低密度微孔聚合物泡沫的制备
Fabrication of low density microporous polymeric foams
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摘要: 介绍了一种利用聚合物和溶剂的相分离，经过冷冻干燥来制备聚合物泡沫（特别是聚苯乙烯类泡沫）的通用技术。采用该技术制备的具有开放状孔洞结构的聚苯乙烯泡沫的密度为0.02~0.1g/cm3，平均孔径为1～20μm，而且泡沫具有各向同性，孔径非常均匀。通过对聚合物泡沫的表征，对影响泡沫形貌和密度的因素，如聚合物/溶剂体系，冷却速率等进行了研究，结果表明：所用溶剂对于该聚合物的Θ温度（溶剂与聚合物作用力为零的温度）必须高于该溶剂的熔点；采用单轴冷却方式可以减小由于溶液中心处和外围处的温差而引起的热应力对泡沫形貌的影响，冷却速率为100℃/min。Abstract: By the general freezing-dry technology, low density, open-celled microporous polymeric foams, such as polystyrene, can be fabricated. The density of polystyrene foam is 0.02~0.1g/cm3, and the average cell size is 1~20μm. The factors that affect the cellular structure of foams, such as the process of phase separation between polymer and solvent, the system of polymer and solvent, and the freezing rate have been studied. In order to obtain the homogeneous defect-free foams, the technology must pick a system in which the theta temperature of solvent to polymer is higher than the solvent melting point temperature, and use unidirectional freezing whose quench rate exceeds 100℃/min．
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Key words:
- freezing-dry /
- phase separation /
- polystyrene /
- foam
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