聚合物化学翻译 第八章课件

Chapter8PolymerDegradation

indefinitely：无止境的;无限期地

exposure：暴露

desirableproperties:预期的性质P139-1

Organicpolymersarenotindefinitelystableunderallconditions.Inparticularinfiresoronexposuretooutdoorconditionsespeciallysunlight,theywilltendtoundergoreactionsthatleadtoalossoftheirdesirableproperties.INTRODUCTION有机的聚合物并非在所有条件下无限期的稳定存在。特别是着火或暴露在户外尤其是阳光下，它们倾向于发生反应导致失去预期的性质。degradation:降解

weathering：气候浸蚀

minimising：减少Thisisknownasdegradationandofteninvolvesbothreactionwithoxygenandreductioninmolarmass.Polymerdegradationbothinfiresandonweathering,togetherwithtechniquesforminimisingthedamagecausedbytheseconditionsarethesubjectsofthischapter.这被称为降解并常常伴随有与氧的反应和摩尔质量的降低。在燃烧和气候浸蚀两种作用下，聚合物降解及减少由这些条件引起危害的技术是本章的主题。ascloselyaspossible尽可能近期

adepartmentstore:商店stack：堆放

vicinity：附近P139-2Thesewerechosentorepresentascloselyaspossibleafirethathadoccurredinadepartmentstoreandwhichhadresultedin10deaths.Theitemswerestacked,astheyhadbeeninthestore,andignited.Oneminuteafterignition,atemperatureof1000℃wasrecordinthestack;theconcentrationofoxygenfellrapidlyinthevicinityofthestack,reaching6.5%after2minutesandafinallevelof3%duringtheperiodofsustainedcombustion.挑选尽可能近期发生在一处百货商店的一场火灾为代表，它致使10人丧生。物品被堆放在一起，当它们贮藏时被点燃了。点燃后一分钟，在火堆中记录到1000℃的温度，在火堆的附近氧气浓度迅速降低，2分钟后达到6.5%，最终维持燃烧期间达到3%的水平。illustrates：说明

unique：独一无二的P139-3Thisexampleillustratestherangeofoxygenconcentrationsandthekindoftemperaturethatcanoccurinarealfire,butthisisonlyanillustration.Therearenostandardconditionsforrealfires,sinceeachfireisauniquephysico-chemicalevent.这个例子表明发生真实火灾中氧气浓度的范围和温度，但这仅仅是一个例子。对于真实火灾不存在标准的条件，因为每一次燃烧都是一个独一无二的物理化学事件。Firebrigades：火灾救援队P140-1Withtheincreasinguseofpolymersinboththehomeandtheworkplace,thereseemstohavebeenachangeinthenatureoffires.Firebrigadesnowreportfiresthatareshorterandmoreintensethanpreviously;thereisalsomuchmoresmokeandsignificantlygreateramountsoftoxicgases.Allofthesearisefromthenatureofthepolymersbeingusedineverydaylife.随着聚合物在家居和工作单位中使用的增加，火灾的本性似乎存在某种改变。现在火灾救援队报告火灾比以前更快更猛烈；存在更多的烟和明显更大量的有毒气体。所有这些来自于在每日生活中使用聚合物的性质。migrate：迁移

out：放出P140-2Combustionofpolymersoccursintwobroadstages.Firstlythereisinitiationinwhichanearbysourceofheatcausesthetemperaturetorisetosuchapointthatchemicalbondsbegintobreak.Thisgenerateslowmolarmassproductsthatmigratethroughthepolymerandoutintothegasphase,theretheyundergooxidation,i.e.theyburn.

聚合物燃烧发生在两个广泛的领域。首先存在点燃阶段，在热源附近引起温度升高达到化学键开始断裂的那一点。这产生低摩尔质量的产物它迁移经过聚合物并放出气体相，它们经历氧化过程，如它们燃烧起来。hinders：阻碍

thecombustionzone:燃烧区域

bestarvedof:缺乏P140-3Thermosetsandthermoplasticsbehavedifferentlyfromeachotherinfires.Thermosetsdonotmeltwhenheatedbutmaywellundergofurthercrosslinking.Thepresenceofsuchadditionalcrosslinkshindersmovementofanyvolatiledegradationproductsthroughthepolymermatrix.Hencethecombustionzonetendstobestarvedoffuelandforthisreasonthermosetstendtoberelativelynon-flammable.热固性塑料和热塑性塑料在燃烧中相互间表现有所不同。热固性塑料加热时不融化但可以进一步交联。这种额外交联的存在会阻碍从聚合物基体中挥发性降解产物的移动。因此燃烧区域趋向于缺少燃料并且由于这个原因热固性塑料倾向于相对来说不易燃烧。residue：残留物

char:焦渣

P140-5Polymersdonotburnwithcompleteefficiency,eventhosecomposedonlyofcarbon,hydrogen,andpossiblyoxygen.Insteadtheygiveoffsignificantamountsofsmokeandleavebehindasolidresidueofchar.Thequantityofbothsmokeandcharproducedmayvarywidely,dependingonboththefireconditionsandthematerialinvolved.聚合物不会燃烧十分完全有效，甚至仅由碳、氢和可能出现的氧组成。取而代之的是它们释放出极其大量的烟并留下烧焦的固体残渣。产生的烟和焦渣两者的数量可宽范围变化，依赖于燃烧的条件和涉及的材料两个方面。prevailing：占优势的;主要的

aerate：使快速地暴露于空气中;使通气

P141-1Anumberofthermoplasticsundergodepolymerisation（解聚）onheating.Theseincludepoly(styrene),poly(methylmethacrylate),andpoly(oxymethylene)（聚甲醛）.Suchdepolymerisationwilloccurregardlessoftheprevailingoxygenconcentrationandunderwellaeratedconditionswillprovideareadysourceoffuelforsustainedcombustion.PVCbehavesdifferentlyinfires.TheBehaviourofIndividualPolymers

许多热塑性塑料在热作用下经历解聚。包括聚苯乙烯、聚甲基丙烯酸甲酯和聚甲醛。这种解聚发生时不考虑氧气的浓度是否占优势并且，在良好的通风条件下将对维持燃烧提供容易的燃料源。PVC在燃烧中表现有所不同。left

：留下的

conjugatedstructure：共轭结构

orangy-red：橙红色extensivedegradation:广泛的降解P141-2ItreadilylosesHClfromalongthebackboneinaprocessthatisautocatalytic.Theproductleftbehindhasahighlyconjugatedstructurethatgivesrisetoadeeporangy-redorblackcolourandmakestheproductverybrittle.Thehydrogenchloridegivenoffisnot,ofcourse,flammablesothatdespiteextensivedegradationPVCneverundergoesself-sustainingcombustion.聚氯乙烯在燃烧过程中沿主链容易失去HCl这是自动催化的。留下的产物有高度共轭结构它显出橙红色或黑色并使产品很脆。当然，释放的氯化氢不可燃烧所以尽管深度降解的PVC从来不会自行维持燃烧过程。theleastthermallystable：稳定性最小

themajortonnagepolymers：主要的通用聚合物P141-3

Dehydrochlorination（脱去氯化氢）ofPVCwilloccuratthekindoftemperaturesusedinthecommercialprocessing,makingittheleastthermallystableofallthemajortonnagepolymers.BecauseofthisPVCalwayscontainsastabiliser,theprecisenatureofwhichwilldependontheproposedend-useoftheparticularbatchofPVC.PVC可以在商业使用过程中的温度下发生脱去氯化氢的过程，使它在所有通用聚合物中成为热稳定性最差的。由于PVC总是含有稳定剂，它的详细性质依赖于PVC最终使用目的。photolytically：光敏感的still:尽管如此Thestabilisersusedtoprotectagainstfiredamagearedifferentfromthoseusedtoprotectagainstdegradationinprocessing.Stillothersareusedwhenprotectionagainstphotolyticallyinduceddehydrochlorinationisneeded.用来防止燃烧损害的稳定剂不同于那些防止降解的稳定剂。尽管如此，其它试剂也有所使用，包括所需除氯化氢的防止光催化的试剂。taint:污染，沾污P141-3Therangeofstabilisersmayalsobeinfluencedbyotherconsiderations;forexample,PVCfilmforuseinfoodpackaginghastobestabilisedwithanadditivethatwillnotmigrateintothefoodortaintatthepointofcontact.稳定剂的范围也受其它条件影响，例如，用在食品包装中的PVC薄膜必须带附加的稳定性，不能迁移进食品或污染与之接触的食品。specimen：样本，实例Inthetechnique,whichusespolymerspecimensofastandardsize,variousoxygenconcentrationsinanoxygen-nitrogenmixtureareusedandtheminimumamountthatwilljustallowflamingcombustiontocontinueforatleast3minutesisdetermined.技术上，使用标准的聚合物样品，在氧氮混合气体中使用各种氧气浓度，在允许燃烧火焰至少持续3分钟决定氧气的最少量。Percentage:百分数P142-1Thisvalue,expressedasapercentage,isknownastheLimitingOxygenIndex.TypicalresultsareshowninTable8.1这个值，表示为一个百分数，被称为极限氧指数。典型的结果见表8.1over-estimate：高估

supplemented:增补,补充;P142-2Hot,well-oxygenatedairismorelikelytoinitiatesubstantialdamagetoorganicpolymersthanthegaseousmixtureusedintheLOItest.TheuseofanartificiallylowtemperaturereducestheapparentflammabilityofthemeasuredLOIandhencemayover-estimatethesafetyofagivenpolymerunderfireconditions.BecauseoftheselimitationsdatafromtheLOItestsneedtobesupplementedbyresultsfromothertestmethods.热，很好氧化性的空气比LOI测定中使用的气体混合物对有机聚合物更有可能引发实质损害。人为使用低温度减少LOI测量中的表面燃烧，因此可以在燃烧条件下高估给定聚合物的安全性。因为LOI测量的这些极限数据需要由其它测试方法进行补充。sought:seek的过去式

mutuallyincompatible：相互矛盾evolution

：(气体的)放出P142-3Themajorimprovementsoughtinpolymersintermsoftheirfirebehaviourisreductionofflammability.Forcertainapplications,however,reductioninsmokeevolutionissoughtbutthesetwoaimstendtobemutuallyincompatible.Reductioninflammabilityisbroughtaboutbymakingthecombustionprocesslessefficient.IMPROVEMENTOFSTABILITYOFPOLYMERSINFIRES

根据聚合物的燃烧行为在聚合物中寻找最重要的事就是减少火焰。可是对于一定的应用，寻求减少烟气释放，但这两个目标倾向于相互矛盾。由燃烧过程效率下降就会带来火焰的减少。incorporation：合并，加入

confer…on：给予assistwith：有助于

retardancy：阻止P143-1Reductioninflammabilityisachievedbytheincorporationofflameretardantsintothepolymer.Twopossibleapproachestothisareavailable;eithertheuseofadditivesblendedintothepolymeratprocessingstage(additivetype)ortheuseofalternativemonomerswhichconferreducedflammabilityonthefinalproduct(reactivetype).火焰的减少可由在聚合物中加入火焰阻碍剂完成。有两种可能的手段来达到，可以是在加工阶段使用添加剂混合进入聚合物（添加型）或使用替代性单体，它能在最终的产物中给予火焰减少的性能（反应型）。Anumberofelementshavebeenfoundtoassistwithconferringflameretardancyonpolymers,themainonesbeingbromine,chlorine,nitrogen,andphosphorus.P143-2Alargenumberofmaterials,generallyinorganicinnature,havebeenusedasadditive-typeflameretardants,ofwhichhydratedalumina(水合氧化铝)andantimony（锑）oxideareamongthemostimportant.大量的物质，一般自然界的无机物，可以被用作添加型火焰阻碍剂，其中水合氧化铝和氧化锑是最重要的。metalborates：金属硼酸盐

imperviousglassylayer：不可渗透的玻璃状层

hydrogenhalide:HClhalogengas:卤素气体P143-3Theuseofcertainglassysolids,suchasmetalborates,mayleadtotheformationofanimperviousglassylayerwhichpreventsthepassageofvolatilesouttothecombustionzone.Finallytheincorporationofchlorinatedorbrominatedadditivesmaygiverisetosubstantialquantitiesofeitherhydrogenhalideorhalogengaswithinthevolatiles,thusquenching（淬火）vapourphaseoxidationinthecombustionzone.一定玻璃状固体的使用，如金属硼酸盐，可以导致不可渗透的玻璃状层的形成，它防止挥发物传递出燃烧区域。最终氯化物和溴化物添加剂的加入可以在挥发物中提供相当数量的氯化氢或卤素气体，因此在燃烧区域淬灭气相的氧化反应。refersto：涉及

this：指代前面比较的结果P143-4Increatinglessflammablegradesofpolymeruseisoftenmadeoftheso-calledantimony-halogensynergism（锑-卤素协同作用）.Synergismreferstothesituationinwhichthejointeffectisgreaterthanthesumoftheindividualeffectsandinthecaseofantimony-halogensynergism//thismeansthatsmalleramountsofeachmaterialcanbyusedthanwouldhavebeenexpectedonthebasisoftheindividualeffectsofaddingSb2O3orincorporatingco-monomerscontainingbromineorchlorine.为达到较小的燃烧级别聚合物使用的是所谓的锑-卤素协同作用。协同作用涉及下列情况，其中加合作用大于个别作用的效果并且在锑-卤素协同作用中，这意味着比单独加入Sb2O3和加入溴化物或氯化物共单体所起的作用，每种物质的用量更小。evolve：放出P143-5Themechanismofantimony-halogensynergismisbelievedtobe:Polymer,incombustionconditions,beginstoevolve

HClorHBr;HClorHBrreactswithSb2O3togiveSbOX;锑-卤素协同作用据信如下：聚合物，在燃烧条件下，开始放出HCl或HBrHCl或HBr与Sb2O3反应生成SbOX；III.SbOXundergoesself-reactiontoyieldSbX3,agas,plusSb2O3;IX.SbX3quenchestheflamebyactingasaradicaltrapandbypreventingaccesstooxygen.Assuch,itismoreeffectivethaneitherofthehydrogenhalides

orthehalogengasesasanagentforquenchingcombustion.III.SbOX经历自反应产生SbX3，一种气体，加上Sb2O3IX.SbX3由反应作为自由基捕捉剂并且防止氧化过程从而淬灭火焰。由此，比氯化氢或卤素气体作为试剂灭除燃烧这会更有效。flameextinctiontime：火焰熄灭时间

minimum：最小值P144-1Thereisgoodexperimentalevidenceforthismechanismofantimony-halogensynergism,mostsignificantlythatflameextinctiontimeisaminimumforpolymerscontainingantimonyandhalogeninthemoleratio1:3.锑-卤素协同作用的这个作用机理有很好的实验证据，最有意文的是对于含有锑和卤素摩尔比1：3的聚合物火焰熄灭时间是一个最小值。Weathering:耐候性

ultravioletlight:紫外光P144-2Weatheringisabroadetermthatisappliedtothechangesthattakeplaceinapolymeronexposureoutofdoors.Themainagentsofweatheringaresunlight(particularlyultravioletradiation),temperature,thermalcycling,moistureinvariousforms,andwind.WEATHERINGOFPOLYMERS

耐候性是个宽泛的术语，它被用于暴露在户外的聚合物所发生的变化。耐候性的主要介质是阳光（尤其是紫外线），温度、热循环，各种形式的湿气和风。Themaindegradationisbroughtaboutbyultravioletlight,assistedbycontributionsfromthevisibleandnear-infraredportionsoftheelectromagneticspectrum.Inparticularthenear-infraredradiationacceleratesdegradationreactionsbyraisingthetemperature.主要的降解由紫外光带来，辅助于电磁光谱中可见光和近红外辐射部分。特别是，近红外辐射通过升高温度来加速降解反应。and

：后省略了to

bothseasonallyandgeographically:即随季节性也随地理性P144-3Allofthefactorsinvolvedinweathering,includingboththeamountand(书上错写成of)intensityofsunlight,varybothseasonallyandgeographically.Tounderstandfullyandpredicttheweatheringbehaviourofanypolymerrequiresinformationaboutexactlyhowthesefactorsvaryandhowtheythencontributetotheoveralldegradationprocess.耐候性涉及的所有的因素，包括阳光的强度和量，即随季节性也随地理性发生变化。为了完整和预见性的理解任一聚合物的耐候性行为必需精确知道关于这些因素怎样变化和它们对整个降解过程的贡献的信息。experienced:经受的P144-4Solarradiationexperiencedbypolymersattheearth’ssurfacehastwocomponents,directradiationfromthesunandindirectradiationfromthesky.AtallpartsoftheEarth’ssurface,solarirradianceishighestatnoon,whenthesunishighestinthesky.Theactualintensity,though,variesgeographically.在地球表面聚合物经受太阳辐射有两种成份，来自于太阳的直接辐射和从天空中间接的辐射。地球所有的表面，中午的太阳辐射最高，此时太阳在天空中最高。虽然实际的强度随地域不同而变。Thisisduenotonlytoregionalvariationsintheamountofdirectsunlight,butalsobecausetheclarityoftheatmospherevariesgeographically,dependingontheamountofwatervapourorpollutinggasesthatarepresentlocally.这不仅是由于直射阳光的量发生地域性变化，而且是因为空气的清澈度也随地理性变化，信赖于水蒸气的量或局部出现的污染气体。P144-5OnepartoftheworldwheresolarirradianceisverystrongisinFlorida.Hightemperatures,directsunlight,andrelativeabsenceofpollutionallcontributetothisstrongirradianceandbecauseofittherearemanysitesinFloridathatareusedtotesttheresistanceofpolymerstooutdoorexposure.世界上太阳辐射很强的一个区域是Florida。高温、直射的阳光和相对少的污染导致强的辐射，并且因此在Florida存在很多地点用于对聚合物暴露在户外的抵抗性进行测试。banksofrack:架子的边坡

Inclined:倾向于

subjectively:客观的Typicallybanksofracksholdingpolymerorpaintsamplesinclinedat45C°areexposedtothesunforseveralmonthsorevenyears.Theextentofphotodegradationmaythenbeassessed,oftenfairlysubjectively,basedontheunderstandingthatpolymersampleswhichsurviveinthehighirradianceofFloricawilltendtodowellalmostanywhereelseintheworld.典型的固定聚合物或油漆试样的架子的坡板倾斜成45C°，暴露在阳光下几个月或甚至几年。能达到的光降解程度常常是客观变化的，基于这样一种理解，聚合物样品能在Florica的高辐射阳光下存留下来也就能在世界上任何其它地方很好的存留下来。peroxyradicals：过氧自由基P145-1Sunlightaloneisnotresponsibleforthedegradationofpolymers;theprocessisassistedbythepresenceofoxygensothatphoto-oxidationisabletooccur.Oxygencanpromotepolymerdegradationinthepresenceofsolarradiationinanumberofways.Freeradicalsformedinthepolymerbyphotolysiscanreactwithoxygentoformperoxyradicalswhichinitiateaseriesofradicalchainreactions.只有阳光不会造成聚合物降解；过程中氧气的存在会帮助光氧化能够发生。在阳光辐射下氧气能以许多方式促进聚合物的降解。在聚合物中由光化学形成的自由基能与氧反应形成过氧自由基，它引发一系列的自由基链式反应。excitedstate：激发态

deterioration：恶化,变坏;退化P145-1Theseprocessesoccurbyreactionwithoxygeninthegroundstate.However,reactionofground-stateoxygenwithsensitisers,suchasdyesintheexcitedstate,causestheformationofexcited-stateoxygen.Intermsofelectronicspinstates,thisgeneratesthemorereactivesingletoxygenfromthelessreactivetripletoxygen（三重氧）.Singletoxygenisresponsibleforthedeteriorationinsunlightofunsaturatedpolymericmaterialssuchasnaturalrubberandsyntheticelastomers.这些过程靠与氧的反应在基态发生。可是，基态氧与光敏剂的反应，如在激发态下的染料，引起激发态氧的形成。根据电子自旋状态，这使从反应性低的三重氧产生了更多的反应性单线态氧。单线态氧会促使不饱和聚合物材料如天然橡胶和合成弹性体在阳光下降解。alone:单独

rutile:金红石P145-2Polymersarerarelyusedaloneinapplicationsinvolvingout-doorexposurebutareusuallyeitherfilledorpigmented.Pigmentsorfilersmaythemselvesinfluencethecourseofphoto-oxidativedegradation.Forexampletherutileformoftitaniumdioxideisthemostwidelyusedwhitepigmentforbothpolymersandpaintsanditmayeitherassistorinhibitdegradation.涉及到暴露在户外应用的聚合物很少单独使用但是常常加入填料或被染色。染料或填料自身可以影响光氧化降解。例如二氧化钛的金红石形式对于聚合物和油漆二者是使用最广泛的白色染料并且它即可以助推也可以阻止降解。TiO2mayassistdegradationbecauseitactsasaphotosensitiser.Thisoccursbythefollowingmechanism:二氧化钛可以助推降解因为它作用如同一种光敏剂。这由如下机理进行。singlet:单(谱)线,单线态

P145-3Henceeitherthereactivesingletoxygenmoleculeoroxygenatomsareproduced;eitherofthesemayinitiateradicalchainprocessesthatleadtodegradation.因此产生活性的单线态分子氧或氧原子，它们中的任何一个都可以引发自由基链式过程从而导致降解。Alternatively：二者选一

predominates:优势P146-1

Alternativelybecauseofthedegreetowhichitbothreflectswhitelightandabsorbsintheultraviolet,itmayinhibitphotodegradation.WhichofthesetwopossibititiespredominatesdependsinavarietyoffactorsincludingtheconcentrationoftheTiO2（titaniumdioxide）pigmentused,thenatureofanysurfacetreatments,andtheextenttowhichthepolymeritselfisabletoresistphotodegradation.另外因为一定程度上它即可以反射白光又可以吸收紫外线，它可以阻止光降解。这两种可能中哪一个占优势信赖于所用二氧化钛的浓度、表面处理的性质和聚合物自身的范围是否抵抗光降解等一系列因素。bestressed：强调

cooperative：合作的P146-2Thetestingofpolymersforresistancetoweatheringisdifficult.Apartfromexposingsamplesinplacesthatnaturallyexperiencehighsolarirradiance,suchasFlorida,variousartificialweatheringdevicesareavailable.Itmustbestressedthattheseareartificialweatheringdevices.Theycannotaccelerateweathering,becausethefactorswhichcauseweatheringarecomplexandcooperative.Hencetheycannotbereadilyaccelerated.聚合物耐候性的测试是不同的。除了暴露在天然具有高太阳辐射的地方，如Florida，还可以使用人造的耐候性装置。必须强调的就是人造耐候性装置的存在。它们不能加速气候浸蚀，因为引起气候浸蚀的影响因素是复杂而协同的。因此它们不能轻易被加速。artificialweathering

：人造耐候性

comprise：包含P146-3Thereisgreatdifficultyincorrelatingresultsobtainedfromartificialweatheringtestswiththoseinvolvingoutdoorexposure.Partoftheproblemisthatitisnotpossibletomimicsolarradiationcompletely.Solarradiationcomprisesaspreadofwavelengths,withintensitiesvaryingaccordingtowavelength.涉及暴露在户外从人造耐候性测试中获得相关结果存在很大困难。部分问题是不可能完全模拟出太阳辐射。太阳辐射包含一股光波，强度根据波长发生变化。Artificialweatheringusingarelampscannotcompletelyreproduceboththespectralspreadandthevariationinintensity,eventhoughthebasicrequirementsofheat,ultravioletlight,andmoisturemaybemet.人工耐候性用的灯光不能完全再现光谱宽度和强度变化，虽然具备基本必需的热、紫外光和湿度。incident：易发生的;伴随而来的

Interpretation：解释;阐明careandexperience：用心和经验

substitute：替代品P146-4AnotherdifficultywithtestingisthatexposureofspecimensatasitesuchasFloridamaygiveadifferentpatternofdegradationfromtestsinvolvingexposureatasitehavinglessincidentsunlight.Interpretationoftheresultsofanyweatheringtest,whetherartificialornatural,requirescareandexperience.Intheendthereisnosubstituteforseeinghowthepolymerperformswhenexposedtotheconditionsunderwhichitwilleventuallybeused.测试中另一个困难是把样品暴露在一个象Florida这样的地方，与一个涉及较少阳光的地方，可能给出不同的降解情况。任何耐候性测试结果的解释，无论是人造的还是天然的，都要求用心和经验丰富。最后，当聚合物暴露在最终使用的条件下，要观察它的表现到底怎样，不存在替代品。additives：添加剂P146-5Avarietyofadditivesareavailableforincorporationintopolymerstoactasantioxidants.AselectionoftheseadditivesislistedinTable8.2togetherwiththenamesofthepolymersforwhichtheyaremostsuited.PROTECTIONOFPOLYMERSFROMPHOTO-OXIDATION很多添加剂可以加入聚合物中用作抗氧化剂。表8.2列出了可选择的添加剂和与它们最适合的聚合物名称。exhaustive：彻底的;详尽无疑的，消耗的

interferingwith:干扰P146-6WhilstnotanexhaustivelistthecompoundsgiveninTable8.2dorepresentthemajorclassesofantioxidant.OnefeaturethatisclearfromthisTableisthattheseantioxidantstendtobeeffectiveinmanydifferentpolymers,showingthattheyoperate

by

interferingwiththeagentsofphoto-oxidationrather

thanbyaspecificinteractionwiththeparticularpolymer.与此同时在表8.2中列出的化合物并不详尽确实代表了抗氧剂的主要种类。从这个表中一个表显的特点是这些抗氧剂在很多不同聚合物中都是有效的，这表明它们起作用靠得是干扰光氧化过程的介质，而不是靠与特定聚合物的具体相互反应。Indoingso：靠这种作法

competewith：与…竞争

appropriate：适当的,恰当的,相称的hydrogen-donating:可提供H的P147-1Onegeneralmechanismbywhichantioxidantsactisbyreactionwithperoxyradicals.Indoingsotheycompetewiththepolymer,thusreducingtheextenttowhichthedegradationmediatedbyperoxyradicals.Inthepresenceofappropriatehydrogen-donatingantioxidantsperoxyradicalsundergooneoftwopropagationsteps(Reaction8.1or8.2).抗氧化作用的一般机理是与过氧化自由基反应。靠这种作法它们与聚合物竞争，因此减少由过氧化自由基引起降解的范围。在适当的可提供H的抗氧剂的存在下过氧化自由基经历两个增长步骤中的一个。substitutedphenols:取代的苯

secondaryaromaticamines.:第二芳族的胺P147-2TherateconstantofReaction8.1issuchgreaterthantherateconstantofReaction8.2,whichmeansthatantioxidantsofthistypecanbeusedinverylowconcentrationswithgoodeffect.Atypicalthermoplasticwouldcontainonly0.01%-0.5%bymassofsuchanantioxidant.Typicalcompoundswhichworkbythismechanismincludesubstitutedphenolsandsecondaryaromaticamines.反应8.1是速率常数比反应8.2式的要大，这意味着这种类型的抗氧剂只要很低的浓度就能达到很好的效果。一个典型的热塑性塑料仅含有0.01%-0.5%质量含量这样抗氧剂。以这种作用机理的典型化合物包括取代的苯和第二芳族的胺。radicaltrapping:自由基捕捉剂P147-3Analternativemechanismbywhichadditivesmayprotectpolymersfromphoto-oxidationisradicaltrapping.Additiveswhichoperatebythismechanismarestrictlylightstabilisersratterthanantioxidants.Themostcommonmaterialsinthisclassarethehinderedamines(受阻胺),whicharetheusualadditivesfortheprotectionofpoly(ethylene)andpoly(propylene)..添加剂可以保护聚合物不发生光氧化的另一个机理是自由基捕捉。以这种机理作用的添加剂是严格意义上的光稳定剂而不是抗氧化剂。这种最普通的物质是受阻胺，它常作为保护聚乙烯和聚丙烯的添加剂。TheactionofthesestabilisersisoutlinedinReactions8.3-8.5这种稳定剂的作用在反应式8.3-8.5中列出。consume:消耗P148-1Theseadditivesarethusabletotrapbothalkyl（烷基）andperoxyradicals.Inthiswaytheyinterferewiththepropagatingstepsofthedegradationprocess.Sinceoverallthenitroxyl（硝酰）

radicalsarenotconsumedinthismechanismtheseadditivesareeffectiveatlowconcentrationsinthepolymer.因此这种添加剂能够捕捉烷基和过氧化自由基。用这种方法它们干扰降解过程的增长步骤。因此整个砂酰自由基在这个机理中并不消耗在聚合物中添加剂在很低的浓度下就十分有效。decomposer:分解剂

fragmentating：分裂hydroperoxide：过氧化氢P148-2Thefinalpossiblemodeofactionforanantioxidantisasaperoxide

decomposer.Inthesequencesthatleadtophotodegradationofapolymerthereadyfragmentatingofthehydroperoxidegroupstofreeradicalsistheimportantstep.Ifthisstepisinterferedwithbecausetheperoxidehasundergoneanalternativedecompositionthismajorsourceofinitiationisremoved.这是主句抗氧剂最终可能的作用方式是作为一个过氧化自由基分解剂。在一系列导致聚合物的光降解过程中过氧化氢分裂产生自由基是重要的步骤。如果这一步骤因为过氧化自由基经历另一个分解过程被干扰，引发降解的主要来源v被去除了。expansion：扩展;扩张;膨胀

thevalencestate：价态P148-2Theadditiveswhichactbydecomposinghydroperoxidegroupsincludecompoundscontainingeitherdivalentsulfer(二价硫)ortrivalentphosphorus(三价磷).Themechanisminvolvesexpansionofthevalencestateoftheelementtoaccommodate（接纳）

oxygen,asillustratedinReactions8.6and8.7.作用于分解过氧化氢基团的添加剂包括含有二价硫或三价磷的化合物。机理涉及到为了接纳氧元素价态的增加，如反应式8.6和8.7中所示。synergistic：协同的

convert…into：转变为poly(alkenes),：聚烯烃P148-3Dependingonthenatureofthesulfurorphosphoruscompoundused,theproductR2S=OorR3P=OmayundergoanumberoffurtherreactionswithROOHgroups,allofwhichconvertthehydroperoxidegroupintoanalcohol.Thesecompoundstendtobeonlyweaklyeffectivesoaregenerallyusedinconjunctionwithsynergistic

promoters(促进剂).Suitablemixturesareusedtostabiliseavarietyofpolymersincludingpoly(alkenes),

ABS,andpoly(stryrene).依据所用硫化物和磷化物的性质，产物R2S=O或R3P=O可以经历与ROOH基团的进一步反应，所有反应把过氧化氢基团转变为羟基。这些化合物反应仅是弱效的，所以常常用于与协同促进剂一起起作用。适当的混合物被用于许多聚合物起稳定作用，包括聚烯烃、ABS和聚苯乙烯。toxicity:毒性impart：给予depletes：用尽P149-1Compoundsforuseasantioxidantshavetofulfilanumberofrequirementsinadditiontotheireffectivenessinstabilisingthepolymer.Forexample,theymusthavelowtoxicityandbyinexpensive.Theymustalsobyfullycompatiblewiththepolymerofchoicesinceotherwisetheytendtomigratetothesurfacewheretheyimpart

anunacceptableappearance.Anysuchmigrationalsodepletestheconcentrationinthebulkwhichleadstoalossofprotectionforthepolymer.除了对聚合物稳定性有效之外，用作抗氧剂的化合物必须满足许多要求。例如，它们必须低毒且价格低廉。它们也必须与所选聚合物充分相容因为不相容使之倾向于向表面迁移，在表面它们一无是处（给予一个不能接受的表现）。任何这样的迁移也耗尽本体中的浓度导致失去对聚合物的保护。resistantto：抑制

canbeconferredby：获得P149-2Themajorcommercialpolymersarethepolyolefins,poly(ethylene)andpoly(propylene),andtheseareextremelyresistanttobiologicaldegradation.Somedegreeofbiodegradability（生物降解能力）canbeconferredbycopolymerisingtheprincipalmonomerwithamorepolarmonomer,typicallyanester.BIOLOGICALDEGRADATIONOFPOLYMERS通用聚合物有聚烯烃、聚乙烯和聚丙烯，它们具有极大的抗生物降解性。一定程度的生物降解能力能由主单体与极性单体共聚获得，如酯类。donotfullydegrade：不完全降解since：由于

afinelydividedpowder：良好分散的粉末

debris：残渣obtrusive：伤害P149-2Alternatively,blendingthepolyolefinwithahighlybiodegradablepolymer,suchasstarch,canbeemployed,suchmaterialsdonotfullydegrade

sincethepolyolefincontinuestoresistsuchdegradation.However,theproductofdegradationtendstobeafinelydividedpowder,ratherthanlargepiecesofpolymericdebris,andthismaybelessobtrusiveintheenvironment.另外，能使用聚烯烃与高度生物降解的聚合物如淀粉共聚，这种物质不会完全降解因为聚烯烃能抵抗这种降解。可是，降解的产物倾向于是一种良好分散的粉未，而不是大块的聚合物残渣，这可以降低对环境的伤害。microorganisms：微生物

susceptible：敏感的biologicalattack:生物进攻P149-3Syntheticpolyestersarecapableofbeingdegradedbymicroorganisms,polyesterswithaliphatic（脂肪族的）backbonesbeingmoresusceptibletosuchdegradationthanthosewitharomaticbackbones.Polyamides（聚酰胺）oflowmolarmass,too,maybedegradedbymicroorganisms,butcommercialpolyamides,thenylons,tendtobeoftoogreatamolarmassandhencearealmostcompletelyresistanttobiologicalattack.合成聚酯是能被微生物聚解的，带有脂肪族主链比带芳香族主链的的聚酯对这种降解更为敏感。低摩尔质量的聚酰胺也可以被微生物降解，但商用聚酰胺，尼龙，倾向于摩尔质量太大，因此几乎完全能够抵抗生物的攻击。metabolised:新陈代谢polarsubstituents：极性取代基

preferably：最好是

biodegradablepackaging：生物可降解的包装P149-5Ontheotherhandtherearepolymersthatarecapableofbeingdegraded,generallyinacontrolledway,toyieldlowmolarmassmoleculesthatcanbesafelymetabolisedbylivingorganisms.Polymersofthistypeneedtohaverelativelypolarsubstituents,preferablyesterandhydroxylgroups（羟基）.Onesuchpolymerthathasachievedsometechnicalsuccess,forexampleasamaterialforbiodegradablepackaging,ispoly(hydroxybutyrate)(PHB聚羟基丁酸酯).另一方面存在能够被降解的聚合物，一般以一种可控的方式，产生低摩尔质量的分子，它能被活的生物安全的代谢掉。这种聚合物需要相对极性的取代基，最好是酯和羟基。一种成功达到这一技术的聚合物，例如作为生物可降解包装的材料，是PHB聚羟基丁酸酯。bindsto：粘合

analogue：类似物

P149-6Biodegradationisanenzyme-catalysed（酶催化的）process,andtypicallyoccursintwostages.Inthefirstofthem,theenzymebindstothepolymer,afterwhich,inthesecondstage,hydrolytic（水解的）

cleavage（分裂）occurs.Generallythemore

hydrophilicthepolymer,themoresusceptibleitistohydrolysis.生物降解是一个酶催化的过程，典型的发生步骤有两个。第一个步骤，酶粘合到聚合物上，之后，第二个步骤，发生水解分裂.一般，聚合物的亲水性越大，水解的敏感性越高。amorphous：非结晶的，无定形的However,otherfactorsalsoaffectthesusceptibilitytowardshydrolysis（水解）,suchasmolarmassandcrystallinity.Lowermolarmasspolymersdegradequickerthanthe