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首页> 外文期刊>Journal of Applied Polymer Science >Effect of multi-branched PDLA additives on the mechanical and thermomechanical properties of blends with PLLA
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Effect of multi-branched PDLA additives on the mechanical and thermomechanical properties of blends with PLLA

机译：PDLA多支化添加剂对PLLA共混物力学和热机械性能的影响

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Stereocomplex formation between poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) in the melt state was investigated and altered via the addition of multi-branched poly(d-lactide) (PDLA) additives. Two different multi-branched PDLA additives, a 3-arm and 4-arm star-shaped polymeric structure, were synthesized as potential heat resistance modifiers and incorporated into PLLA at 5, 10, and 20 (w/w) through melt blending. Mechanical and thermomechanical properties of these blends were compared with linear poly(l-lactide) (PLLA) as well as with blends formed by the addition of two linear PDLA analogs that had similar molecular weights to their branched counterparts. Blends with linear PDLA additives exhibited two distinct melting peaks at 170-180 degrees C and 200-250 degrees C which implied that two distinct crystalline domains were present, that of the homopolymer and that of the stereocomplex, the more stable crystalline structure formed by the co-crystallization of both d- and l-lactide enantiomers. In contrast, blends of PLLA with multi-branched PDLA formed a single broad melting peak indicative of mainly formation of the stereocomplex, behavior which was confirmed by X-ray diffraction (XRD) analysis. The heat deflection temperature determined by thermal mechanical analysis was improved for all blends compared to neat PLLA, with increases of up to180 degrees C for 20% addition of the 3-arm PLLA additive. Rheological properties of the blends, as characterized by complex viscosity (*), remained stable over a wide temperature range. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42858.
机译：研究了熔融状态下聚（l-乳酸）（PLLA）和聚（d-乳酸）（PDLA）之间的立体配合物形成，并通过添加多支化聚（d-lactide）（PDLA）添加剂来改变。合成了两种不同的多支PDLA添加剂（3臂和4臂星形聚合物结构）作为潜在的耐热性改性剂，并通过熔融共混以5、10和20（w / w）的比例掺入PLLA中。将这些共混物的机械和热机械性质与线性聚（l-丙交酯）（PLLA）以及通过添加两种分子量与支链对应物相似的线性PDLA类似物形成的共混物进行了比较。与线性PDLA添加剂的共混物在170-180摄氏度和200-250摄氏度下表现出两个不同的熔融峰，这表明存在两个不同的结晶域，即均聚物和立体配合物的结晶域，由它们形成的晶体结构更稳定。 d-丙交酯和l-丙交酯对映异构体的共结晶。相反，PLLA与多支PDLA的共混物形成单个宽熔融峰，该熔融峰主要表示立体复合物的形成，这通过X射线衍射（XRD）分析证实。与纯PLLA相比，通过热力学分析确定的所有共混物的热变形温度均得到改善，添加20％的3臂PLLA添加剂可将温度提高至180摄氏度。以复数粘度（*）为特征的共混物的流变特性在很宽的温度范围内保持稳定。 （c）2015 Wiley Periodicals，Inc. J. Appl。 Polym。科学2016，132，42858。

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