Momeni Sarieh, Rezvani Ghomi Erfan, Shakiba Mohamadreza, Shafiei-Navid Saied, Abdouss Majid, Bigham Ashkan, Khosravi Fatemeh, Ahmadi Zahed, Faraji Mehdi, Abdouss Hamidreza, Ramakrishna Seeram
Department of Chemistry, Amirkabir University of Technology, Tehran 15875-4413, Iran.
Center for Nanotechnology and Sustainability, Department of Mechanical Engineering, National University of Singapore, Singapore 117581, Singapore.
Polymers (Basel). 2021 Mar 25;13(7):1019. doi: 10.3390/polym13071019.
As a hydrophilic renewable polymer, starch has been widely used in biocompatible plastics as a filler for more than two decades. The present study aimed at investigating the effects of polyethylene glycol (PEG), as a plasticizer, on the physicochemical properties of a hybrid composite-polylactic acid (PLA) and thermoplastic starch (TPS). A solvent evaporation process was adopted to gelatinize the starch and disparate PEG contents ranging from 3 to 15 wt.% (with respect to the sample weight) were examined. It was revealed that the increase in the PEG content was accompanied by an increment in the starch gelatinization degree. Referring to the microstructural analyses, the TPS/PLA mixture yielded a ductile hybrid composite with a fine morphology and a uniform phase. Nevertheless, two different solvents, including acetone and ethanol, were used to assess if they had any effect on the hybrid's morphology, tensile strength and thermal properties. It was found that ethanol culminated in a porous hybrid composite with a finer morphology and better starch distribution in the PLA structure than acetone. As the result of PEG addition to the composite, the crystallinity and tensile strength were decreased, whereas the elongation increased. The hydrolytic degradation of samples was assessed under different pH and thermal conditions. Moreover, the microbial degradation of the PLA/TPS hybrid composite containing different PEG molar fractions was investigated in the soil for 45 days. The rate of degradation in both hydrolytic and biodegradation increased in the samples with a higher amount of PEG with ethanol solvent.
作为一种亲水性可再生聚合物，淀粉作为填料在生物相容性塑料中已被广泛使用了二十多年。本研究旨在探究作为增塑剂的聚乙二醇（PEG）对混合复合材料——聚乳酸（PLA）和热塑性淀粉（TPS）物理化学性质的影响。采用溶剂蒸发工艺使淀粉糊化，并考察了3至15 wt.%（相对于样品重量）范围内不同的PEG含量。结果表明，PEG含量的增加伴随着淀粉糊化程度的提高。根据微观结构分析，TPS/PLA混合物产生了一种具有良好形态和均匀相的韧性混合复合材料。然而，使用了两种不同的溶剂，即丙酮和乙醇，来评估它们是否对混合物的形态、拉伸强度和热性能有任何影响。结果发现，与丙酮相比，乙醇使混合复合材料具有多孔结构，形态更精细，且淀粉在PLA结构中的分布更好。由于向复合材料中添加了PEG，结晶度和拉伸强度降低，而伸长率增加。在不同的pH值和热条件下评估了样品的水解降解情况。此外，还研究了含有不同PEG摩尔分数的PLA/TPS混合复合材料在土壤中的微生物降解情况，为期45天。在使用乙醇溶剂且PEG含量较高的样品中，水解降解和生物降解的速率均有所增加。
