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Developing vegetable-fibre-based composite materials raises the question of resource availability: what is at stake for composites development? To ensure a stable supply, material producers are seeking answers to two questions: What kind of availability at what price? How consistent is the quality?
(Published on January-February 2009 – JEC Magazine #46)
PIERRE BONO, GENERAL MANAGER,
& LAURENT AUGIER, R&D MANAGER, FIBRES RECHERCHE DÉVELOPPEMENT®
Ten organizations – either producers of natural fibres (hemp, flax, wood, etc.) or major players in the agricultural industry – have created a dedicated technical centre called Fibres Recherche Développement® to promote the development of vegetable-fibre agro materials in France. By joining forces within FRD®, these producers expect to be able to reinforce their capacity to provide the types of fibres that are in demand by markets for composites with polymer or mineral matrices. The idea is to anticipate the needs of material manufacturers, both in quality and quantity.
Availability of vegetable fibre resources in Europe
According to the FAO, 4.5 to 5 million metric tons (MT) of vegetable fibres, excluding cotton and wood, are grown worldwide each year. Production is concentrated in Southeast Asia (75%), mostly in India and Bangladesh with jute, coir and kenaf fibres.
About 10% of global production comes from Europe. France plays a major role here, thanks to the organization of its flax and hemp industries, by producing about two-thirds of the European volumes. However, most of the fibres produced in Europe are going for use in traditional markets like textiles (60% of flax) or speciality papers (90% of hemp), meaning that there still are prospects for transfer to the engineering-fibre market.
In France, 88 000 ha were planted in hemp and flax in 2005. But according to a forecast from the French energy conservation agency Ademe, France is going to need to devote about 375,000 hectares to hemp and flax by 2030. To meet these projected needs, fibre producers could take action in three areas:
In this regard, FRD® has just launched a prospective study to quantify France’s potential hemp stocks: i.e. just how much area could be planted over in hemp, based on the current surface area of 10,000 ha. devoted to hemp and given constraints such as climate and the profitability of other crops? Another goal is to learn more about imports of exotic fibres into Europe.
From a more general point of view, FRD® suggests reasoning out supply choices as part of a “multifibre” approach. Surface area is not expandable, and given the debate on the competition between using agricultural land for growing food and using it for non-food crops, such an approach would help to:
Even if the resources are actually available, the real issue over the long term is being able to control the stability and quality of the fibre supply, and to standardize the fibres by type of use.
Many manufacturers, particularly in the building & construction and transport industries, are taking a greater interest in the properties of vegetable fibres. Material specifications – and therefore those for the constituent fibres – are very stiff, especially for a natural resource subject to unpredictable weather conditions that can affect growth. One of the industry’s major challenges is to control the links between the botanical fibre (composition, properties, and role of the fibre within the plant) and the industrial fibre (fibre properties and specifications of the industrial applications).
Identifying key properties
Before developing the solution that will best meet a set of specifications in terms of fibre types and manufacturing processes, you must first identify key properties. To address this challenge, FRD® (like other specialized technical centres) is developing its expertise in taking a set of industrial specifications, translating it into material properties, then expressing these in terms of key fibre properties.
Understanding and controlling variability
While understanding and controlling variability is not an issue for the organic/mineral fibre sector, these are still generating a lot of R&D in vegetable fibres. Like any plant resource, natural fibres present a wide quality range (also called variability), both within a single plant species and across the entire vegetable fibre category. Quality is affected by cultivation techniques and soil and climate characteristics; but also by the extraction and final forming processes that are used. For example, fibre quality might depend on:
La Chanvrière de l’Aube, Interval (hemp), Lin Industriel Picard (flax), Groupe Coopération Forestière (wood), Chambre d’Agriculture de l’Aube, nouricia, In vivo (lignocellulosic crops), ARD (biopolymers), Caisse Régionale de Crédit Agricole Champagne-Bourgogne and Sofiprotéol.
5 areas of expertise
Understanding and controlling such variability is now a top priority in developing the use of vegetable fibres in highperformance applications. FRD® is initiating and leading a large number of projects to find solutions to these problems. It is now well-positioned as a provider of technical support to the vegetable fibre industry, in complement to other national technical centres.
One last step in the process of controlling fibre quality will be to propose appropriate characterization protocols for vegetable fibres and the materials they are used in, in order to obtain a universal reference system to be shared by the research and industrial communities. The Dehondt Technologies group and the French flax-growers association, Cipalin, have launched a pilot project on protocols to characterize flax-fibre properties for plastic composite applications. The project is being coordinated by BNPP, the French standards bureau for plastics and plastics processing.
 Bledzki A.K. and Gassan J., Composites reinforced with cellulose based fibres. Progress in Polymer Science 24(2):221-274 (1999)