INFLUENCE OF CROSS-LINK STRUCTURE ON VISC OELASTICITY OF POLYBUTADIENE LATEX FILMS

Dynamic viscoelastic properties of the casted films of polybutadiene l atex, in which gel content was controlled by i) terminating the reacti on at a certain conversion, or ii) increasing the amount of chain tran sfer agent were measured to study the crosslink structure. The glass t ransition temperature (T-g) and tan delta peak at T-g were independent of the gel content, i.e., the cross-linking degree, but dependent on the molecular weight of main chains. T-g of the samples prepared by ii ) was slightly higher than that of the samples by i), which might be a scribed to the difference of mobility of local chains. At a higher tem perature (0 degrees C), \E\ and tan delta were dependent on both the gel content and the amount of chain transfer agent. Because time scale of samples were in the rubbery stage to dow region at 0 degrees C, vi scoelastic properties were strongly influenced by the molecular weight of sol-like portions, which exist at the boundary between the microge l particles.