This study investigated the different viscosity effects of natural isoprene rubber (NR) compared to the synthetic one (IR) on toughening of polylactic acid (PLA). Here, 15 wt% rubber was melt blended with PLA in an internal mixer at 180°C and 50 rpm. It was found that the addition of these rubbers led to a significant increase in the tensile toughness and impact strength. These rubbers were masticated at 50°C and at 200 rpm for various mastication times to reduce their molecular weights. A too-long mastication time was found to adversely affect the impact strength and tensile toughness due to the fast agglomeration of rubber particles. At a comparable viscosity, it was remarkable that the impact strength of PLA/NR was higher than that of PLA/IR regardless of the similar chemical structures probably because the presence of nonrubber components including proteins and lipids could enhance the interfacial interaction between NR and the PLA matrix.

中文翻译：

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咀嚼型天然和合成异戊二烯橡胶的粘度对聚乳酸增韧的影响

这项研究调查了天然异戊二烯橡胶（NR）与合成异戊二烯橡胶（IR）相比对聚乳酸（PLA）增韧的不同粘度影响。在此，在内部混合器中以180℃和50rpm将15wt％的橡胶与PLA熔融共混。发现添加这些橡胶导致拉伸韧性和冲击强度显着增加。将这些橡胶在50°C和200 rpm的压力下进行各种咀嚼时间，以降低其分子量。发现太长的咀嚼时间由于橡胶颗粒的快速团聚而不利地影响冲击强度和拉伸韧性。在相当的粘度下