聚乳酸及其增韧共混体系超临界CO_2发泡行为  

Foaming Process of Polylactide and Toughened Polylactide Blends Using Supercritical CO_2

作　　者：刘阳[1] 史学涛[1] 张广成[1] 马忠雷[1] 杨全[1] 

机构地区：[1]西北工业大学理学院应用化学系,陕西西安710129

出　　处：《高分子材料科学与工程》2015年第4期61-67,共7页Polymer Materials Science & Engineering

基　　金：国家自然科学基金资助项目(51303149)

摘　　要：利用超临界CO2作为物理发泡剂,采用升温发泡法制备了聚乳酸(PLA)、聚乳酸-聚丁二酸丁二醇酯(PBS)共混物以及聚乳酸-丁二醇-己二酸-对苯二甲酸共聚酯(PBAT)共混物3种体系的微孔泡沫,并探讨了共混体系的结晶行为与形貌、CO2的吸附与解吸附、发泡温度和发泡时间对泡孔结构的影响。结果表明,2种共混体系均为"海-岛"式不相容体系,且差示扫描量热分析表明PLA-10%PBS体系的结晶度最大;在12 MPa,45℃和8h的饱和条件下,3种体系的饱和吸附量均在20%左右,其中PLA-10%PBAT体系最大,PLA-10%PBS体系最小;3种体系呈现出3段式扩散模式,第1段扩散速率最快,为表皮扩散,第2段扩散速率居中,为无定形区扩散,第3段扩散速率最慢,为晶区扩散,应选择第2段作为发泡的初始状态最为合适;扫描电镜照片表明,不同于PLA-10%PBAT体系,PLA-10%PBS体系泡沫的泡孔密度大,泡孔尺寸小,其界面作用高于PLA-10%PBAT体系;PLA泡沫的泡孔结构呈现明显的双峰分布。The microcellular foams of polylactic acid( PLA) and its binary blend with polybutylene succinate( PBS)or butylene glycol-adipic acid-ternary terephthalate polyester( PBAT) were prepared by bath foaming process with supercritical carbon dioxide( SC-CO2) as physical foaming agent. The crystallization behavior and morphology of PLA blends were studied,and the adsorption and desorption of CO2 in PLA or PLA blends were further investigated. The effects of foaming temperature and foaming time on the final morphology of microcellular foam of different PLA systems were also discussed. With 10% PBS or PBAT added into the PLA matrix,the ' sea-island' structure indicates that both PBS and PBAT are incompatible with PLA,and DSC studies show that PLA-10% PBS has the highest crystallinity. The saturated conditions are fixed to be 12 MPa at 45 ℃,and lasting for 8 h. The adsorption capacity of three PLA systems is around20% with slight difference,while that of PLA-10% PBS blend is the maximum and that of PLA-10% PBAT blend is the minimum. The diffusion process of CO2 in those PLA systems shows interesting three-steps diffusion mode with the first stage as skin diffusion having the highest diffusion rate. The second stage shows lower diffusion rate due to dominated CO2 from amorphous area in the PLA systems. The final stage has the lowest rate and the diffusion happens in crystallization area. The second stage is chosen as foaming stage for the final microcellular PLA. The SEM pictures indicate that the microcellular of pure PLA shows a typical bimodal distribution of cell structure. However,PLA-10% PBS system shows a high cell density and smaller average cell diameter compared to PLA-10% PBAT,which is attributed to a higher interfacial interaction of PLA with PBS.

关 键 词：聚乳酸 共混 发泡 泡孔 形貌 

分 类 号：O633.14[理学—高分子化学]