ABSTRACT
Of the hundreds of different polymers in use today, relatively few employ large commercial volumes of plasticizers. Flexible poly(vinyl chloride) (PVC) is by far the largest outlet for alpha olefin-based plasticizers. Many other polymers will readily accept plasticizer but yield no commercially useful products. Polystyrene, for instance, becomes a viscous, sticky, semisolid at plasticizer levels of only 10 to 15%. Even at lower plasticizer
levels, properties such as heat distortion temperature and creep resistance are seriously impaired. When plasticizers are used at all in these plastics, it is at very low levels (V2 to 2%) to enhance melt flow. In these cases the additive is more properly called a "processing aid" than a plasticizer, since modification of the end-use properties of the polymer is not the objective. In general, amorphous, noncross-linked polymers do not form useful compositions when plasticized; a three-dimensional structure, either some forin of cross-linking or a moderate level of crystallinity, is present in all commercially important plasticized systems.
