Implantation of poly(ethyl acrylate) in mesoporus poly(styrene-co- divinylbenzene) microspheres as a particulate sound absorbent

Abstract

Porous microspheres of poly(styrene-co-divinylbenzene) (SD) have been synthesized by suspension polymerization. They present a narrow porosity gap (21-24%) and a mean pore-radius range (106-117 Å). The mesoporous voids are then made use as the polymerization reactor for ethyl acrylate (EA), and as a result of the embedded polymerization, linear EA formed is trapped inside the individual particles (SD-EA), and its Tg is brought up to as high as the ambient temperature. Two specific loadings of EA were attained: 11% and 28% by weight. The acoustic absorption behaviors of SD-EA and SD microspheres are assessed by the attenuation coefficient (α = IAttenuated/I Incidence), in which the incident acoustic waves are two arbitrary audio frequency bands, 100-1000 Hz and 4000-5000Hz. In contrast to porous SD microspheres, SD-EA microspheres apparently relax the incident frequencies and attenuate more effectively the higher frequency sound waves. The maximum attenuation level (a) of SD-EA absorbent is about 80% (dB). It was found that the higher EA loading could improve rather slightly the attenuation level in the higher frequency range. © 2005 Materials Research Society.