15 Comparison of Methyl MethacrylateButadiene-Styrene with Acrylonitrile-
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Butadiene-Styrene Graft Copolymers R U D O L P H D . D E A N I N and ISMAIL S. R A B I N O V I C
1
Departments of Chemistry and Plastics, Lowell Technological Institute, Lowell, Mass. 01854 ANTONIO LLOMPART Chemical Laboratory, DeBell & Richardson, Inc., Hazardville, Conn. 06036
Methyl methacrylate was substituted for acrylonitrile in conventional graft copolymerization of acrylonitrile and styrene onto a polybutadiene backbone. Methyl methacrylate favored more homogeneous polymerization, better melt processability, lighter color, and greater stability toward ultraviolet light aging, while acrylonitrile favored greater strength and higher heat deflection temperature. Ultraviolet light discoloration appeared to be caused by oxidation of C=C bonds to C=O and C—OH groups. This was catalyzed by acrylonitrile units and inhibited by methyl methacrylate units in the graft copolymer.
Copolymerization of styrene and acrylonitrile in the presence of poly^ butadiene produces a graft copolymer polyblend in which the polybutadiene contributes ductility and impact resistance while the styrene^acrylonitrile forms a continuous matrix which contributes rigidity, strength, and reasonably high heat deflection temperature. This com bination of useful properties makes acrylonitrile-butadiene-styrene ( A B S ) polymers one of the fastest growing of our present commercial plastics (9). One major deficiency of these materials is their tendency to discolor, particularly under exposure to ultraviolet light during long term outdoor 1 Present address: Rohm & Haas Co., Bristol, Pa.
229 In Multicomponent Polymer Systems; Platzer, N.; Advances in Chemistry; American Chemical Society: Washington, DC, 1971.
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MULTICOMPONENT
Table I.
Emulsion Polymerizations
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Ingredients and Conditions Polymer Components Firestone FR-S-2004 59.2% polybutadiene latex (polybutadiene equivalent) styrene acrylonitrile methyl methacrylate Dispersion M e d i u m deionized distilled water (total) Hercules Dresinate 731 rosin soap Vanderbilt Darvan 1 polymerized N a alkyl naphthalene sulfonate NaOH Initiator System cumene hydroperoxide FeS0 · 7 H 0 Na P 0 dextrose Chain-Transfer Agent n-dodecylmercaptan Polymerization Conditions temperature, °C time, hours Stabilizers Shell Ionol di-ter
