Polyurethane Recycling and Disposal: Methods and Prospects

Abstract

Growing water and land pollution, the possibility of exhaustion of raw materials and resistance of plastics to physical and chemical factors results in increasing importance of synthetic polymers waste recycling, recovery and environmentally friendly ways of disposal. Polyurethanes (PU) are a family of versatile synthetic polymers with highly diverse applications. They are class of polymers derived from the condensation of polyisocyanates and polyalcohols. This paper reports the latest developments in the field of polyurethane disposal, recycling and recovery. Various methods tested and applied in recent years have proven that the processing of PU waste can be economically and ecologically beneficial. At the moment mechanical recycling and glycolysis are the most important ones. Polyurethanes’ biological degradation is highly promising for both post-consumer and postproduction waste. It can also be applied in bioremediation of water and soil contaminated with polyurethanes. Another possibility for biological methods is the synthesis of PU materials sensitive to biological degradation. In conclusion, a high diversity of polyurethane waste types and derivation results in demand for a wide range of methods of processing. Furthermore, already existing ones appear to be enough to state that the elimination of not reprocessed polyurethane waste in the future is possible.

Use of a Mixture of Polyols Based on Metasilicic Acid and Recycled PLA for Synthesis of Rigid Polyurethane Foams Susceptible to Biodegradation

“…The obtained polyols were subjected to detailed physicochemical, analytical and spectroscopic tests. It was found, on the basis of the obtained test results, that they were odorless liquids with different densities of 1.188 g/cm 3 for PLA-based polyol and 1.250 g/cm 3 for MSA-based polyol and viscosities of 210 mPa•s for PLA-based polyol and 33,442 mPa•s for MSAbased polyol. There were also noted significant differences in the values of the hydroxyl numbers and acid numbers.…”

“…The densities of the obtained polyols were 1.250 g/cm 3 for the MSA-based polyol and 1.188 g/cm 3 for the PLA-based eco-polyol, respectively. During the synthesis of the first polyol, a gradual decrease in density was observed in relation to the initial raw material, which was metasilicic acid (bulk density of MSA-2.4 g/cm 3 ).…”

“…The synthesis of the PLA-based eco-polyol also resulted in a polyol raw material with a lower density than the waste used for reaction. The PLA used for the synthesis had a density in the range of 1.25-1.27 g/cm 3 , while the ethylene glycol used as a glycolyzing agent had a density of 1.11 g/cm 3 . This meant that the use of PLA:MEG mass ratio of 1:1 resulted in obtaining a polyol with an intermediate density between PLA waste density and MEG density.…”

“…Current trends direct the production of polyurethane materials to the use of environmentally friendly raw materials, the addition of raw materials from renewable sources and solving the problem of post-production and post-consumer waste at the design stage of the production process. Building materials (including polyurethane foams) are subject to high requirements regarding their physicochemical, mechanical and flammability properties [ 3 ].…”

Turning Inside Out: Filamentous Fungal Secretion and Its Applications in Biotechnology, Agriculture, and the Clinic

“…Understanding and (re)engineering filamentous fungal secretion is not, however, only relevant for sustainable applications in industrial biotechnology. As the diversity of their secreted repertoire in the natural niche is explored ( Figure 2 and Table 1 ), a wide range of novel applications have been postulated, from bioremediation of plastic waste [ 8 ], using sex pheromones in biosensors [ 9 ], to supplying food and medical products during ultra-long space flight [ 10 ]. Understanding secretion has also become a major avenue of research in both medical and agricultural biotechnology.…”