On the Recyclability of Glass Fiber Reinforced Thermoset Polymeric Composites towards the Sustainability of Polymers’ Industry

Abstract

Short CommunicationThe production of glass fiber reinforced polymers (GFRP) has increased tremendously during the last decades. Their properties of lightness and high resistance, associated to a high resistance to corrosion, allow the application of these materials in a wide range of industries where significant problems of corrosion may occur, such as in the field of chemical industry. The attractiveness of these materials is also enhanced due to their high resistance/cost ratio and ability for application as structural elements in civil construction, transportation and automobile sectors [1].Currently, most of the GFRP wastes are landfilled leading to significant negative environmental impacts. Thus, although the increasing use of thermoset composite materials, the recycling process of their by-products and end-of-lifecycle products comprises an important topic to consider. To reinforce this idea, one must take into consideration the fact that the European Commission directives are becoming more and more restrictive in this matter and the environmental issues posed by materials disposed in landfills is leading to an urgent reach of more industrial scale solutions to the recycling of composites [2]. In addition, with the new European Union's approach to waste management based on the "waste hierarchy", disposal (which includes landfilling and incineration without energy recovery) is the least preferred option while innovation in recycling is strongly encouraged [3].The recyclability of thermoset composite materials is complex and is sometimes seen as a key barrier to the adoption of these materials in some markets. Typically, thermoset GFRP based products are considered demanding to recycle due to both cross-linked nature of thermoset resins, which cannot be remolded, and complex composition of the composite itself, which includes glass fibers, organic matrix and different types of inorganic fillers [4].In the last decade, some recycling techniques have been proposed for GFRP waste materials: (a) incineration and co-incineration, with partial energy and raw materials recovery; (b) thermal and/or chemical recycling, such as solvolysis, pyrolysis and similar thermal decomposition processes, with fiber recovering; and (c) mechanical recycling or size reduction (with reduction to fibrous and/or powdered products) by grinding and milling processes. Thermal and/or chemical processes allow the recovery of fibers, but not always the recovery of valuable products from the resin (i.e. monomers that could be reused to produce resins). Additionally, the original resistance and length of recovering fibers is hardly achieved with these recycling processes. Mechanical recycling has important advantages over the previous ones: there is no atmospheric pollution by gas emission, a much simpler equipment is required as compared with ovens necessary for thermal recycling processes, and does not require the use of chemical solvents with subsequent environmental impacts [5].The pressure on the development of new and economically viab...

A Novel Polymer Concrete Composite with GFRP Waste: Applications, Morphology, and Porosity Characterization

“…The shape of the pores was characterized based on the sphericity (Sp) parameter [33]. The sphericity parameter of pores is calculated based on Equation (1). The parameters involved in Equation (1) are the volume (V) and the surface area (A) of the pore [34].…”

“…possible recycling solutions regarding waste management of composite based products. At present, the main conventional recycling techniques for glass-fiber-reinforced polymer (GFRP) waste materials include incineration, thermal or chemical recycling, and mechanical recycling [1][2][3]. Mechanical recycling through grinding and milling processes is one of the most used techniques; additionally, due to the size reduction of the fibrous products, the recycling process itself does not contribute to atmospheric pollution and much simpler equipment is required as compared to other methods.…”

The Concept of a Compact, Mobile, and Accurate Solution for the Dosing of Protein Substitutes for Medical and Sports Environments

“…Thus, it is critical to identify all possible recycling solutions for the waste management of composite-based products. At present, the main conventional recycling techniques for glass-fiber-reinforced polymer (GFRP) waste materials include incineration, thermal or chemical recycling, and mechanical recycling [8][9][10]. Mechanical recycling through grinding and milling processes is one of the most used techniques; additionally, due to the size reduction of the fibrous products, the recycling process itself does not contribute to atmospheric pollution and much simpler equipment is required compared with other methods.…”

Incorporation of Waste in Thermal Mortars—A Literature Review

“…This indicates that the circular economy and sustainability of the construction sector are areas that are receiving particular attention. The issue of waste production is also one of the highlights of the action plan for the circular economy, so it has been addressed by several studies [26][27][28][29] over the last few decades.…”