wood composites

of 63/63

Post on 18-Nov-2014




27 download

Embed Size (px)


Presentation about wood plastic composites, wood filler, plastic wood & wood cement


Presentation on Wood Composites

Course Teacher


Dr.I.SekarAssociate Professor


Wood Plastic Composites

Wood plastic

Plastic ranging from polypropylene to PVC Binders/Fillers Wood flour to Wax Wood saw dust & scrap wood products


True hybrid materials & combine best features of wood & plastics Use low cost & plentiful raw materials Competitively priced Easily produced & easily fabricated Available in broad range of finishes & appearance Easily recycled after use No further processing is needed Weather, water, & mould resistant



High resistance to moisture (0.7% compared to 17.2% in Pine) Moisture not transmitted across plastic boundaries Good stiffness & impact resistance Dimensional stability Resistance to rot Excellent thermal properties

Environmental Benefits

Negligible waste & that produced is reused No volatile organic compound Recycled & reused after their service life Disposed using standard methods Increase efficiency up to 40% compared to traditional wood


Mix of wood & plastic - modified with process & additives - to improve processing / final properties of WPC Compatibiliser/coupling agent Improve blending Basic wood product fine saw dust(40-60mesh range) Simple die can be used even for most complex profile

Wood filler

Wood putty or Plastic wood wood dust combined with a binder that dries and a diluent and a pigment fill imperfections, nail holes or pores in wood Wood putty or plastic wood - thicker version Wood filler - thinner version

Plastic wood

The base product -100% recycled High-Density Polyethylene (HDPE) shampoo and detergent bottles, to milk jugs Some, entirely of HDPE recycled HDPE + with wood fibers, rubber, fiberglass, or other plastics

Like Natural wood, Plastic lumber is

expand & contract with heat (Magnitude varies) cut and shaped with traditional wood working tools

Plastic wood will not:

Rot (seawalls, docks) crack warp splinter degrade

Plastic wood is:

denser than wood virtually maintenance free long lasting stain resistant waterproof UV resistant aesthetically pleasing impervious to insects not affected by exposure to most substances

Plastic wood also:

works with any deck fastener requires no painting or sealing used in composite extruded panel plastic wood for flooring Provides a good shock-absorbing surface for pedestrian traffic, such as runners and hikers.

Plastic lumber and Wood-plastic composites - difference

fiber plastic lumber can have less than 50% wood fiber. balloted in ASTM by Committee D20 Standard Test Method for Shear Properties of Plastic Lumber and Plastic Lumber Shapes.

Wood-plastic composites have at least 50% or more wood balloted in ASTM by committee D07 Standard Test Methods for Evaluating the Mechanical and Physical Properties of Wood-Plastic Composite Products

New technology in plastic composite lumber

post-consumer plastics such as high density polyethylene (HDPE) mixed environmental wastes and plastic material into extruded composite lumber 65% recycled Cellulostics materials and 30% recycled plastic materials.

CATEGORIES1. 2. 3. 4. 5. 6. Material Preparation Extruder Design Screw Design Cooling Technology Die technology Fillers

Wood cement

Wood cement

wood wool cement boards (WWCB) cement bonded particleboard (CBPB)

General Properties

durable and resistant to frost/thaw, fire, moisture, rot, vermin, fungus and termites easy workability


of Wood Wool Cement Board

of Cement Bonded Particle Boards


of Cement Bonded Fibre Boards

Manufacture of WWCB

Long wood + cement wool strands (or excelsior) - cut from debarked logs

400-500mm length prior to cutting the wood wool treated to prevent blue-staining

The logs stored on racks a month to reduce the moisture & sugar content

Manufacture of WWCB

wood is shredded salt (CaCl2) solution + Portland cement (2:1 ratio) spread onto plywood moulds & stacked The mats pressed at room temperature under 10 psi. stack is clamped under pressure for another 24 hours then removed from the moulds & cured for 2-3 weeks. They are subsequently trimmed and finished.

Workers collecting sawn logs for shredding

Logs being shredded into wood wool

The wood wool is then soaked in a salt solution

Eltomation Rotating Wood Wool Machine Boards

The pressed and finished boards

Manufacture of CBPC

wood is in particle rather than strand form softwood logs debarked & stored to reduce moisture and sugar content Portland cement: wood: water in ratio 3:1:1 Water evaporation is monitored CaCl2 added - cement setting The mixture fed to a conveyor

Manufacture of CBPC

mat subsequently cut These stacked & compressed together to 1/3rd of its original height over a 2-3 minute period. The mats are clamped and heated in a chamber at 70-80 degrees Celsius for 6-8 hours. boards dried, trimmed and stored for 12-18 days until the cement cures.

Modern CBPB plant

Manufacture of CBFB

wood pulped cellulose fibre (with an air-dry moisture content of 12-16%) Silica + alumina + water + pulped cellulose Binders added water removed and mixture is rolled onto mats, cut, and sized, or moulded


Properties of WWCB

insulation fire retardation water resistance resistance to organism attack mechanical properties


WWCB provides very good insulation, both thermally and acoustically. Acoustic Insulation Resistance of a plastered wall of 5cm Wood Wool Cement Boards 36-40dB Resistance of a plastered double wall with air space between WWCBs 53-57dB Resistance of a permanent shuttered wall with 12cm concrete core 354-56dB Noise Reduction Coefficient for 2.5cm board 0.7 Thermal Insulation (Evans,1996) Thermal resistance (R) for 2.5cm board 5

Fire Resistance

5cm boards 1 hour resistance 10cm boards 2 hours resistance

Water ResistanceDimensional change after soaking in water for 48 hours: 0.84% thickness swelling 0.21% linear expansion 22% water absorption

Resistance to Organism AttackWWCB is highly resistant to dry rot and other fungal growth as well as to termites.

Mechanical Properties

Specific Gravity

light boards for insulation only 360kg per cubic metre denser boards for roofs and permanent shuttering 450kg per cubic metre

Bending Strength = 20-30kg per cubic centimeter Design load for 2cm board = 50psf Ultimate load for 2cm board = 200psf Allowable span for 2cm board = 122cm Deflection at design load = 0.2cm

Properties of CBPB

insulation machinability water resistance mechanical properties


Thermal Insulation

Thermal conductivity (k value) = 0.35W/m.K Linear thermal expansion = 0.01W/m.K

Electrical Insulation

CBPB is resistant to tracking and does not build up static charges, thus be used as backing panelling for electrical appliances.

Acoustic Insulation

The sound reduction for boards of various thicknesses is as follows:

6mm - 28dB 10mm - 31dB 20mm - 33dB 30mm - 36.5dB 40mm - 38dB


working - CBPB can be worked using hard tipped tools in a similar manner to timber,plywood or chipboard. sawing - can be sawn with handsaws, jigsaws with suitable blades or power saws with tungstentipped blades. drilling - use hand drill or high speed power drill sanding - manual sanding or mechanical sander preferably applied to both sides of board simultaneously. fixing - drilling of pilot holes for nails and screws is recommended for most board thicknesses.

Water Resistance

Thickness swelling