塑化聚乙烯醇的流变性能及发泡行为研究

Rheological and Foaming Behaviors of Plasticized Poly(vinyl alcohol)

采用毛细管流变仪对聚乙烯醇(PVA)的流变性能进行了表征,用差示扫描量热仪研究了降温速率对PVA结晶性能的影响,并通过在PVA中添加化学发泡剂熔融挤出的方法制备了PVA发泡材料,用扫描电子显微镜和密度测试仪分别对发泡材料的泡孔形态和密度进行了表征。结果表明,PVA对剪切作用非常敏感,在低剪切速率下熔体黏度较大,泡孔分布均匀,材料密度较小;在高剪切作用下熔体黏度低,气体容易逃逸,导致发泡材料泡孔破裂或合并;低降温速率下熔体黏度小,泡孔易合并、塌陷;在较高的降温速度下,由于气体压力过大而造成气泡合并、连通,材料密度大。

The rheological behavior of plasticized poly （vinyl alcohol） （PVA） was investigated with capillary rheometer. The effect of cooling rate on crystallization properties of PVA was studied with differential scanning calorimetry analyzer （DSC）. The PVA foams were fabricated by filling chemical foaming agent through melt extrusion, and the cell morphology and the density of the foams were investigated with scanning electron microscope （SEM） and density tester. It showed that PVA was sensitive to the shearing effect. At low shear rate, the melt viscosity of PVA was high, leading to the homogeneous distribution of the cells and a low density; at high shear rate, the melt viscosity of PVA was low and the gas was easy to escape, leading to the break or combination of the cells. At lower cooling rate, the melt viscosity was lower, leading to the combination or collapse of the cells. At higher cooling rate, the cell combined due to the excessive gas pressure, resulting in the higher density of the foams.