Recycling of polyurethanes: where we are and where we are going

Abstract

Polyurethanes (PUs) represent a family of useful synthetic polymers (thermoplastic or thermosetting) obtained from polycondensation reactions between diisocyanates and diols/polyols. Within the circular economy concept and also considering the current...

Electrochemical recycling of polymeric materials

“…17 They find a wide range of applications from rigid/flexible foams to coatings, fibers, adhesives, and elastomers. 64,65 In Europe in 2017, the end-of-life management of this class of polymeric materials principally consisted of landfilling (0.9 Mt per year), incinerating (0.6 Mt per year) and recycling (mechanical and chemical, 0.5 Mt per year). 66 The wide range of chemical structures, molecular weights, degrees of crystallinity, crosslinking densities, and hard-to-soft segment ratios make the chemical recycling of polymeric materials containing C–N groups particularly challenging.…”

“…66 The wide range of chemical structures, molecular weights, degrees of crystallinity, crosslinking densities, and hard-to-soft segment ratios make the chemical recycling of polymeric materials containing C–N groups particularly challenging. 65 Similar to PET, the principal chemical recycling technique is solvolysis to (partially) recover monomers from polyurethanes and polyamides. 64,67 For example, BASF, Maincoop and Polytecna, among others, have implemented this technique at the industrial scale to recover the polyol fractions from flexible polyurethane foams.…”

Mechanistic insight into the role of the aspect ratio of nanofillers in the gas barrier properties of polymer nanocomposite thin films

“…These polymers exhibit a wide range of desirable characteristics, including exceptional elasticity, excellent lowtemperature flexibility, strong tensile strength, good abrasion resistance, chemical resistance, and ease of processing. [1][2][3] In addition to their adaptable characteristics, PUs find application across a diverse spectrum, including coatings, adhesives, sealants, flexible and rigid foams, paints, varnishes, leathers, rubbers, fibers, films, biomimetic materials, and many other domains. 1,4,5 Nevertheless, PUs bear a substantial drawback: they exhibit inherent permeability to various gases and vapors, encompassing oxygen (O 2 ), nitrogen (N 2 ), carbon dioxide (CO 2 ), helium (He), water, and organic vapors.…”

Influence of Carboxylic Acid Structure on the Kinetics of Polyurethane Foam Acidolysis to Recycled Polyol

“…7 Mechanical recycling of PU waste is typically performed by shredding or grinding the material and then either reusing the material as a filler or rebinding the material via extrusion, compression, or molding. 8,9 These methods are simple, inexpensive, and ecofriendly and therefore have potential utility in the management of PU waste. However, they result in materials with inferior thermal and mechanical properties and can only be repeated a finite number of times and are therefore not a circular sustainable waste management practice.…”

“…For example, 1.3 million tons of PU waste is discarded annually in the USA . Mechanical recycling of PU waste is typically performed by shredding or grinding the material and then either reusing the material as a filler or rebinding the material via extrusion, compression, or molding. , These methods are simple, inexpensive, and eco-friendly and therefore have potential utility in the management of PU waste. However, they result in materials with inferior thermal and mechanical properties and can only be repeated a finite number of times and are therefore not a circular sustainable waste management practice. ,, In contrast, chemical recycling offers the possibility to convert plastic waste into valuable chemicals with little to no loss in quality, creating a pathway to a circular plastic economy.…”