最新《高分子物理》精品复习资料复习题Word文档格式.docx
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最新《高分子物理》精品复习资料复习题Word文档格式.docx
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Theratiobecomes
2、Itiswellknownthatpolyvinylchloride(PVC)isnotmisciblewithitsownmonomer(VC).Thisgivesthepolymeracharacteristicparticlestructurewhichremainsevenaftermelt-processingandleadstopoormechanicalproperties.ThesolubilityparametersofPVCare:
(Barton1983).ThesolubilityparametervaluesofVCare:
.ConfirmthatPVCisimmisciblewithVConthebasisofthesedata.
CalculatefirstthedistancebetweenPVCandVCinthree-dimensionalsolubilityspace;
keepinmindthatthedispersionvaluesshouldbedoubled:
ItisthuspredictedthatPVCshouldbeinsolubleinVC.
3、TheglasstransitiontemperatureofpolyisobuteneisTg=202K.ThecharacteristicvaluesC1、C2aretakenasC1=-16.6,C2=104KinitsWLFequation.Ifonemodulusmeasuredat-800Cfor1hourisequaltotheothermodulusatcertaintemperatureandmeasuredfor10-6hour.Atwhichtemperatureisthemodulusmeasured?
LetT2bethemeasuringtemperature,andTs=Tg=202Kbethereferencetemperature,thenC1=-16.6,C2=104K.AccordingtotheWLFequation,itisknownthat:
where
andthus
Substitutingtheknowndataintheaboveequation,
(3points)
Bysolvingtheequations
(1)and
(2),T2=239.82K,i.e.,-33.30Cisobtained.
4、由文献查得涤纶树脂的密度ρc=1.50×
103kg·
m-3,和ρa=1.335×
m-3,内聚能ΔΕ=66.67kJ·
mol-1.今有一块1.42×
2.96×
0.51×
10-6m3的涤纶试样,重量为2.92×
10-3kg,试由以上数据计算:
(1)涤纶树脂试样的密度和结晶度;
(2)涤纶树脂的内聚能密度
(l)密度
结晶度
或
(5分)
(2)内聚能密度
5、Amiscibleblendshowsahigherglasstransitiontemperaturethanthepurepolymers.Suggestapossibleexplanation.Suggestalsoanotherexperimentwhichwillcriticallytestyourhypothesis.
Thereshouldbestrongspecificinteraction(e.g.hydrogenbondingorcharge-transfercomplexformationbetweentwogroupsofwidelydifferentpolarities)betweenthetwopolymers.Infraredspectroscopymaydetectafrequencyshiftofcertainabsorptionbandscausedbythespecificinteraction.
6、WhatisphysicalmeaningofHugginsparameter
?
Whatistheotherparameterthatisusedtojudgesolventisgoodorpoor?
Whataretheirvalueswhenthecorrespondingsolventisgood,poorandthetatoapolymer,respectively?
Howaboutthethermodynamicscharacteristicandconformationofapolymermoleculeintheabovethreecorrespondingsolvent?
Hugginsparameter
indicatesthechangeofinteractionenergywhenpolymermixeswithsmallmolarmasssolvent.ThesecondvirialcoefficientA2.
1).A2>
0,
<
1/2.Goodsolvents.Macromolecularchainsexpandandextendinthesolvent.
(1)
.Exothermicdissolving.Thedissolvingcanhappenspontaneously.
(2)
.Athermaldissolvingoridealsolutionsystem..Spontaneousprocess.
(3)
.Endothermicdissolving.Spontaneousprocess.
2).A2=0,
=1/2.
solvent.Atthiscondition,thedifferencebetweenthissolutionandideasolutiondisappears,andmacromolecularchainsareinunperturbedstate.
3).A2<
0,
.Poorsolvent.Phaseseparatesinsolution,andmacromolecularchainsshrinkanddeposit.
7、Explainwhymeasurementofcolligativepropertiesyieldsthenumberaveragemolarmass.
Colligativepropertiesarethosepropertiesofasolutionwhichdependonlyuponthenumberofsolutespeciespresentinacertainvolume,andnotonthenatureofthesolutespecies.Itisthuslogicalthatmeasurementofthecolligativepropertiesmakesdeterminationof
possible.
Colligativepropertiesonlydependonthenumberofmolecules:
.Themassofpolymer(B)inthesampleisequalto
andthenumberaveragemolarmassisobtainedfromthefollowingformula:
8、YouhaveapolymerblendwhichshowsoneTgbutisopaque.Explain.AnotherpolymershowstwoTg’sbutthismaterialistransparent.
Asimilarityinthetwopolymers’Tgvaluesgivesrisetoasingleglasstransitiondespitethefactthatthepolymersareimmiscibleasjudgedbytheiropaqueness.Thesecondcasecanbegiventwodifferentexplanations.Thefirstisthatthepolymersareimmisciblebutthesimilarityinrefractiveindexofthetwopolymersresultsinonlynegligiblelightscattering,i.e.atransparentmaterial.Thesecondexplanationisthatthepolymersareimmisciblebutthedispersionisconsiderablyfinerthanthewavelengthoflight.
9、Presentanexplanationoftheobservationsrelatingtothedie-swellphenomenonshowninfollowingFig.
Theconvergentflowcausesaxialorientationofthechains.Thedie-swelloccursinresponsetotheaxialorientation.Duringtheflowthroughthenarrowpipesection,relaxationoftheorientedmoleculesoccurs.Thedegreeofdie-swelldecreaseswithincreasinglengthofthenarrowpipesection.
10、近程相互作用和远程相互作用的含义及它们对高分子链的构象有何影响?
所谓“近程”和“远程”是根据沿大分子链的走向来区分的,并非为三维空间上的远和近。
事实上,即使是沿高分子长链相距很远的链节,也会由于主链单键的内旋转而会在三维空间上相互靠的很近。
高分子链节中非键合原子间的相互作用——近程相互作用,主要表现为斥力。
近程相互排斥作用的存在,使得实际高分子的内旋转受阻,使之在空间可能有的构象数远远小于自由内旋转的情况。
受阻程度越大,构象数就越少,高分子链的柔性就越小。
远程相互作用可为斥力,也可为引力。
当大分子链中相距较远的原子或原子团由于单键的内旋转,可使其间的距离小于范德华距离而表现为斥力,大于范德华距离为引力。
无论哪种力都使内旋转受阻,构象数减少,柔性下降,末端距变大。
高分子链占有体积及交联和氢键等都属于远程相互作用。
11、有两种乙烯和丙烯的共聚物,其组成相同(均为65%乙烯和35%丙烯),但其中一种室温时是橡胶状的,一直到稳定降至约-70℃时才变硬,另一种室温时却是硬而韧又不透明的材料。
试解释它们内在结构上的差别。
前者是无规共聚物,丙烯上的甲基在分子链上是无规排列的,这样在晶格中难以堆砌整齐,所以得到一个无定形的橡胶状的透明聚合物。
后者是乙烯和有规立构聚丙烯的嵌段共聚物,乙烯的长嵌段堆砌入聚乙烯晶格,而丙烯嵌段堆砌入聚丙烯晶格。
由于能结晶从而是硬而韧的塑料,且不透明。
12、Manyrubbermaterialsexhibitatimedependenceintheirmechanicalproperties(seethefollowingfigure).Makealistofpossiblereasons.
Figure:
Resultsfrommeasurementsofcontinuousstressrelaxationofnitrilerubber(lownetworkdensity).DatafromBjÖ
rk(1988).
Physical’relaxationcausedbydisentanglementofchains.Theentanglementscanbeconsideredastemporarycrosslinks.
13、WhatisphysicalmeaningofHugginsparameter
1.请描述聚合物的力学松弛现象及其有关主要数学描述方法。
2.试讨论非晶、结晶、交联和增塑高聚物的温度形变曲线的各种情况(考虑相对分子质量、结晶度、交联度和增塑剂含量不同的各种情况)。
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