Investigation of the Relationship Between Polymer Structures and Thermal, Mechanical, Viscoelastic Properties

Ethem Kaya


The research presented in this dissertation involves four distinct areas: physical crosslinking systems, UV curable coatings for enhanced oxygen and carbon dioxide barrier properties, synthesis, and investigation of melting behavior/crystallinity relations of linear polyamides with long alkyl chains, and synthesis and characterization of cyclic diamides as precursors to linear polyamides 6 4. The physical crosslinking section involves synthesis of monomers and polymers bearing cyclodextrin and adamantane pendent groups, and investigation of non-covalent interactions between these polymers (Chapter II). Two methacrylate monomers bearing cyclodextrin and adamantane were synthesized, and copolymerized with poly(ethylene glycol) methyl ether methacrylate. The specific interaction between copolymers bearing pendent cyclodextrin and adamantane were examined. The viscoelastic properties of supramolecular assemblies were investigated with frequency and temperature sweep experiments. The specific host-guest interaction between pendent adamantyl and cyclodextrin lead to large increases of viscosity, and depending on the concentration of these groups, also to gel formation. The second section involves the investigation of methyl (α-hydroxymethyl)acrylate (MHMA) and its various copolymers as coatings for barrier improvement (Chapter III). The UV curable coating of MHMA gives excellent barrier improvement when coated onto PET biaxially oriented thin films. Blown bottle side walls from coated PET preforms show 2-3 times improvement over uncoated side walls. The affect of photoinitiator concentration, initiator types, and temperature on photopolymerization kinetics of MHMA was investigated. The photopolymerization kinetics of MHMA with methyl methacrylate was also studied. The third section involves synthesis and characterization of long alkyl chain nylons (Chapter IV), and investigation of melting and crystallinity of nylons with high aliphatic content (Chapter V). Nylon 18 18 and nylon 18 ADA (1,3-adamantanedicarboxylic acid) have been synthesized via melt polycondensation and characterized by thermal and spectroscopic techniques. Crystallization and melting behaviors of both polymers were investigated. There is no observed melting for nylon 18 ADA by DSC. However, solution cast samples of nylon 18 ADA shows some ordered structures that can grow into more stable crystals with annealing. The fourth section involves synthesis and characterization of cyclic diamides and exploration of the affect of the reaction conditions on yield and final cyclic formation. Ring-opening polymerization of these novel cyclic diamides was also investigated with different methods. Copolymerization of cyclic diamides with [varepsilon]-caprolactam via an anionic route gave a block copolyamide with a two distinct endotherms in DSC analysis. However, copolymerization by the hydrolytic route gave only nylon 6 with a terminal 6 4 units.