Buchatip Suthawan, Supmak Wilairat, Sangroniz Leire, Opaprakasit Mantana, Petchsuk Atitsa, Opaprakasit Pakorn, Müller Alejandro J
National Metal and Materials Technology Center, Thailand Science Park, Pathum Thani 12120, Thailand.
POLYMAT and Department of Polymers and Advanced Materials: Physics, Chemistry and Technology, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel de Lardizabal, 3, Donostia-San Sebastian 20018, Spain.
ACS Omega. 2025 Jul 16;10(29):32015-32028. doi: 10.1021/acsomega.5c03596. eCollection 2025 Jul 29.
A process for enhancing polylactide films' heat resistance, shape stability, and toughness has been developed. A star-shaped poly-(ε-caprolactone--d-lactide) (starPCL--PDLA) copolymer was synthesized by using a four-armed PCL macroinitiator. The material was blended with linear poly-(l-lactide) (-PLLA) to form a specific amount of stereocomplex, which endows the material with improved heat resistance. The effect of blend composition on their thermal and heat-resistant properties, toughness, and dynamic mechanical properties was investigated. The melt viscosity was optimized for a blown-film process by the star-shaped polymer's unique rheology. A pouch form package was fabricated with the blends, whose thermal-resistant performance was assessed by in-package thermal pasteurization. The pouches exhibited no visual deformation at the pasteurization temperatures, especially those containing 20 wt % starPCL--PDLA, while -PLLA could not withstand similar treatment conditions. This specific blend also showed an increased toughness of 4.5 times compared to that of -PLLA due to the appropriate content of the flexible PCL star blocks. The properties of the blends were studied by differential scanning calorimetry and wide angle X-ray scattering to understand the role of the star copolymer. Since the extruded pouch initially contains a low amount of crystallinity, the pasteurization triggered the formation of stereocrystals and homocrystals, leading to property enhancement. The judicious design of a star copolymer able to induce stereocomplexation results in high-performance PLA-based degradable packaging.
已开发出一种提高聚乳酸薄膜耐热性、形状稳定性和韧性的方法。通过使用四臂聚己内酯（PCL）大分子引发剂合成了一种星形聚（ε-己内酯-d-丙交酯）（starPCL-PDLA）共聚物。将该材料与线性聚（l-丙交酯）（-PLLA）共混以形成特定量的立体复合物，从而赋予材料更高的耐热性。研究了共混物组成对其热性能、耐热性能、韧性和动态力学性能的影响。通过星形聚合物独特的流变学特性对吹膜工艺的熔体粘度进行了优化。用这些共混物制成了袋状包装，并通过袋内热巴氏杀菌法评估了其耐热性能。这些袋子在巴氏杀菌温度下没有出现明显变形，特别是那些含有20 wt% starPCL-PDLA的袋子，而-PLLA无法承受类似的处理条件。由于柔性PCL星形嵌段的含量合适，这种特定的共混物与-PLLA相比韧性也提高了4.5倍。通过差示扫描量热法和广角X射线散射研究了共混物的性能，以了解星形共聚物的作用。由于挤出的袋子最初结晶度较低，巴氏杀菌引发了立体晶体和均晶体的形成，从而导致性能增强。能够诱导立体复合的星形共聚物的合理设计导致了基于聚乳酸的高性能可降解包装。
