专业外语讲稿第10课Wood FiberThermoplastic CompositesWord下载.docx
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专业外语讲稿第10课Wood FiberThermoplastic CompositesWord下载.docx
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n,-'
stiərin]
n.聚苯乙烯
Polystyrene:
聚苯乙烯|聚本.烯|聚本乙烯
polystyrenefoam:
聚苯乙烯泡沫塑料|聚苯乙烯泡沫|聚苯乙烯
expandablepolystyrene:
聚苯乙烯|可膨胀的聚苯乙烯|可发聚苯乙烯
Polyethylenes
n.聚乙烯类
Polyethylenes:
聚乙烯类
Woodflourisareadilyavailableresourcethatcanbeusedasafillerinthermoplasticcomposites.
Woodflourisprocessedcommercially,oftenfrompost-industrialmaterialssuchasplanershavings,chips,andsawdust.
Severa;
gradesareavailabledependinguponwoodspeciesandparticlesize.
Woodfibers,althoughmoredifficulttoprocesscomparedwithwoodflour,canleadtosuperiorcopositepropertiesandactmoreasareinforcementthanasafiller.
Awidevarietyofwoodfibersareavailablefrombothvirginandrecycledresources.
virgin['
və:
dʒin]n.处女adj.处女的;
纯洁的;
未经利用的,处于原始状态的
Virgin:
维京|处女|维珍集团
VirginIslands:
美属维尔京群岛|维尔京群岛|处女岛
virginforest:
原始森林|原始林|处女林
Othermaterialscanbeaddedtoaffectprocessingandproductperformanceofwood-thermoplasticcomposite.
Theseadditivescanimprovebondingbetweenthethermoplasticandwoodcomponent(forexample,couplingagents),productperformance(impactmokifiers,UVstabilizers,flameretardants),andprocessability(lubricants).
lubricant['
lu:
brikənt]n.润滑剂;
润滑油adj.润滑的
lubricant:
润滑剂|滑润剂|润滑油
solidlubricant:
固体润滑剂|凝固润滑脂|黄油
moldlubricant:
脱模剂|塑模润滑剂|模油
Severalconsiderationsmustbekeptinmindwhenprocessingwoodwiththermoplastics.
Moisturecandisruptmanythermoplasticprocesses,resultinginpoorsurfacequality,voids,andunacceptableparts.
void[vɔid]n.空间;
空虚;
空隙adj.空的;
无效的;
无人的vt.使无效;
排放
void:
空集|焊接空隙|空隙
Voidfiller:
填充物|填隙料|填空料
voidratio:
孔隙比|孔隙率|孔隙度
Materialsmusteitherbepredriedorventedequipmentmustbeusedtoremovemoisture.
Thelowdegradationtemperatureofwoodmustalsobeconsidered.
Asageneralrule,melttemperaturesshouldbekeptbelow200℃,exceptforshortperiods.
Highertemperaturescanresultinthereleaseofvolatiles,discoloration,odor,andembrittlementofthewoodcomponent.
Therearetwomainstrategiesforprocessingthermoplasticsinlignocellulosiccomposites.
Inthefirst,thelignocellulosiccomponentservesasareinforcingagentorfillerinaconditionsthermoplasticmatrix.
matrix['
meitriks]n.矩阵;
基质;
模型;
脉石;
母体;
子宫
matrix:
矩阵|黑客帝国|矩阵点阵
InverseMatrix:
逆矩阵|逆阵|反矩阵
MatrixRecognition:
模式识别
Inthesecond,thethermoplasticservesasabindertothemajoritylignocellulosiccomponent.
Thepresenceorabsenceofacontinuousthermoplasticmatrixmayalsodeteminetheprocessabilityofthecompositematerial.
Ingeneral,ifthematrixiscontinuous,convetionalthermoplasticprocessingequipmentmaybeusedtoprocesscomposites;
however,ifthematrixisnotcontinuous,otherprocessedmayberequired.
Forthepurposesofdiscussion,wepresentthesetwoscenariosforcompositeswithhighandlowthermoplasticcontent.
CompositeswithHighThermoplasticContent
Incompositeswithhighthermoplasticcontent,thethermoplasticcontentisinacontinuousmatrixandthelignocellulosiccomponentservesasareinforcementorfiller(Fig.10-1).
Inthegreatmajorityofreinforcedthermoplasticcompositesavailablecommercially,inorganicmaterials(forexample,glass,clays,andminerals)areusedasreinforcementsorfillers.
Lignocellulosicmaterialsoffersomeadvantagesoverinorganicmaterials;
theyarehigher,muchlessabrasive,andrenerable.
Asreinforcement,lignocellulosiccanstiffenandstrengthenthethermoplasticandcanimprovethermalstabilityoftheproductcomparedwiththatofunfilledmaterial.
Fig.10-1Theuseoflignocellulosicasreinforcingfillersallowsthermoplasticstobemoldedintoawidevarietyofshapesandforms
Thermoplasticsinpelletformhavebulkdensityintherangeof500to600kg/m3.
bulk[bʌlk]vt.使扩大,使形成大量;
使显得重要n.体积,容量;
大块;
大多数,大部分
bulk:
散装|正货|大批
BULKPRODUCTION:
大量生产
bulkmaterial:
散装材料|疏松材料|散状物料
bulkdensity容积密度,体积密度;
单位体积重量
bulkdensity:
堆积密度|体密度|松密度
bulk-density:
单位体积重量、密度
松装密度
Ignocellulosictypicallyhaveanuncompactedbulkdensityof25to250kg/m3.
Woodfibersareatthelowendofthelignocellulosicbulkdensityconinuumandwoodfloursatthehighend.
Althoughprocessingofwoodflourinthermoplasticsisrelativelyeasy,thelowbulkdensityanddifficultyofdispersingfibrousmaterialsmakethermoplasticsmoredifficulttocompound.
Dispersingn.分配,分散adj.分散的
v.使散开;
散布;
驱散(disperse的现在分词)
Dispersing:
分散|具有分散作用的|分配
dispersinglens:
色散透镜|散光透镜
dispersingprism:
色散棱镜
Moreintensivemixingandtheuseofspecialfeedingequipmentmaybenecessarytohandlelongerfibers.
Themanufactureofthermoplasticcompositesisusuallyatwo-stepprocess.
Therawmaterialsarefirstmixedtogether,andthecompositeblendisthenformedintoaproduct.
Thecombinationofthesestepsiscalledin-lineprocessing,andtheresultisasingleprocessingstepthatconvertsrawmaterialstoendproducts.
In-lineprocessingcanbeverydifficultbecauseofcontroldemandsandprocessingtrade-offs.
trade-off['
treidɔf,-ɔ:
f]n.交换,交易;
权衡;
协定
trade-off:
权衡|协定|取舍
trade-offtheory:
权衡理论|平衡理论|抵换理论
timetrade-off:
时间权衡法|时间拆衷
Asaresult,itisofteneasierandmoreeconomicaltoseparatetheprocessingsteps.
Compoundingisthefeedinganddispersingofthelignocellulosiccomponentinamoltenthermoplastictoproduceahomogeneousmaterial.
homogeneous[,hɔmə'
dʒi:
niəs,,həu-]adj.同种的;
均匀的;
齐次的
homogeneous:
均质|同一种族(种类)的|均匀的
homogeneousreactor:
均匀反应堆|均匀堆|均质原子反应堆
homogeneoussystem:
均匀系|均匀体系|均匀系统
Variousadditivesareaddedandmoistureisremovedduringcompounding.
Compoundingmaybeaccomplishedusingeithetbatchmixers(forexample,internalandthermoplasticmixers)orcontinuousmixers(forexample,extrudersandkneader).
Kneadern.面团捏和机
kneader:
混合机|捏和机|碎纸机
kneaderpulper:
碎浆机
kneaderblade:
碎纸机刀片
Batchsystemsallowclosercontrolofresistancetime,shear,amdtemperaturethandocotinuoussystems.
Batchsystemsarealsomoreappropriateforoperationsconsistsofshortrunsandfrequentchangeofmaterials.
Ontheotherhand,continuoussystemsarelessoperator-dependentthanarebatchsystemsandhavelessbatch-to-batchdifference.
Thecompoundedmaterialcanbeimmediatelypressedorshapedintoanendproductwhilestillinitsmoltenstateorpelletizedintosmall,regularpelletsforfuturereheatingandforming.
Themostcommontypesofproduct-formingmethodsforwood-thermoplasticcompositesinvolveforcingmoltenmaterialthoughadie(sheetorprofileextrusion)intoacoldmold(injectionmolding)orpressingincalender(calendering)orbetweenmoldhalves(thermoformingandcompressionmolding).
Propertiesofwood–plasticcompositescanvarygreatlydependinguponsuchvariablesastype,form,andweightfractionsofconstituents,typesofadditives,andprocessinghistory.
Compositeswithhighthermoplasticcontentarenotwithouttradeoffs.
Impactresistanceofsuchcompositesdecreasescomparedwiththatofunfilledthermoplastics,andthesecompositesarealsomoresensitivetomoisturethanunfilledmaterialorcompositesfilledwithinorganicmaterial.
Fromapracticalstandpoint,however,thethermoplasticcomponentusuallymakesthetemperaturesensitivityofthecompositemoresignificantthananychangeinpropertiesbroughtbymoistureabsorption.
CompositeswithLowThermoplasticContent
Compositeswithlowthermoplasticcontentcanbemadeinavariatyofways.
Inthesimplestform,thethermoplasticcomponentactsmuchthesamewayasathermosettingresin;
thatis,asabindertothelignocellulosiccomponent.
Analternativeistousethethermoplasticintheformofatextilefiber.
Thethermoplastictextilefiberenablesavarietyoflignocellulosictobeincorporatedintoalow-density,nonwoven,textile-likemat.
Thematmaybeaproductinitself,oritmaybeconsolidatedintoahigh-densityproduct.
Experimentally,low-thermoplastic-contentcompositeshavebeenmadethatareverysimilartoconventionallignocellulosiccompositesinmanyperformancecharacteristics.
Intheirsimplistform,lignocellulosicparticleorfiberscanbedry-blendedwiththermoplasticgranules,flakes,orfibersandpressedintopanelproducts.
Becausethethermoplasticcomponentremainsmoltenwhenhot,differentpressingstrategiesmustbeusedthanwhenthermsettingbindersareused.
Twooptionshavebeendevelopedtoaccommodatethesetypesofcomposites.
accommodate[ə'
kɔmədeit]vt.供应;
使适应;
调解;
容纳vi.适应;
调解
accommodate:
调节|适应|供给
accommodatevt:
向...提供住宿
accommodateto:
使适应/提供|适应
Inthefist,thematerialisplacedinthehotpressatambienttemperature.
Thepressthenclosesandconsolidatesthematerial,andheatistransferredthroughconductiontomeltthethermoplasticcomponent,whichflowsaroundthelignocollulosiccomponent.
Thepressisthencooled,“freezing”thethermoplasticsothatthecompositecanberemovedfromthepress.
Alternatively,th
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