Oxypropylation of Cork and the Use of the Ensuing Polyols in Polyurethane Formulations

Abstract

Cork particles, recovered as byproducts of the processing of this natural material, were oxypropylated under pressure and relatively high temperature in the presence of KOH as catalyst. Various parameters were explored in order to assess the most suitable conditions, which led to the almost complete conversion of the solid cork into a viscous polyol. This product was a mixture of oxypropylated cork macromolecules and propylene oxide oligomers, which were thoroughly characterized. The use of these polyols as macromonomers in the synthesis of polyurethane foams gave promising results, thus showing that it should be possible to exploit the residues of this important renewable resource to manufacture original materials.

Cork-Containing Barks—A Review

“…Due to its high content in suberin, birch outer bark has been proposed as a source of monomers, e.g., of ω-hydroxyfatty acids, α,ω-dicarboxylic acids, and homologous mid-chain dihydroxy or epoxy derivatives for production of novel macromolecular materials (Gandini et al, 2006), polyesters (Olsson et al, 2007;Sousa et al, 2007), polyols (Evtiouguina et al, 2000(Evtiouguina et al, , 2002, polyurethanes (Cordeiro et al, 1997(Cordeiro et al, , 1999Evtiouguina et al, 2001) and has also been considered as a source of extractives, namely, of triterpenoids and in particular of betulinol (Pinto et al, 2009). Some patents have already addressed the possibility of using birch bark as a source of chemicals (Krasutsky et al, 2003(Krasutsky et al, , 2005(Krasutsky et al, , 2009).…”

Suberin: A Biopolyester of Plants' Skin

“…[41] Promising results were obtained in the synthesis of polyurethane foams, after the oxypropylation of cork suberin. [42,43] Important amounts of plant wastes rich in suberin are available each year. The Portuguese cork industry produces about 40 000 ton/year of cork powder as a by-product.…”

Biopolyols obtained via crude glycerol-based liquefaction of cellulose: their structural, rheological and thermal characterization

“…The essence of this method is to enhance the reactivity of hydroxyl groups by shifting them towards the end of the main chain (Briones et al 2011a, b). The resulting polyols are liquid mixtures of oxypropylenated biomass, homopolymer of propylene oxide, and unreacted biomass (Evtiouguina et al 2002). This method of polyol production was investigated by many research groups which incorporated into the process various types of biomass such as, coffee grinds (Evtiouguina et al 2002), sugar beet pulp (Pavier and Gandini 2000), gambier tannin (Arbenz and Averous 2015), soy hulls (Rosa et al 2015), rapeseed cake residue (Briones et al 2010), and olive stones (Matos et al 2010).…”