Polymer additives: the miscibility of blends

Abstract

Publisher Summary Polymers as made are usually not suitable for industrial use as plastics, so industry uses additives and modifiers to adjust the properties of the as made polymers to make most of the plastics used today. Polymer additives or modifiers are necessary to perform three essential functions. First, additives are required in order to process or fabricate many polymers. Several as made polymers have thermal stability limitations that force the producers to find and utilize stabilizers that allow melt processing. The second type of additive is for property enhancement. In the above example, a wetting agent may be necessary to process the polymer, but a coupling agent can be added as an enhancement to provide long-term durability. Fillers improve the flexural modulus and DTUL (deflection temperature under load). Color, odor, surface gloss, and other properties are improved by additives of this second category. Rubber improves impact resistance. Fibers improve both impact and modulus in many cases. Flame retardants enhance properties of a plastic and make it more valuable. Additives of this second type pay for themselves by giving much more performance value than the added cost of the additive. The third type or class of additive corrects the flaws of the first two classes. Plasticizers are required to fabricate flexible PVC. Some of these plasticizers provide food for organisms like mildew and fungus. An additive is needed to correct this. Plastics make useful complex shapes as well as inexpensive high-volume items. In order to meet these diverse demands, commercial polymers are modified with additives to make plastics. Compounding of polymers with additives and modifiers to make commercially useful plastics is a business that is constantly changing, owing to new materials, price changes, improved processing machinery, changing customer needs, environmental laws and concerns, etc. Some needs are persistent, such as the requirement to fabricate parts, ways to upgrade properties, how to correct for problems introduced by the use of additives to accomplish the first two items, and controlling costs. This chapter deals with additives from these points of view. No perfect solutions exist, so polymer additives and modifiers may be seen as a truly dynamic field of study.