Laura Mazzocchetti

Pyrolysis as a way to close a CFRC life cycle: Carbon fibers recovery and their use as feedstock for a new composite production

Pyrolysis is shown to be an efficient method for recycling carbon fiber composites in the form of both uncured prepregs scraps or as cured end-of-life objects. The pyrolytic process leads to different products in three physical states of matter. The gaseous fraction, called syngas, can be used as energy feedstock in the process itself. The oil fraction can be used as fuel or chemical feedstock. The solid residue contains substantially unharmed carbon fibers that can be isolated and recovered for the production of new composite materials, thus closing the life cycle of the composite in a “cradle to cradle” approach. All the pyrolysis outputs were thoroughly analyzed and characterized in terms of composition for oil and gas fraction and surface characteristics of the fibers. In particular, it is of paramount importance to correlate the aspect and properties of the fibers obtained with different composite feedstock and operational conditions, that can be significantly different, with the reinforcing performance in the newly produced Recycled Carbon Fibers Reinforced Polymers. Present results have been obtained on a pyrolysis pilot plant that offers the possibility of treating up to 70kg of materials, thus leading to a significant amount of products to be tested in the further composites production, focused mainly on chopped carbon fiber reinforcement.

Investigation of a carbon fiber/epoxy prepreg curing behavior for thick composite materials production: An industrial case-study

A case-study is presented, in cooperation with RI-BA Composites srl, where the industrial production of a thick part for primary structural application is analysed. The final product is a bulk carbon fiber reinforced object characterized by great dimensions, with thickness ranging between 10mm and 35mm and obtained by Hand-Lay-Up of prepregs. The study shows that prepregs age along the time required for the process work up. Moreover, the isothermal curing investigation of the prepreg used in the production gives some useful hint for the design of a new thermal curing cycle, in order to avoid exotherm problems along the thickness of the object. The effect of the applied curing cycle on thermal properties of the object are reported.

Evaluation of Tryptophan – Late curing agent systems as hardener for epoxy resin

In order to obtain a low-toxic and environmentally friendly epoxy system, the novel green curing agent L-Triptophan was used, in combination with the two commercial late curing agents 2-Undecyl-1H-imidazole and 3,3’-(4-Methyl-1,3-phenylene)bis(1,1-dimethylurea), as hardener system for the cross-link of Diglycidyl Ether of Bisphenol A (DGEBA). The thermal behavior of the precursors mixtures was evaluated by dynamic and isothermal Differential Scanning Calorimetry (DSC) and confirmed L-Tryptophan as a possible novel green curing agent for DGEBA. These encouraging results pave the way for a further study of a new class of low-toxic and sustainable curing agent systems for the production of fully bio-based epoxy resins.In order to obtain a low-toxic and environmentally friendly epoxy system, the novel green curing agent L-Triptophan was used, in combination with the two commercial late curing agents 2-Undecyl-1H-imidazole and 3,3’-(4-Methyl-1,3-phenylene)bis(1,1-dimethylurea), as hardener system for the cross-link of Diglycidyl Ether of Bisphenol A (DGEBA). The thermal behavior of the precursors mixtures was evaluated by dynamic and isothermal Differential Scanning Calorimetry (DSC) and confirmed L-Tryptophan as a possible novel green curing agent for DGEBA. These encouraging results pave the way for a further study of a new class of low-toxic and sustainable curing agent systems for the production of fully bio-based epoxy resins.

Synthesis, Characterization and Transesterification Activity of Cross-Linked Styrenic Resins Containing the Triphenyltincarboxylate Moiety Spaced by a Dimethylene from the Aromatic Ring

An organotin monomer, triphenyltin 3-(4-styryl)-propionate (TPTSPr) has been synthesized and copolymerized in different ratios with styrene and 1,4-divinylbenzene in order to obtain resins with catalytic activity in transesterification reactions. The resins and a low molecular weight model compound, triphenyltin 3-(4-ethylphenyl)-propionate (TPT-C2-Pr), mimicking the catalytic co-unit, have been characterized by FT-IR and NMR spectroscopy, with particular attention paid to the coordination at tin and how it correlates to the catalytic activity. The activity of both the resins and of the model compound have been tested in a transesterification model reaction between ethyl acetate and primary alcohol. All the resins show catalytic activity that decreases with increasing content of the active co-unit in the resins, owing to the interaction of the active sites among themselves.