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By
A.MaheshwaranBSF-04-012
PresentationonWood Composites
Course Teacher
Dr.I.SekarAssociate Professor
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Wood Plastic Composites
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Wood plastic
Plastic ranging from polypropylene to PVC
Binders/Fillers Wood flour to Wax
Wood saw dust & scrap wood products
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Benefits
True hybrid materials & combine best features ofwood & 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
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Properties
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Properties
High resistance to moisture (0.7%compared to 17.2% in Pine)
Moisture not transmitted across plasticboundaries
Good stiffness & impact resistance
Dimensional stability Resistance to rot
Excellent thermal properties
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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 totraditional wood
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Processing
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Mix of wood & plastic - modified with
process & additives - to improveprocessing / final properties of WPC
Compatibiliser/coupling agent Improve
blending Basic wood product fine saw dust(40-60-
mesh range)
Simple die can be used even for mostcomplex profile
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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
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Plastic wood
The base product -100%
recycled High-Density
Polyethylene (HDPE)
shampoo and detergentbottles, to milk jugs
Some, entirely of HDPE
recycled HDPE + with
wood fibers, rubber,fiberglass, or other plastics
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Like Natural wood, Plastic lumber is
expand & contract with heat (Magnitude
varies)
cut and shaped with traditional woodworking tools
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Plastic wood will not:
Rot (seawalls, docks)
crack
warp splinter
degrade
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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
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Plastic wood also:
works with any deck fastener
requires no painting or sealing
used in composite extruded panel plasticwood for flooring
Provides a good shock-absorbing surface
for pedestrian traffic, such as runners andhikers.
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Plastic lumber and Wood-plasticcomposites - difference
fiber plastic lumber canhave less than 50%wood fiber.
balloted in ASTM byCommittee D20
Standard Test Methodfor Shear Properties ofPlastic Lumber and
Plastic Lumber Shapes.
Wood-plasticcomposites have atleast 50% or more wood
balloted in ASTM bycommittee D07
Standard Test Methodsfor Evaluating theMechanical and
Physical Properties ofWood-PlasticComposite Products
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New technology in plasticcomposite lumber
post-consumer plastics such as high
density polyethylene (HDPE)
mixed environmental wastes and plasticmaterial into extruded composite lumber
65% recycled Cellulostics materials and
30% recycled plastic materials.
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CATEGORIES1. Material Preparation
2. Extruder Design
3. Screw Design4. Cooling Technology
5. Die technology
6. Fillers
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Wood cement
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Wood cement
wood wool cement boards (WWCB)
cement bonded particleboard (CBPB)
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General Properties
durable and resistant to frost/thaw, fire,
moisture, rot, vermin, fungus and termites
easy workability
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MANUFACTURING PROCESSES
Manufacture of Wood Wool Cement Board
Manufacture of Cement Bonded ParticleBoards
Manufacture of Cement Bonded FibreBoards
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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 reducethe moisture & sugar content
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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 thenremoved from the moulds & cured for 2-3 weeks.
They are subsequently trimmed and finished.
Manufacture of WWCB
W k ll ti l f h ddi
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Workers collecting sawn logs for shredding
L b i h dd d i t d l
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Logs being shredded into wood wool
Th d l i th k d i lt l ti
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The wood wool is then soaked in a salt solution
Elt ti R t ti W d W l M hi B d
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Eltomation Rotating Wood Wool Machine Boards
The pressed and finished boards
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The pressed and finished boards
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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
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Manufacture of CBPC
mat subsequently cut
These stacked & compressed together to1/3rd 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 6-8hours.
boards dried, trimmed and stored for 12-18days until the cement cures.
M d CBPB l t
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Modern CBPB plant
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Manufacture of CBFB
wood pulped cellulosefibre (with an air-drymoisture content of 12-16%)
Silica + alumina + water +pulped cellulose
Binders added
water removed and mixture
is rolled onto mats, cut, andsized, or moulded
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Properties
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Properties of WWCB
insulation
fire retardation
water resistance resistance to organism attack
mechanical properties
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Insulation
WWCB provides very good insulation, both thermally andacoustically.
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 12cmconcrete core 354-56dB
Noise Reduction Coefficient for 2.5cm board 0.7
Thermal Insulation (Evans,1996)
Thermal resistance (R) for 2.5cm board 5
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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 Attack
WWCB is highly resistant to dry rot and other fungal growth as wellas to termites.
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Mechanical Properties
Specific Gravity light boards for insulation only 360kg per cubic metre
denser boards for roofs and permanent shuttering 450kgper cubic metre
Bending Strength = 20-30kg per cubiccentimeter
Design load for 2cm board = 50psf
Ultimate load for 2cm board = 200psf Allowable span for 2cm board = 122cm
Deflection at design load = 0.2cm
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Properties of CBPB
insulation
machinability
water resistance mechanical properties
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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 beused 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
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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 bladesor power saws with tungstentipped blades.
drilling - use hand drill or high speed power drill
sanding - manual sanding or mechanical sander preferably appliedto both sides of board simultaneously.
fixing - drilling of pilot holes for nails and screws is recommendedfor most board thicknesses.
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Water Resistance
Thickness swelling
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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
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APPLICATIONS
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Applications of CBPB
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External Applications
flat roofing
prefabricated structures(including housing)
mobile homes
permanent formwork
balcony parapets and floors
cladding for industrial and warehouse
buildings tunnel linings
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External Applications
sound barrier walls on highways
fire barriers
pavillions
separating and party walls
soffits
agricultural buildings
swimming pool surroundings andpaving
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Internal Applications
sound insulation and fireresistant partitions anddoors
linings for timber framehousing
fire resistant doors, wallsand ceilings
built-in furniture
column and beam casings
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Internal Applications
lift shaft and duct linings
back boards for electricaland gas appliances
glue laminated structuralmembers
flooring in greenhouses
linings for bathrooms and
laundries
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Applications of WWCB
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Most important applications
thermal and acoustic insulation
for low-cost housing
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thermal and acoustic insulation
basements floor units permanent shuttering
partitioning sound insulation in walls, ceilings and floors roofs sound barriers
thermal insulation (often combined withother insulation products such as polystyreneand polyurethane)
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Applications for Low-Cost Housing
relative low price of products since wood wool canbe produced from inferior quality wood which isunsuitable 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 thecomponents of cement are readily available
low enough weight to allow handling panels withoutthe use of cranes or heavy machinery
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Applications for Low-Cost Housing
highly skilled labourers are not required for boardmanufacture or building construction which allowsboards to be made and buildings to be constructedlocally and cheaply
the construction process is quite fast and simple
high insulation value
easy handling and workability
important properties such as fire, water, termite andfungi resistance
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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
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p // g/ /
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
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Thank you