Life Cycle Assessment of a Thermal Recycling Process as an Alternative to Existing CFRP and GFRP Composite Wastes Management Options

There are forecasts for the exponential increase in the generation of carbon fibre-reinforced polymer (CFRP) and glass fibre-reinforced polymer (GFRP) composite wastes containing valuable carbon and glass fibres. The recent adoption of these composites in wind turbines and aeroplanes has increased the amount of end-of-life waste from these applications. By adequately closing the life cycle loop, these enormous volumes of waste can partly satisfy the global demand for their virgin counterparts. Therefore, there is a need to properly dispose these composite wastes, with material recovery being the final target, thanks to the strict EU regulations for promoting recycling and reusing as the highest priorities in waste disposal options. In addition, the hefty taxation has almost brought about an end to landfills. These government regulations towards properly recycling these composite wastes have changed the industries’ attitudes toward sustainable disposal approaches, and life cycle assessment (LCA) plays a vital role in this transition phase. This LCA study uses climate change results and fossil fuel consumptions to study the environmental impacts of a thermal recycling route to recycle and remanufacture CFRP and GFRP wastes into recycled rCFRP and rGFRP composites. Additionally, a comprehensive analysis was performed comparing with the traditional waste management options such as landfill, incineration with energy recovery and feedstock for cement kiln. Overall, the LCA results were favourable for CFRP wastes to be recycled using the thermal recycling route with lower environmental impacts. However, this contradicts GFRP wastes in which using them as feedstock in cement kiln production displayed more reduced environmental impacts than those thermally recycled to substitute virgin composite production.

Upcycling of Waste Polyethylene and Cement Kiln Dust to Produce Polymeric Composite Sheets Using Gamma Irradiation

Cement kiln dust (CKD) is a residue produced during the manufacture of cement that contains hazardous solid waste of high toxicity that affects the environment and public health. In this study, the possibility of using cement waste as a filler in the plastic and rubber industry was studied. Different concentrations of (CKD) and gamma irradiation on the mechanical, thermal stability of the prepared composites sheets were investigated. Different concentrations of (CKD) 10, 15, 20, 30, 35, and 40 wt % were prepared with double screw extrusion by mixing waste polyethylene (WPE), de-vulcanized rubber (DWR), and EPDM rubber. These prepared composites were irradiated with doses 25, 50, 75, 100, and 150 kGy to study the effect of radiation on the physical, mechanical properties, and thermal stability of the prepared composite sheets. The prepared composite sheets were characterized and verified by FTIR and soluble fractions. The morphology of the composite sheets was investigated by SEM. Mechanical and thermal properties were investigated to evaluate the possibility of its application in the plastic and rubber industry.

Influence of B2O3 doping on synthesis of MgTiO3 ceramics from recycled magnesia-hercynite materials

Herein, magnesium metatitanate (MgTiO3) ceramics were synthesised using recycled magnesia-hercynite (MH) bricks as the raw materials to achieve solid waste reusing of cement kiln refractories. The recycled MH materials were mixed with anatase TiO2 to investigate the effect of addition of doped B2O3 during the synthesis of MgTiO3 ceramics at 1400 °C. Phase compositions and microstructural studies were performed using x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. In addition, energy-dispersive spectroscopy (EDS) was conducted and the dielectric properties of the samples were studied. Results show that the addition of B2O3 can promote sintering, improve shrinkage, promote densification, stabilise MgTiO3 lattice, and inhibit the formation of MgTiO3. In addition, the presence of appropriate amount of B2O3 can accelerate the material diffusion and result in grain growth through the formation of intercrystalline liquid phase. Results also suggest that an increase in dielectric constant results in a decrease in dielectric loss. It was concluded that 2 wt% was the optimum amount of B2O3 required to obtain the most favourable synthesis rate of MgTiO3 (98.2%). The samples exhibited a maximum density of 3.69 g·cm−3 and excellent microwave dielectric properties at ε r = 18.28 and tanδ = 0.086.