The use of structural core/shell latex particles as toughening agents
provides a model system which allows independent control of several ke
y factors that influence the fracture toughness of modified plastics.
This paper focuses on varying the shell composition of poly(butadiene-
co-styrene) [P(B-S)] core/poly(methyl methacrylate) (PPMA) shell parti
cles by incorporating acrylonitrile (AN) comonomer into the PMMA shell
at various AN/MMA ratios and by crosslinking of the shell at various
AN/MMA ratios. It was found that the degree of particle dispersability
in the epoxy matrix can be precisely controlled by the AN content in
the PMMA shell and by crosslinking the PMMA in the shell. It was also
found that the degree of particle dispersability plays a crucial role
on the fracture toughness of the modified epoxies. A microclustered mo
rphology provides a much higher toughness than a uniform particle dist
ribution. Copyright (C) 1996 Elsevier Science Ltd.