外消旋聚乳酸/纳米碳酸钙复合材料的熔体流动性能

摘要

采用双螺杆挤出机挤出造粒得到外消旋聚乳酸(PDLLA)/纳米碳酸钙(nano-CaCO3)复合材料.复合材料的熔体体积流动速率(MVR)随着温度、载荷的增加而升高,但随着w(nano-CaCO3)的增加而降低;在相同载荷或温度下,PDLLAano-CaCO3复合体系[w(nano-CaCO3)为4%]的MVR较PDLLA树脂低;在相同w(nano-CaCO3)下,载荷越大,复合材料的MVR越大.复合材料的熔体密度(ρ)随着温度的增加而降低,但随着载荷和w(nano-CaCO3)的增加而升高;在相同的载荷或温度下,复合材料的ρ较PDLLA树脂高;在相同w(nano-CaCO3)下,载荷越大,复合材料的ρ也越大.%Preparation of microcellular foamed plastics with supercritical carbon dioxide was considered as the current research focus for its advantages of efficient foaming, environmental protection and less impact on mechanical properties and appearances of the finished products. This paper reviewed the progress in studies on microcellular foamed plastics prepared with supercritical carbon dioxide; introduced the foaming mechanism of homogeneous nucleation, heterogeneous nucleation and external force field enhanced nucleation; summarized the foaming methods such as intermittent foaming, semi-continuous foaming and continuous foaming; expounded the methods of preventing microcellular from conglutination and rupture as well as the influential factors during the preparation of the microcellular foams. Expectation of and suggestions on the microcellular foamed plastics prepared with supercritical carbon dioxide were presented.