Discontinuous aligned composites are a recent type of technical
composite material
A composite or composite material (also composition material) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a ...
s. This type of composite is neither random nor unidirectional, although it shares some characteristics with both. Discontinuous aligned composites are made of discontinuous fibers, just like
random mat composites and a have preferential orientation closer to that of unidirectional composites.
The first method developed to manufacture discontinuous aligned composites is called "rolling drum", developed at the
University of Nottingham
The University of Nottingham is a public research university in Nottingham, England. It was founded as University College Nottingham in 1881, and was granted a royal charter in 1948.
Nottingham's main campus (University Park Campus, Nottingh ...
. This method borrows the technique from the
papier-mâché
file:JacmelMardiGras.jpg, upright=1.3, Mardi Gras papier-mâché masks, Haiti
Papier-mâché ( , , - the French term "mâché" here means "crushed and ground") is a versatile craft technique with roots in ancient China, in which waste paper is s ...
industry, using a nozzle that delivers a
suspension of water and chopped fibers into a rolling drum.
The second method is known as HiPerDiF (high performance discontinuous fibre), developed at the
University of Bristol
The University of Bristol is a public university, public research university in Bristol, England. It received its royal charter in 1909, although it can trace its roots to a Merchant Venturers' school founded in 1595 and University College, Br ...
. HiPerDiF uses an array of nozzles to direct the water-fiber suspension towards alignment plates that are perpendicular to the nozzles. The change in
momentum
In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. ...
of the water hitting the plates, orients the fibers in the direction of the plates. After hitting the plates, the suspension falls on a continuous belt that dries and laminates the composite
Discontinuous aligned composites present a great alternative for the recycling of composite materials, as they can use fibers that are anywhere from 2mm to 20mm long. The current forecast for waste
carbon composite materials estimates that it will reach 25,000 tons in 2025.
[.] This is a material that can have a second life when used in discontinuous aligned composites.
References
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Composite material fabrication techniques