Abstract

Due to the rapid growth of the composite market, several European laws have emerged to minimize their environmental impact (EU 2000/53 / EC, End of life vehicles), as well as to make rational use of landfills (EU 1999/31 / EC). For example, in the aeronautical sector, composites can reach 50% by weight of the aircraft. Consequently, recyclability is a key issue. The objective of this work is the study of the recycling techniques of carbon fiber composites with thermoset polymer matrix in order to obtain fibers with similar properties to the original ones. In this way, the fibers could be reused in new composites by themselves or together with flass fibers in the manufacture of new hybrid composite materials. By this hybridization, materials with properties far superior to the GFRP would be obtained, but at much lower cost than the original CFRP. Therefore, this recycling and reprocesing strategies provides great economical attractiveness.  The main objective of the project is to study and optimize the recyclability of cured carbon fiber / epoxy prepregs for use in hybrid materials. Starting from a pyrolysis in a controlled atmosphere reactor, followed by a oxidation, carbon fibers with properties similar to virgin fibers are obtained, with a loss less than 20% of the tensile strength. An evaluation of the different parameters of the recycling process has been carried out in order to optimize the procedure. The characterization of the fibers includes tensile tests, scanning electron microscopy and Raman spectroscopy.

Abstract

In terms of energy, the Earth is an open system: it constantly receives energy from solar radiation and emits the same amount of energy in the form of more degraded radiation; the displacement of the equilibrium point between these two flows due to the growth of greenhouse gases, increases the average temperature of the Earth and causes climate change. On the other hand, in relation to matter, the Earth is a closed system, apart from the sporadic fall of some meteor. Nature has the ability to regenerate the organic materials of living beings but not with many other materials.

Today, the volume of materials involved in human activities is 12.5 tons per person per year (1.5 to 4 times more in rich countries): 25% of the total comes from biomass (including food), 15% are fossil fuels, 10% are metal ores, 42% are other minerals (mainly for construction) and 8% are recycled. On the other hand, obtaining and transporting materials worldwide requires more than 40% of the energy of the human system, a value that is growing with the use of increasingly rare, scarce and dispersed materials. The overexploitation of resources coupled with the increasing use of non-renewable energy resources (fossil fuels and uranium), with the consequent energy and climate crisis and the deterioration of the environment, leads both to a change in the energy model and to rethinking the practices today dominant of continuous economic growth and the linear economy based on extract-use-throw.

The purpose of this communication is, after presenting the figures on the global metabolism of materials, to reflect on some of the new attitudes and actions that will need to be adopted within the framework of sustainable development. By way of example, the following are cited: 1) Moderate, reduce, eliminate the use of materials where possible; 2) Extend the life of goods and material infrastructures; 3) Reuse, recover, recycle materials; 4) Return as much as possible biologically based materials, more recyclable; 5) Avoid, as far as possible, technologies based on rare or scarce materials; 6) Avoid the dispersion of materials in the environment (atmosphere, water, soil); 7) Encourage the use of local materials in order to minimize transport and its energy impact; 8) Take care of the quality and good health of basic resources: air, water and fertile soil.

Abstract

In an attempt to cover the needs and requirements of consumers, packaging without good recyclability is sometimes introduced in the market. This is more evident in the case of polyethylene terephthalate (PET). PET is a highly recyclable material that results in a recycled product with enhanced quality. However, there are other type of PET multilayered packaging that are being introduced in the market. These packaging products include additional materials such as other type of polymers, metals, paper, etc., as well as different type of pigments, colouring agents and impurities confering a critical colour to the packaging. When this new packaging arrives to the recycler it generates problems, resulting in low quality products or even rejected, being deposited in landfill. This implies an important environmental reduction (mainly in the CO2 emissions) and in the economic affairs. For this reason, the recycling companies and, in general, waste management companies, are interested in alternatives that allow these residues to have a viable outlet. This development is presented as a solution to the problem of these particular PET multilayered residues. The main objective is the industrial development of thermosetting resins (alkyds and unsaturated polyesters) that include in their composition materials obtained from the chemical recycling of these multilayered packaging, at an affordable price and with reduced environmental impact.