Thermal processing color compounding

The color of the polymer can also be affected by inappropriate reaction conditions in the polymerization process, such as temperature, residence time, deposits of degraded polymer or the presence of oxygen. Degradation of polyesters and the generation of chromophores are thermally effected [29b, 29c, 39], The mechanism of thermal decomposition is based on the pyrolysis of esters and the formation of unsaturated compounds, which can then polymerize into colored products. It can be assumed that the discoloration takes place via polymerization of the vinyl ester end groups or by further reaction of AA to polyene aldehydes. 

As mentioned previously (see p. 237), the 1,2,3-benzotriazinones function as masked diazonium compounds, and the so-called Pologenowe dyes developed in Poland are operated on this principle and have been in use there since 1959. There are three major advantages associated with the use of 1,2,3-benzotriazinones as azo-dye equivalents (1) The equilibrium that theoretically exists between the heterocyclic system and the diazonium compound normally lies completely to the side of the cyclic compound. Opening of the heterocyclic ring can be easily accomplished thermally, and hence dye formation can be induced by heat treatment processes. (2) Many 1,2,3-benzotriazinones are reasonably water soluble and the sodium salts even more so consequently, complete permeation of fabric fibres by the dye precursors immediately prior to generation of the dye can be ensured. (3) The colors produced are fast, and some of them can be made highly water insoluble. ... 

The improved thermal stability of the chlorinated paraffins also reflects the purity of the n-alkanes. The heat stability of PVC plasticized with chlorinated n-paraffin at 177°C. is better than that of similar compounds using commercial chlorinated wax. This is shown in Table I by the color that developed during thermal treatment for samples in which 40% of the dioctyl phthalate was replaced by chlorinated paraffins. (In this example and those that follow, the total plasticizer concentration is constant at 33 / %.) The color development in this test is significant as a measure of the comparative processing conditions that can be employed. 

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