Improvement of the chemical recycling process of waste carbon fibre reinforced plastics using a mechanochemical process: Influence of process parameters

Abstract

We present the experimental results of an optimal recycling method for waste carbon fibre reinforced plastics (CFRPs) that is based on the application of a set of unit mechanochemical processes. The objectives of this study were to highlight the influence of process factors that are inherent in the chemical recycling process of waste CFRP. We investigated the influence of the soaking period, the application of a catalyst and impurities on the recycling process and recovery efficiency of the waste CFRP. Different combinations of the unit mechanochemical processes were investigated, and the effectiveness of the combination was analysed. The chemical recycling process was conducted using benzyl alcohol under ordinary pressure at initial solvent temperatures lower/equivalent to its flash point temperature. Experimental results showed that the solvent temperature increased up to boiling temperature levels when the mechanochemical process was initiated, thereby enhancing the mechanochemical process. The presence of impurities did not influence the recovery rate. Likewise, this experimental study highlighted the importance of accounting for the soaking period during the chemical recycling process: an extended soaking period resulted in a higher recovery rate, a lower portion of undissolved solids and recovered fibres of better quality. This research highlighted the significance of choosing the proper combination for the chemical recycling process as well as the benefits of recycling the waste CFRP with negligible application of the catalyst.

A review on the recycling of waste carbon fibre/glass fibre-reinforced composites: fibre recovery, properties and life-cycle analysis

“…Similarly, using ECR, Zhu et al [110] and Chen et al [111] both retained mechanical properties similar to vCF; this method is inexpensive and suitable for large-scale application [111]. Recently, a mechanochemical process (MCP) similar to ECR has been tested [112], but limited information is available regarding the rCF quality. Recent approaches also involve ultrasonics, Das and Varughese [113] investigated a sonochemical recycling process by reacting the CFRP waste with dilute nitric acid and H 2 O 2 under ultrasonics at 60 °C, achieving a 95% decomposition ratio.…”

A Thermo-Catalytic Pyrolysis of Polystyrene Waste Review: A Systematic, Statistical, and Bibliometric Approach

“…On the other hand, tertiary recycling involves valuable chemical intermediate recovery (depolymerization, solvolysis, pyrolysis, gasification, hydrocracking, and others) [ 27 , 28 , 29 , 30 ]. Nowadays, chemical or feedstock recycling is attracting much attention, as it is environmentally friendly [ 31 ]. Chemical recycling overcomes the quality issue of thermoplastic recycling by enabling the production of virgin materials such as monomers, oligomers, and higher hydrocarbons from chemically-recycled feedstock [ 27 , 32 ].…”

Thermo-catalytic pyrolysis of polystyrene in batch and semi-batch reactors: A comparative study

“…These include primary (recycling of scrap materials), secondary (recycling through melt extrusion), tertiary (chemical or feedstock recycling into original monomers or other valuable chemicals) and quaternary (energy recovery through incineration) recycling (Okan et al, 2019; Poulakis and Papaspyrides, 1997). Nowadays chemical or feedstock recycling is attracting much attention as it is environmentally friendly and it can reduce the demand for energy and feedstock and hence can boost the circular economy of plastics (Nzioka et al, 2018; Okan et al, 2019; PlasticsEurope, 2019; Punkkinen et al, 2017). The environmental sustainability of the process can be evaluated through life cycle assessment study.…”