Morphology, design and characterization of IPN-containing structured latexparticles for damping applications

We have prepared a series of novel structured latex particles with interpen etrating polymer network (IPN) cores and glassy SAN shells. The IPN cores w ere composed of two polymers: polybutadiene-based and acrylic-based. The mo rphologies of these latex particles were determined by TEM. The glass trans ition temperature and mechanical behavior of the polymers were characterize d by DMS. The effect of different components on the final core/shell partic le morphologies and mechanical properties was studied. The mechanical behav ior of core/shell particles with IPN cores was also compared with that of s eparate core/shell and multilayered core/shell particles. In addition, norm al core/shell synthesis (rubbery part first, then the glassy part) and inve rted core/shell synthesis (glassy part First, then the rubbery part) were p erformed to provide another access for morphology design and control. It wa s found that the core/shell latex particles with poly(butyl acrylate)-based copolymers are more miscible than poly(ethylhexyl methacrylate)-based copo lymers. The high grafting efficiency of poly(butyl acrylate) plays an impor tant role in governing phase miscibility. The latex particles synthesized b y the inverted core/shell mode showed higher miscibility than the normal sy nthesized ones. The damping properties of different core/shell particles we re evaluated based on the loss area (LA) from dynamic mechanical spectrosco py measurements. The IPN core/shell polymers were found to be the best damp ers due to their more miscible chemistry. The highest level of damping was achieved by inverting core/shell particles with dual-phase continuity compa red to normal core/shell particles. (C) 1999 Elsevier Science B.V. All righ ts reserved.