Pyrolysis of Polyamide-Containing Materials. Process Features and Composition of Reaction Products

An enhance in the manufacturing and consumption of polyamide products used in the light, food, textile, construction, engineering, and medicine industries leads to the formation of large volumes of polyamide-containing waste that must be processed and disposed of. Thermal processing of polyamides in an inert atmosphere (pyrolysis), as well as polymer degradation in the presence of atmospheric oxygen, result in the formation of a large number of organic compounds—lactams, ketones, various nitriles, as well as carcinogenic polycyclic aromatic and nitrogen-containing compounds, including valuable organic products, used for further processing. In this regard, the question arises of determining the optimal conditions for the polyamide-containing waste processing, under which the yield of valuable products increases and the amount of by-product, carcinogenic compounds, is minimized. The review describes the features of the thermal degradation of polyamides and materials based thereon in an inert atmosphere and in the presence of atmospheric oxygen and the mechanisms of depolymerization of polyamides. The influence of the polymer structure, temperature, composition of the gaseous medium, flame retardant additives, and the presence of a catalyst on the formation of degradation products in the gas and condensed phases is considered. Co-pyrolysis of polyamides with other polymers brings about an increase in the yield of gaseous products and the formation of pyrolysis oil containing a smaller amount of oxygen-containing compounds, which indicates a co-pyrolysis synergistic effect. As an example of the pyrolysis of industrial polyamide-containing waste, the process of thermal degradation of fishing net materials (both new commercial products and spent ones) is considered.