Study On The Interfacial Polymerization Technology Of Semiaromatic Polyamide PA10T、PA12T And PA6T

With the increase of heat resistant material requirements, due to the excellent mechanical properties, heat resistance and dimensional stability, semiaromatic polyamides are more and more widely used. At present only the polyhexamethylene terephthalamide (PA6T) and polynonamethylene terephthalamide (PA9T) were commercially applied. However, PA6T cannot be processed by melting method because its melting point is higher than the thermal decomposition temperature, and the production cost of PA9T is too high, which, to some extent, limit their wide application. Since2002, Our laboratory began to research work of long chain semiaromatic polyamide, and successfully developed a series of new type of long carbon chain and semiaromatic polyamides.It is found that the comprehensive performances of poly(decamethylene terepethalamide)(PA10T) and poly(dodecamethylene terephthalamide)(PA12T) are superior to these of PA6T and PA9T. And they are expected to replace PA9T in many fields in the future.In this paper, terphthalic acid respectively reacted with triphosgene that is environmental friendly instead of traditional chlorinating agent, especially phosgene and diphosgene to synthesize terephaloyl dichloride (TPC) through Vilsmeier reaction. The yield of TPC reached91.33%, and its purity reached90.12%. We studied the synthetic technological conditions of TPC. The structure of TPC was characterized by IR Spectrum and1H-NMR.The semiaromatic polyamides PA10T, PA12T and PA6T were prepared from reactions of TPC and three distinct cheap aliphatic diamines (1,10-decanediamine,1,12-dodecaediamine and1,6-adipic amine) through interfacial polymerization method, respectively. The interfacial polymerization conditions on PA10T and PA6T have been in-depth investigated. The structures of PA10T, PA12T and PA6T were characterized by IR Spectrun and1H-NMR, respectively. Through the solid phase polymerization, the molecular weight of PA10T, PA12T and PA6T was futher improved. The relative viscosity of PA10T increased from1.32to1.96. The relative viscosity of PA12T increased from1.27to1.69. The relative viscosity of PA6T increased from1.18to1.46.The relationship of the melting temperature (Tm) and the polymerization reaction condition of PA10T was analysised by DSC. It was found that the melting point of PA10T after solid phase polymerization was not much improved. The melting temperatures of PA10T, PA12T and PA6T were314℃,302℃and373℃, and their crystallization temperatures were288℃,275℃,332℃, respectively. Thermal degradation processes of PA10T, PA12T and PA6T were analysised by TGA. It was found that their thermal degradation temperatures were over400℃. It was proved that the degradation of PA10T, PA12T and PA6T was step degradation reaction.