ABSTRACT
This chapter describes a variety of additives. Some of these additives are polymeric while others are not. Polypropylene (PP) and many other polymers are attacked during processing or outdoor use in the absence of stabilizers because of chain degradation reactions as shown in the following: by initiation; by propagation; and by termination. Flexibilizing of polymers can be achieved through internal and external plasticization. Plasticizers with solubility parameters and type of bonding similar to those of the polymer are more apt to be compatible than when the solubility parameters are different. Internal plasticization can be produced through copolymerization, giving a more flexible polymer backbone or by grafting another polymer onto a given polymer backbone. External plasticization is achieved through incorporation of a plasticizing agent into a polymer through mixing and/or heating. The development of plasticizers has been plagued with toxicity problems. Plasticizers should be relatively nonvolatile, nonmobile, inert, inexpensive, nontoxic, and compatible with the system to be plasticized.
