New technology in plastic composite lumber
Recycled plastic composite lumber has
been in manufactured for over twenty years, most commonly from
relatively pure post-consumer plastics such as high density
polyethylene (HDPE). Until now there was no way to produce a
consistently high quality product from mixed feedstock. However,
new technology from Cierra Industries Inc enables processing of
mixed environmental wastes and plastic material into extruded
composite lumber which can be used for building materials such as:
window and door trim, outdoor flooring materials, complete panels for
structural buildings, outdoor furniture, marine application and other.
Years of research and trial and error development have finally
resulted in a reliable system that yields a quality assured product
from low end materials. Third generation Cierra lines are now
producing up to 65% recycled Cellulostics materials and 30% recycled
This technology can be separated into
1. Material Preperation: Uniform melt blending
of plastic and cellulostics is a difficult and exacting process.
The cellulosic is a porous powder which will absorb the plastic.
This absorption is the characteristic which binds the materials
together and gives the finish product greater strength,
however it also increases molten viscosity and restricts ability
to flow in the extrusion prosess. Cellulostics also usually
contain moisture and are more sensitive to processing heat than
plastic polymers. The Cierra system addresses these problems by
careful use of additives such as curing, coupling agents,
lubricants and processing aids. The end product can then
become sufficiently strong to be used as construction material.
2. Extruder Design: A standard extruder is
not properly designed to blend and compound composites. Proper
gear boxes, thrust bearings, length to diameter ratio, all must
be engineered into the design in order to insure adequate mixing
and drying of the cellulosic material. Cierra remanufactured
machines incorporate all these features into the design.
3. Screw Design:
The screw design is configured to uniformly mix and control
temperature of recycled plastic and cellulosic material while
compressing sufficently to obtain uniform strength.
4. Cooling Technology: Standard
cooling tanks limit production rate. Cierra designs speed the
cooling rate by use of proprietary techniques and enable higher
5. Die technology: It has long been
known that pressure forming increases strength. Cierra's
dies apply uniformly controlled die pressure to assist in
forming the part as it is being extruded. The pressure is
monitored and is increased or decreased to main constant within
a predetermined varient. This permits a higher loading of non
plastic material without loss of strength and it also produces a
precise board by eliminating
6. Fillers: Cierra formulations are specific to
the customer requirements and are
designed to produce a high quality product from the materials which
are available to the customer. Cierra has developed a low
density inorganic filler to be incorporated for the purpose of
reducing product weight.
If you have further questions please address them to
Questions concerning equipment for plastic recycling equipment or plastic
lumber will be answered as soon as possible.