Composites made with bioresins and natural fibers have benefits beyond sustainability.
Most people associate crops in farmers’ fields with food production. What they don’t realize is that those plants, or at least some parts of them, could one day be incorporated into their cars, tennis rackets or shoes.
Biocomposite materials made from natural fibers and/or bio-based resins are making inroads into markets ranging from automotive and building materials to clothing and sporting goods. According to Lucintel, the global biocomposites market should grow by 7.9 percent from 2018 through 2023, reaching an estimated $7.6 billion in value.
In Europe, biocomposites made their first appearances in 1972, when Fiat introduced a 50 percent wood/50 percent polypropylene “woodstock” material into its vehicles. This material is still used successfully in different markets.
Some European automotive manufacturers today use components that contain as much as 70 percent natural fibers like kenaf or hemp and only 30 percent oil-based resin. “You can have savings on the CO2 footprint and have very good technical properties, and at the same time the material is very lightweight,” says Asta Partanen, who specializes in bio-based materials and composites at Germany’s nova-Institute, a consulting organization with a focus on the bio and CO2-based economy.
Biopolymers used in European composite production include bio-polyethylene (bio-PE), polyactic acid (PLA) and bio-based polybutylene succinate (PBS). Natural fibers are derived from many sources, including wood, cork, linen, flax, hemp, bamboo and sunflower shells.
The benefits of using natural fibers for composites begin with their optical and haptic properties, according to Partanen. Natural materials allow composites to cool much sooner, reducing the cycle time in injection molding.
In general, natural fibers can’t achieve the strength of carbon fiber composites and they don’t have the same tensile or impact strength as GFRP. “But they may have different properties that are important in the differentiation of products from standard plastic products. It’s always a matter of application,” says Partanen. Natural fiber composites are a better environmental choice than GFRP because they have a 20 to 50 percent lower carbon footprint.
Working with Biofibers
In Canada, the Composites Innovation Centre (CIC) in Winnipeg, Manitoba, helps composites manufacturers incorporate biofibers into their products. “We’re trying to address some of the technology gaps and hurdles that our clients and industry are facing,” says Lin-P’ing Choo-Smith, vice president of CIC’s biomaterials program.
To minimize the adjustments that composites manufacturers must make to use natural fibers, the CIC primarily uses traditional industry resins, processes and equipment in its research. “If [manufacturers] have to change too many things, it becomes a barrier,” says Choo-Smith.