University of Portsmouth researchers are at the forefront of a drive to develop environmentally-friendly materials from agricultural waste for use in the automotive, marine and aerospace industries.
A team from the University’s School of Engineering are producing and developing lightweight materials from farming leftovers (agriculture biomass) – a process that could provide significant environmental benefits.
The sustainable composite materials are produced from flax, hemp, jute and waste biomass date palm fibres to provide parts like car bumpers and door linings – mainly non-structural components. Using natural plant fibres for composite manufacturing has the potential to provide farmers with extra income and reduce C02 emissions from the burning of waste.
Dr Hom Nath Dhakal, who leads the Advanced Materials and Manufacturing (AMM) Research Group at the University, said “We are working to address the key challenges of using natural reinforced composites for structural and semi-structural applications such as internal engine covers, seat back and roof structures, among others.
The impact of this work would be extremely significant because these lightweight alternatives could help reduce the weight of vehicles, contributing to less fuel consumption and fewer C02 emissions. The sustainable materials can be produced using less energy than glass and carbon fibres and are biodegradable, therefore easier to recycle.”
Advantages of natural fibres include high specific strength (strength divided by density) and stiffness, a lower production cost than synthetic fibres and reduction of wear on the machinery used to process the fibres. They offer reduced health and safety concerns during processing because glass and carbon fibres have a tendency to emit some toxic materials compared to natural fibres. However, natural fibres also have their drawbacks. These include a tendency to absorb moisture, which reduces strength, and mechanical properties that do not match structural property requirements.
Dr Dhakal and his team have been working closely with industry to address these problems and test the strength and viability of parts made from the sustainable materials. These test results are compared to that of hybrids of the natural materials with more traditional glass and carbon fibres. The AMM Research Group has been working in collaboration with researchers from various institutions from around the world.
In the last 12 months, the group has published many high impact factor papers in journals including Composites Science and Technology, Composites Part A and Composites Part B.
A recent collaborative study, published in the journal of Composite Part A: Applied Science and Manufacturing explored the potential of waste leaf sheath date palm fibres for composite reinforcement.
Date palm is cultivated extensively in North Africa and the Middle East and the accumulated bio-waste of plant fibres is in the order of millions of tonnes per annum. While there are a number of traditional uses of this bio-waste (including ropes and baskets), a large amount of the residue is burnt or land-filled.
The study looked at the structure, physio-chemical and mechanical properties of date palm fibres to assess whether they had the potential as reinforcements for composite materials. It found they could be cost-effective and environmentally-friendly reinforcements for better impact resistance and improved damping properties. This investigation looked at the relationships of property structures. It showed that components such as door linings, front and rear car bumpers and parcel shelves could be manufactured using these reinforcements.
One of the issues with materials created from natural fibres is the lower strength compared to carbon and glass fibre composites, as they are susceptible to increased moisture absorption. A study published in Composites Science and Technology (Almansour et al., 2018) tested the effect of water absorption on the mechanical properties of a composite of flax and basalt fibres. The study revealed that this hybrid of natural and basalt fibres had high mechanical strength.
Dr Dhakal said “The way forward for natural fibre composites to be used in structural applications would be a combination of both materials (natural and synthetic fibres) with a hybrid approach. Meeting these challenges requires further research and innovation between academic institutions and industry.”