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首页> 外文期刊>Journal of Applied Polymer Science >Influence of extrusion temperature on molecular architecture and crystallization behavior of peroxide-induced slightly crosslinked poly(L -lactide) by reactive extrusion
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Influence of extrusion temperature on molecular architecture and crystallization behavior of peroxide-induced slightly crosslinked poly(L -lactide) by reactive extrusion

机译：挤出温度对过氧化物诱导的轻度交联聚乳酸交联反应的分子结构和结晶行为的影响

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摘要

The influence of temperature during reactive extrusion of poly(L-lactide) (PLLA) on the molecular architecture and crystallization behavior was investigated for OO-(t-butyl) O-(2-ethylhexyl) peroxycarbonate-modified polymer. The long chain-branched PLLA (LCB-PLLA) content and its structure in the resulting slightly crosslinked PLLA (χ-PLLA) containing linear and LCB-PLLA were characterized by both analyses, size exclusion chromatography equipped with multiangle laser light scattering and rheological measurements. A reduction of LCB-PLLA content in χ-PLLA and an increase of number of branches in LCB-PLLA were found with increasing the extrusion temperature. An increase of extrusion temperature induces different process in the polymer: decrease of the lifetime of peroxide, increase of the radical concentration due to rapid peroxide decomposition rate, and increase of the chain diffusion to the amorphous phase. Among these indices, the lifetime of peroxide is a good index for crosslinking behavior of PLLA during extrusion. As for the isothermal crystallization behavior from the melt, the Avrami crystallization rate constant of χ-PLLA increases as an increase of LCB-PLLA content in χ-PLLA. This implies that LCB-PLLA acts as a nucleating agent for PLLA. Furthermore, regime analysis and the free energy of nucleus of χ-PLLA were investigated using Hoffman-Lauritzen theory.
机译：研究了OO-（叔丁基）O-（2-乙基己基）过氧碳酸酯改性聚合物对聚（L-丙交酯）（PLLA）反应挤出过程中温度对分子结构和结晶行为的影响。通过分析，配备多角度激光散射的尺寸排阻色谱法和流变学测量来表征所得长支链PLLA（LCB-PLLA）的含量及其在含有线性和LCB-PLLA的微交联PLLA（χ-PLLA）中的结构。随着挤出温度的升高，发现χ-PLLA中LCB-PLLA含量降低，LCB-PLLA中支链数量增加。挤出温度的升高在聚合物中引发了不同的过程：过氧化物的寿命缩短，由于过氧化物的快速分解速率导致的自由基浓度增加以及链扩散至无定形相的增加。在这些指标中，过氧化物的寿命是挤出期间PLLA的交联行为的良好指标。至于熔体的等温结晶行为，随着PLLA中LCB-PLLA含量的增加，χ-PLLA的Avrami结晶速率常数也随之增加。这意味着LCB-PLLA充当PLLA的成核剂。此外，使用霍夫曼-劳里森理论研究了态势分析和χ-PLLA核的自由能。

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