Studies On The Preparation Of Polymer Latex With Porous Structure And Their Damping Property

It is well known that latex particles with hollow structure have excellent damping function and other performance. The preparation of those should offer the broader spectrum of properties. In this paper, two ways of preparation of polymer latex particles with hollow structure were studied in detail. One is the stepwise alkali/acid method, the other is the causing-porous solvent method.In the first method, P(styrene-acrylate) latex particles were synthesized by semi-continuous seeded emulsion polymerization free emulsifiers, in which there is gradient distributing of glass transition temperature(Tg). And these particles consist of the core based on ethyl acrylate and methyl methacrylate, the intermediate shell based on ethyl acrylate, methyl methacrylate and acrylic acid, and the outer shell based on styene(St), acrylic acid, methacrylic acid and divinylbenzene(DVB). The particles gained above were treated in alkali and acid solution subsequently, with 17% butanone as swelling agent, at 120癈 for 1.5 hours. Particles sizes and morphologies were characterized by TEM. Obvious hollow structure could be found. The condition of polymerization, the influence of crosslinking agent, the treating temperature, the initial pH value during acid treating and the amount of swelling agent on the stability of emulsion and the formation of hollow structure were also investigated in detail.In the second, P(styrene-divinylbenzene)latex particles were synthesized by emulsion polymerization in the presence of toluene and heptane as diluents for the monomers to cause porous structure. Afterpolymerization, the latex particles were treated by the water vapour distillation. The effects of Tol/Hep ratio, diluents/monomer ratio and emulsifiers content on the stability of emulsion and porous structure were also investigated.After mixed with pure acrylate latex, with the purpose of improving filming characteristic, the dynamic viscoelastic property had been studied. It is showed that there is good consistence between latex and the porous particles obtained by the stepwise alkali/acid method had more excellent damping property than those gained by the causing-porous solvent method.