MATERIALE PLASTICE ♦ 56 ♦ no. 4 ♦ 2019 1021 http://www.revmaterialeplastice .ro New Sound Absorbing Materials Obtained from Waste Rigid Polyurethane Foam ANCUŢA-ELENA TIUC 1 , OVIDIU NEMEȘ 1 *, HORAŢIU VERMEŞAN 1 *, DANIELA-ROXANA TĂMAȘ-GAVREA 2 , OVIDIU VASILE 3 1 Technical University of Cluj-Napoca, Faculty of Materials and Environmental Engineering, 103-105 Muncii Blvd., 400641, Cluj-Napoca, Romania 2 Technical University of Cluj-Napoca, Faculty of Civil Engineering, 15 C-tin Daicoviciu Str., 40020, Cluj-Napoca, Romania 3 University “Politehnica” of Bucharest, Department of Mechanics, 313 Splaiul Independente, 060042 Bucharest, Romania Polyurethane foam wastes is one of the environmental problems for which are not still the efficient solutions of valorization. This paper presents the possibility of recovering polyurethane foam waste by obtaining some new materials with sound absorption properties. The polyurethane foam wastes were ground and mixed, in proportion of 0, 3, 5, 7 and 12 wt%, with bicomponent polyurethane foam as a binder, resulting 5 new materials. The sound- absorbing properties of the new materials have been determined and it can be observed that the sound-absorbing properties of rigid polyurethane foam with closed pores can be improved by adding polyurethane foam waste to its structure. In addition, the mechanical properties and thermal conductivity of the new materials were studied. Keywords: waste polyurethane foam, acoustic materials The circular economy represents an organized effort within society in order to find solutions to the current environmental problems that are generated by the development of the society. Sustainable development and the respect for the environment are social values that have to be encouraged through the implementation of strategies that valorize the waste products generated in industrial processes and transform them into resources [1]. Polyurethane products are present in many industrial goods either in flexible or rigid foams, depending on their mechanical performance and cross-link densities [2]. Rigid polyurethane foams (PURs) are widely used in building insulation, domestic appliances, the automotive industry and as an insulation and lining material for refrigerators and freezers [3,4]. The presence of polyurethane foam in municipal waste is related to the end of product life, but it may also be derived as scrap from the manufacturing process which can account for approximately 10–15% of produced foam [5]. The recycling of PUR foam wastes, meets a serious difficulty arising from their considerably low density of 10 –100 kg/m 3 . Thus, the volume reduction is a crucial issue in the management of waste PUR foam [6]. It is therefore necessary to establish recycling procedures or ways of reusing industrial waste in order to minimize its environmental impact. The major recycling and recovery methods for polyurethanes [7] used up to date are mechanical recycling, advanced chemical and thermo-chemical recycling, energy recovery and product recycling respectively. Less efficient are the traditional recycling methods such as landfill storage and incineration which lead to land occupation, resource consumption, toxic gas emission, and environmental pollution [8]. Effectively disposing waste polyurethane foam plays an important role in protecting environment and recycling resources [9]. The thermal degradation of polyurethane foams leads to a significant amount of hazardous and harmful compounds that can arise during the decomposition process. The direct utilization of PU foam for waste-to-energy applications is not advised due to the possibility of the degradation of this, with the formation of hazardous chemical compounds. The chemical pretreatment or mixing with other waste materials is recommended to achieve safe and sustainable performance [2, 10-13]. The use of polymeric waste in the manufacture of mortar and concrete implies an important environmental benefit [14]. Specifically, the incorporation of rigid polyurethane waste in the design of lightweight cement mortars, and their manufacture for use in construction, has been widely researched, both in reference to the characterization of their physical properties and to the study of their mechanical behavior [15]. Rigid PUR foams are an ideal solution to lightweight, low-energy or zero-energy building and constitute ca. 23% of all PURs [16]. Developing a porous polyurethane matrix with low cost waste polyurethane foam is an excellent way to decrease the price of rigid PUR foams which are the most effective thermal and phono insulation commercially available materials. There is a growing awareness towards using materials with less social, economic and environmental impacts, in the construction and rehabilitation of buildings. *email: ovidiu.nemes@imadd.utcluj.ro, horatiu.vermesan@imadd.utcluj.ro