27926765 wood composites

7/30/2019 27926765 Wood Composites

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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

27926765 wood composites

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