Search Results (8)

The growing use of fibre-reinforced polymers (FRPs) is driving a demand for the development of sustainable end-of-life strategies. Solvolysis, a chemical recycling method using solvents to decompose the polymer matrix, has emerged as a promising approach for reclaiming both fibres and organic compounds from FRP waste. This work provides a comprehensive overview of solvolysis techniques by discussing the environmental benefits and economic opportunities of this technology, summarising the process conditions, and evaluating the characteristics of the recovered products. The economic viability of solvolysis lies in recovering high-value components; predominantly carbon fibres from CFRPs and organic products from GFRPs, which are suitable for reuse or as a feedstock for new composites. Solvolysis can operate under low temperature and pressure (LTP) or high temperature and pressure (HTP) conditions. The choice of solvent, catalyst, reaction time, and temperature is crucial to achieving high resin decomposition while preserving fibre properties. To achieve an economically viable and environmentally beneficial process, it will be essential to optimise these parameters. A key challenge is maintaining the strength and surface properties of the recovered fibres, as degradation in their performance can limit their suitability for high-performance applications. The implication of this is that, without careful consideration of the recycling process, FRPs cannot be fully circular. They will be continuously downgraded into low-value applications and ultimately incinerated or landfilled. This review further explores the diversity of organic products obtained, which can range from monomers to oligomers to complex mixtures. Efficient separation and upgrading techniques, such as distillation and liquid–liquid extraction, are essential to maximise the value of the recovered organics. These additional processing steps are likely to result in greater financial and resource costs within a commercial recycling system. This review concludes with a summary of commercial solvent-based recycling ventures and an outlook on future research directions, which includes the need to develop processes capable of recovering high-value, long carbon fibres. Successful development of such a process would represent a step-change in the value proposition of a carbon fibre recycling industry. Full article

There is great interest in using bio-based materials to reduce the climate impact of materials. Similarly, there is an increased focus on the circular economy and recycling of materials to increase material efficiency and reduce waste. In the case of wood waste, this provides a cluster of benefits but has led to a high demand for the reclaimed material. This review provides updates on several technologies where wood fibre recycling and products from recycled wood fibre are breaking into new markets, including wood fibre insulation products, wood plastic composites, oriented strand boards, and fibreboards. Emerging technologies, such as the ability to recycle medium-density fibreboards, in addition to the more commonly recycled solid wood or particleboard, will allow for a new set of options within the wood cascading chain. Looking ahead, there are likely to be advances in new composite products, as well as other feedstock materials derived from reclaimed wood, such as nanocellulose, pyrolysis oils, or wood polymers reclaimed from the wood feedstock. This review arose from an investigation into the wood recycling sector in the UK. So, the horizon scanning exercise presented here considers the needs and challenges that may arise, if the volume of recycled wood fibre can be increased, in an already highly active market. Such developments would permit an increase in the manufacture of new-generation long-service-life products to enhance carbon storage, and potentially a shift away from bioenergy generation. Full article

This study articulates findings from research pertaining to the utilisation of recycled geogrid in asphalt concrete. The issue of contamination of reclaimed waste with geosynthetic materials persists as a significant concern that warrants attention. In Poland, the allowable quantity of geogrid contaminants within the mineral–asphalt composition is 0.1% w/w. The preliminary evaluation of the validity of the research topic was conducted based on an analysis of correspondence and survey outcomes. The fundamental material research was executed employing elements of experimental design theory. The experimental domain considered two qualitative factors: the type of bituminous mixture for the binding layer (AC16W and AC22W) and the type of geogrid material (glass, carbon), in addition to two quantitative factors: the length of the recycled geogrid fibres ranging from 1 cm to 5 cm, and the quantity of recycled geogrid fibres varying from 0.2% to 1%. A generalised linear model was employed for the analysis, enabling the consideration of dependent qualitative factors in forecasting characteristics. The qualitative evaluation of the resultant solution was conducted using multi-criteria optimisation via the Harrington function. Consequently, recycled carbon mesh fibres demonstrated a notably positive impact, enhancing the material’s quality by 22%. Regarding glass mesh, the fibre content should not exceed 0.2% in the AC22W mixture, whereas it can be increased to 1% in the AC16W mixture. Comparing all evaluated mixtures, it was ascertained that surpassing the allowable contamination limit of 0.1% in geogrid form does not result in a significant reduction in the quality of asphalt concrete compared to the reference mix. Full article

During Carbon Fibre Reinforced Polymers (CFRPs) manufacturing, large quantities of scrap are being produced and usually disposed to landfill or incinerated, resulting in a high environmental impact. Furthermore, CFRP parts that have been damaged or reached their end-of-life, follow the same disposal route and because of this, not only the environment is affected, but also high added-value materials, such as carbon fibres (CFs) are lost without further valorisation. Several recycling technologies have been suggested, such as pyrolysis, to retrieve the CF reinforcement from the CFRPs. However, pyrolysis produces CFs that have residual resin and pyrolytic carbon at their surface. In order to retrieve clean long fibres, oxidation treatment in high temperatures is required. The oxidation treatment, however, has a high impact on the mechanical properties of the reclaimed CFs; therefore, an optimised pyrolysis procedure of CFRPs and post-pyrolysis treatment of reclaimed fibres (rCFs) is required. In this study, CFRPs have been subjected to pyrolysis to investigate the reclamation of CF fabrics in their primal form. The temperature of 550 °C was selected as the optimum processing temperature for the investigated composites. A parametric study on the post-pyrolysis treatment was performed in order to remove the residues from the fabrics and at the same time to investigate the CFs reusability, in terms of their mechanical and surface properties. Full article

This paper presents a review of waste disposal methods for fibre reinforced polymer (FRP) materials. The methods range from waste minimisation, repurposing, reusing, recycling, incineration, and co-processing in a cement plant to dumping in a landfill. Their strength, limitations, and key points of attention are discussed. Both glass and carbon fibre reinforced polymer (GFRP and CFRP) waste management strategies are critically reviewed. The energy demand and cost of FRP waste disposal routes are also discussed. Landfill and co-incineration are the most common and cheapest techniques to discard FRP scrap. Three main recycling pathways, including mechanical, thermal, and chemical recycling, are reviewed. Chemical recycling is the most energy-intensive and costly route. Mechanical recycling is only suitable for GFRP waste, and it has actually been used at an industrial scale by GFRP manufacturers. Chemical and thermal recycling routes are more appropriate for reclaiming carbon fibres from CFRP, where the value of reclaimed fibres is more than the cost of the recycling process. Discarding FRP waste in a sustainable manner presents a major challenge in a circular economy. With strict legislation on landfill and other environmental limits, recycling, reusing, and repurposing FRP composites will be at the forefront of sustainable waste-management strategies in the future. Full article

Exploring improved tropical forages is considered to be an important approach in delivering quality and consistent feed options for dairy cattle in tropical and subtropical regions. The present study aimed to study the suitability of three improved tropical grasses, Chloris gayana ‘Rhodes grass cv. Reclaimer’ (RR), Megathyrsus maximus ‘Gatton Panic’ (GP), and Brachiaria ruziziensis x B. decumbens x B. brizantha ‘Brachiaria Mulato II’ (BM) evaluating their carbon assimilation, canopy structure, herbage plant–part accumulation and quality parameters under irrigated conditions. An experiment was conducted at Gatton Research Dairy (27°54′ S, 152°33′ E, 89 m asl) Queensland, Australia, which has a predominantly subtropical climate. Photosynthesis biochemistry, canopy structure, herbage accumulation, plant part composition, and nutritive value were evaluated. Photosynthesis biochemistry differed between pasture species. Efficiency of CO₂ assimilation was highest for GP and quantum efficiency was highest for BM. Pasture canopy structure was significantly affected by an interaction between pasture species and harvest. Forage biomass accumulation was highest in GP, while BM produced more leaf and less stem compared to both GP and RR. A greater leafy stratum and lower stemmy stratum depth were observed in the vertical sward structure of BM. Brachiaria Mulato II showed greater carbon partitioning to leaves, leaf: stem ratio, canopy, and leaf bulk density. It also demonstrated greater nutritive value (Total digestible nutrients (TDN), acid detergent fibre (ADF), neutral detergent fibre (NDF), neutral detergent insoluble protein (NDICP), Starch, nonfibre carbohydrates (NFC), metabolisable energy (ME), mineral profile (Mg, P, K, Fe, Zn) and dietary cation–anion difference (DCAD) for leaf, stem, and the whole plant. Greater quantum efficiency, leaf accumulation, and nutritive value of BM observed in the present study suggest BM as an attractive forage option for dairying that warrants further research in pasture-based systems in tropical and subtropical climates. Full article

The feasibility of using the HiPerDiF (high performance discontinuous fibre) method to manufacture highly aligned discontinuous fibres intermingled hybrid composites with flax and reclaimed carbon fibres (rCF), and the potential benefits of so doing, are investigated in this paper. It is demonstrated that, despite their hydrophilic nature, flax fibres are not affected by this water-based process. Intermingled flax/rCF hybrid composites are characterised in terms of their tensile and vibrational response. It is concluded that natural/rCF fibre hybrid composites can be a viable solution for those applications where a reduction in primary mechanical properties, e.g., stiffness and strength, is an acceptable trade-off for the enhancement of secondary properties, e.g., noise, vibration, and harshness (NVH) mitigation, and the reduction of monetary costs. Full article

Recycling carbon fibre is crucial in the reduction of waste from the increasing use of carbon fibre reinforced composites in industry. The reclaimed fibres, however, are usually short and discontinuous as opposed to the continuous virgin carbon fibre. In this work, short recycled carbon fibres (rCF) were mixed with flax and poly-lactic acid (PLA) fibres acting as the matrix to form nonwoven mats through wet-laying. The mats were compression moulded to produce composites with different ratios of rCF and flax fibre in the PLA matrix. Their flexural behaviour was examined through three-point-bending tests, and their morphological properties were characterised with scanning electron and optical microscopes. Experimental data showed that the flexural properties increased with higher rCF content, with the maximum being a flexural modulus of approximately 14 GPa and flexural strength of 203 MPa with a fibre volume fraction of 75% rCF and 25% flax fibre. The intimate mixing of the fibres contributed to a lesser reduction of flexural properties when increasing the flax fibre content. Full article