(A) study on properties and morphology of PPTA-nilon composite

Abstract

This study is concerned with the development of new materials by extending the macroscopic fiber-reinforcing principle to the molecular or supramolecular level. In order to solve the problem of dispersing the rigid molecules (PPTA) homogeneously into the matrix of flexible molecules, Nylon-PPTA composite was prepared by in-situ polymerization of p-phenylene diamine and terephthalic chloride in Nylon and N-methyl 2, Nyrrolidone (NMP) mixture. Thermal and mechanical properties, crystal structure, morphology and rheological properties of the composites were investigated by rheovibron, differential scanning calorimeter (DSC), X-ray diffractometer, scanning electron microscope (SEM) and tensile tester. For the PPTA/Nylon composite, the shift of glass transition temperature of Nylon to the higher temperature were observed with eovibron. It suggests that the composite become homogeneous DSC and X-ray studies revealed that PPTA microfibrils acted as a nucleating agent for Nylon in the quenched Nylon and the PPTA/Nylon composites. It is due to the strong interaction between the PPTA surface and Nylon. The structures of Nylon, PPTA and the composite were observed with X-ray diffractometer and FT-IR spectrophotometer. The crystal structure of PPTA in the composite is not changed with the composition of Nylon, on the other hand, that of Nylon is changed considerably by even small amount of PPTA. However, X-ray and DSC results show little crystallinity in the 60/40 PPTA/Nylon composite, which means that the composite is in a homogeneous state at this composition. Electron microscopy revealed that microfibrils of PPTA were homogeneously dispersed in the Nylon matrix. Phase transition behavior was also observed at the 50/50 PPTA/Nylon composition with SEM and X-ray. The liquid crystalline behavior of PPTA was observed by the viscoelastic measurement: shear thinning and relatively long relaxation time, large increase of melt viscosity with increase of PPTA content was also ob...