CURE OF UNSATURATED POLYESTER RESINS .2. INFLUENCE OF LOW-PROFILE ADDITIVES AND FILLERS ON THE POLYMERIZATION REACTION, MECHANICAL-PROPERTIES AND SURFACE RUGOSITIES
Jc. Lucas et al., CURE OF UNSATURATED POLYESTER RESINS .2. INFLUENCE OF LOW-PROFILE ADDITIVES AND FILLERS ON THE POLYMERIZATION REACTION, MECHANICAL-PROPERTIES AND SURFACE RUGOSITIES, Polymer, 34(9), 1993, pp. 1886-1890
The effects of poly(vinyl acetate) (PVAc) and CaCO3 on the cure kineti
cs, mechanical properties and surface rugosities of unsaturated polyes
ter (UP) resins were studied. When the ratio of styrene to UP unsatura
tion was kept constant, PVAc did not have any effect on cure kinetics,
maximum conversion or glass transition temperature of the crosslinked
UP resin. The addition of CaCO3 led to a decrease in the induction pe
riod of the copolymerization, without any significant action on the su
bsequent cure rate. The addition of PVAc was only effective in promoti
ng an excellent copy of the mould surface at concentrations higher tha
n the critical one leading to co-continuous structures (8 wt% for the
formulation used in the present study). The use of PVAc at concentrati
ons beyond the critical value did not produce further improvements in
the surface quality. The simultaneous use of both PVAc and CaCO3 in UP
formulations led to materials with very low strength and impact resis
tance, and with only a moderate ability to reproduce the mould surface
.