Periodic Reporting for period 1 - FURHY (FULLY RECYCLABLE HYBRID BIO-COMPOSITE FOR TRANSPORT APPLICATIONS)
Période du rapport: 2023-07-01 au 2024-12-31
The growing demand for reducing CO2 emissions has made automotive and aerospace industry to invest significantly into the development of new forms of sustainable mobility, that are enabled by innovation in Advanced Materials, particularly in lightweight and sustainable materials. The FURHY project envisages to contribute placing Europe at the leading position in automotive and aerospace, by contributing to the development of resilient, sustainable and secure raw materials value chains, to the production of new sustainable-by-design, low cost and lightweight composite materials with enhanced functionalities, and to a leadership in circular economy by developing a recycling process that allows to recover the 100% of the material, reusable for new and high value composites.
The formulation of a bio-based, recyclable, fast curing epoxy resin, on the basis of specific requirements, was developed. Cleavable Units and Cleavable Hardeners were synthesized, purified and characterized at lab scale. The protocol to validate the hardener cleavage capacity in terms of reversibility was defined. A study of the epoxy resin formulation and of its physic-chemical properties to fulfil the defined key parameters from a performance and process point of view was also performed. The new formulations based on epoxy bio-resins were characterized to determine curing kinetic, thermal stability and glass transition temperature and the selected formulations were loaded with different expanded graphite (EG) percentages to determine the electrical percolation threshold, thermomechanical properties, thermal stability, curing degree and rheological properties of the formulated systems. A numerical model was developed to describe the electrical behaviour of the composite material and to predict the percolation threshold. The reinforcing textiles were prepared by adjusting the textile process for the hybrid hemp/rCF non-woven and developing the coating for fiber improvement. It was confirmed that the hybrid rCF/hemp non-woven at desired ratios can be achieved with some modifications to the carding process whilst remaining suitable for prepregging and that a 100% hemp non-woven can be also manufactured with further adjustments and process optimisation. An atmospheric pressure plasma deposition process for the surface modification of hemp fabric was developed to increase the adhesion of hemp reinforcement to an epoxy resin. Furthermore, it was verified and demonstrated that a silane-based sizing formulation previously developed for rCFs improves the mechanical properties of hemp reinforced composites materials and, therefore, can be applied to hybrid hemp/rCF fabrics without any modifications. Moreover, good quality prepregs were manufactured by holt-melt process using three types of non-woven (from 100% rCFs, 100% hemp fibers and mixed rCF/hemp fibers) and an epoxy resin system (fossil-based at this stage) suitable for automotive field. The possibility to apply Joule heating on 100% rCFs non-woven and on commingled rCF/hemp non-woven was also verified and the efficacy of both the non-wovens to the response related to the Joule heating was evaluated and demonstrated. Then, composites hardened via electrocuring were manufactured using the two typologies of non-wovens as reinforcement. The non-wovens were impregnated both with only resin (fossil and bio-based) and resin (bio-based) containing an optimized loading of EG. The developed electrocured composites were characterized by evaluating curing degree, glass transition temperature and thermomechanical properties. The electrocuring was successful applied to the composites and the results obtained are very promising. A new numerical model was also developed in order to obtain the percolation curve for the composites with the three different types of non-woven.
The FURHY contributions towards the expected impacts are in line with the results and developments obtained in the 1st period of the project. Depolymerizable building blocks at gram scale were successfully prepared and the reversibility of these hardeners was tested to validate the hardener cleavage capacity. Depolymerizable systems were obtained by using these building blocks and preliminary validation of the recyclability of DCLE systems were conducted by exposing the specimens to aqueous acidic conditions. Different bio-resins with potential recyclability were developed and the feasibility study to determine the reduction of cost and depolymerization yield is now ongoing. Low environmental impact fibers were used to manufacture the reinforcing textiles, in particular rCFs that otherwise will be disposed into landfill. In addition, rCF was mixed with natural fibre and a non-woven was manufactured completely with natural fibre (hemp). Both materials are deemed to be sustainable materials that have a positive impact on the environment. Three smart functions, deicing/antiicing, self-sensing, were successfully integrated in electrocured composites. Furthermore, a methodology on the possibility to monitor the progress of electrocuring process was proposed. From the first results obtained, the out-of-autoclave (OoA) manufacturing process assisted via electro-curing allows saving over 87% of the energy compared to the traditional process of curing in autoclave. In this scenario, the developed technology guarantees to produce components with mechanical properties similar to those of traditional cured composites. Moreover, a prepreg manufacturing process using the hot melt technique with non-wovens from 100% rCFs, 100% hemp fibers or commingled rCF/hemp fibers and commercially available epoxy resin systems was developed. This approach enables the production of a prepreg partially composed of sustainable materials. By employing conventional curing techniques (vacuum bagging in an autoclave or oven), the process to produce laminates and advanced composite components containing approximately 50% renewable raw materials was optimized.