化妝品流變學(xué)

1、Rheology in Cosmetics,化妝品中的流變學(xué),LIN GANG Estée Lauder Companies Innovation Institute (China),牛頓將粘度定義為所加應(yīng)力與流動梯度的比例。,剪切力（Shear Stress）,剪切率 (Shear Rate),粘度,*假定: 板的長度遠(yuǎn)大于板的間距。,一、流變學(xué)介紹 定義I Rheology introduction I,,漆刷的速

2、度Estimate the velocity of the paint brush = 50 cm/sec油漆的厚度Estimate the thickness of the layer of paint being applied = y = 0.01 cm剪切率計算Calculate shear rate = 50 cm/sec0.01cm= 5,000 sec-1,Example: 刷油漆 Shear r

3、ate of applying paint with a brush:,,,,,,,,,,,,,,,,,v,y,,,,剪切率SHEAR RATE RANGE & PRACTICAL APPLICATIONS,一、流變學(xué)介紹 定義I Rheology introduction I,觸變性(thixotropic)和震凝性(rheopectic)指在等溫條件下,某些液體的流動粘度隨外力作用時間的長短發(fā)生變化的性質(zhì)。粘度變小的

4、稱觸變性,變大的稱震凝性,或稱反觸變性。 THIXOTROPY - structure present in a sample which takes time to rebuild after it has been sheared屈服點，使流體開始流動所需的最小切應(yīng)力 YIELD POINT - the stress which needs to be placed on a material in order for

5、 the sample to flow,一、流變學(xué)介紹 定義II Rheology introduction II,評價屈服“點”/屈服“應(yīng)力” :,方法1(CSR 模式 / 單獨使用或通過 SST s/w): 應(yīng)力增加,方法2 (CSS 模式/ 通過 Rheo 2000 s/w): 應(yīng)力線性增加,,Stress Rate,一、流變學(xué)介紹 定義II Rheology introduction II,a. 牛頓流體，n=1；b. 假

6、塑性流體, n1；d. 塑性流體,,牛頓流體,a.,b,c,d.,μ為表觀粘度，非牛頓流體的μ與速度梯度有關(guān),n=1, г0=0牛頓流體n?1，非牛頓流體,,一、流變學(xué)介紹 定義III Rheology introduction II,,,牛頓型流體(Newtonian fluid)剪應(yīng)力與速度梯度的關(guān)系完全符合牛頓粘性定律的流體.NEWTONIAN FLUID - a fluid that does not change vi

7、scosity with change in shear rate,例如氣體、水、醋、酒、 丙三醇、 礦物油，阿拉伯膠水溶液（<40%）等,一、流變學(xué)介紹 定義III Rheology introduction II,,,非牛頓型流體-假塑性(non-Newtonian -Pseudoplastic fluid )-粘度隨剪切率升高而減小Performance of the Pseudoplastic fluid materi

8、al which displays a decrease in viscosity with increasing shear rate,蛋黃醬、血液、番茄醬、果醬, 蒸煮過的淀粉糊，纖維類溶液，乳液，有不少油墨，包括其它許多高分子溶液以及絕大部分的乳液類化妝品,一、流變學(xué)介紹 定義III Rheology introduction II,,,非牛頓流體-塑性(non-Newtonian -Plastic fluid ) 塑性流體表現(xiàn)

9、為粘度隨剪切率升高而減小，有屈 服值(剪切變稀) Performance of the Plastic fluid material which displays a decrease in viscosity with increasing shear rate; this type of material also exhibits a yield point; these materials are shear-thinning

10、,干酪、巧克力漿、肥皂、紙漿、泥漿、絕大部分的油墨, 油漆,某些化妝品都是塑性流動的典型流體。,,,非牛頓流體-脹性 (non-Newtonian - Dilatant fluid ) 脹性流體表現(xiàn)為粘度隨剪切率升高而增大Performance of the Dilatant fluid material which exhibits an increase in viscosity as shear rate increases,

11、面團(tuán)，泥漿、粘土、糖制品 ，蜂蜜,二、流變學(xué)中有關(guān)粘度 ,Viscosity-典型液體的大概粘度值 (Pa s),Viscosity粘度,Rheology 流變,sheer,sheer,,,,vs.,通過比較觸變曲線/屈服數(shù)據(jù)等進(jìn)行配方改進(jìn)和QC 測試。 MORE ADVANCED TEST METHOD,,,用于乳液，膏霜的開發(fā)和檢驗Can be applied for lotion and cream’s formula