has been used to capture the influence of the surrounding temperature, which affects the thinning of the fiber through surface rather than volumetric interactions. Finally, experiments on melt electrospun polycaprolactone are utilized in order to validate the model predictions.
Advisors/Committee Members: Green, Micah (advisor), Naraghi, Mohammad (committee member), Elabd, Yossef (committee member).
Subjects/Keywords: melt electrospinning; downstream heating
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APA (6th Edition):
Mayadeo, N. (2017). Modeling of Downstream Heating in Melt Electrospinning of Polymers. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/165747
Chicago Manual of Style (16th Edition):
Mayadeo, Nikhil. “Modeling of Downstream Heating in Melt Electrospinning of Polymers.” 2017. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/165747.
MLA Handbook (7th Edition):
Mayadeo, Nikhil. “Modeling of Downstream Heating in Melt Electrospinning of Polymers.” 2017. Web. 13 Apr 2021.
Vancouver:
Mayadeo N. Modeling of Downstream Heating in Melt Electrospinning of Polymers. [Internet] [Masters thesis]. Texas A&M University; 2017. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/165747.
Council of Science Editors:
Mayadeo N. Modeling of Downstream Heating in Melt Electrospinning of Polymers. [Masters Thesis]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/165747
Texas A&M University
3.
Colbert, Keegan David.
An Experimentally Verified Model for Thermal Microactuators Including Nonlinear Material Properties, Radiation, and Intra-Device Heat Conduction.
Degree: MS, Aerospace Engineering, 2016, Texas A&M University
URL: http://hdl.handle.net/1969.1/157167
► A multi-physics model and computational method is presented for predicting the performance of thermal microactuators at high input powers. The model accounts for nonlinear temperature…
(more)
▼ A multi-physics model and computational method is presented for predicting the performance of thermal microactuators at high input powers. The model accounts for nonlinear temperature dependence of material properties, heat loss due to radiation, and intra-device heat transfer by conduction across an air gap. To solve the highly nonlinear governing heat equations and compute the temperature distribution in the actuator, the Galerkin method with Newton-Raphson iteration is employed, enabling the calculation of device displacement. To verify accuracy, the model is applied to the case of a flexure actuator operating at steady state, and model predictions are compared with experimental voltage, current, and displacement measurements. To investigate the effects of each nonlinearity in the model, the predictions of six additional hypothetical models are considered in which (1) intra-device heat transfer is neglected, (2) heat loss due to radiation is neglected, (3) the thermal conductivity of silicon is assumed to be temperature-independent, (4) the thermal conductivity of air is assumed to be temperature-independent, (5) the electrical resistivity of silicon is assumed to be a linear function of temperature, and (6) the thermal expansion coefficient of silicon is assumed to be temperature-independent. With the exception of heat transfer due to radiation, each source of non-linearity was shown to have a significant impact on the accuracy of model predictions at high electrical power input. The model is further applied to predict the dynamic performance of the flexure actuator using an implicit Euler method to predict the evolution of the temperature distribution over time. The dynamic implementation is then used to calculate the thermal time constant for the flexure actuator, and model predictions for the transient voltage-current response are verified experimentally.
Advisors/Committee Members: Boyd, James G (advisor), Naraghi, Mohammad (advisor), Banerjee, Debjyoti (committee member).
Subjects/Keywords: Microactuator; Thermal Actuator; Flexure Actuator; MEMS; Finite Element Analysis; Intra-Device Heat Transfer; Galerkin Method
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APA (6th Edition):
Colbert, K. D. (2016). An Experimentally Verified Model for Thermal Microactuators Including Nonlinear Material Properties, Radiation, and Intra-Device Heat Conduction. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/157167
Chicago Manual of Style (16th Edition):
Colbert, Keegan David. “An Experimentally Verified Model for Thermal Microactuators Including Nonlinear Material Properties, Radiation, and Intra-Device Heat Conduction.” 2016. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/157167.
MLA Handbook (7th Edition):
Colbert, Keegan David. “An Experimentally Verified Model for Thermal Microactuators Including Nonlinear Material Properties, Radiation, and Intra-Device Heat Conduction.” 2016. Web. 13 Apr 2021.
Vancouver:
Colbert KD. An Experimentally Verified Model for Thermal Microactuators Including Nonlinear Material Properties, Radiation, and Intra-Device Heat Conduction. [Internet] [Masters thesis]. Texas A&M University; 2016. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/157167.
Council of Science Editors:
Colbert KD. An Experimentally Verified Model for Thermal Microactuators Including Nonlinear Material Properties, Radiation, and Intra-Device Heat Conduction. [Masters Thesis]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/157167
Texas A&M University
4.
Zhang, Li.
Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams.
Degree: MS, Civil Engineering, 2013, Texas A&M University
URL: http://hdl.handle.net/1969.1/151002
► In the past few decades, several researchers have studied the effects of ASR induced expansion in concrete. Several models have been proposed to model the…
(more)
▼ In the past few decades, several researchers have studied the effects of ASR induced expansion in concrete. Several models have been proposed to model the effects of ASR in concrete. While most of these models focus on plain concrete, there is limited amount of research to model the influence of ASR expansion in reinforced concrete. Additionally, the existing models are complex and difficult to implement for practicing engineers. In this study the shortcomings with the existing models are addressed.
A minimalist semi-empirical model is developed to represent the degradation of reinforced concrete due to ASR expansion. The model is validated using historical experimental data. Only two key parameters are needed to represent the expansive behavior, specifically, the maximum unreinforced concrete strain due to ASR expansion and the rise time. Mechanical properties of the reinforced concrete are also needed.
From the predicted expansions, it is then shown that it is possible to model the number and spacing of cracks of a partly restrained reinforced concrete beam affected by ASR gels. The model is validated with recent experimental results on large scale reinforced concrete specimens. Predictions agree well with the observed number of cracks.
Advisors/Committee Members: Mander, John (advisor), Park, Philip (committee member), Naraghi, Mohammad (committee member).
Subjects/Keywords: ASR; semi-empirical model; strain; cracking
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APA (6th Edition):
Zhang, L. (2013). Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/151002
Chicago Manual of Style (16th Edition):
Zhang, Li. “Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams.” 2013. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/151002.
MLA Handbook (7th Edition):
Zhang, Li. “Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams.” 2013. Web. 13 Apr 2021.
Vancouver:
Zhang L. Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams. [Internet] [Masters thesis]. Texas A&M University; 2013. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/151002.
Council of Science Editors:
Zhang L. Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams. [Masters Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/151002
Texas A&M University
5.
Hong, Seokjin.
Controlling the Wettability and Adhesion of Carbon Fibers with Polymer Interfaces via Grafted Nanofibers.
Degree: MS, Materials Science and Engineering, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/156234
► Interfacial properties in carbon fiber composites is one of the key parameters controlling their structural functionality. Here, we introduce a novel method to engineering carbon…
(more)
▼ Interfacial properties in carbon fiber composites is one of the key parameters controlling their structural functionality. Here, we introduce a novel method to engineering carbon fiber-epoxy interfaces, via inclusion of nanofibers, towards higher interfacial strength and energy dissipation. In our method, thermally stabilized polyacrylonitrile (PAN) nanofibers are grafted onto carbon fibers via electro-spinning process, followed by nanofiber consolidation via solvent vapor and thermal treatment. These treatments partially dissolve nanofibers along the nanofiber-fiber interface and trigger entropic elasticity in nanofibers thus, increasing the nanofiber-fiber interactions. The hybridization of carbon fibers with PAN nanofibers increased the interfacial shear strength (IFSS) by ~48%, from 10.8 ±2.6 to 15.9 ±4.9 MPa. Postmortem fractography points to mechanical interlocking between nanofibers and epoxy and reinforcing effects of nanofibers in matrix as root causes of IFSS enhancement. As a result of adding nanofibers to carbon fiber, junction failure mode changes from a dominantly adhesive failure (at epoxy-fiber interface) to dominantly cohesive failure, and failure plane slightly shifts away from epoxy-fiber interface to within the epoxy. Compared to other types of whiskers grown on carbon fibers, such as CNTs, the method proposed here requires low temperatures (below 300°C), during which no surface damages are expected to accumulate on carbon fibers.
Advisors/Committee Members: Naraghi, Mohammad (advisor), Talreja, Ramesh (committee member), Creasy, Terry (committee member).
Subjects/Keywords: Interfacial shear strength; interfacial adhesion; fiber-matrix interaction; hybrid carbon fiber; and fiber-reinforced composites
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APA (6th Edition):
Hong, S. (2015). Controlling the Wettability and Adhesion of Carbon Fibers with Polymer Interfaces via Grafted Nanofibers. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/156234
Chicago Manual of Style (16th Edition):
Hong, Seokjin. “Controlling the Wettability and Adhesion of Carbon Fibers with Polymer Interfaces via Grafted Nanofibers.” 2015. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/156234.
MLA Handbook (7th Edition):
Hong, Seokjin. “Controlling the Wettability and Adhesion of Carbon Fibers with Polymer Interfaces via Grafted Nanofibers.” 2015. Web. 13 Apr 2021.
Vancouver:
Hong S. Controlling the Wettability and Adhesion of Carbon Fibers with Polymer Interfaces via Grafted Nanofibers. [Internet] [Masters thesis]. Texas A&M University; 2015. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/156234.
Council of Science Editors:
Hong S. Controlling the Wettability and Adhesion of Carbon Fibers with Polymer Interfaces via Grafted Nanofibers. [Masters Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/156234
Texas A&M University
6.
Sumit, FNU.
FORMATION OF CARBON NANOSPRINGS VIA PRECURSOR CONSTRAINED FIBER MICROBUCKLING.
Degree: MS, Aerospace Engineering, 2019, Texas A&M University
URL: http://hdl.handle.net/1969.1/188804
► Flexible carbon nanosprings and wavy nanofibers can be used in micro and nanoelectromechanical system devices, deployable structures, flexible displays, energy storage, catalysis, nanocomposites and a…
(more)
▼ Flexible carbon nanosprings and wavy nanofibers can be used in micro and nanoelectromechanical system devices, deployable structures, flexible displays, energy storage, catalysis, nanocomposites and a multitude of other uses. A novel method to produce wavy and helical carbon nanofibers (CNFs) is presented here. The CNFs with controlled geometry were fabricated via pyrolysis of electrospun polyacrylonitrile (PAN) nanofibers as the precursor. The waviness/helicity of nanofibers was achieved by subjecting the precursor nanofibers to constraint buckling inside a thermally shrinking matrix. The much higher tendency of the matrix to shrink, compared to PAN nanofibers, was achieved by controlling the microstructure and crystallinity of the precursors.
The formation of the wavy/helical geometry was explained quantitatively via mechanistic models, by minimizing the total mechanical energy stored in the PAN-matrix system during the matrix shrinkage. Despite its simplicity in considering elastic deformations only, the model provided reasonably quantitative matching with the experiments. Compared to existing methods in generating wavy/helical nanofibers, such as chemical vapor deposition growth methods, our method provides a more controllable geometry which is suitable for large scale production of aligned buckled CNFs.
Advisors/Committee Members: Naraghi, Mohammad (advisor), Kinra, Vikram (committee member), Pharr, Matt (committee member).
Subjects/Keywords: Microbuckling; Wavy nanofibers; Helical nanofibers; Nanocoils; Nanosprings
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APA (6th Edition):
Sumit, F. (2019). FORMATION OF CARBON NANOSPRINGS VIA PRECURSOR CONSTRAINED FIBER MICROBUCKLING. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/188804
Chicago Manual of Style (16th Edition):
Sumit, FNU. “FORMATION OF CARBON NANOSPRINGS VIA PRECURSOR CONSTRAINED FIBER MICROBUCKLING.” 2019. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/188804.
MLA Handbook (7th Edition):
Sumit, FNU. “FORMATION OF CARBON NANOSPRINGS VIA PRECURSOR CONSTRAINED FIBER MICROBUCKLING.” 2019. Web. 13 Apr 2021.
Vancouver:
Sumit F. FORMATION OF CARBON NANOSPRINGS VIA PRECURSOR CONSTRAINED FIBER MICROBUCKLING. [Internet] [Masters thesis]. Texas A&M University; 2019. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/188804.
Council of Science Editors:
Sumit F. FORMATION OF CARBON NANOSPRINGS VIA PRECURSOR CONSTRAINED FIBER MICROBUCKLING. [Masters Thesis]. Texas A&M University; 2019. Available from: http://hdl.handle.net/1969.1/188804
Texas A&M University
7.
Ai, Yin.
Effects of Manufacturing Induced Defects on Mixed-Mode Delamination Kinking in Composite Laminates.
Degree: MS, Aerospace Engineering, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/174202
► With the superior mechanical performance, such as high strength and stiffness, fiber-reinforced polymer composites are widely used on main structures, like airfoil for aircraft or…
(more)
▼ With the superior mechanical performance, such as high strength and stiffness, fiber-reinforced polymer composites are widely used on main structures, like airfoil for aircraft or wind turbine. Manufacturing induced defects draw people’s attention for a long time and porosity content was characterized as critical factor that would destroy composite structure. In recent years, it has been noticed that rather than defects’ content, the shape, size and distribution are also important.
Some of the research focused on influence of defects on crack propagation along interface. Not much attention has been placed on effects for delamination crack kinking. In the current study, in order to explore how voids affect composites delamination kinking, a double cantilever beam (DCB) model with a delamination pre-crack was simulated under tensile loading condition. By a revised Virtual Crack Closure Technic, the strain energy release rates for crack extension in Mode I and Mode II were evaluated. A parametric research was performed with present of various shapes and sizes of voids in resin area. With applying the mixed-mode fracture criterion, the potential kinking angle was determined. In addition, the effects of circular voids in resin area after delamination kinked out was also examined.
Some of the following results have been found. The delamination in the current DCB model is Mode I dominated fracture process. The failure is governed by dilatational energy and it’s an elastic failure problem. Voids located in resin-reach area cause stress perturbation at crack tip and activate the delamination kinking at around 15-degree angle. The parametric study of voids with different geometry shows that elliptical voids compared with circular ones are more threatening to crack branching out. Size of voids is also a critical character that with identical distance from crack tip, larger voids accrete the crack kinking possibility. More importantly, distance between of crack tip and voids, regardless of their size and shape, is the most crucial factor for delamination kinking.
Advisors/Committee Members: Talreja, Ramesh (advisor), Naraghi, Mohammad (committee member), Reddy, Junuthula N. (committee member).
Subjects/Keywords: Delamination kinking; Void; DCB; Laminated composites; FEM
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APA (6th Edition):
Ai, Y. (2015). Effects of Manufacturing Induced Defects on Mixed-Mode Delamination Kinking in Composite Laminates. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/174202
Chicago Manual of Style (16th Edition):
Ai, Yin. “Effects of Manufacturing Induced Defects on Mixed-Mode Delamination Kinking in Composite Laminates.” 2015. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/174202.
MLA Handbook (7th Edition):
Ai, Yin. “Effects of Manufacturing Induced Defects on Mixed-Mode Delamination Kinking in Composite Laminates.” 2015. Web. 13 Apr 2021.
Vancouver:
Ai Y. Effects of Manufacturing Induced Defects on Mixed-Mode Delamination Kinking in Composite Laminates. [Internet] [Masters thesis]. Texas A&M University; 2015. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/174202.
Council of Science Editors:
Ai Y. Effects of Manufacturing Induced Defects on Mixed-Mode Delamination Kinking in Composite Laminates. [Masters Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/174202
Texas A&M University
8.
Cai, Jizhe.
The Effect of Templated Graphitization on Electromechanical Properties of Carbon Nanofiber.
Degree: PhD, Aerospace Engineering, 2018, Texas A&M University
URL: http://hdl.handle.net/1969.1/173351
► Theory predicts that carbon nanofibers (CNFs), processed via carbonizing polymeric nanofibers, as down-sized version of carbon fibers (CFs) should be significantly stronger than CFs, due…
(more)
▼ Theory predicts that carbon nanofibers (CNFs), processed via carbonizing polymeric nanofibers, as down-sized version of carbon fibers (CFs) should be significantly stronger than CFs, due to size-dependent defects in CFs such as skin-core radial inhomogeneity. To close the gap between the predictions and experimentally achieved strength of CNFs, the processing-microstructure-properties relationship in CNFs was studied. The CNFs in my study were fabricated by thermal stabilization and carbonization of electrospun polyacrylonitrile (PAN) nanofibers which contain CNTs inclusions. In this research the formation of graphite-like structures (turbostratic domains) within CNFs was promoted by adding CNTs to the precursor in a process known as templated graphitization, in which the presence of CNTs can facilitate the arrangement of carbon atoms, obtained as a result of the carbonization of PAN, into a graphite-like structure (sp² carbon bonds) similar to what exists in CNTs. It is further demonstrated that the templating effect of CNTs is more pronounced when PAN chains are aligned with each other and with CNTs, as was achieved in this research by hot-drawing the precursors. The existence of CNTs effectively promotes the formation of highly ordered polymer interphase.
The study on the microstructure and mechanical properties of CNFs confirms that the modification of the precursor microstructure, such as enhanced chain alignment, can be maintained during carbonization, and indeed leads to enhanced graphitic alignment. Based on the MEMS-based nano-mechanical tension tests on CNFs, the combined effect of precursor hot-drawing and graphitic templating effect resulted in CNFs with tensile strength and modulus of 6.9 GPa and 250 GPa, respectively, which are the largest values reported up to date for this type of material. Moreover, the multifunctional properties of electrospun CNFs, including piezoresisitivty and electrical conductivity, were restudied both experimentally and via continuum models, demonstrating the strong correlation between microstructure modification and properties improvement.
In summary, a clear strategy for developing low-cost high performance CNF/CNTs hybrid nanofibers was obtained based on new understanding of the load bearing mechanism within CNF. These nanofibers can be used as the multifunctional building blocks for a host of applications, including aerospace and automotive industry.
Advisors/Committee Members: Naraghi, Mohammad (advisor), Lagoudas, Dimitris (committee member), Boyd, James (committee member), Shao, Lin (committee member).
Subjects/Keywords: carbon nanofibe; , carbon nanotubes; templating; mechanical properties
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APA (6th Edition):
Cai, J. (2018). The Effect of Templated Graphitization on Electromechanical Properties of Carbon Nanofiber. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/173351
Chicago Manual of Style (16th Edition):
Cai, Jizhe. “The Effect of Templated Graphitization on Electromechanical Properties of Carbon Nanofiber.” 2018. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/173351.
MLA Handbook (7th Edition):
Cai, Jizhe. “The Effect of Templated Graphitization on Electromechanical Properties of Carbon Nanofiber.” 2018. Web. 13 Apr 2021.
Vancouver:
Cai J. The Effect of Templated Graphitization on Electromechanical Properties of Carbon Nanofiber. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/173351.
Council of Science Editors:
Cai J. The Effect of Templated Graphitization on Electromechanical Properties of Carbon Nanofiber. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/173351
Texas A&M University
9.
Thomas, Nithin.
On the Effects of Stress State and Microstructure Induced Anisotropies on Ductile Fracture.
Degree: PhD, Aerospace Engineering, 2016, Texas A&M University
URL: http://hdl.handle.net/1969.1/159104
► A major challenge that is currently facing the mechanics of materials community is the accurate prediction of fracture in advanced ductile materials. The intertwined effects…
(more)
▼ A major challenge that is currently facing the mechanics of materials community
is the accurate prediction of fracture in advanced ductile materials. The intertwined
effects of intrinsic and extrinsic factors make ductile fracture one of the most complex
phenomena in materials mechanics. Intrinsic factors include large plastic deformations,
induced anisotropies, microstructural evolution, and stress state effects.
Extrinsic factors relate to the effect of boundary conditions and to the onset of plastic
instabilities, either material (e.g., shear bands) or structural (e.g., necking). This
dissertation sheds light on three fundamental topics - effect of non proportional loadings,
anisotropic ductile fracture and failure by shear localization. First, by means
of a simple fracture model, a generic shape of the fracture strain versus average triaxiality
locus and previously published experimental results are rationalized. Then,
a more elaborate ductile fracture model is utilized to carry out three-dimensional
finite element simulations of damage accumulation to failure in initially crack-free
specimens under certain symmetry considerations. The results reveal an emerging
competition between intrinsic and structural effects imparted by plastic anisotropy.
Finally, full 3D simulations are carried out when the triads of loading and plastic
anisotropy are misoriented. The simulations reveal, for the first time, failure by
shear band formation in initially round notched bars, reminiscent of experimental
observations in Al or Mg alloys. These insights have practical and theoretical
consequences and will aid the implementation of improved models of ductile fracture
with accurate predictive capabilities and the design of safer structural components in
the aerospace, automotive and energy industries.
Advisors/Committee Members: Benzerga, Amine (advisor), Talreja, Ramesh (committee member), Naraghi, Mohammad (committee member), Karaman, Ibrahim (committee member).
Subjects/Keywords: ductile fracture; anisotropy; shear localization; shear bands; fracture; non-proportional loadings; path dependent; void shape; void orientation
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APA (6th Edition):
Thomas, N. (2016). On the Effects of Stress State and Microstructure Induced Anisotropies on Ductile Fracture. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/159104
Chicago Manual of Style (16th Edition):
Thomas, Nithin. “On the Effects of Stress State and Microstructure Induced Anisotropies on Ductile Fracture.” 2016. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/159104.
MLA Handbook (7th Edition):
Thomas, Nithin. “On the Effects of Stress State and Microstructure Induced Anisotropies on Ductile Fracture.” 2016. Web. 13 Apr 2021.
Vancouver:
Thomas N. On the Effects of Stress State and Microstructure Induced Anisotropies on Ductile Fracture. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/159104.
Council of Science Editors:
Thomas N. On the Effects of Stress State and Microstructure Induced Anisotropies on Ductile Fracture. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/159104
Texas A&M University
10.
Maxwell, Kevin S.
Computational Analysis of Carbon Nanotube Networks in Multifunctional Polymer Nanocomposites.
Degree: PhD, Materials Science and Engineering, 2013, Texas A&M University
URL: http://hdl.handle.net/1969.1/151710
► Carbon nanotubes (CNTs) have attracted much attention as reinforcements in polymer composite materials because of their unique mechanical, electrical, and thermal properties. The high electrical…
(more)
▼ Carbon nanotubes (CNTs) have attracted much attention as reinforcements in polymer composite materials because of their unique mechanical, electrical, and thermal properties. The high electrical conductivity of CNTs is especially promising for use in multifunctional materials. Dispersing a small amount of CNTs in electrically insulating polymers has been shown to increase the conductivity of the material by many orders of magnitude because the high aspect ratio CNTs form percolating networks at very low volume fractions. Additionally, it has been shown that the application of mechanical strain to these nanocomposites results in a change in material resistivity, or piezoresistivity. Many experimental research efforts have focused on optimizing this effect for strain and damage sensing applications, but much is still unknown about the dominant mechanisms affecting piezoresistivity. The objective of this work was to develop a computational model that can predict and investigate the electrical and piezoresistive properties of CNT/polymer composites.
The nanocomposites were modeled as random networks of resistors in 2D and 3D in order to understand the mechanisms that affect the percolative, electrical, and piezoresistive performance of different material systems. The model was used extensively to analyze and predict the electrical conductivity of 2D single-walled car- bon nanotube thin films and 3D multi-walled carbon nanotube (MWCNT)/polymer nanocomposites. It was found that the contact resistance between individual nanotubes greatly affects the conductivity of 2D films as well as 3D MWCNT/polymer materials. Additionally, it was shown that the electrical conductivity model could be calibrated to experimental results by adjusting the contact resistance alone. The 3D random resistor network model was also used to predict the piezoresis-tive properties for MWCNT/polymer Nano composites. The dominant mechanisms that cause the piezoresistive effect in these material systems were investigated, and the Poisson’s ratio of the composite was found to greatly impact the piezoresistive performance. The predictions indicated that decreasing the Poisson’s ratio of the composite leads to higher strain sensitivity, which could have implications for choosing material systems for strain sensor applications.
Advisors/Committee Members: Whitcomb, John (advisor), Lagoudas, Dimitris (committee member), Naraghi, Mohammad (committee member), Sue, Hung-Jue (committee member).
Subjects/Keywords: carbon nanotube; piezoresistivity; nanocomposites; finite elements; electrical conductivity; resistor network; multifunctional materials
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APA (6th Edition):
Maxwell, K. S. (2013). Computational Analysis of Carbon Nanotube Networks in Multifunctional Polymer Nanocomposites. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/151710
Chicago Manual of Style (16th Edition):
Maxwell, Kevin S. “Computational Analysis of Carbon Nanotube Networks in Multifunctional Polymer Nanocomposites.” 2013. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/151710.
MLA Handbook (7th Edition):
Maxwell, Kevin S. “Computational Analysis of Carbon Nanotube Networks in Multifunctional Polymer Nanocomposites.” 2013. Web. 13 Apr 2021.
Vancouver:
Maxwell KS. Computational Analysis of Carbon Nanotube Networks in Multifunctional Polymer Nanocomposites. [Internet] [Doctoral dissertation]. Texas A&M University; 2013. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/151710.
Council of Science Editors:
Maxwell KS. Computational Analysis of Carbon Nanotube Networks in Multifunctional Polymer Nanocomposites. [Doctoral Dissertation]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/151710
Texas A&M University
11.
Choi, Woongchul.
Synthesis and Fabrication of Carbon Nanotube Based Composite Materials for Fuel Cell Catalyst and Ultra-Resilient Aerogel.
Degree: PhD, Materials Science and Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/187209
► Carbon nanotubes have been actively investigated in a wide range of applications since carbon nanotubes have excellent electrical, thermal, and mechanical properties. In particular, a…
(more)
▼ Carbon nanotubes have been actively investigated in a wide range of applications since carbon nanotubes have excellent electrical, thermal, and mechanical properties. In particular, a great deal of research is being carried out to improve and control their properties by different functionalization methods. Among them, I have developed two functionalization methods for the controlling of properties, which are doping carbon nanotubes with heteroatoms and fabricating polymer composite based on carbon nanotubes.
I studied a facile one-step synthesis method of nitrogen-iron coordinated carbon nanotube catalysts without precious metals. Our catalyst shows excellent onset ORR potential comparable to those of other precious metal free catalysts, and the maximum limiting current density from our catalysts is larger than that of the Pt-based catalysts.
In addition to the development of carbon nanotubes-based aerogel composite, I studied the facile and quick process for the scalable production of super resilient CNT-PDMS composite by microwave heating with ultra-low thermal conductivity and high electrical properties. This report describes that the microwave heating process can lead to a quick reaction and allow for the uniform polymer layer on CNT, which enhance the mechanical properties of carbon nanotube composite. Furthermore, CNT-PDMS composite aerogel shows high mechanical strength (0.18 MPa), compressibility, thermal insulation (26 mW
m-
1 K
-1) and elasticity-dependent electric conduction.
Advisors/Committee Members: Yu, Choongho (advisor), Radovic, Miladin (committee member), Naraghi, Mohammad (committee member), Mukherjee, Partha (committee member).
Subjects/Keywords: Carbon nanotube; composites
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APA (6th Edition):
Choi, W. (2017). Synthesis and Fabrication of Carbon Nanotube Based Composite Materials for Fuel Cell Catalyst and Ultra-Resilient Aerogel. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/187209
Chicago Manual of Style (16th Edition):
Choi, Woongchul. “Synthesis and Fabrication of Carbon Nanotube Based Composite Materials for Fuel Cell Catalyst and Ultra-Resilient Aerogel.” 2017. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/187209.
MLA Handbook (7th Edition):
Choi, Woongchul. “Synthesis and Fabrication of Carbon Nanotube Based Composite Materials for Fuel Cell Catalyst and Ultra-Resilient Aerogel.” 2017. Web. 13 Apr 2021.
Vancouver:
Choi W. Synthesis and Fabrication of Carbon Nanotube Based Composite Materials for Fuel Cell Catalyst and Ultra-Resilient Aerogel. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/187209.
Council of Science Editors:
Choi W. Synthesis and Fabrication of Carbon Nanotube Based Composite Materials for Fuel Cell Catalyst and Ultra-Resilient Aerogel. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/187209
Texas A&M University
12.
Moghbelli, Ehsan.
Scratch Behavior of Multiphase Styrenic Copolymers and Effects of Environmental Conditioning.
Degree: PhD, Materials Science and Engineering, 2014, Texas A&M University
URL: http://hdl.handle.net/1969.1/153652
► Scratch-induced surface deformation is a tribological research area that falls under the abrasive wear category. A variety of factors including high strain rate, large-scale deformation,…
(more)
▼ Scratch-induced surface deformation is a tribological research area that falls under the abrasive wear category. A variety of factors including high strain rate, large-scale deformation, non-linear material response, heat dissipation, and the evolution of a complex stress field, renders scratch a complex mechanical process. The dependence of polymers on testing rates, temperature, and pressure, along with the surface characteristics of the two materials in contact bring the rate, time, temperature, and pressure dependent behaviors of polymers, and the surface condition of the interacting surfaces also add to the complications of scratch analysis. In order to gain an in-depth understanding of polymer scratch behavior, this dissertation focuses on the scratch response of multiphase systems made up of a plastic matrix and a dispersed rubber phase. The introduction of a rubber phase and the effect it has on scratch behavior is explored through a number of factors including rubber size and type, environmental conditioning through heat processing, moisture exposure, and water immersion.
A standardized progressive load scratch test (ASTM D7027/ISO 19252) is used to examine the mechanical response to scratch deformation in ASA and ABS systems with varying rubber particle size. Previous simulation results from finite element methods are used to assess the scratch response of the multiphase systems and comparisons are made to results based on single phase plastics and their respective scratch behavior. The key scratch damage transitions identified and studied are: (1) the onset of scratch groove formation, (2) the onset of periodic cracking, (3) the onset of material removal (plowing), and (4) the onset of scratch visibility. The onset of groove formation is generally related to the secant modulus at the point of compressive yielding. The onsets of crack formation and plowing are more complex to quantitatively evaluate, and are strongly influenced by the material tensile and/or shear strength.
For ASA copolymers, enhanced scratch performance is observed in systems with rubber particles the size of 1 micron relative to 100 nm sized rubber particle systems, while ABS copolymers containing 100 nm sized rubber particles are more scratch resistant than ASA copolymer systems with similar rubber particle size and distribution. The fact that these three model systems exhibit similar mechanical properties in uniaxial tension and compression bulk testing does not explain their differences in scratch resistance based on our previous FEM modeling and experimental results for single phase systems. The local stress state generated by the rubber particles and the scratch process at the surface, along with changes in surface coefficient of friction, are used to explain these findings.
In order to minimize orientation and residual stress effects from the injection molding process, heat treatments at temperatures above and below Tg were carried out on ASAs with varying rubber content, rubber size, and rubber type. Low temperature…
Advisors/Committee Members: Sue, Hung Jue (advisor), Creasy, Terry (committee member), Liang, Hong (committee member), Naraghi, Mohammad (committee member).
Subjects/Keywords: polymer; scratch
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APA (6th Edition):
Moghbelli, E. (2014). Scratch Behavior of Multiphase Styrenic Copolymers and Effects of Environmental Conditioning. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/153652
Chicago Manual of Style (16th Edition):
Moghbelli, Ehsan. “Scratch Behavior of Multiphase Styrenic Copolymers and Effects of Environmental Conditioning.” 2014. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/153652.
MLA Handbook (7th Edition):
Moghbelli, Ehsan. “Scratch Behavior of Multiphase Styrenic Copolymers and Effects of Environmental Conditioning.” 2014. Web. 13 Apr 2021.
Vancouver:
Moghbelli E. Scratch Behavior of Multiphase Styrenic Copolymers and Effects of Environmental Conditioning. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/153652.
Council of Science Editors:
Moghbelli E. Scratch Behavior of Multiphase Styrenic Copolymers and Effects of Environmental Conditioning. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/153652
Texas A&M University
13.
Gardea, Frank.
Damping in Carbon Nanotube Nanocomposites by Interfacial Slippage and Thermally Augmented Polymer Relaxation.
Degree: PhD, Aerospace Engineering, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/155748
► The present work investigates the damping potential of carbon nanotube (CNT) reinforced polymer matrix composites through integrated experiments and continuum modeling techniques. Both “passive" and…
(more)
▼ The present work investigates the damping potential of carbon nanotube (CNT) reinforced polymer matrix composites through integrated experiments and continuum modeling techniques. Both “passive" and “active” damping are studied. The passive damping here refers to the inherent capability of a composite to damp vibrations in the absence of external stimuli, such as electrical signals, by exploiting different damping mechanisms introduced by the presence of the nanoscale reinforcements. Among the targeted passive damping mechanisms in nanocomposites is a ‘slip-stick’ mechanism in which the interactions between the filler and polymer results in energy dissipation in a frictional mode along the interface. Microstructural design of nanocomposites, such as the development of CNT alignment, was pursued here to enhance the contribution of interfacial sliding to damping, relative to other mechanisms such as stress concentrations within the matrix and matrix plasticity. A micromechanics model was used to provide additional insight into the experimental observations by showing that the nonlinear variation of damping with dynamic strain can be attributed to slip-stick behavior. The dependence of the interfacial load-transfer reversibility on the dynamic strain history and characteristic time scale was experimentally investigated to demonstrate the relative significance of van der Waals (vdW) interactions, mechanical interlocking, and covalent bonding on shear interactions.
In this effort, we also studied the controllability of energy dissipation capability in nanocomposites via electrical signals, referred to as active damping. This mechanism benefits from the electrically conductive network of CNTs, as well as their high surface to volume ratio, to thermally enhance viscous phenomena, such as chain relaxation in polymers. For active damping, the thermomechanical response of the polymer is targeted and studied as a potential damping source within the nanocomposite. By taking advantage of the polymer relaxation resulting from an increase in temperature, the composite shows the potential for damping enhancement. However, the non-uniform temperature distribution in the composite sample has a large effect on the overall damping enhancement. The non-uniformity of the temperature distribution, both locally and globally, was studied via experiments and multi-resolution models to further shed light on this phenomenon.
This effort clearly points to the significance of interface phenomena, both friction between filler and matrix and energy transfer from the fillers to the matrix, in controlling the damping mechanisms in nanocomposites and presents insights, both qualitative and quantitative, into the origins of these effects.
Advisors/Committee Members: Naraghi, Mohammad (advisor), Lagoudas, Dimitris C (advisor), Whitcomb, John (committee member), Park, Philip (committee member).
Subjects/Keywords: Damping; Nanocomposites; Interfacial Slippage; Polymer Relaxation
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APA (6th Edition):
Gardea, F. (2015). Damping in Carbon Nanotube Nanocomposites by Interfacial Slippage and Thermally Augmented Polymer Relaxation. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155748
Chicago Manual of Style (16th Edition):
Gardea, Frank. “Damping in Carbon Nanotube Nanocomposites by Interfacial Slippage and Thermally Augmented Polymer Relaxation.” 2015. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/155748.
MLA Handbook (7th Edition):
Gardea, Frank. “Damping in Carbon Nanotube Nanocomposites by Interfacial Slippage and Thermally Augmented Polymer Relaxation.” 2015. Web. 13 Apr 2021.
Vancouver:
Gardea F. Damping in Carbon Nanotube Nanocomposites by Interfacial Slippage and Thermally Augmented Polymer Relaxation. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/155748.
Council of Science Editors:
Gardea F. Damping in Carbon Nanotube Nanocomposites by Interfacial Slippage and Thermally Augmented Polymer Relaxation. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155748
Texas A&M University
14.
Hawkins, Spencer Allistor.
Hybrid Epoxy Films Containing Well-Exfoliated Multi-Walled Carbon Nanotubes and Nylon-12 with Enhanced Tensile Properties, Fracture Toughness, and Electrical Conductivity.
Degree: PhD, Materials Science and Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/187218
► In order to gain a more fundamental understanding of multifunctional epoxy nanocomposites, model systems containing surface functionalized multi walled carbon nanotubes (MWCNTs) and thermoplastic microparticles…
(more)
▼ In order to gain a more fundamental understanding of multifunctional epoxy nanocomposites, model systems containing surface functionalized multi walled carbon nanotubes (MWCNTs) and thermoplastic microparticles were fabricated and studied. Epoxies are inherently brittle and electrically insulative and therefore require the introduction of fillers with different functionalities to produce a truly multifunctional epoxy composite. The mechanical, electrical, and fracture properties of a conventional aerospace grade epoxy resin were enhanced by the addition of ZnO functionalized MWCNTs and nylon 12 (PA) microparticles.
Carbon nanotubes (CNTs) are an emerging class of carbon based materials that have dominated polymer nanocomposite research in recent years due to their potential application in energy storage, electronic thin films, biotechnology, multifunctional materials, etc. The strong push for fundamental research is driven by their superior mechanical, electrical, and thermal properties. However, there are numerous problems related to processability and fabrication of nanocomposites. In order to solve these problems, which include insolubility in organic solvents and polymers and dispersability, surface functionalization is used to break up large aggregates of CNTs resulting in better dispersion and enhanced compatibility with various solvents and polymers. Traditional approaches such as chemical functionalization of the CNT surface are less commonly used due to their lacking efficiency and effectiveness at controlling the exfoliation of CNTs, which are critical to the development of tailored nanocomposites with superior mechanical and electrical behavior. Further advances in the field are required whereby a fundamental understanding of the necessary steps involved is gained. MWCNTs were decorated with ZnO quantum dots (QDs) by refluxing zinc acetate dihydrate and potassium hydroxide in the presence of pristine (P MWCNTs) or oxidized (O MWCNTs). The physical decoration of ZnO QDs on MWCNTs yielded a system of well exfoliated CNTs with little to no degradation of their material properties.
PA was introduced to enhance the ductility and fracture toughness of the epoxy resin by undergoing a severe level of plastic deformation when under tensile stress with and without a pre existing crack. The glass transition and elastic modulus of epoxy tends to decrease when a large concentration of a relatively soft filler is introduced resulting in a somewhat softer material. This was not observed when ZnO/MWCNTs were introduced into the PA toughened epoxy systems, which contradicts findings currently found in the literature.
The morphology and dispersion of the various fillers was unambiguously confirmed via X ray diffraction (XRD), transmission electron microscopy (TEM), UV Vis NIR spectroscopy, x ray photoelectron spectroscopy (XPS), and optical microscopy (OM). The tensile, fracture, and thermos mechanical properties of the model hybrid epoxy nanocomposites have been investigated. This dissertation has expanded the…
Advisors/Committee Members: Sue, Hung-Jue (advisor), Balbuena, Perla (committee member), Naraghi, Mohammad (committee member), Whitcomb, John (committee member).
Subjects/Keywords: CNT; nylon; epoxy; tensile; conductivity; fracture; film; nanocomposite
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APA (6th Edition):
Hawkins, S. A. (2017). Hybrid Epoxy Films Containing Well-Exfoliated Multi-Walled Carbon Nanotubes and Nylon-12 with Enhanced Tensile Properties, Fracture Toughness, and Electrical Conductivity. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/187218
Chicago Manual of Style (16th Edition):
Hawkins, Spencer Allistor. “Hybrid Epoxy Films Containing Well-Exfoliated Multi-Walled Carbon Nanotubes and Nylon-12 with Enhanced Tensile Properties, Fracture Toughness, and Electrical Conductivity.” 2017. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/187218.
MLA Handbook (7th Edition):
Hawkins, Spencer Allistor. “Hybrid Epoxy Films Containing Well-Exfoliated Multi-Walled Carbon Nanotubes and Nylon-12 with Enhanced Tensile Properties, Fracture Toughness, and Electrical Conductivity.” 2017. Web. 13 Apr 2021.
Vancouver:
Hawkins SA. Hybrid Epoxy Films Containing Well-Exfoliated Multi-Walled Carbon Nanotubes and Nylon-12 with Enhanced Tensile Properties, Fracture Toughness, and Electrical Conductivity. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/187218.
Council of Science Editors:
Hawkins SA. Hybrid Epoxy Films Containing Well-Exfoliated Multi-Walled Carbon Nanotubes and Nylon-12 with Enhanced Tensile Properties, Fracture Toughness, and Electrical Conductivity. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/187218
Texas A&M University
15.
Humood, Mohammad Muneer Mutlaq.
Nanomechanics, Nanotribology and Fabrication of Flexible Multilayer Nanocomposites.
Degree: PhD, Mechanical Engineering, 2018, Texas A&M University
URL: http://hdl.handle.net/1969.1/174053
► Polymer-based multilayer nanocomposites have become favorable material choice for many applications such as gas barriers, water membranes, optoelectronic devices, biosensors, corrosion inhibitors and energy devices.…
(more)
▼ Polymer-based multilayer nanocomposites have become favorable material choice for
many applications such as gas barriers, water membranes, optoelectronic devices, biosensors,
corrosion inhibitors and energy devices. They are finding their ways as a replacement of traditional
metal, silicon oxides and hard inorganic coatings. The present work is dedicated to addressing the
fabrication of new polymer flexible nanocomposites and their mechanical response against normal
and lateral deformation modes, known as nanoindentation and nanoscratch. Particularly, the
scratch resistance of these nanocomposites is critical for many applications.
Little is known in the literature about their nanomechanics, hence reliability and durability
for long-term applications. Better understanding of the nanomechanics and nanotribology of 2D
multilayered thin films and 3D multilayered structures was achieved in this thesis through a series
of different experiments using low and high load nanoindentation, nanoscratch and flat-punch
compression. Complementary computational modeling supported the experimental findings and
further explains their nano- and micromechanical behaviors.
Based on the findings of these nanomechanical experiments, functional multilayered
polymeric coatings consisting of different arrangements of polymers, graphene oxide and clay
were found to be potential material choices for a range of different applications such as low-friction
tribological coatings, vapor/gas barriers and self-healing coatings. Furthermore, 3D
silicon/polymer structures specifically under extreme deformation were found to be a potential
candidate for wearable electronics and flexible microelectromechanical systems (MEMS) sensors
due to the resilient and elastic behavior driven by the geometry-dependent deformation of these
structures.
The last part discusses the development of a new material pertaining to the development of
nanocomposites. On the quest of continuous search of 2D materials, which can act as
reinforcements, a new material, Aluminum diboride (AlBv2) flakes, was introduced and discussed.
High aspect ratio AlBv2 flakes is a potential reinforcement for conductive polymer nanocomposites
due to the metallic conductivity in the axis parallel to the basal hexagonal plane.
In summary, the findings above focused on the mechanics and tribology of nanocomposites
at the nanoscale mainly for gas barrier applications and MEMS devices. However, the knowledge
can also be extended to other devices such as energy harvesting devices and membranes where
tribology issues at the nanoscale are of important concerns.
Advisors/Committee Members: Polycarpou, Andreas A. (advisor), Grunlan, Jaime C (committee member), Hipwell, M. Cynthia (committee member), Naraghi, Mohammad (committee member), Pharr, Matt (committee member).
Subjects/Keywords: Nanomechanics; Nanoindentation; Nanocomposites; Flexible; Wearable Electronics; Food Packaging
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APA (6th Edition):
Humood, M. M. M. (2018). Nanomechanics, Nanotribology and Fabrication of Flexible Multilayer Nanocomposites. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/174053
Chicago Manual of Style (16th Edition):
Humood, Mohammad Muneer Mutlaq. “Nanomechanics, Nanotribology and Fabrication of Flexible Multilayer Nanocomposites.” 2018. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/174053.
MLA Handbook (7th Edition):
Humood, Mohammad Muneer Mutlaq. “Nanomechanics, Nanotribology and Fabrication of Flexible Multilayer Nanocomposites.” 2018. Web. 13 Apr 2021.
Vancouver:
Humood MMM. Nanomechanics, Nanotribology and Fabrication of Flexible Multilayer Nanocomposites. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/174053.
Council of Science Editors:
Humood MMM. Nanomechanics, Nanotribology and Fabrication of Flexible Multilayer Nanocomposites. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/174053
Texas A&M University
16.
Lan, Pixiang.
Tribological Performance of Advanced Polymeric Coatings Under Extreme Operating Conditions.
Degree: PhD, Mechanical Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/173092
► Polymers and their composites have favorable tribological performance such as low coefficient of friction (COF) and good corrosion resistance, when working as bearing materials. The…
(more)
▼ Polymers and their composites have favorable tribological performance such as low coefficient of friction (COF) and good corrosion resistance, when working as bearing materials. The present work is studying the tribological performance of thin (~ 10s of microns) high-bearing polymeric coatings under extreme working conditions, including high temperature, cryogenic temperature, high contact pressure, high chamber pressure, starved lubrication, and abrasive wear. This work is an important contribution in proving the concept of application of thin polymeric coatings in environments such as dry sliding bearing, valve sealing surfaces, hydrodynamic bearings and drilling application under different extreme working conditions. Three groups of polymers, namely Polytetrafluoroethylene (PTFE)-based, Polyether ether ketone (PEEK)-based, and Aromatic Thermosetting coPolyesters(ATSP)-based coatings were extensively studied. Out of the three groups of polymers, ATSP-based coating showed the most desirable tribological performance: ‘zero wear’ at different temperature from -160°C to 260°C with dry sliding, extremely low wear coefficient (4.15×10⁻⁸ mm³/Nm) under starved lubrication condition, stable coefficient of friction (COF) and low wear rate under sand abrasive condition, and extreme low COF for oil and gas drilling application.
Traditionally, the friction force between two solids is attributed to adhesion and deformation effects; where the adhesion force involves the shearing between the real contact surfaces and deformation is due to the hard material‘s asperities plowing on the softer material. This work proposes a phenomenological model of friction for viscoelastic materials by using the viscosity and elasticity parameters acquired by nano-indentation measurements at elevated temperatures. Substituting the viscosity and elastic modulus terms, the model showed reasonable COF for the coatings up to temperatures that were lower than the glass transition temperature.
Advisors/Committee Members: Polycarpou, Andreas A. (advisor), San Andrés, Luis (committee member), Liang, Hong (committee member), Felts, Jonathan (committee member), Naraghi, Mohammad (committee member).
Subjects/Keywords: Tribology; Polymeric coating; High temperature; High load
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APA (6th Edition):
Lan, P. (2017). Tribological Performance of Advanced Polymeric Coatings Under Extreme Operating Conditions. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/173092
Chicago Manual of Style (16th Edition):
Lan, Pixiang. “Tribological Performance of Advanced Polymeric Coatings Under Extreme Operating Conditions.” 2017. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/173092.
MLA Handbook (7th Edition):
Lan, Pixiang. “Tribological Performance of Advanced Polymeric Coatings Under Extreme Operating Conditions.” 2017. Web. 13 Apr 2021.
Vancouver:
Lan P. Tribological Performance of Advanced Polymeric Coatings Under Extreme Operating Conditions. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/173092.
Council of Science Editors:
Lan P. Tribological Performance of Advanced Polymeric Coatings Under Extreme Operating Conditions. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/173092
Texas A&M University
17.
Sweeney, Charles Brandon.
Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing.
Degree: PhD, Materials Science and Engineering, 2018, Texas A&M University
URL: http://hdl.handle.net/1969.1/188880
► Polymer nano-composites may be engineered with specific electrical properties to achieve good coupling with electromagnetic energy sources. This enables a wide range of novel processing…
(more)
▼ Polymer nano-composites may be engineered with specific electrical properties to achieve good coupling with electromagnetic energy sources. This enables a wide range of novel processing techniques where controlling the precise thermal profile is critical. Composite materials were characterized with a variety of electrical and thermographic analysis methods to capture their response to electromagnetic energy. COMSOL finite element analysis software was used to model the electric fields and resultant thermal profiles in selected samples. Applications of this technology are demonstrated, including the use of microwave and radio frequency energy to thermally weld the interfaces of 3D printed parts together for increased interlayer (Z) strength. We also demonstrate the ability to bond various substrates with carbon nanotube/epoxy composite adhesives using radio frequency electromagnetic heating to rapidly cure the adhesive interface. The results of this work include 3D printed parts with mechanical properties equal to injection molded samples, and RF bonded joints cured 40% faster than traditional oven curing.
Advisors/Committee Members: Green, Micah J (advisor), Naraghi, Mohammad (committee member), Harris, James A (committee member), Akbulut, Mustafa (committee member).
Subjects/Keywords: Polymer; 3D; print; nanocomposite; carbon; nanotube; microwave; electromagnetic; plasma; weld; bond; thermoplastic; interlaminar; radio; frequency
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APA (6th Edition):
Sweeney, C. B. (2018). Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/188880
Chicago Manual of Style (16th Edition):
Sweeney, Charles Brandon. “Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing.” 2018. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/188880.
MLA Handbook (7th Edition):
Sweeney, Charles Brandon. “Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing.” 2018. Web. 13 Apr 2021.
Vancouver:
Sweeney CB. Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/188880.
Council of Science Editors:
Sweeney CB. Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/188880
18.
Sengab, Ahmed M.
Effect of Voids on the Crack Kinking in Single Lap Joints.
Degree: MS, Materials Science and Engineering, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/155166
► Polymer matrix composites are used extensively for their exceptional mechanical properties. The effect of voids on the energy release rate of interface crack has been…
(more)
▼ Polymer matrix composites are used extensively for their exceptional mechanical properties. The effect of voids on the energy release rate of interface crack has been studied before; however none of the studies investigated the effect of voids on the kinking of a crack from the interface into the adhesive film.
In the following report, a parametric study is conducted to understand the effect of the void size, the void shape and the void location on the kinking of an interface crack in single lap joint. An interface crack can originate from the maximum shear stress or the maximum normal stress that occurs at the interface between the adherend and the adhesive. A void is placed ahead of the crack tip at various distances in the Finite elements model to determine the critical distance. After determining the critical distance, the effect of the void radius and the void shape are examined on the crack kinking process. The interface crack is assumed to propagate a distance of 0.1mm at different angles ranging from 0 to 90 degrees with an increment of 10 degrees. The energy release rate is calculated by the revised virtual crack closure technique (RVCCT). The total energy release rate is calculated by adding Mode I and Mode II from the revised virtual crack closure technique (RVCCT) and justified by the J- integral method. Since the crack is an interface crack, the crack is expected to have a mixed mode behavior. A force boundary condition is applied. As the force increases, Mode I and Mode II increase. Moreover, it is evident from the results obtained that a void could lead an interface crack to kink into the adhesive, if the distance between the void and crack tip is significantly small to cause an interaction between the crack tip and the void.
Advisors/Committee Members: Talreja, Ramesh (advisor), Creasy, Terry (advisor), Naraghi, Mohammad (committee member).
Subjects/Keywords: Single lap Joints; Interface crack; voids; Multiple cracks; crack kinking
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APA (6th Edition):
Sengab, A. M. (2015). Effect of Voids on the Crack Kinking in Single Lap Joints. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155166
Chicago Manual of Style (16th Edition):
Sengab, Ahmed M. “Effect of Voids on the Crack Kinking in Single Lap Joints.” 2015. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/155166.
MLA Handbook (7th Edition):
Sengab, Ahmed M. “Effect of Voids on the Crack Kinking in Single Lap Joints.” 2015. Web. 13 Apr 2021.
Vancouver:
Sengab AM. Effect of Voids on the Crack Kinking in Single Lap Joints. [Internet] [Masters thesis]. Texas A&M University; 2015. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/155166.
Council of Science Editors:
Sengab AM. Effect of Voids on the Crack Kinking in Single Lap Joints. [Masters Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155166
19.
McQuien, Jeffrey Scott.
Evaluation of Independent Mesh Modeling for Textile Composites.
Degree: MS, Aerospace Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/161631
► The Independent Mesh Method (IMM) was used to analyze stress distributions within a unit cell model for a symmetrically stacked plain weave textile composite. Results…
(more)
▼ The Independent Mesh Method (IMM) was used to analyze stress distributions within a unit cell model for a symmetrically stacked plain weave textile composite. Results from these analyses were compared to those of conventional finite element analyses, which are well established. Preliminary comparisons showed extreme disagreement between the two methodologies. Further investigation into the source of these differences led to significant corrections to the IMM implementation. After these updates, much better agreement between the two methodologies was observed; however, noticeable differences were still present. The remaining differences were characterized using a simple two-inclusion model upon which the impacts of the penalty displacement method, which the IMM relies upon heavily, were more apparent. It was shown that the implementation of the penalty displacement method for maintaining approximate displacement continuity between two surfaces induces significant error in stress distributions close to the interface. While these effects are less noticeable in the plain weave model, they are still present and diminish the fidelity of stress information in important tow-matrix interface regions, prohibiting the reliable prediction of damage initiation and growth.
Advisors/Committee Members: Whitcomb, John (advisor), Creasy, Terry (committee member), Naraghi, Mohammad (committee member).
Subjects/Keywords: composites; textiles; textile composites; finite elements; finite element analysis
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APA (6th Edition):
McQuien, J. S. (2017). Evaluation of Independent Mesh Modeling for Textile Composites. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/161631
Chicago Manual of Style (16th Edition):
McQuien, Jeffrey Scott. “Evaluation of Independent Mesh Modeling for Textile Composites.” 2017. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/161631.
MLA Handbook (7th Edition):
McQuien, Jeffrey Scott. “Evaluation of Independent Mesh Modeling for Textile Composites.” 2017. Web. 13 Apr 2021.
Vancouver:
McQuien JS. Evaluation of Independent Mesh Modeling for Textile Composites. [Internet] [Masters thesis]. Texas A&M University; 2017. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/161631.
Council of Science Editors:
McQuien JS. Evaluation of Independent Mesh Modeling for Textile Composites. [Masters Thesis]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/161631
20.
Rodriguez Atencio, Ana Karina.
Effect of Strain Rate and Temperature on Fracture and Damage of Magnesium Alloy AZ31B.
Degree: MS, Materials Science and Engineering, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/155147
► Due to their low density and high specific strength, magnesium and its alloys are structural metals attractive for the aerospace and automotive industries. However, wide…
(more)
▼ Due to their low density and high specific strength, magnesium and its alloys are structural metals attractive for the aerospace and automotive industries. However, wide spread use of wrought magnesium is challenged by its limited formability at low temperature compared to aluminum and steel. This results in costly production and processing of sheet and plate material. Extensive research has been carried out on deformation mechanisms, mechanical characterization, new processing routes and alloying systems in order to overcome these limitations. However, the available literature on damage and fracture is limited. In particular, the effects of temperature and strain rate on damage and fracture remain unexplored. The purpose of this study is to investigate this effects on damage accumulation to fracture in a magnesium alloy. Twin roll cast magnesium plates of AZ31B were used to that end. An extensive experimental campaign of tensile tests at various strain rates and temperatures was performed with this aim. In addition, a series of interrupted tests were carried out to investigate the microscopic damage mechanisms by means of optical and scanning electron microscopy.
The materials were found to have a positive strain rate sensitivity and showed thermal softening. Microstructural studies revealed an increased propensity to form deformation twinning at higher strain rates and lower temperatures, as expected. The fracture behavior was characterized in terms of the work to fracture (Wf). Wf exhibited a maximum at some strain rate dependent on temperature. Conversely, at a fixed strain rate, Wf showed a maximum at a temperature dependent on strain rate. To understand these trends, microscopy analysis was carried out on selected conditions. Under all the conditions examined, two main damage sites were identified: second phase particles and twinning. However, the propensity for twin-sized cracks was highest under conditions where the density of twinning was lowest. Different scenarios are explored in order to rationalize this behavior.
Advisors/Committee Members: Benzerga, Amine (advisor), Karaman, Ibrahim (advisor), Naraghi, Mohammad (committee member), Ayoub, Georges (committee member).
Subjects/Keywords: Fracture; Damage; Magnesium; AZ31, Twinning; Voids; Strain rate; Temperature.
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APA (6th Edition):
Rodriguez Atencio, A. K. (2015). Effect of Strain Rate and Temperature on Fracture and Damage of Magnesium Alloy AZ31B. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155147
Chicago Manual of Style (16th Edition):
Rodriguez Atencio, Ana Karina. “Effect of Strain Rate and Temperature on Fracture and Damage of Magnesium Alloy AZ31B.” 2015. Masters Thesis, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/155147.
MLA Handbook (7th Edition):
Rodriguez Atencio, Ana Karina. “Effect of Strain Rate and Temperature on Fracture and Damage of Magnesium Alloy AZ31B.” 2015. Web. 13 Apr 2021.
Vancouver:
Rodriguez Atencio AK. Effect of Strain Rate and Temperature on Fracture and Damage of Magnesium Alloy AZ31B. [Internet] [Masters thesis]. Texas A&M University; 2015. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/155147.
Council of Science Editors:
Rodriguez Atencio AK. Effect of Strain Rate and Temperature on Fracture and Damage of Magnesium Alloy AZ31B. [Masters Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155147
21.
Chawla, Sneha Anil.
Microstructure-Mechanical Property Relationships in Carbon Nanofibers.
Degree: PhD, Materials Science and Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/161305
► Carbon nanofibers, though radially more homogeneous compared to carbon fibers, currently do not possess mechanical properties as high as carbon fibers. By principles of size…
(more)
▼ Carbon nanofibers, though radially more homogeneous compared to carbon fibers, currently do not possess mechanical properties as high as carbon fibers. By principles of size effect, carbon nanofibers are expected to possess considerably higher strengths than carbon fibers. Theoretically, CNFs are expected to have strengths as high as 14GPa. However, at present, CNFs possess strengths much lower than expected. The gap in theoretical and experimental work points to three main reasons: graphitic alignment in the nanofiber, radial structure of the nanofiber and presence of surface defects. The work presented in this dissertation aims at closing the gap via relating the microstructure and mechanical properties of carbon nanofibers. Graphitic alignment in carbon nanofibers imparts high modulus and strength to the fibers. This alignment of graphitic domains arises from the induced molecular alignment in precursor fiber. The precursor is polyacrylonitrile (PAN) fiber obtained from electrospinning of PAN in Dimethylformamide (DMF) solution. Limited molecular alignment is achievable with electrospinning, which creates the need to use other methods to improve molecular alignment. The research uses a method for hot drawing, which takes place at temperatures above the Tg of the polymer. The temperature aids chain mobility in the fiber, allowing it to stretch. The molecular alignment obtained in the hot drawing process facilitates the improvement in graphitic alignment in the carbon nanofiber formed. The effect of this enhanced alignment on single carbon nanofibers is studied via mechanical tests performed on single carbon nanofibers, with diameters of 250nm-700nm, using a microelectromechanical system (MEMS) device in conjunction with digital image correlation (DIC). It has been observed that improvement in the molecular alignment of the precursor fiber leads to improvement in strength and modulus of carbon nanofibers. This increase can be related to improvement in graphitic orientation and size of crystallites in the CNF.
In summary, it has been observed that molecular alignment in the PAN fiber prior to the stabilization stage is crucial in the evolution of graphitic domains, which was achieved via hot drawing. This effort presents a systematic study of molecular alignment and its effect on the mechanical properties of CNFs. Qualitative assessment of the morphology of the fibers is accomplished using Fourier Transform Infrared (FTIR), X-Ray diffraction (XRD), Selected Area Electron Diffraction (SAED), and Transmission Electron Microscopy (TEM).
Advisors/Committee Members: Naraghi, Mohammad (advisor), Benzerga, Amine (committee member), Boyd, James (committee member), Shao, Lin (committee member), Talreja, Ramesh (committee member).
Subjects/Keywords: carbon; nanofibers; polyacrylonitrile; PAN; DMF; electrospinning; hot drawing; dry stretch; stabilization; carbonization; turbostratic; graphitic; cyclization; FTIR; single fiber test; mechanical test
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APA (6th Edition):
Chawla, S. A. (2017). Microstructure-Mechanical Property Relationships in Carbon Nanofibers. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/161305
Chicago Manual of Style (16th Edition):
Chawla, Sneha Anil. “Microstructure-Mechanical Property Relationships in Carbon Nanofibers.” 2017. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021.
http://hdl.handle.net/1969.1/161305.
MLA Handbook (7th Edition):
Chawla, Sneha Anil. “Microstructure-Mechanical Property Relationships in Carbon Nanofibers.” 2017. Web. 13 Apr 2021.
Vancouver:
Chawla SA. Microstructure-Mechanical Property Relationships in Carbon Nanofibers. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/1969.1/161305.
Council of Science Editors:
Chawla SA. Microstructure-Mechanical Property Relationships in Carbon Nanofibers. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/161305
. 
Open Access Theses and Dissertations
