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Market demand for more environment-friendly products is rocketing. In two previous articles, we examined biocomposites  and natural-fibre performance . In this one, we review the development of plant-fibre-reinforced polymers and the increased performance we can expect to gain from them.
(Published on January-February 2009 – JEC Magazine #46)
CHRISTOPHE BALEY, PROFESSOR, UNIVERSITÉ DE BRETAGNE SUD, L2PIC
The use of plant fibres as reinforcement for polymers is a topical issue. While it is difficult to briefly sum up the state of the art and the availability of industrial products in that field, we can say that:
Each year new applications emerge, although questions can be raised about the maturity of the products and markets.
These “emerging” materials develop along a typical four-stage curve (Figure 1): research and development (A), industrialization (B), a period of “disillusionment” (C), and the actual development stage (D).
Many factors affect this curve, including material type and availability, field of application, performance and processing technology.
Period C of disillusion is generally due to incomplete or misdirected development, or to immature markets.
Why use plant fibres?
Why would we need to reinforce composites with plant fibres? Does their use lead to real performance gains? Two often-used arguments are highly debatable and might even indicate a lack of long-term vision:
Their use is often associated with an ecodesign initiative – either genuine or for communication purposes – to introduce more environment-friendly materials. Here, it is important at all stages of development to assess the relative sustainability of these bioproducts, i.e. their environmental, social and economic impacts, so as to better understand the exact advantages to be gleaned from their use, limit the risks as much as possible, and develop critical judgment.
Should we speak of “plant-fibre-reinforced polymers”, “fully biosourced composite materials” (from agro-resources), or “biocomposites” (materials that are biocompostable at end of life)? What is really gained from their use? A few such gains are:
Other, non-corporate strategic factors need to be taken into account as well:
Rational use of agro-resources
Many people question the rationality of using agro-resources in the materials field. Something to keep in mind here is that the major global issues we face are water, food, energy and materials, in that order, and that agriculture is connected to all four of them.
Competition does exist among agricultural crops. Since the emergence of biofuels, we have seen a relationship between the price of energy raw materials and the price of agricultural raw materials. Farmers will base their choice of one crop over another on the potential returns in a global market. One important point is that, unlike biofuels, the materials sector does not require a lot of surface area in agricultural production. According to estimates, agricultural production for materials would require only 1% of all available agricultural land by 2030 . Furthermore, agricultural crops can produce both food and plant constituents that can be used for materials.
But arable land worldwide is limited to begin with; populations are increasing; and agricultural land is lost regularly to erosion, desertification, degraded/exhausted soils and urbanization. To take one example, there are about 15 million km² of agricultural land worldwide, or 28 times as much as the entire French territory (= 543,965 km²); and 52 times as much as all French agricultural land (= 295,000 km²). For a long time, environmental changes due to industrial activities was considered to be the price to pay for productivity gains. Today we have new expectations from agriculture, specifically the preservation of natural resources, landscapes, and biodiversity.
A commercial or industrial product that is based on energy, chemicals or processes derived from living organisms. When they are used appropriately, the sources for bioproducts are eminently renewable, as they renew themselves with the help of solar energy. Bioproducts can be used in addition to, or as a substitute for industrial products manufactured from petrochemicals or fossil fuels.
If we can demonstrate that biocomposites are sustainable, the chances of their being adopted by the public and the markets will be all the greater. This demands that they have verifiably genuine advantages – and not just greenwashing – to offer.
We need to promote the spread of acquired know-how, but also to specify where knowledge is limited to avoid misguided use (poor understanding of properties, underrated performance, inappropriate application) and disillusionment.
These days, companies need to factor in environmental constraints. But while there is much talk about sustainable development (which is based on economic, social and environmental factors), the actual commitment of companies is not always as strong as they advertise. If you apply the concept of sustainability, biocomposites will be able to develop only if they are competitive in an economy where social factors are taken into account and where the environment is taken back and protected.