rosnad毛細(xì)管流變學(xué)-中文

1、Rosand 毛細(xì)管流變學(xué)及其應(yīng)用,典型剪切速率,為什么需要不同的流變儀?,,粘度: （水）低粘度的, 到高粘度的材料定量信息: 剪切和拉伸粘度, 壁滑移, 應(yīng)力松弛, PVT, 流動(dòng)不穩(wěn)定性,,,,,樣品： （水）低粘度的 ~ 固體定量信息: 剪切粘度, 屈服, 粘彈性能, 應(yīng)力松弛 等.,,非破壞性的,樣品： 固體定量信息: 復(fù)數(shù)模量, 溫度依賴性, 松弛...,s-1,毛細(xì)管流變儀,設(shè)置

2、:柱塞速度溫度口模直徑測(cè)量:壓力降,壓力傳感器,毛細(xì)管口模,單料筒毛細(xì)管流變儀與Rosand雙料筒毛細(xì)管流變儀比較,單料筒毛細(xì)管流變儀與Rosand雙料筒毛細(xì)管流變儀比較,單料筒毛細(xì)管流變儀與Rosand雙料筒毛細(xì)管流變儀比較,單料筒毛細(xì)管流變儀與Rosand雙料筒毛細(xì)管流變儀比較,影響粘度的因數(shù),（物理/化學(xué)）結(jié)構(gòu) 溫度 壓力 時(shí)間 剪切速率/拉伸速率,毛細(xì)管流變學(xué),設(shè)置:,溫度, 柱塞速度, 口模

3、尺寸,測(cè)量:,熔體壓力 (長(zhǎng) & 短 口模),得到:,剪切應(yīng)力 (at a range or rates),拉伸應(yīng)力 (at a range or rates),流動(dòng)曲線測(cè)量,表觀值 – 數(shù)據(jù)必須校正,穩(wěn)態(tài)剪切 - 測(cè)試壓力,穩(wěn)態(tài)剪切 - 典型結(jié)果,穩(wěn)態(tài)剪切 - 典型結(jié)果,毛細(xì)管流變和旋轉(zhuǎn)流變數(shù)據(jù)之比較,聚丙烯： 190ºC,毛細(xì)管流變和旋轉(zhuǎn)流變數(shù)據(jù)之比較,考察加工條件下的低粘度樣品,,毛細(xì)管/狹縫口模的流動(dòng)壓力降,

4、測(cè)量原理,已知: 柱塞速度 ? 剪切速率測(cè)量: 壓力降 ? 剪切應(yīng)力,毛細(xì)管流變測(cè)量學(xué),測(cè)定真正的剪切應(yīng)力 - Bagley校正,計(jì)算入口壓力降,傳統(tǒng) Bagley方法， DIN 11443,,,,?full,10 20 30 40,高剪切速率,低剪切速率,L/D,,原理: : 測(cè)量恒剪切速率和不同L / D 比值下的總?cè)肟趬毫?線性外推至 L / D = 0,E.B. Bagley, J

5、. Appl. Physics 28 (1957), 624,計(jì)算入口壓力降,2. 傳統(tǒng) Bagley方法的實(shí)際困難,問題: 線性外推產(chǎn)生不符合實(shí)際的結(jié)果 外推產(chǎn)生大的標(biāo)準(zhǔn)偏差,計(jì)算入口壓力降,3. 外推錯(cuò)誤的原因,理由: 小 L/D 值時(shí)，所有樣品都產(chǎn)生非線性 現(xiàn)階段，沒有理論方法 大 L/D值時(shí)， 由于壁滑移, 可壓縮性…, 產(chǎn)生非線性,,,?full,2 4 6 8 10 12,L/D,,非

6、線性：小 L / D,,,傳統(tǒng) Bagley,,,,真實(shí)曲線,?,?,計(jì)算入口壓力降,4. 解決方案: 雙料筒毛細(xì)管系統(tǒng),創(chuàng)新: 測(cè)量 – 不需要外推!同時(shí)測(cè)量長(zhǎng)毛細(xì)管的總壓力降和零口模的入口壓力降Pshear = Pfull - Po,Rosand 雙料筒毛細(xì)管系統(tǒng)（配零口模）,直接測(cè)量口模入口壓力降,拉伸流動(dòng),拉伸流動(dòng),單軸流動(dòng),收斂流動(dòng),吹膜,Force,Force,,,拉伸流動(dòng),在毛細(xì)管口模的入口區(qū)會(huì)發(fā)生什么現(xiàn)象 ?,拉伸

7、流動(dòng),長(zhǎng)口模: 剪切 短口模: 拉伸 在平毛細(xì)管口模入口處的壓力降主要由拉伸流動(dòng)主導(dǎo),拉伸流動(dòng)分析,Cogswell 方法 入口處的Dp ? 拉伸粘度,拉伸粘度,拉伸粘度 vs 剪切粘度牛頓流體 ηE = 3ηs (Trouton Ratio)高分子熔體 Trouton Ratio typically ~ 15 but can be as high as 100.反映分

8、子結(jié)構(gòu)之差異HDPE = 線性聚合物L(fēng)DPE – 高支化剪切流動(dòng)和彈性基本類似 拉伸性能有顯著差異LDPE 拉伸時(shí)發(fā)生應(yīng)變硬化 – HDPE 拉伸變稀,拉伸粘度,,,Log ηE,?,,,,100,LDPE (branched),,,,平臺(tái),加工區(qū)域,應(yīng)變硬化,HDPE (linear),Log εE,拉伸粘度的影響,吹膜 – 膜泡形狀,LDPE,HDPE,拉伸流動(dòng)在吹膜, 吹塑, 紡絲中占主導(dǎo)作用,,拉伸粘度的影響,進(jìn)入平頭

9、口模的收斂流動(dòng),LDPE,HDPE,在加工的收斂和發(fā)散流動(dòng)中，也很重要,,拉伸粘度,測(cè)定:系列恒定剪切速率長(zhǎng)口模 和 零口模獲得數(shù)據(jù):拉伸應(yīng)力，拉伸速率 和 拉伸粘度用途:口模設(shè)計(jì)壓力降預(yù)測(cè)流動(dòng)模擬質(zhì)量控制研發(fā)吹膜紡絲,拉伸 - 典型結(jié)果,,,注: 軟件采用 Cogswell 模型. 其它數(shù)學(xué)上更嚴(yán)格的模型如：Gibbs 或Bnding 也提供.,拉伸 - 典型結(jié)果,毛細(xì)管流變測(cè)量學(xué)的好處,Cogswell: 入

10、口壓力降 ? 拉伸粘度,? 區(qū)別僅僅在拉伸(結(jié)構(gòu)敏感性),壁滑移和其它數(shù)據(jù)校正,3 毛細(xì)管測(cè)量學(xué)常規(guī)的校正,Bagley (入口壓力損失)Rabinowitsch (非牛頓流體)壁滑移 (口模壁處速度不為零),Rabinowitsch 校正,Rabinowitsch 校正,非牛頓流體,?,表觀剪切速率 (牛頓材料),4 Q,? R3,,γa =,.,,4 Q,? R3,3n + 1,4n,?c =,.,,,真實(shí)剪切流動(dòng)

11、 (聚合物熔體)If n = 0.5, = 1.25 * γa,.,校正說(shuō)明了聚合物熔體的塞狀，意味著拋物線型的速度曲線是不真實(shí)的.真實(shí)的粘度正比與?n-1 ，當(dāng)n= 0.23 時(shí)最大校正因子為15% (Cogswell Appendix 1),Rabinowitsch 校正,非牛頓流體,?,表觀剪切速率 (牛頓材料),4 Q,? R3,,γa =,.,,4 Q,? R3,3n + 1,4n,?c

12、 =,.,,,真實(shí)剪切流動(dòng) (聚合物熔體) If n = 0.5, = 1.25 * γa,.,Optional but try to keep consistency!!,壁滑移校正,壁滑移校正,壁滑移,大多數(shù)流變學(xué)的基本假設(shè)：金屬壁處速度 = 0,人所共知，滑移發(fā)生在PVC, HDPE和茂金屬催化的聚合物中,難測(cè)量 – 用毛細(xì)管流變法能近似測(cè)量,滑移受填料和潤(rùn)滑劑影響 Occurs when a c

13、ritical stress is exceeded – typically in the region of 200,000 Pa,,壁滑移校正,,.,,.,.,,,? 結(jié)論: 壁滑移速度依賴于剪切應(yīng)力 (真實(shí)的剪切速率),Mooney, M., J. Rheology 2, 210 (1931),壁滑移證據(jù),壁滑移,熔體彈性,熔體彈性,差異性是什么?,Example: PDMS,彈性儲(chǔ)存能量, 粘性消耗能量!,熔體彈性,Res

14、ponsible for:口模脹大 (Barus Effect)薄膜和注射件取向Produces a memory of deformation導(dǎo)致表面缺陷焊接線 ….Potential To Calculate Shear & Tensile Modulus according to Cogswell – see Appendix 3,口模脹大測(cè)量,1. Die-Swell I (Laser-Die-Swell

15、),口模脹大測(cè)量,2. Die-Swell I (Video-Die-Swell),口模脹大: 例示,與PP2 相比，PP1的 MwD中有高分子量拖尾,粘度曲線幾乎完全相同 – 彈性響應(yīng)對(duì)異型擠出是很重要的,Laun, H. M.: Progr. Coll. Polym. Sci. 75 (1987), 111,毛細(xì)管流變測(cè)量學(xué)的優(yōu)點(diǎn),Engineers viewpoint:壓力驅(qū)動(dòng)工藝模擬 (經(jīng)過(guò)口模/噴嘴的流動(dòng))簡(jiǎn)便易用結(jié)

16、實(shí)耐用易于理解精確的驅(qū)動(dòng)系統(tǒng)精確的溫度控制,毛細(xì)管流變測(cè)量學(xué)的優(yōu)點(diǎn),Rheologists viewpoint:寬剪切速率范圍, from 0.01 - >100,000/s剪切 和 拉伸絕對(duì)數(shù)據(jù) (Bagley, Rabinowitsch, 壁滑移）密度, 可壓塑性口模脹大 & 彈性單軸拉伸,儀器,Desktop and floor standing devices,RH7D &

17、 RH10D,RH2100/2200,測(cè)量,Example: Desktop-RH2000,RH2200 (研究牙齒用復(fù)合材料，找出泵輸送和表面效果的最佳幾何尺寸),測(cè)量附件,測(cè)量附件,口模脹大單軸 或 雙軸 熔體 和 口模切刀PVT熔體強(qiáng)度/Haul OffOptional 擠出物恒溫系統(tǒng)狹縫口模高級(jí)分析軟件/ 特殊測(cè)量模式熔體破裂/流動(dòng)不穩(wěn)定性壁滑移材料降解/熱穩(wěn)定性特性熔體粘度應(yīng)力松弛,更多選件,氮?dú)馇?/p>

18、洗For hygroscopic materials e.g. Nylon 66, PET低溫1Intermediate Temperature controlled by circulator低溫2Low Temperature controlled by Liquid Nitrogen加長(zhǎng)的加熱料筒 Maintains temperature of long dies,PVT / 密度測(cè)定,Test:Dat

19、a obtained:Uses:,Compresses melt Special plug die & piston tip,Melt compressibility (versus pressure)Melt density (?5%),Flow simulationFiller & additive investigationMaterial specificationTroubleshooting,

20、,PVT / 密度測(cè)定,PVT / 密度測(cè)定結(jié)果LDPE at 200°C,,熔體強(qiáng)度/紡絲 (Haul Off),測(cè)試:數(shù)據(jù):用途:,特殊的haul-off 馬達(dá) 和 天平Haul-off 速度,力 vs haul-off 速度斷裂點(diǎn), 拉伸力,單軸拉伸，雙軸拉伸的指示測(cè)定拉伸強(qiáng)度,熔體強(qiáng)度/紡絲 (Haul Off),,實(shí)際測(cè)量,Uni-axial extension (Haul Off):Exten

21、sional properties at small extension rates,Haul-off （配卷軸）,Melt tension apparatus with automatic spooling,Apparatus compatible with Rosand RH7D & RH10D capillary rheometers.Design provides wide operating range &

22、exceptional versatility.Melt take up speeds up to 2000metres/min.Dynamic speed range of 100000:1.Melt tension measurable down to 0.005g.Unit can be used in conjunction with Rosand post-extrusion oven to provide a te

23、mperature-controlled environment below the die.,Haul-off （配卷軸）,Melt tension apparatus with automatic spooling,Features automated spooling device for neat collection & storage of the extrudate. Avoids tangling which

24、may occur at high take up rates on a conventional ‘pinch’ roller system.Interchangeable spools allow easy management of extruded samples for other measurements e.g. tensile testing.Directly operated from Rosand Flowmas

25、ter software.,Haul Off: 例示,LDPE at different temperatures,主要興趣在于斷裂力,Laun, Schuch.: J. Rheol. 33 (1989), 119,Rosand 毛細(xì)管流變儀的高級(jí)測(cè)試與分析軟件,,流變軟件,,流變軟件結(jié)果分析,,熔體破裂 vs 斷裂,測(cè)試:數(shù)據(jù):用途:,研究熔體不穩(wěn)定區(qū)域長(zhǎng)口模 和/或 零口模, 或2 種材料,準(zhǔn)確測(cè)定不穩(wěn)定發(fā)生的

26、條件,口模設(shè)計(jì), 異型擠出, 故障排除, 擠出成型HDPE, PVC, 高填充,,應(yīng)用: 熔體破裂,熔體破裂的證據(jù),,材料降解,不同的等待時(shí)間，系列剪切速率長(zhǎng)口模 和/或 零口模,系列剪切速率下，剪切和拉伸隨時(shí)間的變化,時(shí)間依賴性的材料濕氣依賴性的材料停留時(shí)間設(shè)計(jì)，故障排除,,測(cè)試:數(shù)據(jù):用途:,材料降解,,低速降解,恒定的低剪切速率長(zhǎng)口模 和/或 零口模,系列剪切速率下，剪切和拉伸隨時(shí)間的變化,,測(cè)試:

27、數(shù)據(jù):用途:,時(shí)間依賴性的材料濕氣依賴性的材料停留時(shí)間設(shè)計(jì)，故障排除,低速降解,,應(yīng)力松弛,恒速時(shí)，壓力衰減長(zhǎng)口模 和/或 零口模,壓力隨時(shí)間的衰減- 彈性行為的指示,時(shí)間依賴性的材料高彈性材料質(zhì)量控制，熱成型,,測(cè)試:數(shù)據(jù):用途:,應(yīng)力松弛,,應(yīng)力松弛結(jié)果LDPE with Mg(OH)2 filler,,,流動(dòng) / 不流動(dòng),溫度降低時(shí)，恒定剪切速率, 單口模,最低流動(dòng)溫度,工藝設(shè)計(jì)，材料指標(biāo),,測(cè)試:

28、數(shù)據(jù):用途:,流動(dòng) / 不流動(dòng),,壁滑移,穩(wěn)態(tài)剪切， 3套 相同L:D 值，不同直徑的口模,滑移速度 vs. 剪切應(yīng)力,口模設(shè)計(jì)，工藝設(shè)計(jì)故障排除，填料影響,,測(cè)試:數(shù)據(jù):用途:,壁滑移,,壁滑移,,其它應(yīng)用,Capillary Rheometers - Where are they used?,Typical Usage Polymer processing applications account fo

29、r >80% applications Ceramics (pastes and slurries - mould flow) Rubbers (unvulcanised only!)Also used in Coatings ( - need for high shear rate flow behaviour) Inks (some printing inks need to be measured at hig

30、h shear rates) Foods - extrusion properties of cereals, doughs & flow of chocolates Pharmaceutical,,,Testing Non-Polymeric Materials,May Require Alternative Barrel MaterialsE.g. Food – stainless steel barrelsOft

31、en Lower Viscosity than PolymersRequire low range pressure transducersNarrow bore capillary diesHigh shear rates onlySpecial Piston TipsAlternative Temperature ControlOften require measurement at or close to room t

32、empUse Cooling Coils or Liquid Nitrogen or room thermostat!,Testing Non-Polymeric Materials,Materials That have been measured include:ChocolateStarch/FlourDog FoodCeramic PastesInksPaintsPaper CoatingsPlastisols

33、Toothpaste,低粘度流體測(cè)量,,,,Special Fluids Piston Tip,,“O” ring seal prevents back-flow Seals available in different materials Seals are easily replaced,低粘度流體測(cè)量,Shear rate rangesThe maximum shear rate before the transition

34、 from laminar to turbulent flow is determined by the Reynolds number: The Critical Reynolds number (which describes the onset of turbulent flow) is known from literature to be approximately 2300.For a nominally

35、1 mPas fluid, using 0.2 mm diameter dies, the critical Reynolds number corresponds to a shear rate of approximately 5E+5 s-1.,,,高剪切 – 牛頓流體,Uncorrected data for 16 mPas oil Dies: 180 degree entrance.Uncorrected data sho

36、w rise of viscosity,高剪切 – 牛頓流體,Corrected data for 16 mPas oil Viscosity is constant to 240,000 s-1,高剪切 – 牛頓流體,Uncorrected data for water Dies: 180 degree entrance.Uncorrected data show rise of viscosity,高剪切 – 牛頓流體,Cor

37、rected data for waterViscosity is constant to over 500,000 s-1Evidence of Turbulence at 600,000 s-1,高剪切 – 紙用涂料,Paper coating sample 180 degree flat die with 0.25mm diameterMaximum shear rate on a rotational rheometer

38、 is ~1E5,高剪切 – 塑溶膠,PVC Plastisol 180 degree flat die with 0.5mm diameterSample fractures at >1E3s-1 using rotational rheometers,牙膏,EVA/臘 – 剪切數(shù)據(jù) 0.5x16mm口模,EVA/臘 – 拉伸數(shù)據(jù) 0.5x0.25mm口模,www.malvern.co.uk,salesinfo@malv