Hybrid free radical-cationic thermal polymerization of methylacryloylpropyl-POSS/epoxy resins nanocomposites

Methylacryloylpropyl polyhedral oligomeric silsesquioxanes (MAP-POSS) was prepared from methylacryloyloxypropyl three methyl silane (MAPTMS) by hydrolytic condensation. The hybrid cationic thermal polymerization of MAP-POSS with bisphenol-A epoxy resin (E-51) using diphenyliodonium fluoride-borate (DPI center dot BF4) as a cationic initiator and benzoyl peroxide (BPO) as co-initiator were investigated by the DSC and FTIR. The dynamic mechanical properties of MAP-POSS/E-51 nanocomposites were characterized by DMA. The results showed that polymerization of MAP-POSS/E-51 are the double hybrid free radical/cationic polymerization. The hybrid cationic polymerizing mechanism and curing kinetics could be simulated by the autocatalytic Sestak-Berggren(S-B) model. The cationic ring-opening average activation energy E-a decrease with added MAP-POSS, when 0, 2, 6, and 10 wt.% MAP-POSS were added into reaction system, the curing reaction E-a of sample is 96.53, 95.16, 93.98, 89.15 kJ/mol, respectively. The glass transition temperature T-g of 8 wt.% MAP-POSS containing sample is 175.6 degrees C, which is 6.1 degrees C higher than the pure E-51 resin.