Polycarbonate networks. Part 2. Cure study and determination of mechanical, adhesive, and crystallization properties

Vinylphenylcarbonate terminated oligocarbonates were thermally cured into insoluble three-dimensional networks. The cure reaction of the functional oligomers with varied molecular weights was studied under different reaction temperatures and cure times. The K1c fracture toughness was determined for the cured samples and the values obtained show that the polycarbonate networks retain some of the toughness of linear thermoplastic polycarbonate. Dynamic mechanical analysis was performed on the uncured, partially cured, and fully cured samples and a shift in glass transition temperature (Tg) to higher values was observed with extent of cure. The low temperature secondary relaxation peaks were observed to broaden toward higher values with extent of cure. Tensile measurements of cured samples demonstrated an increase in tensile strengths for the cured materials relative to low molecular weight oligomers, but with no change in modulus, while the tensile elongations of the cured samples showed an improvement over oligomers. The crystallizability of the cured materials was examined and it was determined that a significant improvement in solvent resistance to crystallization was obtained over that of linear polycarbonate. The materials also show potential as structural adhesives.