PROCESS FOR THE PREPARATION OF POROUS POLYIMIDE

摘要

A process for the preparation of porous polyimide involves mixing of polyamid acid with polyurethane in solution, pouring of the solution prepared to horizontal surface and heating. Preliminarily initial imidization is carried out by mixing 20 % polyamide acid (PAA) solution in N-methylpyrrolidone (N-MP) at 150 °C for 4 hours, thereafter 20 % polyurethane (PU) solution is added to PAA solution at specified ratio and mixed at room temperature for 10 min. Then N-MP is additionally added to PAA/PU/N-MP solution at ratio of 1:1. Mixture is stirred for 5 min. at room temperature, poured at horizontal surface. Complete imidization of PAA to polyimide (PI) is carried out at presence of PU by heating from 25 °C to 300 °C with rate of 0.5 °C/min. PU is removed from system by extraction with boiling methyl-ethyl ketone (T= 79.6 °C) for 32 hours followed by drying of prepared polyimide film to constant weight.