湘大高分子专业英语重点段落(带翻译)

1Charpter2-1Condensation(orStepwise)PolymerizationChapter2:PolymerChemistry2Charpter2-1缩合(或逐步)聚合第二章:高分子化学3Reactantsareintroducedalongwithanyaddedcatalysttothereactionvessel.Heatisappliedtomeltthereactants,permittingtheirnecessaryintimatecontact.Heatingcanbemaintainedatthereactionmelttemperatureorincreasedaboveit.Pressureisreduced.Typicalmeltpolycondensationstakeseveralhourstoseveraldaysbeforethedesiredpolymericproductisachieved.Yieldsarenecessarilyhigh.Solutioncondensationsarealsoequilibriumprocesses,withthereactionoftendrivenbyremovalofthebyproductbydistillationorbysaltformationwithaddedbase.Reactantsgenerallymustbemorereactiveincomparisonwiththemelttechnique,sincelowertemperaturesareemployed,withanumberofsolutionprocessesoccurringnearroomtemperature.Solvententrapmentisaproblem,butsinceareactionmayoccurunderconsiderablyreducedtemperaturescomparedtothemelttechnique,thermallyinducedsidereactionsareminimized.Sidereactionswiththesolventhavebeenaprobleminsomecases.Becausethereactantsmustbequiteenergetic,manycondensationsarenotsuitableforthesolutiontechnique.考过4反应物以及任何加入到反应容器的催化剂被引入。加热以熔化反应物，从而允许他们能有必须的紧密接触。加热应保持在该反应的熔融温度或往上增加（熔融温度以上）。压力降低。典型的熔融缩聚需要数小时到数天在制得所需的聚合产物之前。产量必然是高。溶液缩合也是平衡过程，反应通常由蒸馏除去副产物或加入碱形成盐产生驱动力。与熔融技术相比反应物通常必须是更具反应性，由于采用较低的温度，与在接近室温下一些溶液过程的发生。溶剂滞留是个问题，但与熔融技术相比在温度显着降低下反应仍会发生，热引起的副反应是最小化的。溶剂副反应某些情况下一直是一个问题。因为反应物必须有相当有活力，因此许多缩合反应对溶液技术是不适合的。5SummaryManynaturallyoccurringandsomesyntheticpolymersareproducedbycondensationreactionswhicharedescribedkineticallybythetermstep-reactionpolymerization.Sinceahighfractionalconversion(p)isrequired,onlyarelativelyfewusefullinearpolymers,suchaspolyestersandpolyamides,maybesynthesizedbystepreactions.Sincethefractionalconversionsareveryhigh,usefulpolymersmaybeproducedbythestepwisecondensationofabifunctionalacylorsulfonylchloridewithadiamineorglycol.Therateconstantkforthesesecond-andthird-orderreactionsissimilartocorrespondingreactionsofmonofunctionalreactantsandisessentiallyunchangedasthereactionsproceedthroughdimers,tetramers,octamers,oligomers,andhighermolecularweightpolymers.ThisrateconstantincreaseswithtemperatureinaccordancewiththeArrheniusequation.ThedegreeofpolymerizationDPofareactionofbifunctionalreactantsmaybecalculatedfromtheCarothersequation,DP=1/(1-p).However,thisvaluewillbechangedifcyclizationoccurstoform“wastedloops.”Sincethisisastepreaction,DPincreaseswithtime.Highmolecularweightlinearpolyestersmaybeproducedbyesterinterchangeorbyinterfacialcondensation(Schotten-Baumannreaction).6总结许多天然存在的和一些合成的聚合物是由缩合反应产生，这在动力学上被描述为逐步反应聚合。因为高转换分数（p）是必需的，所以只有相对较少的有用的线性聚合物，如聚酯和聚酰胺，可以通过逐步反应合成。因为转换分数要非常高的，有用的聚合物可通过有双官能的酰基或磺酰氯与二胺或二醇的逐步缩合来制备。对二级和三级反应的速率常数k类似于的单官能反应物的相应反应，且基本上是不变，通过二聚体，四聚体，八聚体，低聚物和较高分子量的聚合物的反应过程。速率常数随温度的增长遵循Arrhenius方程的规律。有双官能团反应物的反应的聚合度DP可以由Carothers方程计算得到，即DP=1/(1-p)。然而，如果对于形成“浪费环路”的环化来说，该值将被改变。由于这是一个逐步反应，因此DP值随时间增加而增加。高分子量的线型聚酯可以通过酯交换或界面缩聚（Schotten-Baumann反应）来生产。7Charpter2-2IonicPolymerizationandCoordinativePolymerization(AdditonPolymerization)8Charpter2-2离子聚合和配位聚合（加成聚合）9SummaryChainreactions,includingionicchainpolymerizationreactions,consistofatleastthreesteps:initiation,propagation,andtermination.Becauseoftherepulsionofsimilarlychargedspecies,terminationbycouplingseldomoccurs.Instead,terminationmaytakeplacebychaintransfertoproduceanewionandadeadpolymer.TheDPofthelatterisequaltothekineticchainlength.SulfuricacidandLewisacidswithacocatalystofwateroretherserveaspossibleinitiatorsincationicpolymerizations,producingacarbonationandagegenion.Monomerswithelectron-donatinggroups,suchasisobutyleneandvinylalkylethers,maybepolymerizedatlowtemperaturesinsolventswithhighdielectricconstants.Therateofanionicpolymerizationisdependentonthedielectricconstantofthesolvent,thestabilityofthecarbanion,theelectronegativityoftheinitiator,thedegreeofsolvationofthegegenion,andthestrengthoftheelectron-withdrawinggroupsinthemonomer.StereospecificpolymersofnonpolarmonomersmaybeproducedbypolymerizationwithaZiegler-Nattacatalyst.Themostwidelyusedsystemconsistsofatitaniumtrichloridecatalystandanalkylaluminumcocatalyst.10总结链反应，包括离子链聚合反应中，包括至少三个步骤：引发，增长和终止。因为类似的带电物质的排斥，耦合终止很少发生。相反，终止反应可能通过链转移发生，以产生新的离子和死聚物。后者的DP等于动力学链长。硫酸和路易斯酸的水或乙醚中的助催化剂作为引发剂，可以在阳离子聚合中，生产出碳酸化和反离子。单体与给电子基团，如异丁烯和乙烯烷基醚，可在低温下具有高介电常数的溶剂中进行聚合。阴离子聚合反应的速率依赖于溶剂的介电常数，碳负离子的稳定性，引发剂的电负性，反离子的溶剂化的程度，在单体中吸电子基团的强度。非极性单体的立体有择聚合物可聚合通过齐格-纳塔催化剂来生​​产。最广​​泛使用系统由三氯化钛催化剂和一种烷基铝助催化剂组成的。Charpter2-3FreeRadical(Addition)Polymerization11Charpter2-3自由基（加成）聚合12SummaryPeroxides,suchasbenzoylperoxide,anddiazocompounds,suchasazobisisobutyronitrile,arereadilyhomolyticallycleavedbyheatorultravioletlighttoproducefreeradicals,whichserveasinitiatorsforchainreactionpolymerization.Therateofinitiationoffreeradicalchainpolymerization,whichistheratecontrollingstep,isproportionaltotheproductoftheconcentrationsofthefreeradical(R⋅)andthemonomer.Therateofpropagationisproportionaltotheconcentrationsofthemonomerandthemacroradicals.Terminationofpropagatingmacroradicalsmaytakeplacebycouplingordisproportionation.ThedegreeofpolymerizationDPisinverselyproportional