PREPARATION AND CHARACTERIZATION OF POLY(BUTADIENE-STAT-STYRENE) POLY(STYRENE-STAT-ACRYLONITRILE) STRUCTURED LATEX-PARTICLES

In rubber toughening of thermoplastics, core/shell polymers have been used extensively. This work introduces the synthesis and characterizat ion of polybutadiene based core/shell latex particles with controlled particle size and crosslinking density of the core. A lithium soap rec ipe was employed to prepare a series of poly(butadiene-stat-styrene) ( 90/10 by wt) core particles by conventional emulsion polymerization th rough a batch process. The shell polymer, poly(styrene-stat-acrylonitr ile) (72/28 by wt), was polymerized by a semicontinuous process in the presence of the core particles to form a core/shell morphology. The e ffects of initiator concentration, monomer feeding rate, core/shell ra tio, and gel-fraction of the core on the core/shell particle morpholog y were studied. The degree of grafting of the shell polymer on the cor e particles was determined as well. The morphology and glass transitio ns of these particles were characterized by transmission electron micr oscopy, differential scanning calorimetry, and dynamic mechanical spec troscopy. These latex particles can be used specifically in toughening polycarbonate. (C) 1997 John Wiley & Sons, Inc.