Dynamic Viscoelastic Properties of ABS Polymers in the Molten State

Abstract

The dynamic viscoelastic properties of ABS resins were measured in the molten state with a rotating cylinder type rheometer over wide ranges of temperature and frequency. Two series of resins with rubber contents, 0, 10, 20, and 30 wt%, were prepared by blending an AS copolymer with two kinds of ABS resins having different ratios of grafted AS copolymer to butadiene rubber. The main results are summarized as follows. 1) At high frequencies (rubbery zone), the magnitudes of the storage shear modulus (G^′) and the loss shear modulus (G^″) are independent of the rubber content, but rubbery plateau shifts to low frequency side as the rubber content rises. 2) At low frequencies (terminal zone), G^′ and G^″ increase progressively with increasing rubber content in each series. G^″ does not depend on the kind of ABS resins but on the gel (rubber+grafted AS copolymer) content. On the other hand, G^′ depends on the kind of ABS resins: The resins with higher grafted AS ratio exhibit the “second plateau” of G^′, and the others do not. 3) Time-temperature superposition principle can be applied in the ABS resins. The temperature dependence of shift factors is expressed by the WLF-type equation. The free volume of ABS resins decreases slightly with increasing rubber content.