Abstract: The present invention relates to a process for the preparation of water expandable polymer beads, which process comprises the steps of: a) providing a starting composition comprising styrene and a cross-linking agent containing a hydrophilic polymer chain and at least two hydrolysable end-groups having a carbon-to-carbon double bond, b) prepolymerizing the starting composition to obtain a prepolymer composition, c) adding an aqueous dispersion of a modifier-free nanoclay to the prepolymer composition to obtain an inverse emulsion, d) suspending the inverse emulsion obtained by step c) in an aqueous medium to yield an aqueous suspension of suspended droplets and e) polymerizing the monomers in the droplets of the suspension obtained by step d) to obtain the water expandable polymer beads.

Abstract: The present invention relates to a process for the emulsifier-free preparation of water expandable polymer beads, which process comprises the steps of: a) providing an emulsifier-free starting composition comprising styrene and a polyphenylene ether resin, b) prepolymerizing the starting composition to obtain a prepolymer composition, c) adding an aqueous dispersion of a modifier-free nanoclay to the prepolymer composition to obtain an inverse emulsion, d) suspending the inverse emulsion obtained by step c) in an aqueous medium to yield an aqueous suspension of suspended droplets and e) polymerizing the monomers in the droplets of the suspension obtained by step d) to obtain the water expandable polymer beads.

Abstract: The present invention relates to a process for the emulsifier-free preparation of water expandable polymer beads. The process comprises the steps of: a) providing an emulsifier-free monomer composition comprising styrene and a polar comonomer comprising a carbon-to-carbon double bond, b) prepolymerizing the monomer composition to obtain a prepolymer composition comprising styrene, the polar comonomer and their copolymer, c) adding an aqueous dispersion of nanoclay to the prepolymer composition to obtain an inverse emulsion, d) suspending the inverse emulsion obtained by step c) in an aqueous medium to yield an aqueous suspension of suspended droplets and e) polymerizing the monomers in the droplets of the suspension obtained by step d).

Abstract: Particles of a copolymer of a vinyl arene and a copolymerizable compound containing a polar moiety and a vinyl moiety containing water may be prepared by forming a mixture of monomers and small amounts of water and polymerizing under agitation to 20 to 70% conversion and then suspending the mass in water and finishing the polymerization. The resulting polymer beads contain finely dispersed water which is useful as an environmentally acceptable blowing agent.

Abstract: It is desirable to reduce the amount of volatile organic blowing agent in expandable polystyrene. This may be accomplished by partially polymerizing a mass of styrene and incorporating therein water together with an emulsifier. The partially polymerized mass is then polymerized to a high conversion using conventional suspension techniques. The polymer beads containing water which acts as a blowing agent are recovered.