Study on copolymerization modification and properties of bio-based trifunctional diphenolic acid epoxy resin by CE and DPR

Diphenolic acid epoxy resin (DPAE), a new type of bio-based epoxy, exhibits many attractive performances, such as high reactivity, low expansion coefficient (CTE), high glass transition temperature (Tg) and high storage modulus. However, the dielectric constant of DPAE is not satisfied for the requirements of high frequency circuit field, which need to be further improved to expand its application in emerging area of electronic information. In this work, both dicyclopentadiene phenol epoxy resin (DPR) and cyanate ester (CE) were used to modify DPAE in order to improve its dielectric property, while keeping good heat resistance and low dimensional stability. Furthermore, the influence of curing agent types on properties of DPAE/DPR system was studied. Compared with DPAE resin, both DPAE/DPR and DPAE/CE composites exhibited higher glass transition temperature (Tg), lower dielectric constant, lower loss tangent with good compatibility between DPAE and those two resins. Moreover, CE resin exhibited better modified effect than DPR on thermal and dielectric properties of DPAE with the same addition. For example, the dielectric constant and loss tangent of DPAE/CE with 50 wt% CE were as low as 3.4 and 0.018 at 1 MHz, respectively.