Studies On Antistatic Plasticized Polyvinyl Chloride

The plasticized polyvinyl chloride (PPVC), which is low cost, facile processing and similar to the elastomers, has wide applications in many fields. The good insulation of PPVC, however, results in easy accumulation of static, which can ignite gas and other flammable mixing gas easily and lead to a lot of calamity. Therefore, the antistatic modification of PPVC becomes very urgent. In addition, it is well established that the macroscopic properties are dominated by the microscopic structure. Based on the investigation of viscoelastic behavior, structure evolution and deformation mechanism of PPVC, the relationship between structure and property can be elucidated and thus academic bases and experimental instructions to some extent are provided.1. The effect of major plasticizer, namely DOP, co-operative plasticizer chloride paraffine (CP), carbon black (CB), calcium carbonate (CaCO₃), the elastomer and antistatic agent on the mechanical properties of PPVC were explored. The results indicated that the synergic effect on the mechanical properties between DOP and CP had been achieved in a certain range. As for filler (CaCO₃. CB)/ resin system, the mechanical property mainly rests on interfacial adhesion strength between the filler and resin, not on the size of filler or dispersion status. Because of strong interfacial adhesion strength, the tensile strength and elongation at break of CaCO3-A /PPVC system were maintained at higher level, in spite of bad dispersion of filler in the matrix. On the contrary, the tensile strength and elongation at break of CaCO3-B/PPVC and CB /PPVC systems were deterioratedas a result of poor interfacial adhesion strength, although good dispersion ot both fillers in the matrix could be achieved. As for NBR/PVC system, the miscibility between elastomer NBR and PVC resulted in good mechanical properties. The elongation at break was increased rapidly with increasing of NBR content. The antistatic agent had somewhat plasticizer-like effects.2. The antistatic property of by-product CB (A) and conductive CB (B) were compared, based on the characterization of surface resistivity. The results indicated that the low-cost CB (A) also had a good antistatic effect. The threshold of percolation was related to dispersion status of CB in the matrix. The rolling time, elastomer content and the kind of CB affected the dispersion of CB in the matrix, and thus had some impacts on antistatic property. Home-made antistatic agent S, having merits of few adding amount, short equilibrium time and long washing durability, could reduce surface resistivity of PPVC efficiently.3. The effect of plasticizer, filler (CaCO3) CB) and the elastomer NBR on the network of PPVC were explored, with aid of step cycle and stress relaxation experiments. The results indicated that the network of PPVC consisted of the primary network, formed by molecular entanglement and microcrystalline domain (Gaussian network), and the secondary network, contributed by molecular interactions (Van Der Waals) inside Gaussian network. The ultimate extension of the primary network only relied on the entanglement density of network, while cycle strain (basic strain) and viscous force were related to the secondary network. The plasticizer, CaCO3, CB and NBR had different effects on the primary network and the secondary network of PPVC, and resulted in different ultimate extension and modulus of the network.