Synergistic toughening of polypropylene by thermoplastic starch acetate and SEBS‐MAH

• Published in: Journal of applied polymer science Vol. 139; no. 25
• Main Authors: Chen, Youxu, Xu, Xiaoyu, Hu, Yuexin, Han, Yuanyuan, Zhao, Fengyang, Yan, Nan, Jiang, Wei, Zhao, Guiyan
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 05.07.2022; Wiley Subscription Services, Inc
• Subjects: Bioplastics; core‐shell structure; Domains; Elastomers; Impact strength; Maleic anhydride; Materials science; Melt blending; Polymers; Polypropylene; SEBS‐MAH; Shells; Shells (structural forms); Styrenes; synergistic toughening; TPAS
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.52395

The plasticized starch exhibits flexible properties, similar to that of elastomer. In this paper, thermoplastic starch acetate (TPAS) and maleic anhydride grafted poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS‐MAH) were used to toughen polypropylene (PP) through melt blending. It is found TPAS and SEBS‐MAH have a synergistic toughening effect on PP, especially the notched impact strength of PP/TPAS/SEBS‐MAH (70/15/15) blend is as high as 83.4 kJ/m2, but only 7.2 kJ/m2 of that for PP/TPAS/SEBS (70/15/15) blend. The structure‐property relationship of the PP/TPAS/SEBS‐MAH blends was investigated. Compared with PP/TPAS/SEBS (70/15/15) blend, the TPAS domains are dispersed homogeneously in the PP/TPAS/SEBS‐MAH (70/15/15) blend with the domain size of TPAS less than 0.2 μm. The incorporation of SEBS‐MAH not only improves the compatibility between PP and TPAS but also facilitates the formation of a core‐shell structure with TPAS as the core and SEBS‐MAH as the shell. Thus formed core‐shell particles play an important role in toughening PP. The spreading coefficient of the multiphase blend reveals that only when the SEBS‐MAH content is higher than TPAS, the core‐shell structure can be formed. Otherwise, TPAS and SEBS‐MAH will disperse separately and the toughness will not be improved. This work provides a new insight into polymer toughening with TPAS. In the case of PP/TPAS/SEBS blends, SEBS and TPAS dispersed separately. For PP/TPAS/SEBS‐MAH blends, the size of TPAS was lower than that of TPAS in the PP/TPAS/SEBS blends at a given content. It indicates the compatibility between PP and TPAS was improved significantly due to the presence of SEBS‐MAH. Only when the content of SEBS‐MAH is not less than TPAS, a core‐shell structure with TPAS as the core and SEBS‐MAH as the shell can be formed, which plays an important role in PP toughening.