Tuning the Rheological, Thermal, and Solid-State Properties of Branched PLA by Free-Radical-Mediated Reactive Extrusion,ACS Sustainable Chemistry & Engineering

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Tuning the Rheological, Thermal, and Solid-State Properties of Branched PLA by Free-Radical-Mediated Reactive Extrusion
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2018-01-19 00:00:00 , DOI: 10.1021/acssuschemeng.7b03617
Praphulla Tiwary ₁ , Marianna Kontopoulou ₁

Affiliation

The purpose of this work is to establish structure–property relations of poly(lactide) (PLA) formulations that were branched by peroxide-mediated reactive extrusion, in the presence of triallyl trimesate (TAM) coagent. Based on detailed evaluations of the molar mass distributions and rheological properties we deduce that modified PLA consists of a population of linear, and long chain branched (LCB) PLA chains, depending upon the amount of the peroxide and coagent. Even though peroxide alone does not induce significant changes in the architecture, TAM is very effective in producing LCB structures, which result in substantial increases in viscosity, elasticity, as well as strain hardening characteristics. At high DCP and TAM loadings, cross-linked structures are obtained. The reactively modified formulations have higher molar mass, which results in improved Izod impact strength, whereas the rest of the properties, including their capacity to degrade hydrolytically, are maintained. Furthermore, these materials develop high amounts of crystallinity, when cooled under well-controlled conditions, revealing a nucleating effect, which promotes crystallization.

中文翻译：

通过自由基介导的反应挤出调节支化PLA的流变，热和固态性质

这项工作的目的是建立在三苯甲基三甲苯甲酸酯（TAM）助剂存在下，由过氧化物介导的反应性挤出分支的聚丙交酯（PLA）制剂的结构-性能关系。根据对摩尔质量分布和流变性质的详细评估，我们推断改性的PLA由线性和长支链（LCB）PLA链组成，具体取决于过氧化物和助剂的量。即使单独使用过氧化物也不会引起体系结构的重大变化，TAM在生产LCB结构方面还是非常有效的，从而导致粘度，弹性和应变硬化特性大大提高。在高DCP和TAM负载下，可以获得交联结构。反应改性的配方具有更高的摩尔质量，这导致改善的艾佐德冲击强度，而其他性能（包括其水解降解能力）得以保持。此外，当在良好控制的条件下冷却时，这些材料会产生大量的结晶度，从而显示出成核作用，从而促进了结晶。

更新日期：2018-01-19

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