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Emulsion copolymers of alpha‐methylstyrene and styrene
Author(s) -
Rudin Alfred,
Samanta M. C.
Publication year - 1979
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.1979.070240810
Subject(s) - copolymer , polystyrene , polymer chemistry , styrene , osmometer , polymer , gel permeation chromatography , materials science , branching (polymer chemistry) , emulsion polymerization , molar mass distribution , monomer , polymerization , thermal stability , chain transfer , emulsion , chemical engineering , radical polymerization , chemistry , organic chemistry , composite material , engineering
This article reports molecular weights and mechanical and processing properties of a series of styrene/alpha‐methylstyrene copolymers produced by emulsion polymerization at various temperatures. Molecular weights were measured by solution viscosity, membrane osmometry, light scattering, and gel‐permeation chromatography. Molecular weight development is controlled by chain transfer to monomer, but the molecular weight distributions are broader than would be expected for such reactions. This is attributed to polymer branching resulting from chain‐transfer events. Molecular weight distributions of copolymers were multimodal. Thermal stability of the copolymers is somewhat lower than that of polystyrene, but addition of conventional antioxidants produces compositions with good stability in thermoplastic processing operations. Copolymers containing 25 wt. % of alpha‐methylstyrene have usage temperatures about 12°C higher than that of polystyrene.