Synthesis of polymer-grafted graphene oxide and polymer-grafted thermally reduced graphene oxide with core-shell structure (CSS) as low-profile additives (LPA) and tougheners for thermoset resins, and their effects on the cured sample morphology, volume shrinkage characteristics, mechanical properties, and thermal conductivities for low-shrink epoxy/4,4’-diaminodiphenylmethane resins (EPR/DDM) after an isothermal stepwise cure of 100oC/180oC have been investigated. These CSS designated as GO-polymer or TRGO-polymer, which contained graphene oxide (GO) or thermally reduced graphene oxide (TRGO) as the core and organic polymer as the shell, were synthesized by the Z supported reversible addition-fragmentation chain transfer (RAFT) graft polymerization using S-Benzyl S'-trimethoxysilyl propyl trithio-carbonate (BTPT) as the coupable RAFT chain transfer agent (CTA). The TRGO was produced by placing the GO in a high-temperature furnace kept at 1050oC for 30 s, which was synthesized from natural graphites with average particle size of 2 to 15 μm by a modified Hummers method. The grafted polymer as the shell structure of the GO-polymer (or the TRGO-polymer) was made from poly(butyl acrylate)-block-poly(methyl acrylate) (PBA-b-PMA) or PBA-b-poly(MA-co-glycidyl methacrylate (GMA)). Depending on the content of GO-polymer (0-5 wt%) (or TRGO-polymer (0-1 wt%)), and the molar composition of GMA (0-20 mol%) incorporated in the outer polymer shell of GO-polymer (or TRGO-polymer), the GO-polymer (or TRGO-polymer) could lead to a reduction of cyclization reaction for epoxy resins during the cure, and the microgel structure during the cure would be less compact, and, in turn, be favorable for the decrease of intrinsic polymerization shrinkage after the cure. In this work, the effects of GO-polymer (or TRGO-polymer) on the volume shrinkage characteristics, mechanical properties, and thermal conductivities of the epoxy/DDM/ GO-polymer (or TRGO-polymer) ternary systems during the cure will be explored and related experimental results will be presented. The experimental results will also be explained by an integrated approach of measurements for the static phase characteristics of the epoxy/DDM/GO-polymer (TRGO-polymer) systems, reaction kinetics, cured sample morphology, and property measurements by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Synthesis of polymer-grafted graphene oxide and thermally reduced graphene oxide by RAFT living free radical solution polymerizations and their effects on the volume shrinkage, mechanical properties, and thermal conductivities of cured epoxy resins

256th National Meeting (2018)

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