Li Yongchao, Qiu Ying, Wei Lan, Song Yu, Guo Wanyuan, Yu Lingxiao, Gao Guangxu, Gao Jialu, Huang Jiangting, Wang Yuanxia, Shi Ying, Liu Li-Zhi, Zhang Qi, Song Lixin
College of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China; Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China.
College of Chemistry, Jilin University, Changchun 130012, China.
Int J Biol Macromol. 2025 Apr;303:140513. doi: 10.1016/j.ijbiomac.2025.140513. Epub 2025 Jan 30.
Application of biodegradable polylactic acid (PLA) is limited by its poor toughness. This research focuses on modifying PLA using thermoplastic elastomers (TPO), primarily due to their dual advantages of enhancing performance and reducing application costs. Two thermoplastic polyolefin elastomers (TPO) (NS06, Versify2300) were blended to prepare a superior elastomer TPO(NV) (NS06:Versify2300 = 80:20). This improved TPO(NV) was then used as a toughening agent to enhance the toughness of polylactic acid (PLA). To enhance the compatibility between PLA and TPO(NV), TPO(NV)-g-(GMA-co-St) graft copolymer and dibutyl itaconate (DBI) were introduced into the PLA/TPO(NV) blend system. The effects of different compatibilizers on the compatibility, crystallization behavior, rheological properties, mechanical properties, and microstructure of the PLA/TPO(NV) blends were systematically studied. The results indicated that glycidyl methacrylate (GMA) and styrene (St) were successfully grafted onto the TPO(NV) molecular chains. The epoxy groups in GMA within the graft copolymer could react with the end groups of the PLA resin, while the double bonds in DBI could react with the main chains of either PLA or TPO(NV) elastomer. This effectively connected the PLA and TPO(NV) molecular chains, collectively enhancing the compatibility between TPO(NV) elastomer and PLA. The non-isothermal crystallization ability of TPO(NV) decreased after blending with PLA, and this effect was further amplified with the introduction of the TPO(NV)-g-(GMA-co-St) graft copolymer or DBI. However, the plasticizing effect of DBI increased the mobility of the polymer molecular chains, thereby enhancing the crystallization ability. Therefore, when DBI was used alone to enhance the compatibility of PLA/TPO(NV) blends, the crystallinity of the blend did not change significantly. In contrast, when the TPO(NV)-g-(GMA-co-St) graft copolymer was used alone or in combination with DBI, the crystallinity of the blend decreased significantly. Mechanical property tests indicated that the addition of either the TPO(NV)-g-(GMA-co-St) graft copolymer or DBI improved the compatibility of PLA/TPO(NV) blends, thereby enhancing their mechanical properties. However, the combined addition of both the TPO(NV)-g-(GMA-co-St) graft copolymer and DBI resulted in a more pronounced effect. The notched impact strength and elongation at break reached optimal values, which were 1.9 times and 10.4 times those of the PLA/TPO(NV) blend, respectively. At this point, the fracture surface of the blend exhibited significant plastic flow, indicating characteristics of ductile fracture.
可生物降解聚乳酸（PLA）的应用因其较差的韧性而受到限制。本研究聚焦于使用热塑性弹性体（TPO）对PLA进行改性，主要是因为其具有增强性能和降低应用成本的双重优势。将两种热塑性聚烯烃弹性体（TPO）（NS06、Versify2300）共混以制备性能更优的弹性体TPO（NV）（NS06:Versify2300 = 80:20）。然后将这种改性后的TPO（NV）用作增韧剂来提高聚乳酸（PLA）的韧性。为增强PLA与TPO（NV）之间的相容性，将TPO（NV）-g-（GMA-co-St）接枝共聚物和衣康酸二丁酯（DBI）引入到PLA/TPO（NV）共混体系中。系统研究了不同增容剂对PLA/TPO（NV）共混物的相容性、结晶行为、流变性能、力学性能和微观结构的影响。结果表明，甲基丙烯酸缩水甘油酯（GMA）和苯乙烯（St）成功接枝到TPO（NV）分子链上。接枝共聚物中GMA的环氧基团可与PLA树脂的端基反应，而DBI中的双键可与PLA或TPO（NV）弹性体的主链反应。这有效地连接了PLA和TPO（NV）分子链，共同增强了TPO（NV）弹性体与PLA之间的相容性。TPO（NV）与PLA共混后非等温结晶能力下降，且随着TPO（NV）-g-（GMA-co-St）接枝共聚物或DBI的引入，这种影响进一步放大。然而，DBI的增塑作用增加了聚合物分子链的流动性，从而提高了结晶能力。因此，当单独使用DBI来增强PLA/TPO（NV）共混物的相容性时，共混物的结晶度没有明显变化。相反，当单独使用TPO（NV）-g-（GMA-co-St）接枝共聚物或与DBI联合使用时，共混物的结晶度显著下降。力学性能测试表明，添加TPO（NV）-g-（GMA-co-St）接枝共聚物或DBI均可改善PLA/TPO（NV）共混物的相容性，从而提高其力学性能。然而，同时添加TPO（NV）-g-（GMA-co-St）接枝共聚物和DBI的效果更显著。缺口冲击强度和断裂伸长率达到最佳值，分别是PLA/TPO（NV）共混物的1.9倍和10.4倍。此时，共混物的断裂表面呈现出明显的塑性流动，表明具有韧性断裂的特征。
