P 0008 (OTTO) Poly(vinyl chloride), average Mw ~233,000 Cas 9002-86-2 - used to give a uniform rate of polymerization. P 0008 (OTTO) Poly(vinyl chloride), average Mw ~233,000 Cas 9002-86-2 - used to make the material softer and more flexible and lowering the glass transition temperature. Plasticizers work by increasing the space and acting as a lubricant between the PVC polymer chains. Higher levels of plasticizer result in softer PVC compounds and decreasing tensile strength.