Toughness modification of cationic UV-cured cycloaliphatic epoxy resin by hydroxyl polymers with different structures. (15th March 2020)

• Record Type: Journal Article
• Authors: Xia, Yuzheng; Zhang, Dong; Li, Zhen; Lin, Heng; Chen, Xiaonong; Oliver, Susan; Shi, Shuxian; Lei, Lei
• Is Part Of: European polymer journal. Volume 127(2020)
• Publication Date: 2020-03-15
• Subjects: Cycloaliphatic epoxy resin -- UV-curing -- Toughness modification -- Hyperbranched polyester terminated with 6 hydroxy groups -- Linear hydroxy-ended polytetramethylene ether glycol; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2020.109594
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Highlights: Toughness modification of cationic UV-cured cycloaliphatic epoxy resin. PTMG was introduced to cationic UV-curing system as soft segment. Compared the effects of hyperbranched H2004 and linear PTMG. Impact strength of epoxy resin was significantly improved by PTMG. Abstract: In this work, cationic UV-curable epoxy-expansive matrix composites based on cycloaliphatic epoxy resin (CE) were prepared using trarysulfonium hexafluorophosphate salt as photoinitiator, and hyperbranched polyester terminated with 6 hydroxy groups (H2004) or linear hydroxy-ended polytetramethylene ether glycol (PTMG) as toughness modifiers. Effects of H2004 and PTMG on the UV-curing kinetics, mechanical and thermal properties were systematically compared. An acceleration phenomenon was observed by real-time FTIR characterisation during the UV-curing of CE/H2004, which may be attributed to the hydroxy group participation of H2004 based on an activated monomer mechanism. However, the epoxy group conversion in the CE/PTMG composite decreased during UV irradiation owing to the random coil morphology of PTMG. Thermal-mechanical properties of the CE/H2004 composite were investigated by dynamic mechanical thermal analysis, which revealed that the glass transition temperature (Tg ) decreased slightly as the H2004 dosage increased, in contrast to the Tg of the CE/PTMG composite, which increased as the PTMG content rose. Compared with CE, the thermal stability of CE/H2004 and CE/PTMG was less, but toughness was improved dramatically by increasing the content of H2004 or PTMG. At concentrations of H2004 and PTMG of 20% and 30%, respectively, the impact strength was improved from 1.14 J/cm 2 for CE to 4.62 J/cm 2 for CE/H2004 and 10.44 J/cm 2 for CE/PTMG. This was further elucidated by fracture surface analysis with a scanning electron microscope.