化妆品种的流变学.ppt

文档介绍：RheologyinCosmetics化妆品中的流变学LINGANGpaniesInnovationInstitute(China)*1牛顿将粘度定义为所加应力与流动梯度的比例。StationaryPlateMoveablePlateA=Areacm2A=Areacm2X=DistanceF=Force(dynes)剪切力(ShearStress)剪切率(ShearRate)粘度*假定:板的长度远大于板的间距。一、流变学介绍定义IRheologyintroductionIDate2漆刷的速度Estimatethevelocityofthepaintbrush=50cm/sec油漆的厚度Estimatethethicknessofthelayerofpaintbeingapplied=y==50cm/ =5,000sec-1Example:刷油漆Shearrateofapplyingpaintwithabrush:vy剪切率SHEARRATERANGE&PRACTICALAPPLICATIONS一、流变学介绍定义IRheologyintroductionIDate3触变性(thixotropic)和震凝性(rheopectic) 指在等温条件下,某些液体的流动粘度随外力作用时间的长短发生变化的性质。粘度变小的称触变性,变大的称震凝性,或称反触变性。 THIXOTROPY-structurepresentinasamplewhichtakestimetorebuildafterithasbeensheared 屈服点,使流体开始流动所需的最小切应力 YIELDPOINT-thestresswhichneedstobeplacedonamaterialinorderforthesampletoflow一、流变学介绍定义IIRheologyintroductionIIDate4评价屈服“点”/屈服“应力”:方法1(CSR模式/单独使用或通过 SSTs/w):应力增加StrainStressYieldStressYieldStrainmodulus方法2(CSS模式/通过Rheo2000s/w):应力线性增加StressRateShearStressYieldStress一、流变学介绍定义IIRheologyintroductionIIDate5非牛顿流体粘弹性流体触变性流体流/震凝性(负触变性)流体与时间无关粘性流体与时间有关无屈服应力有屈服应力du/,n=1;,n<1;,n>1;,非牛顿流体的μ与速度梯度有关n=1,г0=0牛顿流体n1,非牛顿流体一、流变学介绍定义IIIRheologyintroductionIIDate6牛顿型流体(Newtonianfluid)剪应力与速度梯度的关系完全符合牛顿粘性定律的流体.NEWTONIANFLUID-afluidthatdoesnotchangeviscositywithchangeinshearrate例如气体、水、醋、酒、丙三醇、矿物油,阿拉伯胶水溶液(<40%)等一、流变学介绍定义IIIRheologyintroductionIIDate7非牛顿型流体-假塑性(non-Newtonian-Pseudoplasticfluid)-粘度随剪切率升高而减小PerformanceofthePseudoplasticfluidmaterialwhichdisplaysadecreaseinviscositywithincreasingshearrate蛋黄酱、血液、番茄酱、果酱,蒸煮过的淀粉糊,纤维类溶液,乳液,有不少油墨,包括其它许多高分子溶液以及绝大部分的乳液类化妆品一、流变学介绍定义IIIRheologyintroductionIIDate8非牛顿流体-塑性(non-Newtonian-Plasticfluid)塑性流体表现为粘度随剪切率升高而减小,有屈服值(剪切变稀)PerformanceofthePlasticfluidmaterialwhichdisplaysadecreaseinviscositywithincreasingshearrate;thistypeofmaterialalsoexhibitsayieldpoint;thesematerialsareshear-thinning干酪、巧克力浆、肥皂、纸浆、泥浆、绝大部分的油墨,油漆,某些化妆品都是塑性流动的典型流体。Date9非牛顿流体-胀性(non-Newtonian-Dilatantfluid)胀性流体表现为粘度随剪切率升高