As a result of the research on the utilization of polyethylene terephthalate-containing household waste, a promising direction was identified in the production of a new type of secondary polyethylene terephthalate (SPET) - unsaturated polyesters.
It was revealed that the final product, which formed when the alcoholization process is complete in any proportion of of glycol and secondary polyethylene terephthalate, is the bisalkylent terephthalate of terephthalic acid; the content of the alcoholysis product consists of bisalkylent terephthalate, different molecule mass, functionally hydroxyl-containing complex polyester polyol and free diols.
The laws of alcoholization of secondary polyethylene terephthalate have been studied and the mechanism has been established. Studies have shown that, in contrast to existing theories, such as the formation of ethylene glycol in the polycondensation of phthalic anhydride bisalkylene glycol derivatives, the increase in ethylene glycol in the process was found to be due to the exchange of diethylene glycol in the macrochain.
The formation of unsaturated polyesters goes stage by stage, first ethylene-, diethylene glycol acid esters are formed, then they are exposed to hydroxyl-containing oligomers - secondary polyethylene terephthalate alcohol products.
A mathematical model of the process of alcoholization of SPET and diethylene glycol was created, studies showed that the difference between the values obtained as a result of the mathematical model and experiments are less than 5%.
The unsaturated polyesters were synthesized on the basis of SPET alcoholization products. Many of them have shown their superiority over unsaturated polyesters PN-1, PN-3, PN-15, which are used in industry for general purposes. By developing unsaturated polyesters on the basis of secondary polyethylene terephthalate alcohol products, it was found that the structure of these polyesters is close to that of imported resins "Body", 196, 196A, used in industry.