Water absorption behavior and thermal-mechanical properties of epoxy resins cured with cardanol-based novolac resins and their esterified ramifications
writer：Zhuoyu Liu, Jizhen Huo, Yingfeng Yu*
keywords：Cardanol, Novolac Epoxy, Esterification
source：期刊
specific source：Materials Today Communications 2017, 10, 80-94
Issue time：2017年
To study the effect of chain flexibility and polarity on the water absorption and thermal-mechanicalproperties of epoxy materials, different kinds of bio-based novolac resin hardeners were synthesizedby cardanol-formaldehyde condensation reaction and two esterified ramifications were synthesized byesterifying their corresponding phenolic resin. The cure behaviors were evaluated by differential scanningcalorimeter, and the mechanical and thermal properties of cured samples were characterized by dynamicmechanical analyzer and thermogravimetric analysis. Water absorption process was monitored usinggravimetric measurement, and time-resolved ATR-FTIR. The diffusion mechanism was also explainedusing 2D correlation analysis. The addition of cardanol into novolac resins was found to decrease theglass transition temperature due to the plasticizing effect of flexible aliphatic chain. On the other hand,water resistance ability was enhanced due to lower polarity. The effect of esterification on loweringwater absorption is prominent for both esterified ramifications. The water absorption mechanism wasthen characterized and discussed using 2D correlation analysis of time-resolved ATR-FTIR.