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Natural fibre reinforced composites
Today, when sustainable development is a real world concern, many studies and much research are being conducted on the use of composite materials based on natural fibres and notably on plant fibres.
Clextral, which already has expertise in the extraction of lignocellulose fibres and the production of Long Fibre Thermoplastic (LFT), has quite naturally decided to engage in research with public agencies and private companies in order to develop compounding processes of agro-materials, composite materials reinforced with natural fibres.
Extrudeur bivis Clextral utilisé pour les matériaux composites fibres naturelles
What is a composite material ?
Advantages of plant fibres to reinforce composite materials
What is a bio-source material ?
Advantages of twin screw extrusion for agro-materials :
• Feed of low density products (wide range of usable raw materials in terms of form, density, viscosity, etc.)
• Degassing
• Addition of fillers, fibres, pigments, liquid (chemical reagent), etc.
• Less thermal degradation, controlled self-heating
• Modularity : ability to perform several tasks on the same equipment
What is a composite material ?
"A composite material is defined to be an arrangement of fibres – continuous or not – of a resistant material (the reinforcement) embedded in a matrix whose mechanical resistance is much weaker. The matrix (the binder) preserves the reinforcement's geometric arrangement and transfers to it the stresses to which the part is subjected. " Extract of Natural reinforcement fibres for composite materials¬ by Christophe BALEY, PhD, University and Professional Engineering School of Nantes, France - Instructor/Researcher at the University of Southern Brittany, France
A composite material is therefore the association of a matrix (made of resin, for example) and a reinforcement in the form of particles or fibres. The thus-obtained product allows making parts both light and resistant.
A composite material therefore combines the properties of several materials in order to offer performances which are not found in only one and the same material (lightness, stress rigidity, etc.). The fibre most frequently used in the world today is the glass fibre, which significantly improves the mechanical properties of composites. The main applications of these materials are in air, sea and rail transport, construction, aerospace, as well as sports and spare-time activities, notably thanks to their good mechanical strength.
Advantages of plant fibres to reinforce composite materials :
Low impact on the environment :
o neutral in terms of CO2 emissions ;
o renewable resource ;
o possibility to make 100% biodegradable or 100% bio source compounds
The production of plant fibres is less energy costly than with glass fibres.
Plant fibres have very specific mechanical properties and a low density, thus contributing to the lightening of structures.
Today, there is a strong tendency to work with 100% bio-resource materials because if they cannot be mechanically recycled at the end of their service life, they can be incinerated and thus produce clean energy. A bio-source plastic has a more favourable carbon balance sheet than an equivalent issued from fossil resources.
What is a bio-source material ?
Today, problems in terms of vocabulary exist around the notions of bioplastics, bio-sources. Many definitions appear and create confusion.
The explanations may be simplified as follows :
• The notion of biodegradability refers to the end of the material's life
• The notion of bio-source refers to the material's origin
A biosource polymer is synthesized from monomers derived from renewable resources.
There exist different categories of biosource polymers :
• Natural polymers : starch, cellulose, polysaccharide, etc. ;
• Polymers produced from micro-organisms : PHA
• Polymers synthesized from monomers derived from renewable resources : PLA, PA 11
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