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Performance of Hybrid Fiber-reinforced Polymer Nanocomposite pipes
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- Author / Creator
- Bashar, Mohammad T
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Due to their attractive properties, pipes and vessels made from fiber-reinforced polymer composites are increasingly being used for the storage and transmission of pressurized fluids. Yet, the inherent anisotropy and inhomogeneity of fiber-reinforced composites in conjunction with complex loading conditions may result in a variety of failure mechanisms that restrict their application. In composite pipes, structural failure such as burst and collapse is characterized by a fast loss of the contained fluid, whereas functional failure occurs due to transverse matrix micro-cracking that generates interconnected pathways through the pipe thickness allowing for the fluid to escape.
Recently, polymer nanocomposites have evolved as a new class of high-performance multifunctional materials that often outperform conventionally filled and unfilled polymers in terms of their properties. In the present study, the effect of nano-reinforcements on matrix micro-cracking in filament-wound composites was investigated. It was hypothesized that transverse matrix cracking in polymer composites can be mitigated by reinforcing the matrix with an appropriate nano-particulate phase.
This research work involved the synthesis, characterization and property evaluation of bulk epoxy nanocomposites and hybrid fiber-reinforced epoxy nanocomposites modified with organophilic nanoclay and acrylic triblock-copolymer. The epoxy-clay nanocomposites exhibited superior tensile stiffness with a reduction in ductility. Block-copolymer addition enhanced toughness and ductility of bulk epoxy. The present study further demonstrated that optimal mechanical property enhancements in an epoxy can be achieved through the formation of a ternary nanocomposite incorporating nanoclay and acrylic triblock-copolymer.
The presence of nanoparticles in the matrix of fiber-reinforced composites imparted an insignificant effect on delamination fracture toughness, while decreasing fiber volume fraction significantly improved fracture toughness. In block-copolymer modified composite pipes, enhanced matrix ductility caused a build-up of strain energy during applied loading until a sudden release of this energy resulted in the initiation and subsequent propagation of matrix cracks. In response an improvement in leakage failure strain was observed, however the process did not suppress matrix micro-cracking in composite pipes, and failure strength remained unaffected. Strength was even reduced in composite pipes modified with nanoclay, which is thought to stem from nanoclay aggregates that may have acted as stress concentration points expediting micro-crack initiation. -
- Graduation date
- Fall 2013
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.