| Abstract: | Viscoelastic properties of branched polymers vary with their shearing history; notwithstanding, their primary molecular parameters do not change. According to a recent study, such viscoelastic variation was believed to be observed only with crystalline long-chain branched polymers such as low-density polyethylene or polyacetal. That is, the origin of the viscoelastic variation was attributed to the presence of specific entanglements at the branching points, which was formed during the crystallization process. However, the viscoelastic variation of the long-chain branched polymers is the phenomenon at temperatures well above their melting points, namely, it is considered that whether the long-chain branched polymers are crystalline or not is not essential for the occurrence of the viscoelastic variation. Thus, the influence of the shearing history on the rheological properties of an amorphous long-chain branched polymer was investigated in this paper, and it was found that, irrespective of their crystallinity, the viscoelastic properties of long-chain branched polymers vary according to their shearing history. |
