聚乳酸及其共聚物、共混物的流变特性

STUDIES ON THE RHEOLOGICAL BEHAVIORS OF POLYLACTIDE AND ITS COPOLYMERS AND BLENDS

研究了聚乳酸及其共聚物、共混物的流变特性。结果表明,随着分子量的增加,聚乳酸及其共聚物熔体的弹性模量G′、损耗模量G″及动态黏度η*大幅度地提高,出现假固态行为;分子链柔性较好的共聚组分PEG的引入降低了共聚物熔体的G′、G″及η*;聚合物分子量的多分散性导致聚合物熔体的流动出现了非终端效应;聚乳酸的引入使聚丙烯熔体的G′、G″及η*都有所下降,马来酸酐接枝改性的聚丙烯的引入增大了共混物的G′、G″及η*。

Rheological behaviors of polylactide and its copolymers and blends were studied in this paper. It was concluded that the elastic modulus G′, loss modulus G″ and dynamic viscosity η~ of PLA and its copolymers increases with the increasing of the molecular weight. The crossover frequency ω__c at which transition from liquidlike to solidlike behaviors take place shifted toward lower frequencies with the increase of molecular weight, which is called pseudo-solidlike behaviors. The incorporation of PEG decreases the elastic modulus G′, loss modulus G″ and dynamic viscosity η~ of polymers. Non-terminal rheological behavior occurres due to the polydispersity of the polymer weight. The elastic modulus G′, loss modulus G″ and dynamic viscosity η~ of PP/PLA blends decreases with the increasing of the PLA content. And the incorporation of maleic anhydride modified PP increases the elastic modulus G′, loss modulus G″ and dynamic viscosity η~ of the blends.