酚醛泡沫闭孔率测试方法及其主要影响因素的研究

STUDIES ON THE METHODS AND THE MAIN INFLUENCE FACTORS FOR MEASURING THE CLOSED CELL CONTENT OF PHENOLIC FOAMS

用真密度仪研究了酚醛泡沫闭孔率的测试方法,在测试过程中对不同测试压力下体系达到平衡的时间进行跟踪,并结合扫描电镜观察泡沫在不同压力下测试前后的结构变化,进而对测试压力加以优化选择;利用扫描电镜观察了不同闭孔率酚醛泡沫的微观结构,深入讨论了酚醛泡沫闭孔率与不同微观结构的关系;对不同放置时间的样品进行恒温处理,将处理前后样品的闭孔率、微观结构进行对比分析.结果表明,优化测试条件、确定测试压力是保证闭孔率测试结果高效准确的首要前提;泡沫微观结构缺陷(如针孔、裂纹),是造成泡沫闭孔率低的直接原因;泡沫微观孔结构规整度、后处理程度的差异,是影响闭孔率测试过程(如测试时间过长,体系不易达到平衡)的主要因素.

The methods of measuring the closed cell content of phenolic foams were studied by densimeter. The system balance times were recorded under different pressures during the measuring processes, and the structural changes were analysed after the measuring processes combined with scanning electron microscopy in order to optimize the measuring pressure. The microstructure of different phenolic foams was characterized by scanning electron microscopy and the relationship between the closed cell content and microstructure of phenolic foams was further discussed. The samples after storing for different time periods underwent constant temperature treatment, and the closed cell content and microstructure of samples before and after treatmeat were compared and analyzed. The results demonstrated that the first prerequisite for obtaining the accurate results was to optimize the measuring condition and pressure for measuring the closed cell content of phenolic foams,the low closed cell content of phenolic foams was resulted from the flaw of foam microstructure （e. g. pinhole and fissure） ,and the primary cause for the long measuring time due to the balance difficulty was the inhomogeneous cells in the microstructure and different aftertreatment procedures.