Frontal Cationic Curing of Epoxy Resins in the Presence of Defoaming or Expanding Compounds

Thermal frontal polymerization was carried out with trimethylol propane triglycidyl ether using two different BF3-amine complexes, B-950 and B-110 from Leepoxy, as initiators for cationic polymerization. The amounts of filler (kaolin or fumed silica), defoaming, or expansion agents were varied to study how the compositions affected the front velocity, expansion, and flexural modulus of the resulting epoxy resins. The polymer produced with B-950 initiator showed higher modulus than the polymers produced with B-110. Moreover, fumed silica created stronger materials than kaolin. The presence of BYK as a defoamer or an expansion agent such as the Expancel #80 was also able to affect significantly the mechanical properties. differential scanning calorimetry studies indicated that the conversion was complete and that kaolin and silica increased the rate of reaction. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40339.