Extraordinary toughness and heat resistance enhancement of biodegradable PLA/PBS blends through the formation of a small amount of interface-localized stereocomplex crystallites during melt blending

• Published in: Polymer (Guilford) 2022-12, Vol.262, p.125454, Article 125454
• Main Authors: Gu, Zhonghui, Zhang, Jiangang, Cao, Wen, Liu, Xiong, Wang, Jiashun, Zhang, Xianming, Chen, Wenxing, Bao, Jianna
• Format: Article
• Language: English
• Subjects: Biodegradable polymer; Mechanical properties; poly(l-lactide); Stereocomplex crystallites
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2022.125454

Simultaneously improving the toughness and heat resistance of poly(l-lactide) (PLLA) is significant for expanding biodegradable materials' application range. In this work, reactive compatibilizers containing PBS and PLLA (PBS-St-GMA-PLLA (SGL)) or poly(d-lactide) (PBS-St-GMA-PDLA (SGD)) were synthesized and incorporated in blends of commercial PLLA and PBS as compatibilizers. The in situ formation of stereocomplex (SC) crystallites of PLA at the interface of PLLA and PBS was successfully achieved through simple melt blending. The effects of SC crystallites, amount of compatibilizers on morphology, crystallization behavior, mechanical properties, heat resistance and degradability properties of PLLA/PBS blends were studied. Morphological evolution showed that SGL and SGD significantly improved the compatibility of PLLA/PBS blends. After incorporating 5% SGD, the elongation at break and notched impact strength of PLLA/PBS blends with SC crystallites reached 273% and 34 kJ/m2, respectively, 12 and 5 times than that of pristine PLLA/PBS blends. As compared with PLLA/PBS/SGL blends that cannot form SC crystallites, the tensile strength of the blends was effectively improved by the presence of SC crystallites, ascribing to improved interfacial compatibility and remarkable acceleration in matrix crystallization kinetics of PLLA. Consequently, the blends containing 5% SGD exhibited excellent heat resistance (E′80°C > 680 MPa) after brief annealing, which far exceeded the PLLA or PLLA/PBS blends. This work may provide a feasible way to prepare PLLA-based materials with excellent comprehensive properties by the formation of SC crystallites. Supertoughened and heat-resistant biodegradable PLLA/PBS blends were prepared by adding a reactive compatibilizer containing PDLA and PBS. A 82.7 and 8.6-fold increase in elongation at break and impact strength was achieved upon incorporating 5 wt% reactive compatibilizers due to the presence of small amount of interface-localized SC crystallites in PLLA/PBS blends. [Display omitted] •Reactive compatibilizers containing PDLA and PBS were prepared through simple melt blending and incorporated in blends of commercial PLLA and PBS as compatibilizer.•Interface-localized SC crystallites were formed between the grafted PDLA chains and PLLA matrix under shear, which further improved interfacial adhesion and induced morphological evolution.•After incorporation of 5% reactive compatibilizers, the elongation at break and notched impact stre