材料物理实用.pptx

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1、What is polymer solution?Why to study polymer solution?HOW to study polymer solution?3 Questions第1页/共33页WWhat is polymer solution?TraditionalCover第2页/共33页WWhy to study polymer solution?Study Best method on investigation of a single polymerApplictionsBondDopeFilaturePlastic enhancedBlend第3页/共33页HOW W

2、 to study polymer solution?Polymer solution processPolymer solution processHow to select a solventHow to select a solventSolution stateSolution state：Interaction Interaction solution and separate solution and separateSolution thermodynamicsSolution thermodynamics第4页/共33页Josiah Willard Gibbs(1839-190

3、3)Gibbs 方程 G=H-TSInsluable，Phase Seperate 状态第5页/共33页Key points for polymer dissolvingLinear polymersSwelling to solutionCross-linked polymersOnly swellingCrystalline polymersMelting to solution第6页/共33页Solvent selectionSimilar dissolve mutually theory PolarityPolarityNon-PolarityNon-Polarity第7页/共33页(

4、2)Similar solubility parameterGibbs free energy 自由能Enthalpy 焓Entropy 熵Condition of solutionDuring solution processSolubility parameter =1/2=CED Cohesive energy density第8页/共33页Therefore HM is the key(a)Polar polymer to polar solvent，HM 0,Solution is depended on the comparison of HM and T SM.HM T SM,S

5、oluble。HM need be more little。第9页/共33页Hildebrand equation 1,2 Volume fraction of Solvent and polymer,respectively.1,2 Solubility parameter fraction of Solvent and polymer,respectively.VM Volume after blending Hildebrand J.,Scott R.L.,Solubility of Nonelectrolytes,Reinhold Publishing Corporation,New

6、York,Chapter 7(1949)第10页/共33页In general,Polymer is insolubleHildebrand function is good for non-or weak polar polymerFor polar polymer,Hansen公式公式:Blend solvent：第11页/共33页How to get How to get?=1/2=第12页/共33页(a)Swelling methoda)Swelling method：Cross-linked polymer is dissolved in different solvents.The

7、 Cross-linked polymer is dissolved in different solvents.The of the solvent of the solvent with the largest swelling volume is the with the largest swelling volume is the of polymer.of polymer.第13页/共33页(b)Viscoelasticity methodPolymer is dissolved in different solvents.The of the solvent with the la

8、rgest solution viscoelasticity is the of polymer.第14页/共33页聚合物各结构基团的摩尔引力常数聚合物各结构基团的摩尔引力常数重复单元的摩尔体积重复单元的摩尔体积(c)CalculationPMMA269303.465.6668.2303.4F=269+65.6+668.2+303.4*2=1609.6V=M/=(5C+2O+8H)/1.19=100/1.19第15页/共33页 statusGood solventBad solvent“Polymer-Solvent interaction factor 1 Si第19页/共33页Flory-

9、Hunggins Theory(Mean-field theory)Analogous to regular solution in alloysA-B alloysPolymer solution第20页/共33页Three Hypotheses 三点三点假设假设1.Polymer in solution is arranged like crystal.2.Polymer is flexible。3.Chains of polymer is dissolved uniformly 。第21页/共33页Dissolving processPolymer entityPolymer disor

10、ientationSolventPolymer SolutionSdisorientationSsolventSdisorientation第22页/共33页（5）-state（状态）状态）Similar to ideal solution Condition-状态第23页/共33页（6）Discussion of Hunggins parameterChemical potentialMore stableGood solvent良溶剂良溶剂Chemical potentialNot stableBad solvent劣溶剂劣溶剂第24页/共33页Phase equilibrium of p

11、olymer solutionOsmotic pressure SolutionSolventSemipermeable membrane 半透膜：允许小分子通过，不允许大分子通过。第25页/共33页What is the physical meaning of the second Virial coefficient A2?Molar volume of solventDensity of solute第26页/共33页What we can get from the following equation?(2)A2 Second Virial coefficientIntercept=S

12、lope coefficient=Interceptslope(1)Number average molecular weight Mn第27页/共33页Discussion of A2 status良溶剂良溶剂劣溶剂劣溶剂A2=0A20A20Huggins parameterStatusSecond Virial coefficient第28页/共33页Discussion of the plot(a)Add bad solvent into good solvent(b)Decrease temperature solvent temperature第29页/共33页Stable,meta

13、stable and non-stable regions GM can be substituted by 1 and TemperatureCritical point第30页/共33页Different phase equilibrium diagramsPhase separation and dissolution are controlled by three variables:temperature,pressure,and concentration.LCST-Low critical solvency temperatureUCST-Ultra critical solvency temperature第31页/共33页Typical polymer-solution phase equilibrium diagramWeak concentrationHigh concentrationCharacteristic-Non-symmetrye.g.PVC raincoat,using plasticizer 第32页/共33页感谢您的观看。第33页/共33页