Effect of surfactant on dispersion of alumina in photopolymerizable monomers and their UV curing behavior for microstereolithography

Ceramic microstereolithography has recently emerged as a solid free form fabrication techniques for the fabrication of three-dimensional (3D) ceramic components of complex shapes. The spatial resolution of ceramic parts depends upon cure depth and cure width of UV curable ceramic suspensions. Ceramic particle size, its distribution and difference in the refractive indices between ceramic particles and UV curable monomer influence suspension microstructure which will be reflected in viscosity change and extent of colloidal gelation. Suspensions of alumina are formulated in a monomer having hydrophobic backbone structure (monomer chains terminating both ends with –CH2–) by dispersing alumina modified with suitable carboxylic acids (stearic acid and oleic acid). Another suspension was prepared just by dispersing as received alumina in a monomer having hydrophilic backbone structure (monomer chains terminating one end with –OH–). Suspensions exhibit different microstructures owing to solvency of adsorbed layer in monomer having hydrophobic backbone structure, interaction of hydroxyl groups present on alumina particles with monomer having hydrophilic backbone structure as revealed by dynamic rheology. We report effect of microstructure of these suspensions on UV curing behavior by monitoring C=C conversion. The spatial resolution of ceramic part is predicted by measuring cure depth and cure width for the suspensions cured in microstereolithography apparatus.