Abstract: The influences of the content of plasticizer, filler(CaCO₃, carbon black) and n-butyl nitrile rubber(NBR) on the network structure, molecular slippage and Gaussian modulus of plasticized poly(vinyl chloride)(PPVC) were studied by employing stress relaxation experiment and Haward model. The network structure of PPVC comprises the main network formed by macromolecule entanglement and the secondary network formed by interaction forces between molecule(van der Waals force). The viscoelastic behavior of PPVC materials is in accordance with Haward model before their main networks extend to the critical value. Although plasticizer, CaCO₃, carbon black do not change the entanglement structure of PPVC, plasticizer can decrease Gaussian modulus and increase the molecular slippage by decreasing the density of main network and weakening the secondary network. However, CaCO₃ and carbon black can increase Gaussian modulus and decrease the molecular slippage by increasing the density of main network and strengthening the secondary network. NBR not only decreases the entanglement density of macromolecular chain but also weakens the secondary network, which results in the reduction of Gaussian modulus of PPVC material.

Key words: Plasticized poly(vinyl chloride), Molecular network structure, Gaussian modulus, Plasticizer, Filler, Nitrile rubber