Improved processability of PA66-polyimide copolymers with different polyimide contents

Limitations in the properties of polyamide PA66, such as low glass transition temperature and high water absorptivity, limit its applications. Introduction of amorphous polyimide segments into the PA66 main chain lowers the glass transition temperature and melting temperature and also improves its processability. PA66-polyimide (PA-PI) copolymers with different weight ratios of PI are prepared by high temperature and high-pressure solution polymerization. The degree of crystallization of PA-PI copolymers decreases with increasing PI content. The melting point decreases from 261°C for PA66 to 223°C for PA-PI-4. Dynamic mechanical analysis shows that the T g increases from 70 to 90°C, and the storage modulus can be well maintained. Rheological studies show that the temperature for processing can reach 70°C. Copolymers with different PI contents show different processing viscosities. In addition, water absorptivity (about 1.8%) and dielectric constant values of PA-PI and PA6/6T are similar.