Choosing PVC Resins for Formulation Properties

The selection of PVC resins for pipe extrusion is regulated by the Plastic Pipe Institute (PPI) in terms of inherent viscosity (I.V.), and is further mandated to be 0.88 to 0.96 for pressure pipe. In addition, there are cell classification requirements, a system that defines the minimum physical properties a pipe or fitting compound must meet. This paper presents experimental data and analysis showing the evolution of tensile properties, impact properties, heat deflection temperature, viscosity and torque rheometry characteristics of PVC formulations that incorporate ten suspension resins, ranging in K-value from 50 to 88, from two different sources. The effect on properties by blending resins of different K-values was also studied.