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首页> 外文期刊>Journal of Polymers and the Environment >Melt Strength and Rheological Properties of Biodegradable Poly(Lactic Aacid) Modified via Alkyl Radical-Based Reactive Extrusion Processes
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Melt Strength and Rheological Properties of Biodegradable Poly(Lactic Aacid) Modified via Alkyl Radical-Based Reactive Extrusion Processes

机译：烷基自由基反应挤出工艺改性的可生物降解聚乳酸的熔体强度和流变性能

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摘要

Poly(lactic acid) (PLA) has been modified using twin-screw reactive extrusion to improve its melt properties and crystallinity. In this work lauroyl peroxide was used as an alkyl free radical source, abstracting hydrogen atoms from the PLA backbone leading to branching and chain extension reactions. Once the linear viscoelastic region was determined for these polymers, changes in dynamic rheology (dynamic viscosity real and loss modulus) were measured. Gel permeation chroma-tography showed that the molecular weight and polydis-persity increased to a maximum with the addition of 1.00 and 0.50 wt% peroxide, respectively. Low temperature β transitions in dynamical mechanical thermal traces gave further evidence that branching had also occurred. Gottfert Rheotens measurements showed a three fold increase in melt strength due to both increased chain length and branching. Thermal analysis showed the level of crystallisation had decreased also possibly due to branching. Reductions in crystallinity and improved melt strength are known to be critical for film and foam formation.
机译：聚乳酸（PLA）已使用双螺杆反应挤出进行了改性，以改善其熔融性能和结晶度。在这项工作中，月桂酰过氧化物被用作烷基自由基源，从PLA主链中提取氢原子，从而导致分支和扩链反应。一旦确定了这些聚合物的线性粘弹性区域，就可以测量动态流变学的变化（实际动态粘度和损耗模量）。凝胶渗透色谱法表明，分别加入1.00和0.50 wt％的过氧化物，分子量和多分散度增加到最大。动态机械热迹线中的低温β转变进一步证明了也发生了分支。 Gottfert Rheotens的测量结果表明，由于链长和支链的增加，熔体强度提高了三倍。热分析显示结晶水平也可能由于支化而降低。已知降低结晶度和提高熔体强度对于形成膜和泡沫至关重要。

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