A catalytic effect of alumina grains onto polymerization rate of methacrylamide-based gelcasting system

Gelcasting is a promising new technology for manufacturing of advanced ceramic components. However, up to now few articles have been published on the catalytic effect of ceramic filler onto polymerization rate of monomeric systems used in gelcasting. In this work the stress viscosimetry was used to study the catalytic effect of alumina filler onto polymerization rate of methacrylamide-N,N′-methylenebisacrylamide (MAM-MBAM) monomers as a function of alumina volume fraction (0.1-0.5), temperature (20-50 °C) and initiator concentration (0.4-1.3 wt.% on the monomers base). The initiation time of gelcasting suspensions of constant MAM-MBAM volume fraction decreased with increasing initiator/accelerator concentration, temperature and the volume fraction of solids. The alumina effect on the initiation time was more visible at lower initiator concentration, suggesting that ceramic microenvironment is favorable for the gelling process. The calculated activation energies of methacrylamide premix and 50 vol.% ceramic suspension were 32.5 and 21.7 kJ/mol, indicating a catalytic effect of the ceramic filler.