A dense hybrid network of epoxide hyperbranched polyurethane and benzoxazine with improved thermomechanical properties via tuning its curing reaction and physical state

• Published in: Polymer (Guilford) Vol. 179; p. 121659
• Main Authors: Zhang, Chi, Lei, Zixuan, Zhang, Junjie, Jing, Xinli, Wang, Yichao, Liu, Yuhong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 28.09.2019
• Subjects: Benzoxazine; Cross-link density; Epoxidized hyperbranched polyurethane; Self-polymerization and copolymerization; Thermomechanical properties; Benzoxazine; Cross-link density; Thermomechanical properties; Epoxidized hyperbranched polyurethane; Self-polymerization and copolymerization
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2019.121659

In order to reveal the effect of curing reaction and such physical state as gelation and vitrification on the microstructure and the resulting thermo-mechanical properties, a series of epoxidized hyperbranched polyurethane (EHPU) modified benzoxazine resin (BZ) blends (BE) were fabricated. The curing reaction between BZ and EHPU was investigated by nonisothermal DSC, FTIR and isothermal rheology. The self-polymerization or the copolymerization of BZ and EHPU was successfully realized via tuning its curing cycle at different curing temperature. The ether cross-link was realized from the copolymerization between oxazine ring and epoxy groups, which can dilute the rich benzene ring of BZ and weaken the hydrogen bonding of pure BZ. As for BE with 10 wt% of EHPU, both a high cross-link density and an excellent thermomechanical property can be obtained with the curing cycle of entering the vitrification state in the initial stage and then transferring it into the post-curing. As thus, the study provides a novel strategy in fabricating a dense network via tuning the curing reaction and physical state. [Display omitted] •BE with dense cross-link network and improved thermomechanical property was fabricated.•The curing cycle of BE is closely related with its curing physical state.•Tuning the content of ether cross-link and the initial physical state of curing can profoundly influence the microstructure and thermomechanical property.