摘要
研究了超临界CO2/PLA微孔发泡过程中,发泡温度、饱和压力、剪切速率对聚合物PLA泡孔形态的影响。结果表明,发泡温度对泡孔形态影响很大,温度降低,熔体强度增加,泡孔塌陷和合并减少,发泡材料的泡孔密度增大,泡孔尺寸减小,但温度太低时,熔体黏度和表面张力增加,发泡样品泡孔密度较低,泡孔壁较厚;压力对发泡形态的影响也是很显著的,压力太低,CO2的溶解度小,泡孔壁厚,泡孔分布不均匀。随着压力升高,CO2的溶解度增加,发泡样品的泡孔密度增加,泡孔更加均匀;随着转子转速增加,泡孔尺寸减小,气泡成核密度增大。但是转子转速过快,泡孔沿剪切的方向被拉长,泡孔取向严重,泡体质量变差。
The effects of foaming temperature,saturation pressure and shear rate on the cell morphology of foamed PLA in microcellular foaming process of supercritical CO2/PLA were investigated.The experimental results showed the temperature had great effect on the cell morphology,the melt strength increased with the decrease of temperature which caused the cell collapsing and migration decreasing,also,the cell density increased and cell size reduced;However,the melt viscosity and surface tension increased a lot which caused the decrease in cell density and increase in wall thickness when the foaming temperature was too low;Meanwhile,the pressure also had great effect on the cellular morphology;too low pressure induced low CO2 solubility,which led the cell wall thickness increased and non-uniform cell size distribution;the CO2 solubility and cell density increased as the saturation pressure enhanced,and led the more uniform cell;with the increase of the rotational speed,the cell size decreased and cell density increased,however,when the rotational speed was too high,the bubble was elongated along the direction of shearing and oriented strongly thus result in the poor cellular quality.
出处
《塑料工业》
CAS
CSCD
北大核心
2010年第11期41-44,65,共5页
China Plastics Industry
