EMULSION COPOLYMERIZATION OF VINYLIDENE-CHLORIDE AND BUTYL METHACRYLATE, 83-17 IN MOL-PERCENT

Seven 35% solids, (83 : 17 in mol %), vinylidene chloride (VDC)-butyl methacrylate (BMA) copolymer latexes were prepared at 25-degrees-C using redox catalyst by batch and seeded semicontinuous emulsion copolymerization processes: one batch (G), one seeded batch (F), and five seeded semicontinuous polymerizations of five different nonomer feed rates ranging from 0.27 (A) to 1.10 (E) wt % / min. All of the emulsion polymerizations gave stable latexes of almost 100% conversion with negligible coagulum and narrow particle size distributions. The kinetic studies of seeded semicontinuous polymerization A-E showed that the rates of polymerization (R(p)) were controlled by the monomer addition rates (R(a)), and polymerizations A-D (0.27-0.79 wt % / min) were under monomer-starved conditions; polymerization E (1.10 wt % / min) was in near-flooded condition. Significant differences were found in the physical and mechanical properties of the latex films, depending on the mode of monomer addition. Infrared spectroscopy, C-13 solid-state NMR spectroscopy, X-ray diffraction, the T(g) and T(m) values by DSC, dynamic mechanical spectroscopy, and tensile strength measurement of the latex films post-heat-treated for 30 min at 70-degrees-C or aged for several months at room temperature demonstrated that batch polymerizations F and G gave copolymers of heterogeneous composition and a crystalline character. In contrast, semicontinuous polymerizations A-E gave copolymers of more uniform composition and an amorphous character.