Study On Synthesis And The Properties Of Modified Poly (M-phenyleneisophthalamide)

A new variety of polyamide poly (m-phenyleneisophthalamide) (PM1A) was first prepared in 1962. Because of its excellent thermal and flame resistance properties, the papers and fibers made from it have been widely used in industrial and clothes applications. It plays an irreplaceable role in the field of high temperature resistance fiber.With the increasing requirement of high temperature resistance products, the polymer compositions with more excellent high temperature resistance were required. But now in China, facing the big market demand, there are poor productive forces The main producers of relative papers and fibers are Dupont and Teijin. As a part of the 2003 key project of JiangSu province, this thesis, based on realistic production and application, using p-phenylene diamine (PPDA) and terephthaloyl dichloride (TPC) modified PMIA, hopes to find a new modified PMIA with better high temperature resistance through polycondensation.This paper emphasizes on how to obtain new PPDA/TPC modified PMIA dope with high inherent viscosity, good thermal properties by low-temperature-solution polycondensation process. The thermal properties, rheology properties, coagulation properties and stability of modified PMIA were determined. In this paper, PPDA/TPC modified PMIA pulps have been first prepared directly by precipitation.Firstly, the effects of PPDA/TPC modified PMIA reaction, such as reaction temperature,reaction time and monomers molar ratio on the low-temperature-solution polycondensation in N, N- dimethylacetamide solvent system were investigated, and optimal conditions parameters were obtained. The copolymers with the third monomer content from 5% to 15% were compared with each other.Secondly.fpr different dopes, we studied the static and dynamic rheologyproperties, coagulability and stability of the dope, obtained some important parameters such as non-Newton exponent, viscous activation energy, structural viscosity index, etc. These investigations provided important foundation for the subsequent machineing process.Thirdly, the thermal properties of copolymers with PPDA or TPC from 5% to 15% were studied with TG-DTG-DTA. Their heat- stabilities were compared with each other and Nomex. By FTIR, explaining the reason of why the PPDA modified PMIA has better thermal properties was given from the relationship of structure and properties. Analyzing the mechanism of thermo degradation during these modified PMIA was analyzed.At last, in order to applicate the copolymer with better thermal properties, we introduced a new approach to forming modified PMIA pulps in this paper — precipitation. That is, a PPDA or TPC modified PMIA concentrated DMAC/H2O solution was injected into a rapidly stirred coagulant and formed pulps. At last,there is a primary analysis to the micro-structure of Pulps.New ideas mainly brought forward in this paper are:(1) The low-temperature-solution polycondensation of PMIA with 5%~15% PPDA or TPC was first introduced in the preparing of modified PMIA dope. The results showed that PPDA modified PMIA can improve the thermal properties of PMIA; meanwhile the resulted polymers had high inherent viscosity. The dope revealed a prospect of industrialization of modified PMIA because of cheaper payout and convenient process.(2) Using precipitation approach to forming modified PMIA pulps in this paper, obtained some useful technical parameters, which is helpful to industrial of modified PMIA pulps.