Natural composite material is the association of a matrix made of resin and a reinforcement in the form of particles or fibres. The resultant combines the properties of several materials to offer performances which are not found in only one and the same material (lightness, stress rigidity, etc.).
The fibre most frequently used globally today is glass fibre, which significantly improves the mechanical properties of composites. Natural fibers were used earlier in the plastic industry but their lower mechanical performance compared to synthetic fibers resulted into business loss over the years. Currently the natural fiber composite market has a very small market share of the plastic composite market- their application is limited to the production of less than 1 mln tons of reinforced plastic. There is a renewed interest in natural fibers on account of ecological trends. Under environmental pressure, the rate of growth is expected to increase faster in the near future.
Advantages of plant fibres to reinforce composite materials:
- Low impact on the environment :
- neutral in terms of CO2 emissions;
- renewable resource;
- 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.
Some natural fibers that find use in plastics are Bagasse, Cellulose, Cotton, Flax, Hemp, Jute, Sisal. Natural fibres provide environmental and technical added value. Two of these alternatives are natural fibre-reinforced plastics (NFRP) and wood plastic composites (WPC). These are composites that are typically filled or reinforced with plant fibres and wood flour respectively, as well as plastics such as polypropylene (PP), polyethylene (PE) or recently, even bioplastics.
Therefore a large variety of products is possible with the injection moulding technology, as per nova-Institut. In terms of industries, the automotive industry (mainly compression moulding with natural fibre-reinforced thermosets), packaging (biodegradable packagings) and the construction industry (extruded WPC products) are dominating. As for production methods, injection moulding is continuing to gain in importance and is making it possible to penetrate new markets, mainly in the furniture, consumer goods and electrical industries. In the future, a further fusion of the material groups, for example, into natural fibre-reinforced bioplastics, is expected.
One very promising development is the use of natural fibers from tropical and temperate-climate plants as reinforcement additives to the thermoplastics used for injection molding, compression molding, and extrusion processes.
Dr. Prabhat Krishnaswamy, President of Natural Fiber Composites Corporation (NFCC) is leading an effort to develop this next generation of composite materials for application in transportation, building and construction and consumer and industrial products.
These natural fibers have a specific gravity of 1.5 (glass has a s.g. of 2.5) and can be processed using existing equipment with no adjustments or modifications. The increased tensile strength and stiffness of the resulting composites are up to five times better than non-reinforced polypropylene (PP) polymers. Current challenges to the NFCC material include an odor problem and the fact that the fibers are naturally hydrophilic, but when processed into pellet form, the composite becomes hydrophobic. NFCC has made progress to overcome all these challenges.
As per BCC Research, the North American fiber-reinforced plastic/composite market is estimated at 2.7 bln lbs in 2010 and is expected to increase to about 3.1 bln by 2015, reflecting a 2.8% compound annual growth rate (CAGR). Construction/infrastructure and automotive products are the key applications of this market since they comprise about 60% of total volume. This sector is valued at 836 mln lbs in 2010 and is expected to reach 963 mln lbs in 2015, a 2.9% compound annual growth rate (CAGR).
The largest growth will be experienced by the very low volume aerospace market led by the introduction of composite commercial aircraft exterior parts such as fuselages and wings. This sector is estimated at 20 mln lbs in 2010 and should increase at a 7% compound annual growth rate (CAGR) to reach 28 mln lbs in 2015.
Natural fibers take advantage of economic and environmental trends. Moreover they are cheaper than fiberglass, but are exhibit lower performance and compete with food crops leading to an economic unbalance. Despite a renewed interest, their application is far from the production of fiberglass-reinforced plastics. It is difficult to visualize that they will capture a large market share from fiberglass.
- Please see latest data for Bio-Composites in Europe“ (Source: EIHA-press release, “Targets for bio-based composites and natural fibres“, 2010-11-25.)
Source: plastemart.com, 2011-03-14.