From starch to oligoetherols and polyurethane foams
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From starch to oligoetherols and polyurethane foams Renata Lubczak1 · Dominik Szczęch1 · Jacek Lubczak1 Received: 25 June 2019 / Revised: 23 October 2019 / Accepted: 4 December 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract The method of oligoetherols synthesis from starch, glycidol, and alkylene carbonates in water was described. The composition and structure of oligoetherols were determined, and these oligoetherols were used to obtain rigid polyurethane foams (PUFs). The obtained PUFs showed apparent density, water uptake, and polymerization shrinkage similar to classic rigid PUFs, and some of them had considerably improved thermal resistance. Their compression strength was observed to increase upon thermal exposure, which offers useful polymeric materials. Keywords Starch · Hydroxyalkylation · Oligoetherols · Polyurethane foams · Properties
Introduction The polymeric materials like polyurethanes based on natural substrates like bio-polyols become explored in order to obtain biocompatible polymers. Recent obtaining of biofuels from plant oils resulted in enormous increase in glycerol pool for further chemical conversions [1]. Glycerol is regularly used as substrate to obtain higher polyols by hydroxyalkylation with oxiranes like ethylene- and propylene oxides [2]. These polyols are useful substrates to synthesize polyurethane foams. Another raw material for such syntheses is sorbitol, which can be obtained the reduction in glucose. Sorbitol and saccharose can also be hydroxyalkylated in the same way [3]. Such polyols may have increased functionality up to 6 to 8 groups available for further reaction to obtain rigid polyurethane foams [4]. Polyols obtained from sorbitol showed high thermal resistance, and finally, the polyurethane foams obtained from them were applied as insulating materials for heating system tubings [5]. Nowadays, the polymer products like polyurethane foams (PUFs) should meet the biodegradation requirements. It seems reasonable that highly nature abundant * Renata Lubczak [email protected] 1
Department of Organic Chemistry, Rzeszów University of Technology, Al. Powstańców Warszawy 6, 35‑959 Rzeszow, Poland
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Polymer Bulletin
starch and cellulose are good candidates to obtain PUFs, provided they can be liquified by hydroxyalkylation. Cellulose can be hydroxyalkylated with ethylene-(EO) or propylene oxides (PO) to get (hydroxyalkyl)cellulose by reaction of EO or PO with alkalicellulose; the water soluble derivative obtained in aqueous sodium hydroxide solution of cellulose. In such process, the cellulose can be substituted with 1.8–3.0 hydroxyethyl groups per mere. (Hydroxyethyl)cellulose is used as protective colloid in polymerization of vinyl acetate, thickener in latex paints, and in textile industry. (Hydroxypropyl)cellulose is obtained in the similar way and used as additive in food industry [6]. There are no reports in the literature on higher hydroxyalkylation of alkalicellulose leading to liquid polyols based on cellulose me
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