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Structured latex particles as impact modifiers for poly(styrene–co‐acrylonitrile) blends
Author(s) -
Schneider Michael,
Pith Tha,
Lambla Morand
Publication year - 1996
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/(sici)1099-1581(199607)7:7<577::aid-pat544>3.0.co;2-a
Subject(s) - materials science , composite material , natural rubber , dispersity , composite number , scanning electron microscope , acrylonitrile , polystyrene , copolymer , izod impact strength test , polymer , polymer chemistry , ultimate tensile strength
This work was focused on the influence of the morphology of composite natural rubber (NR)‐based particles on the toughness of poly(styrene–co‐acrylonitrile) (PSAN) blends. In order to be suitable for the reinforcement of PSAN blends, the NR‐based particles were coated with a shell of crosslinked poly(methylmethacrylate) (PMMA). Furthermore, polystyrene (PS) subinclusions were introduced into the NR rubber core. PSAN blends were prepared by adding the wet latex directly into a twin screw‐extruder. This new method allowed even tacky pure rubber particles to be dispersed as shown by transmission electron photomicrographs which confirmed the integrity of the soft particles after mixing. Solid NR particles or NR‐based latex particles containing rigid PS subinclusions and no hard shell did not offer any impact improvement to PSAN. Only NR‐based core–shell particles containing at least 25% PMMA in the shell toughened the brittle matrix. Prevulcanized NR‐based latex particles which do not cavitate easily were less effective. Core–shell particles containing PS subinclusions within a natural rubber core allowed more effective use of the rubber phase. From the fracture surface morphology the failure mechanisms of PSAN blends containing the different composite NR particles could be deduced. Monodisperse poly(n‐butylacrylate)‐based core–shell particles were too small to toughen PSAN. However, a similar dependence of the fracture mechanisms on the morphology of the incorporated toughening agent could be established by scanning electron microscopy.