157 Thermoplastics The most commonly used plastics, thermoplastics soften when heated and harden when cooled, which can be repeated multiple times. It is the most commonly used type of plastic and easily recycled. Types include polyethylene (including HDPE, LLDPE/LDPE), polypropylene (PP), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). Thermosets Thermosets are polymers in which there is chemical bonding between macromolecular chains, creating a three-dimensional network. Thermoset composites (for example, in the form of carbon fibre often used in the construction of aircraft cabins) have a heavy environmental impact across their life cycle. Bio-based plastics and natural bio-based polymers To address issues with non-renewable, fossil-fuel-based plastics, bioplastics are being developed based on hydrocarbons from sources such as biomass. Natural bio-based polymers including polysaccharides, cellulose and rubber are synthesised by living organisms. Rubber can be sustainable if issues regarding labour exploitation and harmful pesticides are addressed. Efforts made towards sustainable rubber farming can also help reduce pressure on farmers to switch to less environmentally friendly crops. Cellulose is widely available and can be woven to produce a durable construction material. It is also found in textiles such as linen and cotton. Natural polymers such as collagen, starch and latex are in demand for textiles and other uses. Synthetic bio-based polymers Some polymers from renewable resources require a chemical transformation for conversion to a polymer. “Although its origin is renewable the polymer cannot be considered ‘natural’ as it is synthesised within a chemical plant.”1 Recycled polyester Recycled fabric made out of plastic water bottles broken down into fibres enables plastic to be rescued from landfill and recycled repeatedly. Production of recycled polyester generates fewer carbon emissions than working with virgin materials. Wood Eight out of 10 global consumers expect companies to ensure that their wooden or paper products do not contribute to deforestation or damage wildlife habitats, according to the Forest Stewardship Council, which says: “Responsible sourcing of wood can benefit construction projects in many ways. Wood is more carbon- and energy-efficient in comparison to other building materials.” The main challenge in sourcing sustainable wood products is ensuring that it is the result of proper forest management practices. Choosing FSC-certified wood helps addresses these issues.2 1 Source: British Plastics Federation, Polymer: Bio-based/Degradables 2 Source: Forest Stewardship Council, Construction
RkJQdWJsaXNoZXIy NzQ1NTk=