Mechanical Properties of Bio-Based Epoxy Composites Reinforced with Hybrid-Interlayer Ramie and Recycled Carbon Fibres

The growing environmental concerns have led to attention on bio-based composite materials, such as the natural fibres, recycled carbon fibres and bio-based resins. Herein, the bio-based epoxy composites were reinforced with ramie fibre (RF) and recycled carbon fibre (rCF) via inter-layer hybridisation. The dynamic mechanical analysis, tensile, flexural and impact properties characterisation were conducted to analyse the mechanical behaviour of the specimens. Also, the morphology of fractured surface after mechanical tests was studied under a scanning electron microscope. When the volume ratio between RF and rCF was varied from 100/0 to 0/100, the flexural and tensile strength of composites was significantly increased, while the impact strength was reduced. Thus the maximum values of flexural strength (182 MPa) and tensile strength (165 MPa) were observed for rCF reinforced composite, whilst impact strength of 24 kJ/m2 was found for RF reinforced composite. Furthermore, the values of storage and loss modulus were increased with the rCF incorporation due to a greater degree of restriction with the addition of rCF into the matrix. The hybridisation was able to combine the specific properties of RF and rCF and optimise the mechanical performance of composites. Therefore, the alternative low-cost green composites are prepared which can replace synthetic materials for semi-structural applications.

High temperature tensile,compression and creep behavior of recycled short carbon fibre reinforced AZ91 magnesium alloy fabricated by a high shearing dispersion technique

The present study seeks the feasibility of using short carbon fibres recycled from polymer matrix composites as alternative to virgin carbon fibres in the reinforcement of magnesium alloys.The microstructures,high temperature mechanical and creep properties of AZ91 alloy and its composites with various recycled carbon fibre contents(2.5 and 5 wt.%)and lengths(100 and 500μm)were investigated in the temperature range of 25-200℃.The microstructural characterization showed that the high shear dispersion technique provided the cast composites with finer grains and relatively homogenous distribution of fibres.The materials tested displayed different behaviour depending on the type of loading.In general,while enhancements in the mechanical properties of composites is attributed to the load bearing and grain refinement effects of fibres,the fluctuations in the properties were discussed on the basis of porosity formation,relatively high reinforcement content leading to fibre clustering and interlayer found between the matrix and reinforcement compared to those of AZ91 alloy.The compressive creep tests revealed similar or higher minimum creep rates in the recycled carbon fibre reinforced AZ91 in comparison to the unreinforced AZ91.

Environmental analysis of innovative sustainable composites with potential use in aviation sector -A life cycle assessment review

The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact.Aviation industry is working on promising technologies to mitigate this environmental impact.Lightweight design is a strong lever to lower the fuel consumption and,consequently,with it the emissions of aviation.High performance composites are a key technology to help achieve these aims thanks to their favourable combination of mechanical properties and low weight in primary structures.However,mainly synthetic materials such as petrol based carbon fibres and epoxy resins are used nowadays to produce composite in aviation.Renewable materials like bio-based fibres and resin systems offer potential environmental advantages.However,they have not found their way into aviation,yet.The reasons are reduced mechanical properties and,especially for the use of natural fibres,their flammability.Improvements of these shortcomings are under investigation.Therefore the application of bio-based and recycled materials in certain areas of the aircraft could be possible in the future.Good examples for applications are furnishings and secondary structures.The motivation for this paper is to give an overview of potential environmental properties by using such eco-materials in aviation.Life cycle assessment(LCA) is a tool to calculate environmental impacts during all life stages of a product.The main focus is laid on the bio-fibres flax and ramie,recycled carbon fibres and bio-based thermoset resin systems.Furthermore an overview of environmental aspects of existing composite materials used in aviation is given.Generally,a lack of LCA results for the substitution of synthetic materials by bio-based/recycled composite materials in aviation applications has been identified.Therefore,available information from other transport areas,such as automotive,has been summarized.More detailed LCA data for eco-composite materials and technologies to improve their properties is important to understand potential environmental effects in aviation.