The effect of initiator and weight ratio on dynamic-mechanical properties of multilayer latex IPN with core/shell morphology

Polymers have good dynamic mechanical properties and high damping capacity due to their viscoelastic nature, especially in the glass transition range, and are considered a good damper with a loss factor greater than 0.3 and a peak temperature range of at least 60-80ºC. Two of the best ways to expand the damping range are fabricating the core/shell latex particles with a specific morphology and using interpenetrating polymer networks in the core and shell sections. The aim of this study is to synthesize and investigate the dynamic-mechanical properties of interpenetrating polymer networks with core/shell morphology. A set of multilayer core/shell/shell latex particles with styrene-acrylic monomers were synthesized by varying the initiator (thermal initiator and redox initiator) via semi-continuous emulsion polymerization. In this study, synthesized particles were characterized with fourier transform infrared (FT-IR) spectroscopy, the morphology was determined by transfer electron microscopy (TEM), and the size and size distribution were investigated via dynamic laser scattering (DLS), which represent nano-scale particles with narrow distribution. The damping properties of the formed films were studied by dynamic mechanical analysis (DMA). The factors affecting the formation of poly(styrene/methyl methacrylate/butyl acrylate)-based core/shell particles, including the type of initiator and layer mass ratio, were discussed. The results showed that the IPN core/shell latex particles with a thermal initiator exhibited the best damping properties, with a broad effective damping range (tanδ > 0.3). The influence of the layer mass ratio on damping was also explored in this work.