By

A.MaheshwaranBSF-04-012

Presentationon

Wood Composites

Course Teacher

Dr.I.SekarAssociate Professor

Wood Plastic Composites

Wood plastic

• Plastic ranging from polypropylene to PVCPlastic ranging from polypropylene to PVC• Binders/Fillers – Wood flour to WaxBinders/Fillers – Wood flour to Wax• Wood – saw dust & scrap wood productsWood – saw dust & scrap wood products

Benefits• True hybrid materials & combine best features of True hybrid materials & combine best features of

wood & plasticswood & plastics• Use low cost & plentiful raw materialsUse low cost & plentiful raw materials• Competitively priced Competitively priced • Easily produced & easily fabricated Easily produced & easily fabricated • Available in broad range of finishes & appearanceAvailable in broad range of finishes & appearance• Easily recycled after useEasily recycled after use• No further processing is neededNo further processing is needed• Weather, water, & mould resistantWeather, water, & mould resistant

Properties

Properties

• High resistance to moisture (0.7% High resistance to moisture (0.7% compared to 17.2% in Pine)compared to 17.2% in Pine)

• Moisture not transmitted across plastic Moisture not transmitted across plastic boundariesboundaries

• Good stiffness & impact resistanceGood stiffness & impact resistance• Dimensional stabilityDimensional stability• Resistance to rotResistance to rot• Excellent thermal propertiesExcellent thermal properties

Environmental Benefits

• Negligible waste & that produced is reusedNegligible waste & that produced is reused• No volatile organic compoundNo volatile organic compound• Recycled & reused after their service lifeRecycled & reused after their service life• Disposed using standard methodsDisposed using standard methods• Increase efficiency up to 40% compared to Increase efficiency up to 40% compared to

traditional wood traditional wood

Processing

• Mix of wood & plastic - modified with Mix of wood & plastic - modified with process & additives - to improve process & additives - to improve processing / final properties of WPCprocessing / final properties of WPC

• Compatibiliser/coupling agent – Improve Compatibiliser/coupling agent – Improve blendingblending

• Basic wood product – fine saw dust(40-60-Basic wood product – fine saw dust(40-60-mesh range)mesh range)

• Simple die can be used even for most Simple die can be used even for most complex profilecomplex 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. Material Preparation

2. Extruder Design

3. Screw Design

4. Cooling Technology

5. Die technology

6. 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

MANUFACTURING PROCESSES Manufacture of Wood Wool Cement Board

Manufacture of Cement Bonded Particle Boards

Manufacture 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

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.

Manufacture of WWCB

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

PropertiesProperties

Properties of WWCB insulation fire retardation water resistance resistance to organism attack mechanical properties

Insulation 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

Insulation 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

Machinability 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

<1.0% after 2 hours soaking <1.5% after 24 hours soaking <2.0% after >24 hours soaking

Longitudinal and Transverse Swelling 2.7mm/m from air dry to water saturated 0.1mm/m for each 1% change in moisture content of the

board 1.4mm/m for each 30% change in relative humidity of

ambient air

Mechanical Properties modulus of elasticity = 4500N per cubic

mm bending strength = 10-15N per cubic mm

(depending on density and raw materials) compressive strength = 15N per cu mm density = 1250kg per cubic metre

APPLICATIONSAPPLICATIONS

Applications of Applications of CBPBCBPB

External ApplicationsExternal Applications

• flat roofing • prefabricated structures(including

housing) • mobile homes • permanent formwork • balcony parapets and floors • cladding for industrial and warehouse

buildings • tunnel linings

External ApplicationsExternal Applications

• sound barrier walls on highways • fire barriers • pavillions • separating and party walls • soffits • agricultural buildings • swimming pool surroundings and

paving

Internal ApplicationsInternal Applications

• sound insulation and fire resistant partitions and doors

• linings for timber frame housing

• fire resistant doors, walls and ceilings

• built-in furniture • column and beam

casings

Internal ApplicationsInternal Applications

• lift shaft and duct linings • back boards for

electrical and gas appliances

• glue laminated structural members

• flooring in greenhouses • linings for bathrooms

and laundries

Applications of Applications of WWCBWWCB

Most important Most important applicationsapplications• thermal and acoustic insulation • for low-cost housing

thermal and acoustic thermal and acoustic insulation insulation • basements • floor units • permanent shuttering • partitioning • sound insulation in walls, ceilings and

floors • roofs • sound barriers • thermal insulation (often combined with

other insulation products such as polystyrene and polyurethane)

Applications for Low-Cost Applications for Low-Cost HousingHousing• relative low price of products since wood wool

can be produced from inferior quality wood which is unsuitable for sawmills

• simple technology required to produce boards, etc - see photograph below of plant in the Philippines

• in most countries in the world wood and the components of cement are readily available

• low enough weight to allow handling panels without the use of cranes or heavy machinery

Applications for Low-Cost Applications for Low-Cost HousingHousing• highly skilled labourers are not required for board

manufacture or building construction which allows boards to be made and buildings to be constructed locally and cheaply

• the construction process is quite fast and simple

• high insulation value

• easy handling and workability

• important properties such as fire, water, termite and fungi resistance

References:References:• http://www.umeciv.maine.edu/rla/images/DSC00088.JPG

• http://www.tangram.co.uk/TI-Polymer-Plastic&Composite_Windows.html

• http://www.tangram.co.uk/TI-Wood_Plastic_Composites.html

• http://www.tangram.co.uk/TI-Wood_Plastic_Composites_Review.pdf

• http://www.cis.tennessee.edu/EPAMACT/other/Plywood/pcwpVT1.shtml

• http://www.renewresources.com

• http://www.machinerydata.com/HowToMakePlasticWood.htm

• http://www.cierraindustries.com/plasticlumber.asp

• http://en.wikipedia.org/wiki/Wood-plastic_composite

• http://www.awc.org/Publications/download.html

• http://www.awc.org/HelpOutreach/faq/FAQfiles/Plastic_Wood-Lumber.html

• http://www.panelworldmag.com/vserver/hb/display.cfm?MagazineKey=6&IssueKey=461&SectionKey=389&ArticleKey=620

• http://www.fpl.fs.fed.us/documnts/pdf1997/wolfe97a.pdf#search=%22wood%20cement%20products%22

• http://www.ccaconference.org/pre/pdf/Gong.pdf#search=%22wood%20cement%20products%22

• http://www.anu.edu.au/Forestry/wood/cfb/contents.html

• http://www.fpl.fs.fed.us/documnts/pdf1996/geime96b.pdf#search=%22cement%20wood%22

• http://www.aciar.gov.au/web.nsf/doc/JFRN-5J47AH

• http://www.anu.edu.au/Forestry/wood/nwfp/woodwool/woodwoolphil.html

• http://www.toolbase.org/Technology-Inventory/walls/wood-fiber-composite-forms

Thank you