This paper reviews the state of the art in the field of chemical recycling of poly(ethylene terephthalate) (PET). Advantages of the chemical recycling of PET, the theoretical basis of the ester bond cleavage, and a wide spectrum of degrading agents and final products are presented. Chemical processes applied in polymer recycling are divided into six groups:  methanolysis, glycolysis, hydrolysis, ammonolysis, aminolysis, and other methods. Numerous possibilities for the utilization of waste PET as a very useful raw chemical material are described on the basis of literature. A comparison of chemical recycling methods is carried out. The following aspects were taken into consideration:  (i) flexibility in utilizing a variety of waste types, (ii) conditions necessary for degradation including safety requirements, (iii) economic aspects, and (iv) product versatility. A total of 108 references including 46 patents are cited in this paper.

The epoxy compositions with ionic liquids (ILs) differing in the alkyl chain length of imidazolium cation (butyl or decyl), anion type [N(CN) 2 ¯, BF 4 ¯, Cl ¯], as well as ILs concentration (1, 3, and 9 phr) have been prepared, and their curing characteristics at ambient and elevated temperatures have been investigated. Rheometric, differential scanning calorimetry, and Fourier transform infrared measurements revealed substantial differences in the curing characteristics dependent mainly on the IL anion type and its concentration. TGA results showed that thermal decomposition of IL influenced the onset temperature of epoxy resins cross-linking reactions during heat treatment. Dynamic mechanical thermal analysis measurements showed that the type of IL anion had an effect on T g and tan δ values as well. For materials cross-linked with ILs containing dicyanamide anion the highest T g (ca. 170 °C) and the lowest tan δ (0.26) values have been found. On the basis of the obtained results and literature data the mechanism of epoxy resin cross-linking in the presence of imidazolium ionic liquids has been proposed.

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