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Full-Text Articles in Engineering
Impact Resistant Glassy Polymers: Pre-Stress And Mode Ii Fracture, Jared Steven Archer
Impact Resistant Glassy Polymers: Pre-Stress And Mode Ii Fracture, Jared Steven Archer
Open Access Dissertations
Model glassy polymers, polymethyl methacrylate (PMMA) and polycarbonate (PC) are used to experimentally probe several aspects of polymer fracture. In Chapter 1, the method of pre-stress is employed as a means of improving the fracture properites of brittle PMMA. Samples are tested under equi-biaxial compression, simple shear and a combination of biaxial compression and shear. Equi-biaxial compression is shown to increase the threshold stress level for projectile penetration whereas shear pre-stress has a large effect on the overall energy absorbed during an impact. There is also an apparent interaction observed between compression and shear to dramatically increase the threshold stress. …
Characterization Of Self-Assembled Functional Polymeric Nanostructures: I. Magnetic Nanostructures From Metallopolymers Ii. Zwitterionic Polymer Vesicles In Ionic Liquid, Raghavendra Raj Maddikeri
Characterization Of Self-Assembled Functional Polymeric Nanostructures: I. Magnetic Nanostructures From Metallopolymers Ii. Zwitterionic Polymer Vesicles In Ionic Liquid, Raghavendra Raj Maddikeri
Open Access Dissertations
Two diverse projects illustrate the application of various materials characterization techniques to investigate the structure and properties of nanostructured functional materials formed in both bulk as well as in solutions. In the first project, ordered magnetic nanostructures were formed within polymer matrix by novel metallopolymers. The novel metal-functionalized block copolymers (BCPs) enabled the confinement of cobalt metal ions within nanostructured BCP domains, which upon simple heat treatment resulted in room temperature ferromagnetic (RTFM) materials. On the contrary, cobalt functionalized homopolymer having similar chemical structure and higher loading of metal-ion are unstructured and exhibited superparamagnetic (SPM) behavior at room temperature. Based …
Helical Ordering In Chiral Block Copolymers, Wei Zhao
Helical Ordering In Chiral Block Copolymers, Wei Zhao
Open Access Dissertations
The phase behavior of chiral block copolymers (BCPs*), namely, BCPs with at least one of the constituent block is formed by chiral monomers, is studied both experimentally and theoretically. Specifically, the formation of a unique morphology with helical sense, the H* phase, where the chiral block forms nanohelices hexagonally embedded in the matrix of achiral block, is investigated. Such unique morphology was first observed in the cast film of polystyrene-b-poly(L-lactide) (PS-b-PLLA) from a neutral solvent dichloromethane at room temperature with all the nanohelices being left-handed, which would switch to right-handed if the PLLA block changes to …