Lightweight and minimum energy structures – high strength-to-weight materials for design, fashion, automotive and architecture.

The development of lightweight material technologies has led to revolutionary changes in the world around us. While they can be energy demanding in production, and expensive as a result, their superior strength-to-weight contributes to energy savings and efficiencies throughout their life.

Cutting weight can be expensive. The raw materials for carbon fibre composite are more than 20x that of steel and 5x more than aluminium alloy for the same weight. Carbon fibre’s very high price is a direct result of the energy input in production, which contributes to its significant carbon footprint — many times higher than steel — and relatively low volumes compared to commodity materials like steel. However, carbon fibre offers some incredible advantages in the pursuit of weight savings — it is prized for its stiffness and stability combined with high resistance to weathering, humidity and chemicals. Made up of carbon crystals, it is available only in black (although coating technologies have been developed to produce so-called coloured carbon fibre). The carbon crystal are tightly bonded and entangled in-line with fibre orientation. This is what gives carbon fibre its exceptional mechanical properties, but also contributes to its only major weakness: brittleness. Only 500 g of carbon fibre is required for the same tensile strength as provided by 10 kg of steel.

By contrast, nylon fibre is 1/10 the price of silk, but around 25% stronger and lighter. There are grades available made from 100% recycled material that are themselves fully recyclable — a major step forwards in the development of sustainable advanced materials. Synthetic fibres have much higher strength-to-weight than their moulded equivalents. This is due to alignment of the polymer structure during manufacture. Films and fibres are drawn out while still soft, pulling the polymer chains in the direction of the machine. This has some significant benefits and optimises mechanical properties. For example, whereas an oriented film offers weight savings of 75%, a fibre is up to 90% lighter than moulded plastic for the same strength. In addition, there are improvements in the barrier properties, clarity and toughness. Packaging takes full advantage of these attributes through the use of lightweight films and stretch blow moulded bottles.

Tyvek nonwoven material, a kind of synthetic paper, owes its impressive strength and tear resistance to its fibre structure. It is light enough to float on water and around 10x stronger than paper. Made up of spunbound nonwoven high density polyethylene (HDPE), fine filaments of molten plastic are laid onto a conveyor and calendered with heat and pressure to form a compressed sheet. While the fibre structure imparts some textile-like properties, fusing the fibres together creates a paper-like surface that is suitable for printing, laminating and embossing, like regular paper. This makes it useful for print and graphics, fashion, food packaging, cargo covers and mailers. Manufactured in this way, the compressed structure imparts high resistance to penetration by water, bacteria, dust and chemicals — qualities utilised in construction, protective apparel and personal protective equipment (PPE), packaging and healthcare packaging and anti-tamper wrist bands.

Fibres and textiles help to reduce the weight of the buildings and large structures in the form of cables, tensile structures and membranes. Using the same engineering principals as for fashion, products and packaging, but on a much larger scale, the weight savings can be very significant. For example, ETFE membrane, a type of fluoropolymer famously used to clad the large Buckminster Fuller inspired biomes at the Eden Project in Cornwall, offers protection against the sun, wind and rain for a fraction of the weight of float glass. Its mass is approximately 1% of the weight of glass for the same area, and much less expensive in many cases, offering opportunities for architects. In addition, fluoropolymers are inert and so do not require the use of stabilisers, plasticisers, lubricants or flame-retardant additives. However, high performance materials like these have a significant environmental impact that cannot be overlooked. They use polyfluoroalkyl substances (PFAS) in their production. Also known as ‘forever chemicals’, these hazardous ingredients are found in many industrial materials and applications, and do not degrade or break down — they are shown to be extremely persistent in both the environment and in the human body.