Multifunctionalization of novolac epoxy resin and its influence on dielectric, thermal properties, viscoelastic, and aging behavior



In this article, novolac epoxy was functionalized using p-hydroxybenzoic acid as pendent groups, which offered weak acidic environment and were cured with methyl etherified amino resin (HMMM). Its chemical structure was characterized by Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H NMR) and differential scanning calorimeter (DSC). To comprehensively investigate its performance, HMMM was used as a curing agent. The modified epoxy exhibited higher storage modulus, lower thermal expansion coefficient, better moisture resistance, better resistance to degradation and lower dielectric constant. Furthermore, the aging behavior was investigated using dynamic mechanical analysis and scanning electron microscopy, which showed that the activation energy of glass transition increased after aging and cured MDEN was more difficult to age. Moreover, the relation between storage modulus and curing rate was established; the low curing rate of MDEN decreased the growth rate of storage modulus and reduced the internal stress, which was beneficial for processing. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40157.