摘要
采用熔融复合方法制备了不同填料质量分数的聚乳酸/纳米凹凸棒土复合材料,纳米凹凸棒土的加入可以显著提高聚乳酸纳米复合材料的拉伸强度和断裂伸长率.扫描电镜结果表明,凹凸棒土粒子在复合材料中实现了均匀分散.DSC曲线在降温过程中出现明显结晶峰,说明纳米凹凸棒土对聚乳酸有一定的成核作用.当纳米凹凸棒填料含量>8%时,在聚合物基体中可形成完善的网络状结构.填料粒子作为体系中的物理缠结点使得复合材料熔体的应力松弛时间延长.红外谱图显示纳米凹凸棒土和聚乳酸分子间存在较强的相互作用.我们推测,纳米凹凸棒土的加入减少了PLA基体层的厚度,使其由三维应力转变为二维应变状态,导致最大切应力可以达到剪切屈服强度,产生剪切滑移形变带,使得呈现出韧性材料性质,有效提高了材料的断裂伸长率.
The polylactide/attapulgite nanocomposites （PLA-Att composites） were prepared by melt mixing. The elongation at break and the tensile strength of PLA-Att composites increased first with increasing Att content and then decreased when Att content exceeded 10 wt%. The SEM results showed that the Att nanorods were well dispersed in PLA matrix. The DSC curves during the cooling and the second heating run showed that Att can enhance the crystallization rate of PLA. Furthermore,the rheological behaviors were investigated. When the content of Att was larger than 8 wt% , the storage modulus curve of PLA nanocomposites demonstrated a plateau region at the low frequency range,indicating the formation of a network structure in the composite, where the Att nanorods acted as the physical entanglement points to increase the relaxation time of the PLA-Att composites. FTIR spectrum of the extracted Art fillers from the nanocomposites showed that Art had strong interaction with PLA. PLA chains could be adsorbed at the surface of Att nanorods, reducing the thickness of the matrix layer. We suggest that the addition of Art nanorods changes the strained condition of the samples from the 3-dimensional stress to the 2-dimensional plane strain state and the maximum shear stress could reach the yield strength of PLA matrix so as to induce brittle-ductile transition of the sample.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2012年第1期83-88,共6页
Acta Polymerica Sinica
关键词
聚乳酸
凹凸棒土
纳米复合材料
动态流变
弛豫时间
力学性能
断裂伸长率
PLA, Attapulgite, Nanocomposites, Rheological property, Relaxation time, Mechanicalproperty, Elongation at break
