Toughening of epoxy resin by catalyzed reaction with polycarbonate

Date of Completion

January 1995


Chemistry, Polymer|Engineering, Materials Science|Plastics Technology




Studies were performed to determine the major reaction mechanism involved between bisphenol A derived polycarbonate (BPAPC) and diglycidyl ether of bisphenol A (Epon$\sp\circler$ 828) in the presence of quarternary ammonium salt (QAS) catalysts. Diphenyl carbonate (DPC) and bisphenol A (BPA) were used as model compounds for the BPAPC and 1,2-epoxy-3-phenoxypropane (Eppp) and 1,4-butanediol diglycidyl ether (BUDGE) were utilized as model compounds for Epon$\sp\circler$ 828. It was found via gel permeation chromatography (GPC), Ultraviolet-Visible spectroscopy, and fourier transform infrared spectroscopy (FTIR), that in the presence of tetrabutyl ammonium iodide (TBAI), benzyltrimethyl ammonium chloride (BTMAC), or tetrabutyl ammonium hydroxide (TBAOH), BPAPC is hydrolyzed to an extent which is dependent on the amount of QAS catalyst present within the system. This yields lower molecular weight BPAPC fragments which increased the amount of hydroxyl end groups. In addition, it was determined by FTIR and proton nuclear magnetic resonance spectroscopy (NMR) that in the presence of QAS catalysts the hydroxyl endgroup of the BPAPC reacts with the oxirane group of the Epon$\sp\circler$ 828, which may lead to crosslinked copolymer networks. It was determined that the proper BPAPC/Epon$\sp\circler$ 828 compositions which form optically clear hard materials in the presence of 1.0 wt.% TBAI are between 30 to 50 wt.% BPAPC. Differential scanning calorimetry (DSC) studies show that the extent and rate of reaction between the BPAPC and Epon$\sp\circler$ 828 is dependent on the amount of TBAI present within the system. The final system Tg, as observed by DSC, is found to be dependent not only on the temperature at which the cure is performed but also on the time allowed for curing. Dynamic mechanical thermal analysis (DMTA) analysis indicated the presence of a two-phase morphology which is thought to consist of a BPAPC rich phase and a BPAPC/Epon$\sp\circler$ 828 crosslinked copolymer phase. ^