Abstract: Blends of extrudable, moldable, or heat formable thermoplastic polymers with a surface altering agent for the thermoplastic polymer comprising cross-linked polymer particles having an average size of 1 to 30 microns are disclosed. Also disclosed are processes for preparing such blends.

Abstract: A process for preparing crosslinked spherical particulate addition polymeric (<30 microns in diameter) of ethylenically unsaturated monomers and polyunsaturated crosslinking monomers, such as a polymer of styrene crosslinked with divinylbenzene, is provided. Preferably, subsequent to polymerization of the polymer particles, additional crosslinking is provided by reaction of functional groups in the addition-polymerized monomers other than carbon-to-carbon unsaturation, such as the reaction of an epoxy group with a carboxyl group. The minute particles are utilized as "pigments" in cast, molded, or extruded normally transparent plastics such as polymethyl methacrylate, or in coatings and films, to make such articles translucent, or opaque if in large proportions.The refractive index of the particulate polymer is of course different than that of the continuous plastic matrix of the final article, and is preferably above that of the matrix.