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首页 高分子专业英语课文翻译

高分子专业英语课文翻译.doc

高分子专业英语课文翻译

金星
2011-05-15 0人阅读 举报 0 0 0 暂无简介

简介:本文档为《高分子专业英语课文翻译doc》,可适用于高等教育领域

《高分子材料工程专业英语》A高分子化学和高分子物理UNITWhatarePolymer第一单元什么是高聚物?WhatarepolymersForonething,theyarecomplexandgiantmoleculesandaredifferentfromlowmolecularweightcompoundslike,say,commonsaltTocontrastthedifference,themolecularweightofcommonsaltisonly,whilethatofapolymercanbeashighasseveralhundredthousand,evenmorethanthousandthousandsThesebigmoleculesor‘macromolecules’aremadeupofmuchsmallermolecules,canbeofoneormorechemicalcompoundsToillustrate,imaginethatasetofringshasthesamesizeandismadeofthesamematerialWhenthesethingsareinterlinked,thechainformedcanbeconsideredasrepresentingapolymerfrommoleculesofthesamecompoundAlternatively,individualringscouldbeofdifferentsizesandmaterials,andinterlinkedtorepresentapolymerfrommoleculesofdifferentcompounds什么是高聚物?首先他们是合成物和大分子而且不同于低分子化合物譬如说普通的盐。与低分子化合物不同的是普通盐的分子量仅仅是而高聚物的分子量高于甚至大于。这些大分子或“高分子”由许多小分子组成。小分子相互结合形成大分子大分子能够是一种或多种化合物。举例说明想象一组大小相同并由相同的材料制成的环。当这些环相互连接起来可以把形成的链看成是具有同种分子量化合物组成的高聚物。另一方面独特的环可以大小不同、材料不同相连接后形成具有不同分子量化合物组成的聚合物。Thisinterlinkingofmanyunitshasgiventhepolymeritsname,polymeaning‘many’andmermeaning‘part’(inGreek)Asanexample,agaseouscompoundcalledbutadiene,withamolecularweightof,combinesnearlytimesandgivesapolymerknownaspolybutadiene(asyntheticrubber)withaboutmolecularweightThelowmolecularweightcompoundsfromwhichthepolymersformareknownasmonomersThepictureissimplyasfollows:许多单元相连接给予了聚合物一个名称poly意味着“多、聚、重复”mer意味着“链节、基体”(希腊语中)。例如:称为丁二烯的气态化合物分子量为化合将近次得到分子量大约为被称作聚丁二烯(合成橡胶)的高聚物。形成高聚物的低分子化合物称为单体。下面简单地描述一下形成过程:butadienebutadiene∙∙∙butadiene→polybutadiene(time)丁二烯+丁二烯+…+丁二烯→聚丁二烯(次)Onecanthusseehowasubstance(monomer)withassmallamoleculeweightasgrowtobecomeagiantmolecule(polymer)of(×≈)molecularweightItisessentiallythe‘giantness’ofthesizeofthepolymermoleculethatmakesitsbehaviordifferentfromthatofacommonlyknownchemicalcompoundsuchasbenzeneSolidbenzene,forinstance,meltstobecomeliquidbenzeneat℃and,onfurtherheating,boilsintogaseousbenzeneAsagainstthiswelldefinedbehaviorofasimplechemicalcompound,apolymerlikepolyethylenedoesnotmeltsharplyatoneparticulartemperatureintocleanliquidInstead,itbecomesincreasinglysofterand,ultimately,turnsintoaveryviscous,tackymoltenmassFurtherheatingofthishot,viscous,moltenpolymerdoesconvertitintovariousgasesbutitisnolongerpolyethylene(Fig)因而能够看到分子量仅为的小分子物质(单体)如何逐渐形成分子量为的大分子(高聚物)。实质上正是由于聚合物的巨大的分子尺寸才使其性能不同于象苯这样的一般化合物。例如固态苯在℃熔融成液态苯进一步加热煮沸成气态苯。与这类简单化合物明确的行为相比像聚乙烯这样的聚合物不能在某一特定的温度快速地熔融成纯净的液体。而聚合物变得越来越软最终变成十分粘稠的聚合物熔融体。将这种热而粘稠的聚合物熔融体进一步加热不会转变成各种气体但它不再是聚乙烯(如图)。固态苯→液态苯→气态苯加热℃加热℃固体聚乙烯→熔化的聚乙烯→各种分解产物但不是聚乙烯加热加热图低分子量化合物(苯)和聚合物(聚乙烯)受热后的不同行为AnotherstrikingdifferencewithrespecttothebehaviorofapolymerandthatofalowmolecularweightcompoundconcernsthedissolutionprocessLetustake,forexample,sodiumchlorideandadditslowlytosfixedquantityofwaterThesalt,whichrepresentsalowmolecularweightcompound,dissolvesinwateruptospoint(calledsaturationpoint)but,thereafter,anyfurtherquantityaddeddoesnotgointosolutionbutsettlesatthebottomandjustremainsthereassolidTheviscosityofthesaturatedsaltsolutionisnotverymuchdifferentfromthatofwaterButifwetakeapolymerinstead,say,polyvinylalcohol,andaddittoafixedquantityofwater,thepolymerdoesnotgointosolutionimmediatelyTheglobulesofpolyvinylalcoholfirstabsorbwater,swellandgetdistortedinshapeandafteralongtimegointosolutionAlso,wecanaddaverylargequantityofthepolymertothesamequantityofwaterwithoutthesaturationpointeverbeingreachedAsmoreandmorequantityofpolymerisaddedtowater,thetimetakenforthedissolutionofthepolymerobviouslyincreasesandthemixultimatelyassumesasoft,doughlikeconsistencyAnotherpeculiarityisthat,inwater,polyvinylalcoholneverretainsitsoriginalpowderynatureastheexcesssodiumchloridedoesinasaturatedsaltsolutionInconclusion,wecansaythat()thelongtimetakenbypolyvinylalcoholfordissolution,()theabsenceofasaturationpoint,and()theincreaseintheviscosityareallcharacteristicsofatypicalpolymerbeingdissolvedinasolventandthesecharacteristicsareattributedmainlytothelargemolecularsizeofthepolymerThebehaviorofalowmolecularweightcompoundandthatofapolymerondissolutionareillustratedinFig发现另一种不同的聚合物行为和低分子量化合物行为是关于溶解过程。例如让我们研究一下将氯化钠慢慢地添加到固定量的水中。盐代表一种低分子量化合物在水中达到点(叫饱和点)溶解但此后进一步添加盐不进入溶液中却沉到底部而保持原有的固体状态。饱和盐溶液的粘度与水的粘度不是十分不同但是如果我们用聚合物替代譬如说将聚乙烯醇添加到固定量的水中聚合物不是马上进入到溶液中。聚乙烯醇颗粒首先吸水溶胀发生形变经过很长的时间以后进入到溶液中。同样地我们可以将大量的聚合物加入到同样量的水中不存在饱和点。将越来越多的聚合物加入水中认为聚合物溶解的时间明显地增加最终呈现柔软像面团一样粘稠的混合物。另一个特点是在水中聚乙烯醇不会像过量的氯化钠在饱和盐溶液中那样能保持其初始的粉末状态。总之我们可以讲()聚乙烯醇的溶解需要很长时间()不存在饱和点()粘度的增加是典型聚合物溶于溶液中的特性这些特性主要归因于聚合物大分子的尺寸。如图说明了低分子量化合物和聚合物的溶解行为。氯化钠晶体加入到水中→晶体进入到溶液中溶液的粘度不是十分不同于充分搅拌水的粘度→形成饱和溶液剩余的晶体维持不溶解状态加入更多的晶体并搅拌氯化钠的溶解聚乙烯醇碎片加入到水中→碎片开始溶胀→碎片慢慢地进入到溶液中允许维持现状充分搅拌→形成粘稠的聚合物溶液溶液粘度十分高于水的粘度继续搅拌聚合物的溶解图低分子量化合物(氯化钠)和聚合物(聚乙烯醇)不同的溶解行为GowarikerVR,ViswanathanNV,SreedharJPolymerScienceNewYork:JohnWileySons,UNITChainPolymerization第二单元链式聚合反应Manyolefinicandvinylunsaturatedcompoundsareabletoformchainlikemacromoleculesthrougheliminationofthedoublebond,aphenomenonfirstrecognizedbyStaudingerDiolefinspolymerizeinthesamemanner,however,onlyoneofthetwodoublebondsiseliminatedSuchreactionsoccurthroughtheinitialadditionofamonomermoleculetoaninitiatorradicaloraninitiatorion,bywhichtheactivestateistransferredfromtheinitiatortotheaddedmonomerInthesamewaybymeansofachainreaction,onemonomermoleculeaftertheotherisadded(~monomerspersecond)untiltheactivestateisterminatedthroughadifferenttypeofreactionThepolymerizationisachainreactionintwoways:becauseofthereactionkineticandbecauseasareactionproductoneobtainsachainmoleculeThelengthofthechainmoleculeisproportionaltothekineticchainlengthStaudinger第一个发现一例现象许多烯烃和不饱和烯烃通过打开双键可以形成链式大分子。二烯烃以同样的方式聚合然而仅限于两个双键中的一个。这类反应是通过单体分子首先加成到引发剂自由基或引发剂离子上而进行的靠这些反应活性中心由引发剂转移到被加成的单体上。以同样的方式借助于链式反应单体分子一个接一个地被加成(每秒~个单体)直到活性中心通过不同的反应类型而终止。聚合反应是链式反应的原因有两种:因为反应动力学和因为作为反应产物它是一种链式分子。链分子的长度与动力学链长成正比。Onecansummarizetheprocessasfollow(Risequaltotheinitiatorradical):链式反应可以概括为以下过程(R·相当与引发剂自由基):略Onethusobtainspolyvinylchloridefromvinylchloride,orpolystyrenefromstyrene,orpolyethylenefromethylene,etc因而通过上述过程由氯乙烯得到聚氯乙烯或由苯乙烯获得聚苯乙烯或乙烯获得聚乙烯等等。Thelengthofthechainmolecules,measuredbymeansofthedegreeofpolymerization,canbevariedoveralargerangethroughselectionofsuitablereactionconditionsUsually,withcommerciallypreparedandutilizedpolymers,thedegreeofpolymerizationliesintherangeofto,butinmanycasesitcanbebelowandoverThisshouldnotbeinterpretedtomeanthatallmoleculesofacertainpolymericmaterialconsistof,or,ormonomerunitsInalmostallcases,thepolymericmaterialconsistsofamixtureofpolymermoleculesofdifferentdegreesofpolymerization借助于聚合度估算的分子链长在一个大范围内可以通过选择适宜的反应条件被改变。通常通过大量地制备和利用聚合物聚合度在~范围内但在许多情况下可低于、高于。这不应该把所有聚合物材料的分子量理解为由或或个单体单元组成。在几乎所有的事例中聚合物材料由不同聚合度的聚合物分子的混合物组成。Polymerization,achainreaction,occursaccordingtothesamemechanismasthewellknownchlorinehydrogenreactionandthedecompositionofphosegene聚合反应链式反应依照与众所周知的氯(气)氢(气)反应和光气的分解机理进行。Theinitiationreaction,whichistheactivationprocessofthedoublebond,canbebroughtaboutbyheating,irradiation,ultrasonics,orinitiatorsTheinitiationofthechainreactioncanbeobservedmostclearlywithradicalorionicinitiatorsTheseareenergyrichcompoundswhichcanaddsuitableunsaturatedcompounds(monomers)andmaintaintheactivatedradical,orionic,statesothatfurthermonomermoleculescanbeaddedinthesamemannerFortheindividualstepsofthegrowthreactiononeneedsonlyarelativelysmallactivationenergyandthereforethroughasingleactivationstep(theactualinitiationreaction)alargenumberofolefinmoleculesareconverted,asisimpliedbytheterm“chainreaction”Becauseverysmallamountsoftheinitiatorbringabouttheformationofalargeamountofpolymericmaterial(:to:),itispossibletoregardpolymerizationfromasuperficialpointofviewasacatalyticreactionForthisreason,theinitiatorsusedinpolymerizationreactionsareoftendesignatedaspolymerizationcatalysts,eventhough,inthestrictestsense,theyarenottruecatalystsbecausethepolymerizationinitiatorentersintothereactionasarealpartnerandcanbefoundchemicallyboundinthereactionproduct,ie,thepolymer,Inadditiontotheionicandradicalinitiatorstherearenowmetalcomplexinitiators(whichcanbeobtained,forexample,bythereactionoftitaniumtetrachlorideortitaniumtrichloridewithaluminumalkyls),whichplayanimportantroleinpolymerizationreactions(Zieglercatalysts),Themechanismoftheircatalyticactionisnotyetcompletelyclear双键活化过程的引发剂反应可以通过热、辐射、超声波或引发剂产生。用自由基型或离子型引发剂引发链式反应可以很清楚地进行观察。这些是高能态的化合物它们能够加成不饱和化合物(单体)并保持自由基或离子活性中心以致单体可以以同样的方式进一步加成。对于增长反应的各个步骤每一步仅需要相当少的活化能因此通过一步简单的活化反应(即引发反应)即可将许多烯类单体分子转化成聚合物这正如连锁反应这个术语的内涵那样。因为少量的引发剂引发形成大量的聚合物原料(:~:)从表面上看聚合反应很可能是催化反应。由于这个原因通常把聚合反应的引发剂看作是聚合反应的引发剂但是严格地讲它们不是真正意义上的催化剂因为聚合反应的催化剂进入到反应内部而成为一部分同时可以在反应产物既聚合物的末端发现。此外离子引发剂和自由基引发剂有的是金属络合物引发剂(例如通过四氯化钛或三氯化钛与烷基铝的反应可以得到)Z引发剂在聚合反应中起到了重要作用它们催化活动的机理还不是十分清楚。UNITStepGrowthPolymerization第三单元逐步聚合ManydifferentchemicalreactionsmaybeusedtosynthesizepolymericmaterialsbystepgrowthpolymerizationTheseincludeesterification,amidation,theformationofurethanes,aromaticsubstitution,etcPolymerizationproceedsbythereactionsbetweentwodifferentfunctionalgroups,eg,hydroxylandcarboxylgroups,orisocyanateandhydroxylgroups许多不同的化学反应通过逐步聚合可用于合成聚合材料。这些反应包括酯化、酰胺化、氨基甲酸酯、芳香族取代物的形成等。通过反应聚合反应在两种不同的官能团如羟基和羧基或异氰酸酯和羟基之间。Allstepgrowthpolymerizationfallintotwogroupsdependingonthetypeofmonomer(s)employedThefirstinvolvestwodifferentpolyfunctionalmonomersinwhicheachmonomerpossessesonlyonetypeoffunctionalgroupApolyfunctionalmonomerisonewithtwoormorefunctionalgroupspermoleculeThesecondinvolvesasinglemonomercontainingbothtypesoffunctionalgroupsThesynthesisofpolyamidesillustratesbothgroupsofpolymerizationreactionsThus,polyamidescanbeobtainedfromthereactionofdiamineswithdiacids所有的逐步聚合反应根据所使用单体的类型可分为两类。第一类涉及两种不同的官能团单体每一种单体仅具有一种官能团。一种多官能团单体每个分子有两个或多个官能团。第二类涉及含有两类官能团的单种单体。聚酰胺的合成说明了聚合反应的两个官能团。因此聚酰胺可以由二元胺和二元酸的反应或氨基酸之间的反应得到。nHNRNHnHOCR’COH→H(NHRNHCOR’CO)nOH(n)HO()orfromthereactionofaminoacidswiththemselvesnHRCOH→H(NHRCO)nOH(n)H()ThetwogroupsofreactionscanberepresentedinageneralmannerbytheequationsasfollowsABB→–AABBAB→–AB两种官能团之间的反应一般来说可以通过下列反应式表示反应式略Reaction()illustratestheformer,while()isofthelattertype反应()说明前一种形式而反应()具有后一种形式。图逐步聚合的示意图(a)​ 未反应单体(b)已反应(c)已反应(d)已反应(虚线表示反应种类)Polyesterification,whetherbetweendiolanddibasicacidorintermolecularlybetweenhydroxyacidmolecules,isanexampleofastepgrowthpolymerizationprocessTheesterificationreactionoccursanywhereinthemonomermatrixwheretwomonomermoleculescollide,andoncetheesterhasformed,it,too,canreactfurtherbyvirtueofitsstillreactivehydroxylorcarboxylgroupsTheneteffectofthisisthatmonomermoleculesareconsumedrapidlywithoutanylargeincreaseinmolecularweightFigillustratesthisphenomenonAssume,forexample,thateachsquareinFigarepresentsamoleculeofhydroxyacidAftertheinitialdimmermoleculesfrom(b),halfthemonomermoleculeshavebeenconsumedandtheaveragedegreeofpolymerization(DP)ofpolymericspeciesisAstrimerandmoredimermoleculesform(c),morethanofthemonomermoleculeshavereacted(d),DPisButeachpolymermoleculethatformsstillhasreactiveendgroupshencethepolymerizationreactionwillcontinueinastepwisefashion,witheachesterificationofmonomersThus,molecularweightincreasesslowlyevenathighlevelsofmonomerconversion,anditwillcontinuetoincreaseuntiltheviscositybuildupmakesitmechanicallytoodifficulttoremovewaterofesterificationorforreactiveendgroupstofindeachother聚酯化是否在二元酸和二元醇或羟基酸分子间进行是逐步聚合反应过程的一个例子。酯化反应出现在单体本体中两个单体分子相碰撞的位置且酯一旦形成依靠酯上仍有活性的羟基或羧基还可以进一步进行反应。酯化的结果是单体分子很快地被消耗掉而分子量却没有多少增加。图说明了这个现象。例如假定图中的每一个方格代表一个羟基酸分子。(b)中的二聚体分子消耗二分之一的单体分子聚合物种类的聚合度(DP)是。(c)中当三聚体和更多的二聚体形成大于的单体分子已反应但DP仅仅还是。(d)中当所有的单体反应完DP是。但形成的每一种聚合物分子还有反应活性的端基因此聚合反应将以逐步的方式继续进行其每一步酯化反应的反应速率和反应机理均与初始单体的酯化作用相同。因此分子量缓慢增加直至高水平的单体转化率而且分子量将继续增加直到粘度的增加使其难以除去酯化反应的水或难以找到相互反应的端基。ItcanalsobeshownthatintheAABBtypeofpolymerization,anexactstoichiometricbalanceisnecessarytoachievehighmolecularweightsIfsomemonofunctionalimpurityispresent,itsreactionwilllimitthemolecularweightbyrenderingachainendinactiveSimilarly,highpuritymonomersarenecessaryintheABtypeofpolycondensationanditfollowsthathighyieldreactionsaretheonlypracticalonesforpolymerformation,sincesidereactionswillupsetthestoichiometricbalance在AABB的聚合反应中也可以看到精确的当量平衡是获得高分子量所必需的。假如存在一些但官能团杂质由于链的端基失活反应将使分子量减少。同样在AB类的缩聚反应中高纯度的单体是必要的而且可以归结高收率的反应仅是形成聚合物的实际反应因为副反应会破坏当量平衡。StevensMPPolymerChemistryLondon:AddisonWesleyPublishingCompany,UNITIonicPolymerization第四单元离子聚合反应Ionicpolymerization,similartoradialpolymerization,alsohasthemechanismofachainreactionThekineticsofionicpolymerizationare,however,considerablydifferentfromthatofradicalpolymerization离子聚合反应与自由基聚合反应相似也有链反应的机理。但是离子聚合的动力学明显地不同于自由基聚合反应。()TheinitiationreactionofionicpolymerizationneedsonlyasmallactivationenergyTherefore,therateofpolymerizationdependsonlyslightlyonthetemperatureIonicpolymerizationsoccurinmanycaseswithexplosiveviolenceevenattemperaturebelow℃(forexample,theanionicpolymerizationofstyreneat–℃intetrahydrofuran,orthecationicpolymerizationofisobutyleneat–℃inliquidethylene)()离子聚合的引发反应仅需要很小的活化能。因此聚合反应的速率仅对温度有较少的依赖性。在许多情况下离子聚合猛烈地发生甚至低于℃(例如苯乙烯的阴离子聚合反应在℃在四氢呋喃中或异丁烯的阳离子聚合在℃在液态乙烯中)。()Withionicpolymerizationthereisnocompulsorychainterminationthroughrecombination,becausethegrowingchainscannotreactwitheachotherChainterminationtakesplaceonlythroughimpurities,orthroughtheadditionofcertaincompoundssuchaswater,alcohols,acids,amines,oroxygen,andingeneralthroughcompoundswhichcanreactwithpolymerizationionsundertheformationofneutralcompoundsorinactiveionicspeciesIftheinitiatorsareonlypartlydissociated,theinitiationreactionisanequilibriumreaction,wherereactioninonedirectiongivesrisetochaininitiationandintheotherdirectiontochaintermination()对于离子聚合来说不存在通过再结合反应而进行的强迫链终止因为生长链之间不能发生链终止。链终止反应仅仅通过杂质而发生或者说通过和某些像水、醇、酸、胺或氧这样的化合物进行加成而发生且一般来说(链终止反应)可通过这样的化合物来进行这种化合物在中性聚合物或没有聚合活性的离子型聚合物生成的过程中可以和活性聚合物离子进行反应。如果引发剂仅仅部分地离解引发反应即为一个平衡反应在出现平衡反应的场合在一个方向上进行链引发反应而在另一个方向上则发生链终止反应。IngeneralionicpolymerizationpolymerizationcanbeinitiatedthroughacidicorbasiccompoundsForcationicpolymerization,complexesofBF,AlCl,TiCl,andSnClwithwater,oralcohols,ortertiaryoxoniumsaltshaveshownthemselvestobeparticularlyactiveThepositiveionsaretheonesthatcausechaininitiationForexample:通常离子聚合反应能通过酸性或碱性化合物被引发。对于阳离子聚合反应来说BF,AlCl,TiCl和SnCl与水、或乙醇或叔烊盐的络合物提供了部分活性。正离子是产生链引发的化合物。例如:(反应略)三乙基硼氟酸烊However,alsowithHCl,HSO,andKHSO,onecaninitiatecationicpolymerizationInitiatorsforanionicpolymerizationarealkalimetalsandtheirorganiccompounds,suchasphenyllithium,butyllithium,phenylsodium,andtriphenylmethylpotassium,whicharemoreorlessstronglydissociatedindifferentsolventsTothisgroupbelongalsothesocalledAlfincatalysts,whichareamixtureofsodiumisopropylate,allylsodium,andsodiumchloride然而BF也可以与HCl、HSO和KHSO引发阳离子聚合反应。阴离子聚合反应的引发剂是碱金属和它们的有机金属化合物例如苯基锂、丁基锂和三苯甲基锂它们在不同的溶剂中或多或少地强烈分解。所谓的Alfin催化剂就是属于这一类这类催化剂是异丙醇钠、烯丙基钠和氯化钠的混合物。WithBF(andisobutyleneasthemonomer),itwasdemonstratedthatthepolymerizationispossibleonlyinthepresenceoftracesoftracesofwateroralcoholIfoneeliminatesthetraceofwater,BFalonedoesnotgiverisetopolymerizationWateroralcoholsarenecessaryinordertoallowtheformationoftheBFcomplexandtheinitiatorcationaccordingtotheabovereactionsHowever,oneshouldnotdescribethewaterorthealcoholasa“cocatalyst”BF为引发剂(异丁烯为单体)证明仅在痕量水或乙醇的存在下聚合反应是可以进行的。如果消除痕量的水单纯的BF不会引发聚合反应。按照上述反应为了能形成BF络合物和引发剂离子水或乙醇是必需的。但是不应将水或乙醇描述成“助催化剂”。Justasbyradicalpolymerization,onecanalsopreparecopolymersbyionicpolymerization,forexample,anioniccopolymersofstyreneandbutadiene,orcationiccopolymersofisobutyleneandstyrene,orisobutyleneandvinyethers,etcAshasbeendescribedindetailwithradicalpolymerization,onecancharacterizeeachmonomerpairbysocalledreactivityratiosrandrTheactualvaluesofthesetwoparametersare,however,differentfromthoseusedforradicalcopolymerization正与自由基聚合反应一样通过离子聚合反应也能制备共聚物例如苯乙烯丁二烯阴离子共聚物或异丁烯苯乙烯阳离子共聚物或异丁烯乙烯基醚共聚物等等。正如对自由基型聚合已经详细描述过那样人们可以用所谓的竞聚率r和r来表征每单体对。然而这两个参数的实际意义不同于那些用于自由基共聚合反应的参数。VollmertBPolymerChemistryBerlin:SpingVerlag,PARTB聚合反应工程C聚合物材料的加工、性能和应用UNITPolymerProcessing第二十一单元聚合物加工Polymerprocessing,initsmostgeneralcontext,involvesthetransformationofasolid(sometimesliquid)polymericresin,whichisinarandomform(egpowder,pellets,beads),toasolidplasticsproductofspecifiedshape,dimensions,andpropertiesThisisachievedbymeansofatransformationprocess:extrusion,molding,calendering,coating,thermoforming,etcTheprocess,inordertoachievetheaboveobjective,usuallyinvolvesthefollowingoperations:solidtransport,compression,heating,melting,mixing,shaping,cooling,solidification,andfinishingObviously,theseoperationsdonotnecessarilyoccurinsequence,andmanyofthemtakeplacesimultaneously在其最一般的情况下聚合物加工涉及固体(有时侯是液体)聚合物树脂以一种不规则的形式(例如粉末、颗粒、珠子)转化成一种具有特殊形状、尺寸和性能的固体塑料产品。这借助于转换加工:挤出、模塑、压延、涂敷、热成型等。为了获得上述目的加工通常涉及下述操作:固体输送、压缩、加热、混合、成型、冷却、固化并完成。显然这些操作不必按序发生而许多可以同时发生。ShapingisrequiredinordertoimparttothematerialthedesiredgeometryanddimensionsItinvolvescombinationsofviscoelasticdeformationsandheattransfer,whicharegenerallyassociatedwithsolidificationoftheproductfromthemelt成型是为了给予材料所需要的几何形状和尺寸。它涉及粘弹形变和热传递这种粘弹形变和热传递是和产品从熔体的固化(或冷却)相联系的。Shapingincludes:()twodimensionaloperations,egdieforming,calenderingandcoating,and()threedimensionalmoldingandformingoperationsTwodimensionalprocessesareeitherofthecontinuous,steadystatetype)egfilmandsheetextrusion,wirecoating,paperandsheetcoating,calendering,fiberspinning,pipeandprofileextrusion,etc)orint

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