Browsing by Author "Gu, Jiyou"

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    Bio-based reactive diluents as sustainable replacements for styrene in MAESO resin.
    (Royal Society of Chemistry, 2018-04-12) Zhang, Yuehong; Li, Yuzhan; Thakur, Vijay Kumar; Wang, Liwei; Gu, Jiyou; Gao, Zhenhua; Fan, Bo; Wu, Qiong; Kessler, Michael R.
    Four different biorenewable methacrylated/acrylated monomers, namely, methacrylated fatty acid (MFA), methacrylated eugenol (ME), isobornyl methacrylate (IM), and isobornyl acrylate (IA) were employed as reactive diluents (RDs) to replace styrene (St) in a maleinated acrylated epoxidized soybean oil (MAESO) resin to produce bio-based thermosetting resins using free radical polymerization. The curing kinetics, gelation times, double bond conversions, thermal–mechanical properties, and thermal stabilities of MAESO-RD resin systems were characterized using DSC, rheometer, FT-IR, DMA, and TGA. The results indicate that all four RD monomers possess high bio-based carbon content (BBC) ranging from 63.2 to 76.9% and low volatilities (less than 7 wt% loss after being held isothermally at 30 °C for 5 h). Moreover, the viscosity of the MAESO-RD systems can be tailored to acceptable levels to fit the requirements for liquid molding techniques. Because of the introduction of RDs to the MAESO resin, the reaction mixtures showed an improved reactivity and an accelerated reaction rate. FT-IR results showed that almost all the C[double bond, length as m-dash]C double bonds within MAESO-RD systems were converted. The glass transition temperatures (Tg) of the MAESO-RDs ranged from 44.8 to 100.8 °C, thus extending the range of application. More importantly, the Tg of MAESO-ME resin (98.1 °C) was comparable to that of MAESO-St resin (100.8 °C). Overall, this work provided four potential RDs candidates to completely replace styrene in the MAESO resin, with the ME monomer being the most promising one.
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    High performance thermosets with tailored properties derived from methacrylated eugenol and epoxy-based vinyl ester
    (Wiley, 2018-01-31) Zhang, Yuehong; Li, Yuzhan; Kumar Thakur, Vijay; Gao, Zhenhua; Gu, Jiyou; Kessler, Michael R.
    A renewable chemical, eugenol, is methacrylated to produce methacrylated eugenol (ME) employing the Steglich esterification reaction without any solvent. The resulting ME is used as a low viscosity comonomer to replace styrene in a commercial epoxy-based vinyl ester resin (VE). The volatility and viscosity of ME and styrene are compared. The effect of ME loadings and temperatures on viscosity of the VE-ME resin is investigated. Moreover, the thermo-mechanical properties, curing extent, and thermal stability of the fully cured VE-ME thermosets are systematically examined. The results indicate that ME is a monomer with low volatility and low viscosity, and therefore the incorporation of ME monomer in VE resins allows significant reduction of viscosity. Moreover, viscosity of the VE-ME resin can be tailored by adjusting ME loadings and processing temperature to meet commercial liquid molding technology requirements. The glass transition temperatures of VE-ME thermosets range from 139 to 199 °C. In addition, more than 95% of the monomer is incorporated and fixed in the crosslinked network structure of VE-ME thermosets. Overall, the developed ME monomer exhibits promising potential to replace styrene as an effective low viscosity comonomer. The VE-ME resins show great advantages for use in polymer matrices for high performance fiber-reinforced composites. This work showed great significance to the vinyl ester industry by providing detailed experimental support.