Agriculture Reference
In-Depth Information
Wood fibre blends have made a name for themselves and have been in use for some
years in extrusion. Now they are moving effectively into injection moulding and
compression moulding, though some moulders may be hesitant to use these new
composite resins instead of the traditional resins with which they are more familiar
with. A good example is PCRH.
However, with growing environmental concerns, rising petro-based resins costs, bio-
degradable problems and other factors, injection moulders are showing a great interest
in these new materials. Constant research and recent developments in the manufacture
of these composite resins have significantly improved the quality, processing techniques
and capabilities of these new materials. In fact, the latest generation of these composite
resins can be processed efficiently on traditional equipment with minimal adjustments
in process settings and with no other physical modification of hardware.
These PCRH can be made with various plastic resins such as low- and high-density
PE; PP; PS; PVC; and others. They can be classified as a category of an emerging
family of materials that can be termed 'thermoplastic biocomposites'. It is a huge
advantage for injection moulders that these resins are now available in different grades
and properties. In general, the processing parameters for all grades are more or less
the same and very similar to wood polymer composites.
Why use these composite resins? There are many compelling reasons to create products
or to use them as an alternate material for products from these polymer rice hull resins.
Because they contain ≥50% organic fibre, these materials offer injection moulders
a material option that is more environmentally friendly than petrochemical-derived
polymers. In addition to the 'green' factor, these composite resins reduce the moulder's
exposure to petroleum prices and reduce the energy costs associated with production
while producing components with great structural rigidity, aesthetically pleasing
finishes and highly marketplace-oriented end products. PCRH tend to be lower in cost
and weight than unfilled or glass-filled resins, and are even competitive with resins
filled with calcium carbonate or talc. An added advantage is lower density, which
reduces costs and is beneficial in uses in which a premium is placed on lightweight
applications such as in transportation, automotive, sports, toys, aviation and other
consumer products.
Rice hulls are abundantly available in most countries at virtually no cost and are
basically made up of opaline silica and a polymer called lignin. From the rice-milling
process emerges two basic grades of hulls: coarse and fine. The particle size of hulls is
important, as is the moisture content. Effective drying of hulls and further reduction
of particle size is needed before the manufacture of composites. According to research
and tests, rice hulls do not flame, smoulder transfer heat, or emit odours.
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