Biomaterials: produced by nature, composed by polymer engineers
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Biomaterials: produced by nature, composed by polymer engineers
· The natural fibre polymer composites market is growing, largely in the automotive industry
· Biobased plastics are expected to grow as well, particularly in the packaging sector
· PLA (polylactic acid) is popular as 3D-printing filament and can benefit from the private printing surge
Getting in touch with the bioeconomy sometimes is as easy as sipping a drink on your deck; chances are that the boards that you are standing on are not made from solid wood but from wood polymer composite (wpc). The drink might have come from a bottle containing biobased PET, and if you are at a public event, it might even be served in a PLA-cup.
Biobased composites set the tune
Wood polymer composites consist of finely ground wood fibre and a polymer such as polyethylene, polypropylene or polyvinylchloride. They combine the durability of the plastic material with the woodsy feeling of planks made from trees.
The global market for wpc was valued at USD 4.06 billion in 2015 and decking accounts for 80% it. That is a lot of deck boards and the market is expected to grow. Fencing is another visible and everyday application that will drive the demand in the construction sector, which is the most important industry for composite materials.
In Germany wpc generated a revenue of over 140 million US $ and this number is forecast to grow to nearly 250 million US $ in 2024. Coming in second after the construction sector the German automotive industry used wpc worth 30 million US $ in 2015. BMW, Audi, Opel, Daimler and Volkswagen make sure that the numbers will nearly double within the next eight years by applying wpc in head rests, cabin linings and backrests.
Wood is not the only biomaterial that can be mixed with polymers for composite materials. German Jakob Winter GmbH uses hemp and flax fibre composites to manufacture special cases, for example for musical instruments. And the composite story continues inside the instrument case: San Francisco-based Blackbird guitars offers a ukulele made of a linen and bio-resin composite while Canadian hemp guitars counts on pressed hemp bast for the back, sides and top for its instruments. The bio-composites tolerate humidity and temperature changes much better than solid wood and thus reduce the typical tuning problems of wooden instruments. This is a valuable feature especially to those with frequent traveler status; consequently, composite grand pianos are not on the horizon in the near future, according to German instrument maker Schimmel pianos.
Bamboo fibres are becoming increasingly popular as a replacement for glass and carbon fibres in composite materials. At Leuven university Prof. Jan Ivens and Dr. Aart Van Vuure investigate how processing parameters influence the mechanical properties of fibres made from Colombian bamboo. Although native to Asia bamboo raises a lot of interest in the rest of the world, too. The bamboo technology network Europe aims to promote bamboo technology in Germany, whether as a composite or in its pure form. Special emphasis is on Lower Saxony, a region in the north of Germany. Bamboo is grown there for ornamental reasons only, but you can buy windows and furniture made – if not grown – locally. US-based samambu LLC combines a flexible non-woven bamboo mat with bioplastics to a durable composite and thus forms an interface to another important group of biomaterials: biobased plastics.
The bioplastics conundrum: when does biobased equal biodegradable?
Of the 300 million tons of plastic produced every year bioplastics account for a very small share, about one per cent. This is likely about to change, if simply for the reason that many governments worldwide enforce the use of biodegradable plastic bags in their countries. About the extent of growth hugely diverging numbers are in circulation. European Bioplastics, the association representing the interests of the bioplastics industry in Europe anticipates an increase in global production capacities from 1.7 million tons in 2014 to 7.8 million tons in 2019. Private nova institute forecasts growth from 5.7 million tons in 2014 to 17 million tons in 2020.
However big the increase will be, the materials will likely end up as wrapper or bottle as packaging materials is the largest application field for renewable polymers. In 2019 80% of bioplastics will be used in the packaging sector. It is no secret that the Coca-Cola company became the world’s largest consumer of bioplastics by introducing its PET (polyethyleneterephtalate) plant bottle. This PET is a drop-in solution, like much of the total biopolymer production: of plant origin but with the same characteristics as fossil-based PET. Essentially this means durability; if these bioplastics are not recycled they are as persistent in a landfill as conventional plastics.
Biobased plastics that are also biodegradable, such as PLA (polylactic acid), PHA (polyhydroxyalkanoate) and starch blends are expected to nearly double from 0.7 million tonnes in 2014 to over 1.2 million tons in 2019, according to Bioplastics Europe. These polymers are compostable – albeit compostability in this case often requires a commercial facility and not on the backyard compost heap. This has led to some confusion for end consumers and bioeconomy professionals consider this one of the major communication problems of the biobased industries.
Renewable 3D-printing with PLA, coffee and algae
Especially the PLA market could benefit from 3D-printing becoming mainstream. The 3D-printing market is expected to reach USD 30 billion in 2022 with a CAGR of 28.5% from 2016. The biggest growth rate is forecast in the desktop 3D printer segment as schools and universities strive to allow students to experiment practically with 3D modeling and private interest is also on the rise. Desktop models often use filament as printing material and PLA is one of the favored filament materials. It allows for rapid printing and the prints don’t warp as easily as those made from other polymers. That heated PLA doesn’t smell like hot plastic but sweet and more like waffles certainly is a nice touch.
Just as thermoformed polymers profit from the addition of biobased fillers, 3D printing filaments facilitate more options for designers if powdered natural materials are added to the PLA. The US is expected to be the major driver of market growth; small wonder that many filament innovations come from US based companies. Colorfabb uses all sorts of wood filaments as well as bamboo and cork as an additive. 3Dom Fuel mixes spent coffee grounds, hemp powder and residues of beer making into the PLA and Algix 3D offers a filament composed of PLA and algae.
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