Modification of a polyimide film by blending with nylon 6. Its characterization and thermal property evaluation

A polyimide blend system has been prepared from a base polyimide of PMDA–4,4′ oxydianiline by adding ε-caprolactam at the poly(amic acid) stage where ε-caprolactam is also undergoing polymerization during the curing cycle of the polyimide. The blend has been characterized by elemental analysis, IR, 13C CPMAS NMR, XRD and simple chemical methods. The thermal analysis study (TGA, DTA & DSC) shows that the stability of the blend system is more in comparison to the control polyimide system. The isothermal study at 400°C in inert atmosphere shows that the blend system is equally stable but the isothermal study in air at 400°C shows that the blend films are more stable up to a certain extent of time compared to that of the control film. Also isothermal study in air at 500°C shows rapid loss of weight (more than 90%) for all the films but in inert atmosphere the films show higher thermal stability. XRD pattern of the blend films shows a higher crystallinity. It has been also observed that the density of the blended film is higher than that of the control film.