Abstract: A method and structure for analysis of the size and/or distribution of low-density particles by centrifugal sedimentation in a centrifuge chamber containing a fluid where the particles to be tested are delivered to the bottom of the centrifuge chamber and allowed to float upwards in the higher density fluid within the centrifuge chamber to be analyzed.

Abstract: A process is disclosed for producing vinyl halide homopolymers and copolymers that are suitable for use in clear solutions. The process comprises reacting vinyl halide and optional co-monomers in the presence of an aqueous medium containing a suspending agent, and treating the resulting resin particles with an acidic material. The resins resulting from the process of the invention have improved solution and film properties. When the resin is dissolved in a suitable solvent, the resulting solution has improved clarity, that is, a reduction of haze in the solution phase. When the solution is coated on a substrate and the solvent evaporated, either to provide a coated substrate or a cast film, the resulting films have improved clarity, that is, a reduction in haze in the film. The films and coatings have improved gloss as a result of reduction of seed particles in the film. Fibers produced from the resin solutions have improved integrity and strength.

Abstract: A polyvinyl chloride having high bulk density and enhanced plasticizer absorption is produced by suspension polymerization of vinyl chloride monomer and comonomers wherein the initial suspension of ingredients is generated such that the oil phase droplets formed in the suspension are compositionally equivalent with respect to initiator, and the level of suspending agent and agitation are chosen to substantially preclude agglomeration of resin particles throughout the reaction, thereby producing resin wherein the resin grain size distribution results directly from the oil phase droplet distribution created at or near the start of the reaction. The process is conducted under conditions so that the polymerization is commenced before the final distribution is established. In this manner, seed particles of resin are produced from the vinyl monomer prior to establishing the final particle distribution.

Abstract: A polyvinyl chloride having high bulk density and enhanced plasticizer absorption is produced by suspension polymerization of vinyl chloride monomer and comonomers wherein the initial suspension of ingredients is generated such that the oil phase droplets formed in the suspension are compositionally equivalent with respect to initiator, and the level of suspending agent and agitation are chosen to substantially preclude agglomeration of resin particles throughout the reaction, thereby producing resin wherein the resin grain size distribution results directly from the oil phase droplet distribution created at or near the start of the reaction. The process is conducted under conditions so that the polymerization is commenced before the final distribution is established. In this manner, seed particles of resin are produced from the vinyl monomer prior to establishing the final particle distribution.

Abstract: A polyvinyl chloride having high bulk density and enhanced plasticizer absorption is produced by suspension polymerization of vinyl chloride monomer and comonomers wherein the initial suspension of ingredients is formed such that the oil phase droplets formed in the suspension are compositionally equivalent with respect to initiator, and the level of suspending agent and agitation are chosen to substantially preclude agglomeration of resin particles throughout the reaction, thereby producing resin wherein the resin grain size distribution results directly from the oil phase droplet distribution created at the start of the reaction. Seed particles of resin are introduced to the reaction mixture prior to establishing the final particle distribution.

Abstract: A method for improving the clarity of plastisol resin films includes the steps of polymerizing vinyl chloride alone or in the presence of a copolymerizable monomer to yield a latex, and dissolving a nonionic emulsifier in the latex prior to spray drying. The resulting mixture is thereafter spray dried to yield a resin which in turn can be mixed with a plasticizer to form a paste and spread as a thin layer to be fused into a film with heat. Alternatively, the nonionic emulsifier can be added, after spray drying, during preparation of the paste by mixing the emulsifier and plasticizer followed by addition of the resin. The nonionic emulsifiers of the present invention have the formula R--O--(CH.sub.2 CH.sub.2 --O).sub.n H wherein R is selected from the group consisting of fatty acids, polyol fatty acid esters, fatty alcohols, fatty amines, fatty amides, polypropylene oxide and alkylated phenol, and n is an integer ranging from 1 to about 50.