摘要
微孔物理发泡是利用气体／聚合物熔体系在高温高压下的热力学不稳定性，在释压降温过程中气体产生相分离而获得发泡的方法。在连续挤出过程中，要提高体系的热力学不稳定性则必须有大量的气体在高压下溶解到聚合物熔体中去。利用气体溶解度对压力的敏感关系，快速释放压力，便能产生微孔结构。据此我们获得了泡孔直径小于１０μｍ、泡孔密度大于１０１０孔／ｃｍ３微孔结构。研究证实了提高体系的压力和ＣＯ２的浓度可以提高体系的自由能和体系的不稳定性，成核速率明显提高。温度对泡孔密度和大小的影响不大，但是过高的温度，会引起泡孔塌陷。
When a gas/polymer system is subjected to high pressure and high temperature, followed by the creation of thermodymanic instability through pressure releasing and temperature dropping as well as phase separation, microcellular foams will be formed. In the cause of continuous extrusion, large amounts of pressurized gases will have to be solubilized in the polymer within the thermodynamic instability system. Solubilization of the gas depends highly on pressure exerted on it, and rapid gas releasing is very for the formation of microcells. With the understanding of these concepts, it is possible to obtain microcells with diameter less than 10 μm and density more than 10 10 cells/cm 3. It has also been proved that increasing the system pressure and/or upgrading the concentrate of CO 2 will be able to enhance the free energy and the instability of the system. The nucleating rate will also be thus greatly promoted. Temperature variations have little influence on either the size or density of the microcells; but excessively high temperature may bring about the collapse of the foams.
出处
《中国塑料》
CAS
CSCD
北大核心
1999年第2期54-59,共6页
China Plastics
基金
国家自然科学重点项目基金
