## 1 Introduction
High-temperature solvolysis, on the other hand, operates at higher pressures (80-300 bar) and temperatures, achieving better reaction rates and resin degradation efficiency, often using non-hazardous solvents like water, which, under supercritical conditions, enhances reactivity and may eliminate the need for catalysts [4; 10; 13]. This method yields clean carbon fibers with minimal loss in mechanical properties and also recovers depolymerized resins and monomers [9]. The main solvent used is water, which is non-toxic, easy to handle, and environmentally friendly. [PERSON] et al. [14] succeeded in degrading resins with water at 380 \({}^{\circ}\)C and 250 bar with a DR of 90%. [PERSON] et al. [15] broke down 89.1% of the resin using supercritical water (400 \({}^{\circ}\)C, 372 bar) in 60 min, although they required the use of benzyl alcohol (g400 \({}^{\circ}\)C, 27 bar, 60 min) to bring up the DR to 93.7%. [PERSON] et al. [16] used supercritical water (405 \(\pm\) 2 \({}^{\circ}\)C, 280 \(\pm\) 10 bar) to reach a DR of 90-99% in 10-120 min, but the TS of the recovered fibers went down by 18-36%. Other solvents or co-solvents, such as alcohols and organic solvents, can also be used. In addition, a series of catalysts can be added to increase resin degradation rates so that the process can be conducted at lower temperatures or using shorter reaction times [4; 9; 10]. Thus, [PERSON] et al. [17] used an acetone/water mixture (80:20 \(v/v\)) at near-critical conditions (297 \({}^{\circ}\)C, 120 bar) in combination with different weak Lewis acids to act as a catalyst (ZnCl\({}_{2}\) and MgCl\({}_{2}\) 0.05 M, or AlCl\({}_{3}\) 0.005 M) and degrade a carbon fiber-reinforced RTM6 epoxy resin matrix. Regardless of the catalysts used, they reported DRs \(\approx\) 95% for either 290 \({}^{\circ}\)C and 90 min or 300 \({}^{\circ}\)C and 45 min as the operating conditions. [PERSON] et al. [18] used a KOH/phenol/water mixture at an optimum ratio of 1/10/100 g/g/mL, since they had corroborated that the combination of KOH and phenol exhibited a synergistic effect on the degradation of the studied resin (DGEBA with DDM as curing agent). This allowed them to reach a DR of 95% at 315 \({}^{\circ}\)C and 30 min. In their study, they removed the sizing from the raw and recovered fibers before performing the tensile tests and confirmed that there were no significant TS differences between the raw and recovered fibers. [PERSON] et al. [19] used supercritical n-butanol (330 \({}^{\circ}\)C, 65 bar) together with 0.05 M KOH for 60 min to recycle CFRPs (DGEBA matrix and DICY as the curing agent) and achieved a DR of around 98%. By means of scanning electron microscopy (SEM), they could observe that the sizing of the recycled carbon fibers (rCFs) had been removed. [PERSON] et al. (2008) [20] achieved 95.4% resin degradation using supercritical water (400 \({}^{\circ}\)C, 281 bar) and 0.5 M KOH for 15 min. The CFs recovered using this method had suffered a loss in their original tensile strength (TS) of 2-10%. [PERSON]. [PERSON] et al. [21] achieved a DR \(\approx\) 97-99% of a CFRP (TGDDM matrix with DDS as curing agent) by employing supercritical water (395 \({}^{\circ}\)C, 281 bar) and 0.05 M KOH for 15-60 min in a stirred reactor, and employed the resulting rCFs to fabricate new composites. Our research group has already investigated the recycling of CFRP offcuts from the aeronautics industry. We have tested the effect of using acetone and isopropanol (IPA) either as pure solvents or as aqueous solutions at different concentrations [22; 23]. The use of IPA is particularly interesting from a circular economy viewpoint, as this lays the groundwork for a potential utilization of IPA-rich byproducts from the semiconductor industry [24].