Nonlinear Stress Relaxation of ABS Polymers in the Molten State

Abstract

Large deformation, nonlinear stress relaxation behavior was examined in the molten state for two types of ABS polymers, with one type containing well-dispersed rubber particles and the other, agglomerated rubber particles. These different morphologies were accomplished by adjusting the chemical composition of poly(styrene-co-acrylonitrile) (SAN) grafted on the rubber particles, such that the acrylonitrile content of the grafted SAN is equal to or different from that of the matrix SAN. The time-strain separability was found for the nonlinear relaxation of the matrix/grafted SAN chains in those ABS polymers. In the ABS polymer containing randomly dispersed rubber particles, the damping function h(γ) of the SAN chains was more strongly dependent on the strain γ than h(γ) of the pure matrix SAN chains. This difference was attributed to the filler effect in that ABS polymer. In contrast, in the ABS polymers containing networks of the agglomerated rubber particles, the SAN chains exhibited less γ-dependent h(γ) that is close to the pure matrix chains, possibly due to lack of the filler effect in large pockets formed in this network.

Uniaxial Elongational Viscosity of PC/ A Small Amount of PTFE Blend

“…The tendency has been reported in fine particles and fiber dispersed polymer systems. 16,17) DSC experiments and SEM observations supported the fact that PTFE were dispersed as a phase-separated fibrous structure, therefore, it is supposed that fibrils or network structure formed by fibrils would generate the elastic response in lower frequency region.…”

“…The strong damping by the addition of nondeformed filler was explained by the idea that the local strain in the matrix is larger than strain applied externally. 17,20) The weak damping of PC/PTFE blend (t = 0.2(s)) in Fig. 7 indicates a lager generation of shear stress than that of neat PC in large strain region.…”

“…In filler dispersed polymer systems, two mechanisms of relaxation (fast and slow relaxation processes) have been often seen. 17,18) The former reflects the relaxation of matrix polymer chain from orientation, and the latter is attributed to the relaxation for motions of fillers and their agglomerate structure.…”

“…Their data showed that the magnitude of damping for ABS became stronger than that of pure SAN matrix polymer. 17) Since rubber particles were much stiffer than SAN chains, the rubber particles effectively worked as solid fillers. The strong damping by the addition of nondeformed filler was explained by the idea that the local strain in the matrix is larger than strain applied externally.…”

Nonlinear stress relaxation in palladium(II) complexes with triblock copolymers of styrene and butadiene

“…The strain-dependent damping function reveals strain softening of ethylene/methacrylic acid copolymers at high degrees of Na ϩ and Zn 2ϩ neutralization 28 in the nonlinear viscoelastic regime. Randomly dispersed rubber particles have a considerable effect on strain-dependent damping functions in molten acrylonitrile-butadiene-styrene terpolymers, 32 but the validity of time-strain separability of the nonlinear relaxation modulus is not challenged. However, Tanaka and Edwards 37 demonstrate that the underlying physical basis of time-strain separability is questionable in their transient study of physically crosslinked gels.…”