IMP WOOD wood product and utilisation.ppt

IMP WOOD wood product and utilisation.ppt

1. 7/30/2024 1
Dr BhupenderDutt

2. Improvedwoodisageneraltermforwoodthathasbeen
speciallytreatedinvariouswaystoreduceorretard
working(i.e.alternateswelling&shrinking)orto
increaseitsstrength.OrImprovedwoodisageneralterm
forwoodthathasbeentreatedinvariouswaystoenhance
itsdimensionalstability
Treatmentmayinvolveimpregnationwithsyntheticresins(IMPREG)
andothermaterials,and/orcompression(COMPREG)and/orheating
(LIGNOSTONE) andmaybeappliedtosolidwoodortoveneersthat
aresubsequentlybondedtogether.
Termisnotapplicabletotimbertreatedwithpreservatives
ororthodoxfinishessuchaspaintortoplywoodorsimilar
otherproducts
Thetreatmentshavetheeffectofmodifyingthepropertiesofthe
woodintermsofhygroscopicity,workingdensitystrengthetc.andfor
thisreasonimprovedwoodisalsocalledMODIFIEDWOOD
Improvedwoodshavebeendevelopedfromnormalwoodstomake
uptheirinadequaciesandtoincreasetheirutility
7/30/2024 2
Dr BhupenderDutt

3. 7/30/2024
Dr BhupenderDutt 3
DEPENDING ON THE TREATMENT
1)IMPREGNATED WOOD
2)HEAT STABILIZED WOOD (STAYB WOOD)
3)COMPRESSED WOOD
4)COMPREGNATED WOOD (COMPREG)
5)HEAT STABILIZED COMPRESSED WOOD
(STAYPAK)
6)CHEMICALLY MODIFIED WOOD
7)IRRADIATED WOOD

4. 7/30/2024
Dr BhupenderDutt 4
•Collectivenameforwoodsimpregnatedwithallpossible
impregnants(wax,paraffin's,resins,oilsetc.)withthe
objectofimprovingdimensionalstabilityandpreventing
waterabsorption
•Impregnatedwoodisatypeofwoodwhereinsubdivided
woodcalledveneersobtainedbyrotarycut,slicedorsawn
aretreatedwithresinlikeUrea-formaldehyde,phenol
formaldehydeetcandthenpressedatsuitablepressure
andtemperaturetocuretheresinbonding
•Thebestknownexamplesare”permali”madeinFrance
byimpregnatingBeechalcoholicphenolicresinand
“Impreg”madeinAmericaandelsewherebyimpregnating
woodwithsyntheticresin

5. 7/30/2024
Dr BhupenderDutt 5
PROPERTIES
The Impregnated wood have higher
hygroscopicity,dimensionalstability,resistance
toswelling,shrinkingandcrackingresistanceto
attackoforganisms
Commonspeciesusedare:Cedrelatoona,Meliadubia,
ButeamonospermaSygygiumcuminiPterocapusmarsupium,
MangiferaindicaDalbergialatifolia,Juglansregia,Lagerstoemiaspp,
Athocephalusetc.

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Dr BhupenderDutt 6
HEAT STABILIZED WOOD (STAYB WOOD)
Ithasbeenfeasibletoimpartanappreciabledegreeof
stabilizationofdimensionanddecayresistancetowood
byasimpleheattreatmentwhichreducesthe
hygroscopicity.
Theheatstabilizedwoodisoneinwhichanappreciabledegreeof
stabilizationofdimensionsanddecayresistancetothewoodis
impartedbyheattreatment
Thisentails,however,areductioninthestrengthof
wood,particularly,toughness.
Theprocedureconsistsoftreatingthewoodbypassingunderthe
surfaceofmoltenmetalandthesubjectingittocontrolledhigh
temperatureof260-315
0
Cforfewminutesandundernonoxidizing
conditions
Theproductknownasstaybwoodisindicatedforwindowslash,
windowframesinwhichdimensionalstabilityanddecayresistanceis
importantandstrengthpropertiescanbesacrificed
HeatstabilizedwoodisusedforDoorsandwindowframes

7. 7/30/2024 Dr BhupenderDutt 7
COMPRESSED WOOD
•Developedbymodifyingthecompressingconditions
tocausethelignincementingmaterialbetweenthe
cellulosefiberstoflowsufficientlytoeliminatethe
internalstresses
•Woodiscompressedwithoutimpregnatingitwithany
syntheticresin
•Considerableimprovementinpropertiesofwoodcan
beattainedbycompression.
•Thecompressionacrossthefibersincreasesthe
specificgravityofthewoodandtherebyimprovesthe
strengthproperties.
•Theoreticallyitshouldbepossibletocompresswood
toaspecificgravityof1.46ifnoairspaceisleftinit.
Inpracticepressurevaryingfrom90-140kg/cm
2
is
appliedandmaterialwithspecificgravityofranging
from1.2-1.3isobtained.

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Dr BhupenderDutt 8
•Compressed wood can be either made from solid wood or laminated
wood.
•In Germany compressed solid wood has been manufactured under the
name “lignostone”and compressed laminated wood under the name
“lignofol”
•Compressing woods of number of species has good strength
properties, high resistance to wear and tear and can be used as
substitute to conventional timbers.
•Compressed wood are Straight grained, fine and even textured
•They are reasonably strong having high resistance to impact and
splitting.
•They have density of about 0.8g/cm
3
•Main species used are: Albizzialebbeck, Anogeissuslatifolia,
Casurinaequisetifolia, Hardwickiapinnata, Meliadubia, Mitragyna
parviflora, Populusdeltoides, populusciliata, Eucalyptus sppetc.
•Compressed wood is used in making shuttle for textile and jute
industries
•Also used in picking Sticks, door handles, bearings, rollers, snow
shoes etc.

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Dr BhupenderDutt 9
COMPREGNATED WOOD (COMPREG)
•COMPREGNATED WOODorCOMPREGiswoodthatisboth
impregnatedwithsyntheticresinandcompressed
•Thetimberisconvertedintoveneers,compressed
togetherinapackatsuitabletemperatureand
pressureafterimpregnatingthemwithphenol
formaldehyderesin.
•Theresintreatmentpriortocompressionimproves
thecompressivepropertiesandshearstrengthofthe
woodinaplanerightangletothedirectionof
compression
•Bysuitablechoiceofwood,thicknessoftheveneers,
pressure,temperatureanddirectionforlayingofthe
veneersthepropertiesoftheresultantvariantcanbe
variedandmadetosuitparticularrequirements
•ThetermCOMPREG isgenerallyappliedtothe
materialcompressedtoaspecificgravityof1.3-1.4.

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Dr BhupenderDutt 10
•Theprocessresultsinhighdimensionalstability;
shrinkageorswellingwithatmosphericchangesbecome
negligible
•Thecompressionincreasestensilestrength,MOR,in
bending,MOEindirectproportiontoitsextent
•Theimpregnationofresinreducestheimpactstrength
•Theprocessinvolveimpregnationwithresin(phenol
formaldehyde,taracidetc.)thepredeterminednumberand
thicknessofveneers(rotarycut,slicedorsawn)andthen
pressedathighpressurearound150Kg/cm2toobtain
specificgravityof1.3-1.4
•Compregishighlyresistanttomildacids,alcoholsand
manyothersolvents.
•Compreghave10-20timesthehardnessofnormalwood
andhasincreasedwear-resistance
•Compregisanexcellentmaterialforaeroplanepropellerblades,
suitableforbearings,electricalmachinery,textilemillsaccessories,
furniture,fanblades,facingmaterialforfloors,sanitaryfittingsetc.

11. 7/30/2024
Dr BhupenderDutt 11
SUITABLE WOODY SPECIES FOR COMPREGNTED
(COMPREG) WOOD
•Dipterocarpus turbinatus
•Adina cardifolia
•Ochroma lagopus
•Mangifera indica
•Shorea assamica etc.

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Dr BhupenderDutt 12
HEAT STABILIZED COMPRESSED WOOD (STAYPAK )
Bothimpregnatedandcompregnatedwoodare
morebrittlethanoriginalwoodandtomeetthe
demandfortougherproduct,acompressedsolid
orlaminatedwoodwithoutimpregnationwithresin
hasbeendevelopedcalledSTAYPAK
Heatstabilizedcompressedwoodisstaypak
Staypakismadebymodifyingthecompressing
conditionssoastocausethelignincementing
materialbetweenthefiberstoflowsufficientlyto
eliminatetheinternalstresses.
woodiscompressedtospecificgravityof1.3-
1.4andBothsolidandlaminatedwoodcanbe
madetostaypak.

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Dr BhupenderDutt 13
Staypakisnotwaterresistantascompregbutitis
abouttwiceastoughandhashighertensilestrength,
MOR,andMOE.
Staypakcanbeusedinthesamewayascompreg
whereextremelyhighwaterresistanceisnotneeded.
Italsoshowsuseaspropellers,handles,pulleys,
shuttlesetc.

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Dr BhupenderDutt 14
CHEMICALLY MODIFIED WOOD
IthasbeenDevelopedtomakewoodlesshygroscopicby
useofchemicalswhichreplacethehydroxyl(OH
-
)in
cellulosewithlesshygroscopicgroups,simultaneously
bridgingthestructuralelementsinordertoreducetheir
tendencytoseparate.
HygroscopicityofwoodisattributedtotheOH
-
groupsin
cellulose.
Acetylatedwoodisaproductofsuchtreatmentobtained
throughacetylation
Acetylationcanbedonebyheatingdrywoodwithacetic
anhydrideinpresenceofpyridineascatalyst
Itresultsinreducedhygroscopicityandshrikage/swelling
Thestabilizationsoobtaineddependsupondegreeof
acetylation.

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Dr BhupenderDutt 15
Aminimumof30percentacetylationisnecessaryfor
satisfactorystabilization
MethylationandAllylationaresimilarprocessesfor
impartingdimensionalstabilitytothewood.
OfotherformsofChemicallymodifiedwoodthatbhas
beendevelopedinclude:
--Uralloy(UreaPlasticizedwood)obtainedbytreatment
ofwoodwithUREA
--HYDROXYLENE (Acidhydrolyzedwoodobtained
bytreatmentwithdil.H
2SO
4

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Dr BhupenderDutt 16
WOOD PLASTIC COMPOSITES
•WoodPlasticcompositesaremadebyimpregnatingwood
withamonomerwhichfillsthevoidsinthewoodandthen
polymerizingthesamewithinthewoodeitherby
irradiationorbyheatcuringprocess
Theprocessgivesaproductinwhichtheinternaland
externalsurfacesarecoveredwithalayerofpolymer
whichretardstherateofaccessofwatertothewoodcell
walls
Thechemicalused---methylmethacrylate,dioxaneand
waterforimpregnationandgammaraysfromcobalt-60
sourceforpolymerization
Mainspeciesusedare:Mangiferaindica,Pterocarpus
dalbergiodes,Albizziaprocera,Toonaciliataetc

17. 30-07-2024 17
Dr BhupenderDutt, Forest Products,UHF, SolanHP