塑木發(fā)泡復(fù)合材料

PVC塑木發(fā)泡

復(fù)合材料

PVCwood-plastic-foamedcomposites四川大學(xué)高分子科學(xué)與工程學(xué)院CollegeofPolymerScienceandEngineering,SichuanUniversity黃銳HUANGRui

2010年9月塑木復(fù)合材料的優(yōu)點(diǎn)

TheAdvantagesofWPC1

23PVC塑木發(fā)泡復(fù)合材料PVCWood-plastic-foamedComposites4

塑木復(fù)合材料成型設(shè)備及工藝MoldingEquipmentandTechnology

ofWPC5發(fā)展塑木復(fù)合材料的意義TheSignificanceofDevelopingWPC

國內(nèi)外塑木復(fù)合材料發(fā)展現(xiàn)狀ThePresentDevelopmentofWPCHomeandAbroad概要Summary

塑木復(fù)合材料(wood-plasticscomposites,WPC)是木質(zhì)材料與熱塑性塑料或熱固性塑料復(fù)合而成。其中木質(zhì)材料包括木屑、刨花、竹屑、麥秸、谷糠、椰子殼、甘蔗渣、花生殼、大麻等。WPC(wood-plasticscomposites)ismadeofwoodmaterialsandthermoplasticorthermosettingplastic.AmongwoodmaterialsincludeSawdust,woodshavings,bambooshavings,straw,chaff,coconutshells,bagasse,peanutshells,hemp

etc.

木粉WoodFlour

谷糠Chaff秸稈纖維StrawFiber塑木復(fù)合材料Wood-plasticsComposites與木材相比：具有優(yōu)良的物理化學(xué)特性。容易清洗。制品能回收再利用，也可生物降解，環(huán)境友好?？杉尤胫珓⒖咕鷦?、發(fā)泡劑等，賦予其需要的功能。使用壽命長，維護(hù)成本低。具有塑料的成型加工性，易加工，可擠出、注塑、壓制成型各種尺寸、形狀制品Comparedwiththewood:

Excellentphysicalandchemicalproperties.

Easytoclean.

Productscanberecycled,andbiodegradable,environmentallyfriendly.

Canbeaddedcoloringagents,antibacterialagents,foamingagents,etc.,endowedwithfunctionswhichareneed.

Longservicelife,lowmaintenancecost.

Withplasticmolding,easyprocessing,canbeextrusion,injectionmolding,pressingavarietyofsizes,shapesproducts.

一、塑木復(fù)合材料的優(yōu)點(diǎn)：

TheAdvantagesofWPC

與塑料相比：Comparedwiththeplastic:（1）具有類似木材的二次加工性，可鋸、可刨、可粘接、可用釘子或螺釘固定，容易維修。Secondaryprocessinglikewood,canbesawed,planed,bonded,cannailorscrew,easytomaintain.

（2）原料來源廣、制品成本低于同類塑料制品。Awidesourceofrawmaterials,costlessthansimilarplasticproducts.（3）類似天然木質(zhì)的外觀和手感。Similarlookandfeelofnaturalwood.

（4）尺寸穩(wěn)定性，硬度比塑料好。Dimensionalstabilityandrigiditybetterthanplastic.

WPC綜合了塑料與木材兩種材料的性能特點(diǎn)，具有非常廣泛的用途。WPCsynthesizetheperformancecharacteristics

ofplasticandwoodwithaverywiderangeofuses.

減輕環(huán)境污染ReduceEnvironmentalPollution有效緩解木材資源緊缺的現(xiàn)狀Effectivelyalleviatetheshortageoftimberresources促進(jìn)資源的綜合利用和循環(huán)經(jīng)濟(jì)的發(fā)展。Promotethecomprehensiveutilizationofresourcesandthedevelopmentofrecycleeconomy.二、大力發(fā)展塑木復(fù)合材料的意義：

TheSignificanceofDevelopingWPC主要應(yīng)用領(lǐng)域包括：Mainapplications:(1)建筑和裝飾行業(yè)Construction&Decoration(2)園林方面Gardening(3)市政建設(shè)MunicipalBuilding(4)汽車業(yè)Automotive(5)物流方面Logistics塑木復(fù)合材料的應(yīng)用：TheApplicationofWPC(1)建筑和裝飾行業(yè)Construction&Decoration

(1)建筑和裝飾行業(yè)Construction&Decoration

(1)建筑和裝飾行業(yè)Construction&Decoration

（2）園林方面Gardening（2）園林方面Gardening（2）園林方面Gardening（2）園林方面Gardening（2）園林方面Gardening（2）園林方面Gardening（3）市政建設(shè)MunicipalBuilding

(4)汽車業(yè)Automotive（5）物流方面Logistics

據(jù)PrincipiaPartners咨詢公司專題報(bào)告，北美WPC需求約占世界總量的85％，2001年400kt，2006年1000kt，產(chǎn)值超過10億美元，年增長超過25%。2007年北美WPC年需求總量已超過700kt，預(yù)計(jì)2010年將達(dá)1600kt。

AccordingtoconsultingcompanyPrincipiaPartnersspecialreport,NorthAmericandemandforWPCabout85%oftheworldtotal,thereare400ktin2001,1000ktin2006.Theoutputvalueismorethan1billionU.S.dollars,annualgrowthrateismorethan25%.TheannualtotaldemandingquantityofWPCinNorthAmericain2007isover700kt.Itwillbeexpectedtoreach160ktby2010.三、國內(nèi)外塑木復(fù)合材料發(fā)展現(xiàn)狀ThePresentDevelopmentofWPCHomeandAbroad2006年底統(tǒng)計(jì)表明，美國有101家WPC加工廠，加拿大11家。WPC原料樹脂中PE、PP和PVC分別占75％、12％和10%。塑木鋪板占總鋪板（70萬噸）中的一半，其次為窗框系統(tǒng)，約7萬噸，包括鋪板、門窗框系統(tǒng)的擠出型材和屋面板、墻面板。Statisticsshowthatbytheendof2006,thereare101WPCprocessingplantsintheUnitedStates,11onesinCanada.PE,PPandPVCrespectivelyaccountedfor75%,12%and10%ofWPCresinrawmaterials.Wood-Plasticplankoccupyhalfofthetotal(700,000tons),followedbywindowframesystem,about70,000tons,includingtheplank,doorframesofextrusionsystems,roofprofileandwallpanels.三、國內(nèi)外塑木復(fù)合材料發(fā)展現(xiàn)狀ThePresentDevelopmentofWPCHomeandAbroad歐洲Europe

2009年歐洲生產(chǎn)廠家已達(dá)61家，其中德國19家，英國7家，瑞典6家，芬蘭、奧地利各5家。歐洲WPC用基礎(chǔ)樹脂與美國結(jié)構(gòu)不同，歐洲只有為數(shù)不多的廠家使用PVC為基材，大部分是PP基材料，PP占82％，PE10％，PVC8％。In2009,Europeanmanufacturershavereached61,including19inGermany,7inUnitedKingdom,6inSweden,5inFinland,5inAustria.TheWPCbasedresinusedinEuropehasthedifferentstructuresfromtheUnitedStates,onlyafewEuropeanmanufacturersusePVCforthesubstrate,mostarePP-basedmaterials,includingPPaccountedfor82%,PEaccountedfor10%,PVCaccountedfor8%.亞洲（除中國）Asia(excludingChina)

亞洲WPC開發(fā)比較成熟的主要是日本。日本由于地理和環(huán)保意識等原因，塑木材料的應(yīng)用比較普遍。雖然日本塑木復(fù)合材料發(fā)展較成熟，從1992年開始也較早的進(jìn)行了商品化，但制品發(fā)展仍然緩慢。除日本外，印度近年用量也有較大增加，亞洲其它國家的生產(chǎn)、應(yīng)用都相對較少。AsianWPChasdevelopedmorematurelyinJapanthanothers.Duetogeographicalandenvironmentalawarenessandotherreasons,theapplicationofWPCmaterialsisrathercommon.AlthoughtheJapanesewoodcompositehasdevelopedmorematurely,andsince1992ithasearlierbeencommercialized,theproductdevelopedstillslow.ExceptJapan,Indiahasalargeamountofincreaseinrecentyears,butintheotherAsiancountries,theproductionandapplicationsarerelativelyless.

我國塑木行業(yè)在國家政策的鼓勵和企業(yè)潛在效益驅(qū)動下，發(fā)展迅猛。截止2009年底，全國直接從事塑木材料研發(fā)、生產(chǎn)的企事業(yè)單位超過200家，塑木制品年產(chǎn)量約10萬噸，年產(chǎn)值約12億人民幣。各種類的WPC比例見下圖，可見我國WPC中，PE和PVC約各占一半。Ourplasticwoodindustryencouragedbythenationalpolicyanddrivenbypotentialbenefits,developsrapidly.Bytheendof2009,therearemorethan200enterprises

whicharedirectlyengagedinresearchandproduction

inthewholecountry.Theannualoutputofplasticwoodproductisabout10milliontonsannualproductionvalueisabout1.2billionyuan.TheproportionofdifferenttypesofWPCshownbelow,itcanbeseenthatPEandPVCishalfeach.我國塑木產(chǎn)品市場的一些情況SomecasesaboutmarketsinChina塑木行業(yè)現(xiàn)狀ThePresentSituationintheFieldofWPC發(fā)泡的意義

TheSignificanceofFoaming為了節(jié)省資源，減少塑料廢棄物對環(huán)境的危害，塑料制品輕量化（發(fā)泡）是發(fā)展趨勢。Inordertosaveresourcesandreduceenvironmentalhazardsofplasticwaste,plastictolightweight(foaming)isthetrend.

微孔發(fā)泡能夠顯著提高材料的抗沖擊強(qiáng)度、韌性、疲勞周期、熱穩(wěn)定性等。Microcellularfoam

cansignificantlyimproveimpactstrength,toughness,fatiguecycles,thermalstabilityetc.目前，我國的發(fā)泡加工成型已形成相當(dāng)規(guī)模的生產(chǎn)能力。Atpresent,thefoammoldingprocesshasafairlylargescaleproductioncapacity.

目前發(fā)泡WPC占WPC總量的20%左右，其比例還可能會增加，其中大部分是PVC和PE基。PVC基的塑木復(fù)合物的密度通常為1.3g/cm3左右，發(fā)泡后可使密度降至0.6g/cm3，具有更好的經(jīng)濟(jì)性。CurrentlyWPCfoamaccountsfor20%aboutofthetotalofWPC,theproportionmayincrease,andmostofwhichisPVCandPE-based.ThedensityofPVC-baseWPCmaterialisusuallyabout1.3g/cm3,afterfoamingthedensitywillfallto0.6g/cm3,withabettereconomy.

四、PVC塑木發(fā)泡復(fù)合材料PVCwood-plastic-foamedcomposites

PVC發(fā)泡原理和過程

PrincipleandProcessofPVCFoamingPVC發(fā)泡包括物理發(fā)泡和化學(xué)發(fā)泡兩種。PVCfoamingincludingphysicalandchemicalfoaming.物理發(fā)泡法是用低沸點(diǎn)的物質(zhì)作發(fā)泡劑，靠加熱或減壓揮發(fā)產(chǎn)生的氣體進(jìn)行發(fā)泡。Physicalfoamingistousethelow-boilingmaterialasfoamingagent,itfoamsbyheatingorpressiontovolatilizegases.

化學(xué)發(fā)泡法是利用化學(xué)物質(zhì)加熱時(shí)分解或反應(yīng)產(chǎn)生氣體來使PVC發(fā)泡。ChemicalfoamingistomakePVCfoambythegaseswhenthechemicalisheatedandposedorreact.工業(yè)上PVC發(fā)泡材料多采用化學(xué)發(fā)泡方法。InIndustryPVCfoammaterialmostadoptchemicalfoamingmethod.PVC發(fā)泡材料的成型方法PVC主要分為：PVCFoamingisDivided:注塑發(fā)泡成型InjectionFoaming擠出發(fā)泡成型ExtrusionFoaming模壓發(fā)泡成型MoldFoamingMoldingMethodsofPVCFoaming

PVC塑木復(fù)合材料擠出發(fā)泡的原料，PVC分子量選擇非常重要，它將改變復(fù)合物的流變性，從而對氣泡的生長影響很大。分子量過低，熔體強(qiáng)度較差，對發(fā)泡氣體逃逸的阻礙能力差，很難得到泡孔均勻細(xì)密的泡沫塑料。分子量過高，熔體的拉伸強(qiáng)度很大，抑制泡孔的生長，使發(fā)泡不充分，難以得到高發(fā)泡率的泡沫塑料。選擇K值57～60的PVC較為合適。

RawmaterialsofPVCwoodcompositeforextrusionfoaming,theselectionofPVCmolecularweightisveryimportant,itwillchangetherheologicalbehaviour,andgreatlyinfluenceonthegrowthofbubbles.Whenthemolecularweightislow,themeltstrengthispoor,anditwilldifficulttoblockthefoaminggastoescape,difficulttogettheevenbublesandsmoothfoam.Whenthemolecularweightishigh,thetensilestrengthofmeltisgreat,itwillinhibitedthegrowthofthebubles,sothatfoamingisnotsufficient,itisdifficulttogethighfoamingrateofthefoam.SelectingKvalue57~60ofPVCismoresuitable

.（1）PVC樹脂的選擇(1)TheSelectionofPVCResin不同品種的木粉，生產(chǎn)的塑木材料性能差別大。應(yīng)考慮木粉的種類、表面自由能、填充量、粒徑、含水量等的影響。Withdifferentspeciesofwoodpowder,theperformanceofWPCproductshasalargedifferences.Itshouldconsiderthetypesofwoodpowder,thesurfacefreeenergy,fillingvolume,particlesizes,moistureandotherfactors.

PVC塑木發(fā)泡中多為工業(yè)用木粉，尺寸約150μm。木粉填充量一般為(質(zhì)量分?jǐn)?shù)，下同)30%～60%。填充量越高，越不容易發(fā)泡。發(fā)泡中，木粉含水率較高會導(dǎo)致較差的泡孔結(jié)構(gòu)、泡孔分布不均，泡孔表面差、不光潔等。因此，加工應(yīng)盡量將木粉充分干燥。InPVCwoodcompositefoamingmostlyadoptingindustrialflour,thesizeisabout150μm.Fillingvolumeofwoodpowerusually30%~60%(massfraction).Themoreoffillingvolumethemoredifficulttofoam.Infoaming,ifthemoisturecontentwoodflourishigh,itwillleadtopoorcellstructure,unevendistributionofthecell,thecellsurfaceispoor,notcleanandsoon.Therefore,thewoodflourshouldbefullydried.

（2）木粉的選擇及處理(2)SelectionandTreatmentofWoodFlour木質(zhì)纖維的元素組成為：C約為50%，H約為6%，O約為44%，N約為0.05～0.4%；其主要成分為纖維素、半纖維素和木質(zhì)素。Elementalcomposition

ofwoodfiber:Cisabout50%,Hisabout6%,Oisabout44%,Nisabout0.05~0.4%;themaincomponentiscellulose,hemicelluloseandlignin.纖維素：約占木材的50%，是D-葡萄糖以β-1,4苷鍵結(jié)合起來的鏈狀高分子化合物，具有結(jié)晶結(jié)構(gòu)，對酸或堿的抵抗性較半纖維素強(qiáng)。Cellulose:thecontentisabout50%ofwood,itiscombinedaspolymerchainstructureasβ-1,4glycosidebondstoD-glucose,withacrystallinestructure,havingstrongerresistancetoacidoralkalithanhemicellulose

.

（2）木粉的選擇和處理(2)SelectionandTreatmentofWoodFlour半纖維素：約占20~30%，它是非纖維素的高聚糖類，大部分可溶于堿，通過加熱或NaOH浸泡處理都可除去半纖維素。Hemicellulose:about20~30%,itispolysaccharidesclassofnon-cellulose,mostlyalkali-soluble.ThehemicellulosecanberemovedbyheatingorsoakinginNaOHsolution.

木質(zhì)素：約占木材的20~30%，是以苯丙烷為基元，由C-C鍵和醚鍵結(jié)合起來的高分子芳香族物質(zhì)，大部分不溶于有機(jī)溶劑。Lignin:about20~30%ofwood,itisbasedonphenylpropaneaselement,itispolymeraromaticsubstancescombinedbytheC-Cbondandetherbond

,mostlynotdissolvedinorganicsolvents.

木質(zhì)材料一般根據(jù)外形可分為木粉(L/D=l~2)、木纖維(L/D=10)。根據(jù)不同的生產(chǎn)要求選擇。Woodmaterialcanbegenerallyonappearancedividedintowoodpowder(L/D=l~2),woodfiber(L/D=10).Thechoicecanbemadeaccordingtodifferentproductionrequirements.

通常塑木復(fù)合中選用木粉粒徑一般在20～200目。在此基礎(chǔ)上，要保證木粉和塑料在混合前進(jìn)行烘干處理。Usuallytheparticlesizeofwoodflourwhichisselectedandusedisinthe20to200mesh.Onthisbasis,toensurethatwoodflourandplasticsaredredbeforemixing.

需要一提的是，在用帶排氣功能的擠出機(jī)，特別是雙螺桿擠出機(jī)加工塑木材料時(shí)，可以不對木粉進(jìn)行特別的烘干處理，只需日光下自然干燥即可直接進(jìn)行擠出加工。Needtomentionthat,whenusingextruderwithexhaustfunctionespetionallydouble-screwextrudertoprocessWPCmaterial,thewoodflourcannotbedriedspetially,butonlytodryundersunlight.

表1木材的化學(xué)成分(%)Chemicalcompositionofwood木材的化學(xué)成分Chemicalcompositionofwood%云杉松楊樹木樹枝樹干樹枝樹干樹枝纖維素(不包括聚戊糖)53.8～59.344.856.5～57.618.252.0～52.243.9木質(zhì)素28.0～28.134.426.8～27.027.421.1～21.425.9聚戊糖9.5～10.512.810.4～11.010.122.7～22.928.7甘露聚糖7.5～～7.14.8無無半乳聚糖2.631.4～～0.70.8醚浸出物1.0～～～1.52.5熱水可溶物1.7～～～2.54.9灰分0.20.260.20.270.260.33Table1Chemicalcompositionofwood(%)Chemicalcompositionofwood%spruce

pine

poplar

trunkbranchtrunkbranchtrunkbranchCellulose(notincludingpentosan)

53.8～59.344.856.5～57.618.252.0～52.243.9lignin

28.0～28.134.426.8～27.027.421.1～21.425.9heteropentosan

9.5～10.512.810.4～11.010.122.7～22.928.7mannosan

7.5～～7.14.8無無galactan

2.631.4～～0.70.8ether-solubleextractive

1.0～～～1.52.5Hotwatersoluble1.7～～～2.54.9Ash0.20.260.20.270.260.33表2稻殼的化學(xué)成分稻殼品種水分％灰分％粗纖維％木質(zhì)素％多縮戊糖PH值SiO2在灰分中含量％早稻9.316.6134.7225.1816.397.195.72晚稻10.215.434.626.1316.287.5493.1稻殼粉RiceHuskPowderTable2Chemicalcompositionofricehusk

Varietiesofricehusk

moisture

％Ash％crudefibre：％lignin

％pentosan

PHValueThecontentofSiO2intheash

％earlyrice

9.316.6134.7225.1816.397.195.72laterice10.215.434.626.1316.287.5493.1RiceHuskPowder物理加工法Physicalprocessingmethod物理加工、干燥。Physicalprocessing,drying原纖的表面放電處理TheelectricdischargesurfacetreatmentofFibrillation

低溫等離子處理法Low-temperatureplasmaprocessingmethod氣爆法(STEX)Airblastmethod(STEX)

化學(xué)方法：Chemicalprocessingmethod

表面接枝法

Surfacegrafting界面偶合法Interfacecoupling乙酰化處理法Acetylationtreatment堿處理法Alkalitreatment酸處理法Acidtreatment有機(jī)溶劑處理法Organicsolventapproach（4）木粉處理方法TreatmentofWoodFlour偶聯(lián)劑主要用于聚烯烴基WPC中，對改進(jìn)和提高聚烯烴WPC制品性能十分重要。由于親水的木纖維和憎水的聚烯烴塑料間的不相容性，木纖維與塑料界面粘附力小，未經(jīng)處理木纖維填充的WPC性能不如純聚烯烴，偶聯(lián)劑可以改進(jìn)和提高木纖維與塑料母體樹脂間的粘附力，從而提高WPC性能。CouplingagentmainlyusedforpolyolefinbaseWPC,andimprovingthepropertiesofWPCpolyolefinproductsisveryimportant.Becauseofthepatibilitybetweenhydrophilicwoodenfiberandthosehydrophobepolyolefinplastic,theinterfaceadhesionforcebetweenthemisweek,thepropertiesofuntreatedwoodenfiberfillingWPCareworsethanpurepolyolefin.Socouplingagentcanimproveandenhancetheadhesionforcebetweenwoodfiberandplasticresinmatrix,improvingperformanceofWPC.（5）偶聯(lián)劑CouplingAgent

偶聯(lián)劑能夠幫助:Couplingagentcanhelp

提高拉伸強(qiáng)度Improvethetensilestrength增強(qiáng)彎曲強(qiáng)度Enhancethebendingstrength加大沖擊強(qiáng)度Increasetheimpactstrength降低吸水率Reducethewaterabsorption偶聯(lián)劑能夠增加親水性木材和憎水性塑料之間的親和力Couplingagentcanincreasethebondingbetweenhydrophilicwoodandhydrophobicplastic二、PVC發(fā)泡原理和過程發(fā)泡過程一般都要經(jīng)過：Generaltogothroughthefoamingprocess:

形成氣泡核→氣泡核膨脹→泡體固化定型等階段。Bubbleformation→Bubbleexpansion→Bubblecuringandshapingf.PrincipleandProcessofFoaminginPVC氣泡核的形成氣泡核的形成階段對泡體中泡孔密度和分布情況起著決定性的作用，在溫度和壓力一定的情況下，氣泡核數(shù)量決定了泡孔結(jié)構(gòu)，并對最終制品的密度和發(fā)泡倍率影響重大。因此，氣泡核的形成是控制泡體性能和質(zhì)量的關(guān)鍵階段。Bubbleformationstageplaysadecisiveroleonthedensityanddistributionofthecell,whenthetemperatureandpressurefixed,thenumberofbubbledeterminesthestructureoffoam,andsignificantlyinfluencethedensityandexpansionratioofthefinalproduct.Therefore,theformationofbubbleisthekeystagetocontrolofperformanceandquality.

TheFormationofBubble氣泡核形成機(jī)理一、氣液相混合直接形成氣泡核。Themixingofgasandliquidisdirectlytoformnuclearbubbles.熱固性泡沫塑料大多采用此法。

Thermosettingplastics

mostlyadoptthismethod.二、利用高聚物中的自由體積為成核點(diǎn)。Useofthefreevolumeinpolymersforthenucleationpoint.三、利用高聚物熔體中的低勢能點(diǎn)為成核點(diǎn)。Useofthelowpotentialenergypointinpolymermeltfornucleationsites

將發(fā)泡劑（物理發(fā)泡劑）壓送入高聚物的自由體積中，再通過升溫降壓的方法使自由體積中的發(fā)泡劑氣化膨脹形成氣泡核。Thefoamingagent(physicalfoamingagents)ispressuredintothefreevolumeofpolymer,andthenbywarmingandreducingpressuretogasifyfoamingagentandexpandthefreevolumeformingbubblesnuclear.

The

FormationMechanismofBubble氣泡生長Bubblegrowth氣泡成核后接著進(jìn)入生長階段，聚合物熔體中溶解的氣體不斷向泡核擴(kuò)散，使周圍聚合物中產(chǎn)生氣體濃度梯度，濃度梯度的存在進(jìn)一步促進(jìn)了氣體的擴(kuò)散，也就促進(jìn)了氣泡的進(jìn)一步生長。

Afterbubblenucleate,thengointothegrowthphase,thegasdissolvedinpolymermeltcontinuouslydiffusetobubblenuclear,sothatgasesproduceconcentrationgradientinpolymer.Theconcentrationgradientfurtherpromotethediffusionofgases,alsocontributetothebubblefurthergrowth.形成的氣泡可能繼續(xù)生長，也可能發(fā)生塌陷、破裂或合并。Bubblemaycontinuetogrow,itmaycollapse,crackedormerge.氣泡的生長受多種因素影響，如溫度、成核數(shù)量和氣體的損失。Thegrowthofbubbleisaffectedbymanyfactors,suchastemperature,thenumberofnucleationandgaslosses.氣泡生長Bubblegrowth影響氣泡生長的主要因素

TheMainFactorsofBubbleGrowth影響因素主要兩大類：Thefactorsaremaintwoclasses:一類屬于發(fā)泡體系的物性參數(shù)，如氣體的種類、擴(kuò)散系數(shù)、溶解度、熔體的粘彈性、氣體-聚合物熔體的界面張力等，這些參數(shù)主要通過界面間的物理傳遞來影響氣泡增長；Oneclassisphysicalparameters,suchasthetypeofgas,diffusioncoefficient,solubility,meltviscoelastic,interfacialtensionbetweengasandpolymermelt,etc.Theseparametersinfluencethebubblegrowththroughphysicaldeliveryintheinterface.另一類屬于加工工藝參數(shù)，如壓力、溫度、剪切速率、添加劑等，這類參數(shù)主要通過熱力學(xué)性能來影響氣泡增長。溫度影響氣體的擴(kuò)散速度和熔體粘度，在成型過程中應(yīng)精確控制溫度。氣體擴(kuò)散對氣泡生長影響也很顯著，在熔體溫度較高、擴(kuò)散速度很大且熔體粘度很低時(shí)，氣體的逃逸劇烈，會使泡孔膨脹率顯著下降而無法得到發(fā)泡倍率較高的泡沫。Theotherisprocessparameters,suchaspressure,temperature,shearrate,additives,etc.Theseparametersinfluencethebubblegrowthmainlythroughthethermodynamicproperties.Temperatureaffectsgasdiffusionrateandmeltviscosity,themoldingprocessshouldbeprecisetemperaturecontrol.Gasdiffusioneffectonthebubblegrowthisalsosignificantlyhigherinthemelttemperature,meltviscosityandthediffusionvelocityislow,thegasescapesevere,thecellexpansionratewoulddeclinesignificantlyratiocannotbecomparedwithfoamhighfoam.泡體固化、定型

BubbleSolidifyingandShaping泡體的幾何形狀和結(jié)構(gòu)，如泡孔的大小、開閉孔、泡孔的形狀和分布是由膨脹階段的條件決定的。Geometryandstructureofcell,suchasthecellsize,openorclosedcell,theshapeanddistributionofcellisdecidedbytheexpansionphase.膨脹能否達(dá)到預(yù)期的要求，與泡體的固化過程密切相關(guān)聯(lián)。Ifexpansioncanmeetexpectationsornot,closelyassociatedwiththebubblecuringprocess.為了使已達(dá)到膨脹倍數(shù)的泡體結(jié)構(gòu)固化定型，選擇合適的固化時(shí)機(jī)和提高固化速度非常重要。Inordertohavethebubblestructurewhichhasreachedamultipleexpansioncureandshape,selectingtheappropriatecuringtimeandimprovingthecurerateisveryimportant.表1發(fā)泡劑基本性能名稱縮寫分解溫度/℃氣體產(chǎn)率/(ml·g-1)主要?dú)怏w偶氮二甲酰胺AC200～230280～320N2,CO2(NH3)檸檬酸及其衍生物200～220110～150CO2,H2O4，4－羥基雙（苯甲?；酋ｋ拢㎡BSH140～165120～150N2,H2O5-苯基四唑5-BT240～250190～210N2碳酸氫鈉120～150130～170CO2,H2O鄰甲苯磺酰肼TSH110～140120～140N2,H2O對甲基磺酰氨基脲TSS215～235120～140N2,CO2（6）發(fā)泡劑FoamingAngent（6）發(fā)泡劑Table1ThebasicpropertiesoffoamingagentNameacronym

positiontemperature/℃gasyield/(ml·g-1)MaingasAzodicarbonamideAC200～230280～320N2,CO2(NH3)Citricacidanditsderivatives

200～220110～150CO2,H2O4,4-hydroxydouble

(Benzoylsulfonylhydrazide)

OBSH140～165120～150N2,H2O5-phenyl-tetrazole5-BT240～250190～210N2Sodiumbicarbonate

120～150130～170CO2,H2OO-benzenesulfonylhydrazide

TSH110～140120～140N2,H2OMethylsulfonylsemicarbazide

TSS215～235120～140N2,CO2FoamingAngent對化學(xué)發(fā)泡劑的要求是分解釋放出的氣體應(yīng)為無毒、無腐蝕性、不燃燒，對制品的成型及物理、化學(xué)性能無影響，釋放氣體的速度應(yīng)能控制，發(fā)泡劑在塑料中應(yīng)具有良好的分散性等。Requirementsofthechemicalfoamingagentisthatthegasofpositionshouldbenon-toxic,non-corrosive,non-burning,havenoeffectontheproduct'sshape,andphysicalandchemicalproperties.Thereleasespeedofgasshouldbeabletocontrol.Thefoamingagentinplasticshouldbewelldispersedandsoon.（6）發(fā)泡劑FoamingAngent常用的化學(xué)發(fā)泡劑如AC熱分解溫度高，分解劇烈，易產(chǎn)生泡孔合并，分解溫度過高，會導(dǎo)致木粉燒焦降解，必須添加一些助發(fā)泡劑，通過助發(fā)泡劑的活化引發(fā)它的分解，降低其熱分解溫度，使分解溫度與PVC擠出溫度相適應(yīng)(降到160～170℃)。Commonchemicalfoamingagents,suchasAC,whichhasthehighthermalpositiontemperatures.Thepositionisintense,anditiseasytoproducethecellmerging.Whenthepositiontemperatureishigh,itwillleadtoburninganddegradationofwoodpowder,soyoumustaddsomefoamingpromotor.Theactivationoffoamingpromotorhelpcauseitspositionandreducethethermalpositiontemperature,fitthetemperaturewhichPVCextrudes(downto160~170℃).（7）助發(fā)泡劑FoamingPromotor常用的助發(fā)泡劑是三鹽基硫酸鉛、二鹽基亞磷酸鉛、硬脂酸鈣、硬酯酸鋅等。AC發(fā)泡劑與助發(fā)泡劑的使用比例常為1∶(1～3)。

Commonfoamingpromotoristribasicleadsulphate,dibasicleadphosphate,calciumstearate,zincstearateandsoon.TheoftenusedratioofACfoamingagentandfoamingpromotoris1:(1~3).溫度和時(shí)間對AC發(fā)氣量的影響

TheInfluenceofTemperatureandTime

ontheGasYieldofAC

溫度和時(shí)間的變化直接決定發(fā)氣量的大小，溫度與發(fā)氣量關(guān)系如圖1所示，時(shí)間與發(fā)氣量關(guān)系如圖2所示。Changesintemperatureandtimedirectlydeterminesthesizeofgasevolution,therelationshipbetweentemperatureandgasevolutionshowninFigure1,relationshipbetweenthetimeandgasevolutionshowninFigure2.助發(fā)泡劑對AC發(fā)泡劑分解溫度的影響發(fā)泡劑和助發(fā)泡劑配方①分解溫度/℃發(fā)氣量/(ml/g)AC3195-200220AC+氧化鋅3:1165-180220AC+硬脂酸鋅3:1150-180230－240AC+硬脂酸鈣03:1.5135-160210－230AC+硬脂酸鉛3:1160-200195－220①每百份樹脂中份數(shù)助發(fā)泡劑FoamingPromotor

TheinfluenceoffoamingpromotoronthepositiontemperatureofACfoamingagentFoamingagentandpromotorformular①position/℃Gasevolution/(ml/g)AC3195-200220AC+zincoxide3:1165-180220AC+zincstearate3:1150-180230－240AC+calciumstearate03:1.5135-160210－230AC+leadstearate3:1160-200195－220①fractioneach100resins增塑劑的作用是促使PVC塑化熔融，提高熔體強(qiáng)度和延展性，使發(fā)泡過程較穩(wěn)定。TheroleofplasticizeristopromotePVCplasticizingandmelting,increasedmeltstrengthandextensibility,makingthefoamingprocessmorestable.研究表明，PVC/木粉復(fù)合材料擠出發(fā)泡，丙烯酸是一種非常有效的增塑劑。配方中加入丙烯酸可降低熔體的剛性和粘度，有利于氣體擴(kuò)散和氣泡生長，對減小制品的密度效果明顯。其最佳用量為6%～8%。其它常用的增塑劑有鄰苯二甲酸二丁酯（DBP）、鄰苯二甲酸二辛酯（DOP）及癸二酸二辛酯等。Theresultsshowthat,inPVC/WoodFlourCompositesextrusionfoaming,acrylicacidisaveryeffectiveplasticizer.Formularwithacrylicacidcanreducetherigidandviscosityofmelt,itcanhelpgasdiffuseandgrow,significantlyreducethedensityofproducts.Theoptimumdosageis6%to8%.Othercommonplasticizersaredibutylphthalate(DBP),dioctylphthalate(DOP)anddioctylsebacate,etc.實(shí)際加工過程中，為避免熔體強(qiáng)度不夠，可適當(dāng)減少DOP用量，改加一些發(fā)泡調(diào)節(jié)劑（如530）等。Inactualprocessing,inordertoavoidunenoughmeltstrength,mayappropriatelyreducingtheamountofDOP,addingsomefoamingregulators(suchas530)andsoon.（8）增塑劑Plasticizer

改善填料的混合性、分散性；Improvethemixinganddispersionoffiller

促進(jìn)塑化，改善流動性promotplastifying,improvemobility提高擠出速度，降低設(shè)備扭矩和溫度Improvetheextrusionspeed,reducetorqueandtemperature良好的外觀和質(zhì)感，消除邊緣撕裂；Goodlookandfeel,eliminateedgetear

有助于塑木共混(各項(xiàng)性能更優(yōu))；HelpblendWPC(theperformancebetter);提高產(chǎn)能，降低綜合成本。Increaseproductivity,reducetotalcost.

（9）潤滑劑LubricatingAgent助劑應(yīng)用熱穩(wěn)定劑防止加工過程中聚合物降解抗沖改性劑提高沖擊強(qiáng)度光穩(wěn)定劑防止紫外光對聚合物的傷害著色劑美化制品表面，并有一定紫外防護(hù)能力抗菌劑防止細(xì)菌真菌侵蝕OtherAg