海藻酸盐协效碳酸钙对聚乳酸热性能及断面形貌的影响

Synergistic Effect of Alginate Blended with Calcium Carbonate on Thermal Behavior and Morphology of Polylactic Acid

聚乳酸(PLA)是一种典型的脂肪族聚酯,因其优异的性能逐渐成为一种有前途的石油基聚合物替代物。对PLA的改性研究受到越来越多的关注。以PLA为基体,以纳米无机材料纳米碳酸钙(nano-CaCO3)、海藻酸以及海藻酸盐为填料,通过熔融共混制备了填充型PLA复合材料。并通过场发射扫描电子显微镜(SEM)、动态力学分析(DMA)、差示扫描量热分析(DSC)等表征手段对复合材料的热力学性能、结晶性能及形貌等进行了分析评价。结果表明:海藻酸及其盐类的添加可适当改善复合材料的相容性,随着填料添加量的增加,PLA复合材料的结晶度均有所增加,同时各组分的加入充当了成核剂的作用,缩短了结晶诱导时间,但冷结晶过程的结晶速度相对纯PLA均有所下降;各体系PLA复合材料均表现出脆性断裂面形貌,单纯的加入nanoCaCO3断口表面较粗糙,局部产生凹坑;而复配组分的加入,则使得凹坑减少,界面更平整。

Polylactic acid(PLA)is a typical aliphatic polyester that has become a promising alternative to petroleum-based polymers due to its excellent properties.The research on the modification of PLA has attracted more and more attention.Based on PLA,nano-inorganic materials(nanoCaCO3),alginic acid and alginate as filler,the filled PLA composites have been prepared by melt blending.The thermodynamic properties,crystallization properties and morphology of the composites were analyzed and evaluated by means of field scanning electron microscopy(SEM),dynamic mechanical analysis(DMA)and differential scanning calorimetry(DSC).The results show that the addition of alginic acid and its salts can improve the compatibility of the composites.With the filler content increases,the crystallinity of the PLA composites increases,and the addition of each component acts as a nucleation,shortens the crystallization induction time,however the crystallization rate of the cold crystallization process is lower than that of the pure PLA.The PLA composites of each system show the brittle fracture surface morphology,while the fracture surface of the nano-CaCO3 is rough,the pits are locally generated;and the addition of the compounding components reduces the pits and the interface is flatter.