聚酰亚胺泡沫材料的制备与性能表征

PREPARATION AND CHARACTERIZATION OF POLYIMIDE FOAMS

采用3,3′,4,4′-二苯甲酮四甲酸二酐(酮酐,BTDA)和4,4′-二氨基二苯甲烷(MDA)为主要原料制备了一种聚酰亚胺泡沫材料.采用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、扫描电镜(SEM)、导热系数测定仪、热失重分析(TGA)、差式扫描量热分析(DSC)及驻波管分别对前聚体粉末化学结构、泡沫泡孔结构、热性能及声学性能进行了表征.研究结果表明前聚体粉末以聚酰胺酯和铵盐两种形式存在,所得泡沫泡孔均匀,并且随前聚体干燥温度升高,泡孔尺寸变小.泡沫的导热系数λ为7.62×10-3W/(m.K),失重5wt%的分解温度Td5为540℃,玻璃化转变温度Tg为306℃,表明其具有优良的隔热耐热性.并且由声学测试可知在0～2000Hz频率范围内,吸声系数可达0.79,传声损失可达19.4dB,具有低频吸声、隔声性.

A new kind of polyimide foams was successfully prepared using 3,3＇,4,4＇-benzophenone tetracarboxylic dianhydride （BTDA） and 4,4＇-methylene dianiline （MDA） as main materials. First, BTDA diester was synthesized by esterification with methyl alcohol as a solvent. Subsequently, the polyamie ester precursor was polycondensated in the solution. Finally, polyimide foams were prepared through heating the precursor powder. The chemical structure of precursor powder, morphorlogy and size of cell, thermal properties and acoustical behavior of foams were characterized by Fourier transform infrared spectroscopy （FTIR）, ^1H nuclear magnetic resonance （^1H-NMR）, scanning electron microscopy （ SEM）, thermal conductivity measurer, thermogravimetie analysis （TGA）, differential scanning calorimetry （DSC） and standing wave tube, respectively. The results show that the precursor powder exists mainly as ammonium salt. Cells of the foams are uniform, and the cell size gets smaller with increase of drying temperature for precursor. The thermal conductivity A of foams is 7.62 × 10^-3 W/（ m·K）, temperature of 5 wt% weight loss is 540℃ and glass transition temperature Tg is 316℃ ,which reveals the favorable thermal properties. And it can be known that the sound absorption coefficient comes up to 0.79 while the soniferous loss reaches 19.4 dB at 0 - 2000 Hz, which indicates the foam has low frequency sound absorption and sound insulation properties.