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Preparation of ABS (acrylonitrile/butadiene/styrene) latexes using hydroperoxide redox initiators
Author(s) -
Daniels E. S.,
Dimonie V. L.,
ElAasser M. S.,
Vanderhoff J. W.
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070410945
Subject(s) - polymerization , ammonium persulfate , polymer chemistry , chemistry , acrylonitrile , styrene , monomer , polybutadiene , polymer , copolymer , organic chemistry
The 80/20 (w/w) azeotropic styrene/acrylonitrile mixture was copolymerized at 35, 50, and 70°C in crosslinked polybutadiene seed latexes of varying particle size (range 113–242 nm) using the t ‐butyl or cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA‐chelated Fe +2 redox initiator. Other initiators used for comparison were: (1) ammonium persulfate at 70°C; (2) ammonium persulfate/sodium bisulfite redox initiator at 35 and 50°C; (3) oil‐soluble, 2,2'‐azobis(2,4‐dimethylvaleronitrile) at 50°C. The following polymerization parameters were varied systematically: (1) polybutadiene seed latex particle size; (2) monomer/polymer swelling ratio; (3) polymerization temperature; (4) type and concentration of initiator; and (5) mode (and duration) of initiator addition. The following parameters were determined: (1) polymer yield (final conversion); (2) variation of conversion with time; (3) morphology of the latex particles; (4) amount of coagulum; and (5) fraction of styrene/acrylonitrile monomer mixture grafted to the polybutadiene seed latex (defined here as grafting efficiency). For polymerizations using the t ‐butyl or cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA‐chelated Fe +2 redox initiator, the rates of polymerization were faster, the grafting efficiencies were greater, and the amounts of coagulum were greater at 70°C than at 50 or 35°C. The rates of polymerization were decreased by decreasing the concentration of redox initiator or adding it incrementally. A 1.00/1.00/0.08 (w/w) t ‐butyl or cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA‐chelated Fe +2 ratio gave reasonable polymerization rates at 35 and 50°C, and a 0.48/1.00/0.07 ratio, at 70°C. The latexes were stabilized during polymerization with 3% (based on seed solids) nonionic Igepal CO‐990 at 35°C, and 6% at 50 and 70°C. The grafting efficiency increased with decreasing particle size of the polybutadiene seed latex and decreasing monomer/polymer ratio. The rate of polymerization increased with decreasing monomer/polymer ratio. The monomer/polymer ratio also affected the morphology of the particles; higher values gave inclusions of poly(styrene‐ co ‐acrylonitrile) in the polybutadiene particles. There were no significant differences in polymerization kinetics or grafting efficiency between the t ‐butyl and cumene hydroperoxides.