Papers by Author: Kai Liang Qi

Abstract: Foaming moulding process, cellular structure and dielectric property of polyimide (PI) foam which has been prepared by esterification method were discussed. Research results showed that the cell of prepared PI foam was well-distributed and its pore volume and porosity were bigger by microwave heating when methanol was used as the foaming agent and its content in the polyester ammonium salt (PEAS) precursor powder was 13-15%; meanwhile, the dielectric constant and loss factor of PI foam were lower.

Abstract: High performance polyimide (PI) foam has been prepared by esterification method using benzophenone tetracarboxylic acid dianhydride (BTDA) and diamino diphenylmethane (MDA) as the main materials in the mixture of methanol and tetrahydrofuran (THF). The cellular structure, thermal properties and flame retardance properties of PI foam were characterized by hot stage optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetic analysis (TGA) and limiting oxygen Index (LOI), respectively. The results showed that the cellular structure was more ideal when the particle diameter of polyester ammonium salt (PEAS) precursor powder was 100μm; the glass transition temperature (Tg) of PI foam was more than 300°C, 5% weight loss temperature was above 500°C, LOI was as high as 50% and sound absorption was over 0.5.