The preparation and characteristics of rigid polyurethane foams (RPUFs) synthesized from polyols obtained by glycolysis of post-industrial waste RPUFs have been studied. More precisely, waste rigid foams that have been chemically recycled by glycolysis in this work are industrially produced pieces for housing and bracket applications. The glycolysis products have been purified by vacuum distillation. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn) and viscosity have been analyzed. The chemical structure and thermal stability of the polyols have been studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols increases the reactivity of the RPUFs synthesis, according to short characteristic times during the foaming process along with more exothermic temperature profiles. Foams formulated with recycled polyols have a lower bulk density (88.3–96.9 kg m−3) and smaller cell sizes compared to a conventional reference RPUF. The addition of recycled polyols (up to 10 wt.%) into the formulation causes a slight decrease in compressive properties, whereas tensile strength and modulus values increase remarkably.

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Polyurethane (PU) is one of the most versatile polymers available and can be found in an infinite number of formats ranging from rigid or flexible foams to elastomers. Currently, most Rigid PU Foam (RPUF) waste is landfilled, even though a small amount is mechanically recycled, in which the material is conditioned in size to a very fine powder, which is introduced as a filler. In this work, chemical recycling of two types of rigid PU foams is studied, the major difference being the aliphatic or aromatic nature of the isocyanate used in the synthesis. A solvolysis process is developed, a chemical depolymerization that breaks the chains by means of a chemical agent, a solvent, in the presence of a catalyst and under controlled process conditions. The glycolysis products are purified by vacuum distillation, centrifugation, and acid water treatment, depending on the most suitable process for each waste type. Optimal process conditions are established to obtain high-purity green polyols by performing a set of catalytic glycolysis reactions at laboratory scale with the previously conditioned RPUF waste samples. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn), and viscosity, are analyzed. The chemical structure and thermal stability of the polyols are studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols for RPUF synthesis is studied and characterized.

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Polietilen tereftalato birziklatuaren (rPET) eskaera handiak ingurumenaren sentsibilizazioak eta legediak bultzatuta, kontsumitu osteko PET plastiko-hondakinen sorkuntza handiarekin batera, birziklatze prozesu eraginkorren premiazko beharra eragin du. Birziklapen teknologia klasikoak, birziklapen mekanikoa adibidez, ez dira eraginkorrak birziklatzen zailak diren edo birziklatzen ez diren plastikoen kasuan, hau da, geruza anitzeko eta oso kutsatutako hondakinen kasuan. Teknologia hauek ziklo-kopuru mugatua dute, eta despolimerizazio kimikoak, berriz, jatorrizko PETtik hasierako ekoizpeneko lehengaiak ekoizten ditu. Testuinguru honetan, polietilen tereftalatoaren (PET) hidrolisia, PET hondakinen despolimerizaziorako estrategia jasangarria da, rPET birpolimerizatzeko abiapuntu gisa erabil daitekeena eta, beste despolimerizazio teknologiak ez bezala, oso kutsatuta dauden kontsumo osteko PET hondakinen elikadurak onartzen dituena. Lan honek PET solbolisiaren egungo egoera aztertzen du, eta bereziki PET hidrolisiarena, bai laborategi mailan bai industria eskalan, bere garapenaren alderdirik garrantzitsuenak zehaztuz.