The Study On Modification Of Poly(Trimethylene Terephthalate)

Poly(trimethylene terephthalate) is a new kind of polymer materials achieved industrialization in recent years. Because of some shortcomings, such as low heat distortion temperature, low melt viscosity, and pronounced brittleness, this paper focuses on processing modification of PTT including toughening modification, reinforcing modification and chain extension modification.Firstly, the terpolymer of acrylonitrile-styrene-acrylate (ASA) was used to blend with PTT. The phase inversion behavior of blends was analyzed. The results show that PTT/ASA is a partially miscible system. PTT gives high crystallization temperature with adding0-40wt%ASA. Blends offer relatively unchanged notched impact strength and comparatively low tensile strength. However, PTT gives low crystallization temperature and blends have high notched impact strength and tensile strength with the content of ASA larger than40wt%. The blends with50～70wt%ASA occur phase inversion which is consistent with the result predicted by Utracki model.Secondly, the styrene-acrylonitrile-glycidyl methacrylate copolymer (SAG) was incorporated as reactive compatibilizer. The interfacial tension between the polymers was calculated by combinating dynamic rheology and theoretical model. The results show that the number average and weight average diameters, polydispersity index decrease with increase in compatibilizer addition. The dynamic modulus, complex viscosity, the strength and the time of interfacial relaxation peak increase. The interfacial tension calculated by Palierne and Choi-Schowalter models decreases linearly owing to the in-situ formation of PTT-co-SAG copolymer.4wt%SAG is the optimum content for PTT/ASA blends. The crystallization peak moves to low temperature and the melting peak shifts to high temperature.Thirdly, PTT/ASA/OMMT nanocomposites were synthesized by melt-blending intercalation. The phase morphology and properties based on different OMMT contents were investigated. The results show that droplet size and interfacial tension are decreased by introduction of OMMT. The storage modulus, loss modulus, complex viscosity, notched impact strength and tensile strength are simultaneously increased. The crystallization peak shifts to high temperature with increasing OMMT content. But blend with1.25wt%OMMT gives large droplet size, low notched impact strength and low tensile strength. The interfacial modulus and interfacial layer thickness calculated by Palierne and Gramspacher-Meissner models are enhanced by introduction of OMMT.Finally, PTT was chain extended with multifunctional epoxide chain extender (ADR4370S). The effects of ADR4370S content on the molecular structure and properties of PTT were studied. It is found that a star-type topological structure is formed in PTT by introduction of ADR4370S. The intrinsic viscosity and molecular weight are increased by increasing ADR4370S dosage. The rheological measurement results show that the elastic modulus and complex viscosity of long chain branching PTT are increased by introduction of ADR4370S. The presence of broadened relaxation time spectrum and a long relaxation time mode for the PTT with1.50wt%ADR4370S demonstrate that the crosslinking reaction occurs and the gel forms in the PTT system.