Mechanical Properties and Fracture Surface Analysis of Vinyl Ester Resins Reinforced with Recycled Carbon Fibres

Abstract

This work is focused on the mechanical characterization and fracture surfaces analysis of thermosetting polymers reinforced with short, randomly oriented, recycled carbon fibres (rCFs). This work aims at evaluating fibre/matrix adhesion between recycled CFs - reclaimed via pyrolysis followed by controlled oxidation of the pyrolytic char - and different polymer matrices, namely epoxy and vinyl ester resins. The latter is the main focus in this work, being amongst the most widely used thermosetting resins in SMC processes, which are the typical target for short rCFs. The evaluation of the properties of this new recycled carbon fibre reinforced polymer (rCFRP) has been via thermogravimetric analysis, dynamic mechanical analysis, stress/strain tests in tensile mode, and a subsequent analysis of the fracture surfaces by means of images analysis obtained by macrophotography, Optical Microscopy and Scanning Electron Microscopy. The comparison amongst the results allowed to evaluate the influence of the polymer nature and of the adhesion quality between fibres and polymeric matrix, mainly on the mechanical properties of the rCFRPs.

Optimization of Pyro‐gasification of Carbon Fiber Reinforced Polymers (CFRPs)

“…Such a different behavior could be ascribable to both the different thickness of the treated composites (1 mm versus 5 mm [4] ) and the different mass of the overall treated CFRP (10 g versus 5-7 kg [4] ) and emphasizes the importance of this in the scale up parameter when trying to optimize processing conditions. [11,12] These results are similar to those reported for VC matrix composites but with glass fibers treated in semi-industrial pilot plant. [8] In-vestigation of the EC panels residues by SEM shows, indeed, that, after 40 min of gasification, fibers' surface is clean and no spotted resin residue is detected (Figure 2); after 90 min, instead, fibers are visibly damaged, showing pitting on the surface.…”

Recycling of carbon fiber reinforced composite waste to close their life cycle in a cradle-to-cradle approach

“…recently introduced an innovative static-bed batch pilot reactor [55,56] which soon afterwards was modified into continuous process in two steps able to combine at 500-550°C both the pyrolysis and the oxidation step, drawing the main advantages of the different disposal techniques (Figure 3). In such a plant, pyrolysis can be carried out on the whole parts, up to 2m in diameter, in order to save the energy costs of shredding the feed wastes, and simultaneously recovering energy and materials with Re-CF retaining 95% of their original tensile strength [57,58]. In these conditions the obtained Re-CF maintain the original arrangement they had in the waste part, as depicted in Figure 3.…”

Utilization of Mechanically Recycled Carbon Fibers in Vinyl Ester Composites

“…Further addition of reinforcement results in a decrease in mechanical properties, which indicates agglomeration and porosity in the prepared samples due to the non-uniform mixing of the reinforcement [ 42 , 43 , 44 , 45 , 46 ].…”