Additives for plastics and their transformation products

For samples that meet the solubility requirements of the SEC approach, analyses were also reported for additives in polymers such as PVC and PS [28,29]. Direct SEC analysis of PVC additives such as plasticisers and thermal stabilisers in dissolution mode has been described [28,30,31 ]. In the analysis of a dissolved PS sample using a SEC column of narrow pore size, the group of additives was separated on a normal-phase column after elution of the polymer peak [21]. Column-loading capacity of HPSEC for the analysis of additives, their degradation products and any other low-MW compounds present in plastics has been evaluated for PS/HMBT, PVC/TNPP and PVC/TETO (glyceryl tri[l-14C] epoxyoleate) [31]. It was shown that HPSEC can be used to separate low-MW compounds from relatively large amounts of polymers without serious loss of resolution of the additives the technique has also been used for the group analysis of chlorohydrin transformation products of the TETO model compound [32]. 

Polychlorinated Biphenyls. Polychlorinated biphenyls (PCBs) are compounds derived from substitution of one to ten hydrogen atoms of biphenyl by chlorine atoms. PCBs have been produced and used world-wide in large quantities for many years as transformer oils, metal-cutting oils, hydraulic oils, heat transfer fluids, and as additives in plastics, dyes and carbonless copying paper. The production of PCBs was terminated world-wide around the late 1970s to early 1980s due to their adverse effects on the environment as a result of persistency, bioaccumulation properties and toxicity. 

As was mentioned in previous chapters, plastics are usually processed with the aid of additives that modify their properties and their behavior during processing and practical applications. Homogenization of these substances with polymers is a very important part of processing technology for the preparation of intermediate products such as granules, agglomerates, pellets, and sheets. This facilitates the final transformation process or increases their output. 

Plastics are defined as processable materials based on polymers. These materials can be transformed into finished products, such as bottles, containers, films, hoses, coatings, lacquers, etc. As a result of today s multitude of plastic applications there is a corresponding enormous variety of plastic materials. The polymer matrix as well as the incorporated plastic additives can be made to differ in such a variety of ways with respect to their chemical composition and structure that one finds or can develop a tailor made product for every application. 

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