The investigation of structure-property behavior of extruded cast films prepared from blends of thermotropic liquid crystalline copolyesters with polyethylene terephthalate (PET). Data were obtained which showed not only the temperature dependence of the moduli and stress-strain behavior but also the orientation effects that must be prevalent in order to explain the differences between the moduli measured parallel and perpendicular to the extrusion direction. Only at high liquid crystal polymer (LCP) compositions is the modulus particularly increased. The modulus enhancement with lower LCP content and utilization of process variables are discussed. Specifically, the extruder gear pump speed did not enhance Young's modulus at the same LCP content as extensively as did the effect of extruder screw speed. Also a study to synthesize and characterize new segmented copolymers that could produce unusual film properties are discussed. The approach involved the synthesis of high Tg (220 C) isotropic poly (aryl ether sulfone) oligomers of varying segment molecular weights. The thermal and mechanical studies of the copolymers have been carried out to probe the potential of these copolymers for signs of liquid crystalline character and to note their ability to thermally crystallize as well as to crystallize by solvent or strain inducement. Along these lines, thermal analysis, polarizing hot-stage microscopy, wide angle x-ray scattering and mechanical testing were utilized in this investigation / Master of Science

The polyamide poly(ε-caprolactam) or "nylon 6" is a very important fiber forming polymer which finds many applications in the carpet industry and elsewhere due to the very high strength of this fiber. However, a major drawback is its hydrophilicity. This feature influences both the surface and bulk mechanical behavior. Siloxane based macromolecules are hydrophobic, thermally stable and exhibit dimensional stability over a wide temperature range. Unlike the polyamide nylon 6, these hydrophobic materials display relatively low surface free energy. Thus, they can be used for the surface modification of nylon 6, provided a suitable adhesion or "anchoring" method is feasible. Polyamide-polydimethylsiloxane segmented or block copolymers were found to be suitable "interfacial" agents. They were synthesized by reacting aminopropyl-terminated polydimethylsiloxane (PDMS) oligomers with sebacyl chloride via an interfacial polymerization in which methylene chloride was used as the solvent or organic phase. A second diamine "chain extender" was also utilized, if desired. By varying the mole ratio of soft segment to the chain extender p-aminocyclohexylmethane (PACM-20), copolymers with various percentages of hard segments can be synthesized. Weight fractions of 2, 5, or 10% of the polyamide-poly-dimethylsiloxane block copolymers were physically melt mixed with nylon 6 in an extruder. The presence of polydimethylsiloxane on the surface of the blend was detected by determining the critical surface tensions of wetting using water as the contact angle test liquid. Such modified polyamides were successfully melt spun into fibers which displayed good mechanical properties and enhanced soil resistance. Fibers spun from these modified nylon 6 blends showed surface hydrophobicity. These modified polyamides or related materials may become technologically important in carpeting applications. Additional studies involving attempts at directly polymerizing ε-caprolactam via hydrolytic ring opening polymerization from functional polysiloxanes are also reported. In general, the structural integrity of these copolymers is less well defined. Certain procedures utilizing the aminopropyl polydimethylsiloxane initiated lactam oligomerization, followed by adipic acid chain extension produced interesting materials and should be further examined. / Master of Science / incomplete_metadata