TY - JOUR
T1 - The effect of composition drift and copolymer microstructure on mechanical bulk properties of styrene-methyl acrylate emulsion copolymers
AU - Schoonbrood, H.A.S.
AU - Brouns, H.M.G.
AU - Thijssen, H.A.
AU - Herk, van, A.M.
AU - German, A.L.
PY - 1995
Y1 - 1995
N2 - In order to determine the influence of composition drift and
copolymer microstructure on the mechanical bulk properties of styrene methyl
acrylate copolymers, several copolymers were produced by emulsion
copolymerizalion. Three different average compositions were used. By
perforrming the copolymerizations under batch and semicontinuous conditions
with two different monomor addition strategies (starved conditions and
optimal addition) it was possible to control composition drift and to produce
copolymers with different microstructures (chemical composition
distributions). All these copolymers were processed in a way that ensured
that the original particle structure was lost before the polymers were tested. It
was found that composition drift had an influence on the mechanical
properties (Young's modulus, maximum stress, elongation at break). This
influence could be understood very well on the basis of present knowledge
about structure-mechanical properties relationships. In the case of
homogeneous copolymers maximum stress and elongation at break arc
dependent on the molecular weight, and only weakly dependent on the
chemical composition, and Young's modulus is independent of chemical
composition and molecular weight in the range of compositions investigated,
as expected. ln the case of heterogeneous copolymers, the influence of
copolymer microstructure on Young's modulus, maximum stress and
elongation at break is very large. Depending on the extent of control of
composition drift during the polymerizations, phase separation was observed
in the processed polymers, and the presence of a rubber phase affected the
properties profoundly.
AB - In order to determine the influence of composition drift and
copolymer microstructure on the mechanical bulk properties of styrene methyl
acrylate copolymers, several copolymers were produced by emulsion
copolymerizalion. Three different average compositions were used. By
perforrming the copolymerizations under batch and semicontinuous conditions
with two different monomor addition strategies (starved conditions and
optimal addition) it was possible to control composition drift and to produce
copolymers with different microstructures (chemical composition
distributions). All these copolymers were processed in a way that ensured
that the original particle structure was lost before the polymers were tested. It
was found that composition drift had an influence on the mechanical
properties (Young's modulus, maximum stress, elongation at break). This
influence could be understood very well on the basis of present knowledge
about structure-mechanical properties relationships. In the case of
homogeneous copolymers maximum stress and elongation at break arc
dependent on the molecular weight, and only weakly dependent on the
chemical composition, and Young's modulus is independent of chemical
composition and molecular weight in the range of compositions investigated,
as expected. ln the case of heterogeneous copolymers, the influence of
copolymer microstructure on Young's modulus, maximum stress and
elongation at break is very large. Depending on the extent of control of
composition drift during the polymerizations, phase separation was observed
in the processed polymers, and the presence of a rubber phase affected the
properties profoundly.
U2 - 10.1002/masy.19950920113
DO - 10.1002/masy.19950920113
M3 - Article
SN - 1022-1360
VL - 92
SP - 133
EP - 156
JO - Macromolecular Symposia
JF - Macromolecular Symposia
ER -