高分子材料共混期末复习材料2

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1、1名词解释相结构(相形态)界面层界面张力粘度相反转单相连续结构共连续结构海岛结构相畴尺寸2填空1测试玻璃化转变温度的方法有动态粘弹分析、示差扫描量热、介电松弛谱等。2PPO/PS共混/体系只有一个玻璃化转变温度，而PPO/PMMA共混体系则有两个玻璃化温度，因此共混体系相容性更好3相分离的机理包括成核和增长机理(NG)及。4聚合物共混物形态结构的基本类型包括单相连续结构、及相互贯穿的两相连续结构。5随着聚合物相容性增加，两组分之间的分子链扩散程度增大，相界面越来越模糊，界面层厚度3判断1聚合物A和B组成的共混体系中，随着温度升高，哈金斯参数增大

2、，结合二元体系的相图说明这一共混体系是具有最高临界相容温度还是具有最低临界相容温度。2由显微电镜图可知，未增容的试样分散相粒子尺寸大、界面模糊、界面粘结力弱，增容处理的试样分散相粒径极小、断面光滑。3以PVC/NBR体系为例，其中NBR组分中，丙烯膳含量由0增加到20%再增大到40%时,体系相容性逐渐增大，相区尺寸则减小；丙烯睛含量达到40%时，共混物接近于均相，此时体系的性能最好。分别举出两种完全相容(miscibility)的聚合物共混物及两种具有一定相容性(compatibility)的聚合物共混物.Osmiumtetroxidestai

3、ningcanbeaccomplishedbyexposingsampletoosmiumtetroxidevaporforaweek,orbysoakingina1%aqueoussolutionovernightsAnditwouldselectivelystainandhardentheunsaturatedrubber.Compatibilityrequiresthatthefreeenergyofmixingbenegative,whichcanonlybeachievedbyexothermicmixingoralargeentro

4、pyofmixing*Formostpolymers,however,themixingisendothermicandtheentropycontributionissmallbecauseofthehighmolecularweights.Therefore,mostpolymerblendsarenotcompatible.However,truelymiscibleisnotarequirementinmostcase.Adhesionbetweenthepolymerphasesisnecessary,greatercompatibi

5、litycanbeachivedforpolymerscontainingpolargroups.Fornon-polarpolymers,bettercompatabiltycanonlybeachivedwhenthesolubilityparametersofcomponentsarecloselymatched.Thetypesofstress-straincurvesarebelow:Brittleplasticstress一straincurveislinearuptofractureatabout1%to2%elongation*

6、Ordinarypolystyrenebehavesthisway>(2)Anexampleofatoughplasticispolyethylene,whichissemicrystalline.ItsYoungsmodulus,givenbytheinitialslopeofthestress-straincurve,issomewhatlowerthanthatofthebrittle,glassyplastic.Typicallythisclassofpolymerexhibitsayieldpoint,followedbylargee

7、longationatalmostconstantstress.Thisiscalledtheplasticflowregionandisclearlyaregionofnonlinearviscoelasticity.Themainmethodsonimprovingcompatibilityisintroducingathirdcomponentwhichwascalledcompatibilizer.Basedonthereactionkinds，compatibilizercanbedividedintotwokinds.Oneisre

8、activecompatibilizer,theotherisnon・reactivecompatibilizer.Theimprovingincom