Optimization of the chemical recycling of Polyamide-6

The following work is part of a larger project aimed to chemically recycling waste footwear padding composed of polyamide 6 (PA6) layered with flexible polyurethane (PU) foams. The objective is to obtain polyols to be used as raw material for producing rigid polyurethane foams. Given the challenging nature of separating these two materials, the focus is on finding a method to recycle PA6 and PU together to produce a single PU foam. Chemical recycling offers an environmentally friendly alternative for recovering these materials, which are currently sent to waste-to-energy or landfill disposal, which are unsustainable due to the production of toxic gases and soil consumption, respectively. Among the various chemical recycling processes, hydrolysis is very effective and adaptable for recycling the most common technopolymers. This study therefore focuses on finding a process capable of transforming waste PA6 into a polyol which will be used for producing polyurethane foams. In this way, a recycling method applicable to coupled PA6 and PU waste can be identified. This research is divided in three parts: the first one is devoted to the optimization of hydrolysing PA6 to produce his monomers, the second one to obtain a polyol suitable, by using the recovered PA6 monomers, for the production of polyurethane foams, which represents the third part of the work.