The Importance of How Online Rheometers Accurately Indicate Melt Flow Rate in an Extruder

Azadeh Farahanchi Kevin Craig Dynisco Instruments LLC

ANTEC Society of Plastics Engineering (SPE), Orlando, FL May 9, 2018 Outline

 Application and benefits of online rheology measurements in plastics processing industry

 ViscoIndicator online rheometer design

 Rheological calculations for correlation of capillary rheometer and melt flow rate (MFR) tester in the online rheometer

 Experimental trials and results from online rheometer

2 Necessity of Rheological Measurements in Plastics processing

https://www.thoughtco.com/plastics-polymers- science-fair-project-ideas

Viscosity vs. shear rate

http://www.ilcaffe.tv/articolo https://www.ptonline.com/articles/high-speed- extrusion

Rheology Chain scission https://www.victrex.com

https://www.ptonline.com 3 Online Rheometer Applications

 Continuous data stream of rheological properties at various processing condition

 Using for automatic processing, product development, quality and process control

 Incorporating in variety of extrusion lines

4 Benefits of Using an Online Rheometer

Window into the Process In-Process Product Quality Control

https://www.datastorageinc.com/

http://www.ebay.com/bhp/plastic-pellets

Sustainability & Reduce of Waste Stream Process Productivity & Efficiency

https://dir.indiamart.com/impcat/ http://regainpolymers.com https://www.dreamstime.com/ plastic-scrap.html

5 OBJECTIVE Indication of Rheological Properties in Extrusion

ASTM D1238 ISO 1133 Capillary rheometer Melt flow rate tester

Online Measurements in an extrusion

 Controlled shear rate with speed set point for apparent viscosity ( ) measurements

 Controlled shear stress𝜼𝜼𝒂𝒂 with pressure set point for melt (volume) flow rate ( & ) measurements

𝑴𝑴𝑴𝑴𝑴𝑴 𝑴𝑴𝑴𝑴𝑴𝑴 6 ViscoIndicator Online Rheometer Design

Polymer melt from process

Motor Gear pump

Temperature control zone

Pressure Pump speed Pressure Transducer Capillary die L/D:3.818 Extrudate  Speed Mode: maintaining a pre-set speed by manipulating pressure to calculate  Pressure Mode: 𝑎𝑎 maintaining a pre-set pressure by manipulating gear pump speed to𝜂𝜂 calculate MFR Rheological Calculation from Capillary Rheometer to Online Rheometer

Capillary rheometer On-line rheometer System running under rate control

 ( ) = ( )  = , ( ) = [1 ] 𝑟𝑟 𝑑𝑑𝑑𝑑 𝑑𝑑𝑑𝑑 2𝑄𝑄 𝑟𝑟 2 𝑧𝑧 ( ) = 𝑧𝑧 ( 2 ) = = Wallτ shear𝑟𝑟 stress2 𝑑𝑑𝑑𝑑 : ( ) Apparentγ҅ 𝑑𝑑 𝑑𝑑shear𝑢𝑢 𝑟𝑟rate 𝜋𝜋𝑅𝑅 : − 𝑅𝑅 𝒛𝒛  ( ) 𝑷𝑷 𝟏𝟏 𝒅𝒅𝒖𝒖 −𝟒𝟒𝟒𝟒 : Capillary Pressure 𝒘𝒘 𝑳𝑳  : Capillary radius 𝒔𝒔 𝟑𝟑 𝑷𝑷𝑷𝑷 𝝉𝝉 𝟒𝟒 �𝑫𝑫 𝒅𝒅𝒅𝒅𝒅𝒅 ⁄ 𝜸𝜸휸𝒂𝒂 𝒅𝒅𝒅𝒅 𝝅𝝅𝑹𝑹𝑪𝑪  Apparent viscosity ( ): =  : Volumetric flow rate ( ) 𝒓𝒓=𝑹𝑹 𝑃𝑃 𝑃𝑃𝑃𝑃 𝐶𝐶 3 τ𝑊𝑊 𝑅𝑅 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚  = ( ) 𝑎𝑎 γ𝑎𝑎҅  = × 𝑆𝑆 𝑷𝑷𝑷𝑷 −𝟐𝟐 𝒔𝒔 𝜂𝜂 � 𝑄𝑄 �  : Piston speed 𝝅𝝅𝑫𝑫𝒃𝒃  : Gear pump speed 𝑸𝑸 𝑺𝑺 𝟒𝟒 𝑸𝑸 𝑺𝑺 𝑽𝑽  : Barrel diameter𝑚𝑚𝑚𝑚 ( )  : Pump volume ( ) 𝑚𝑚𝑚𝑚𝑚𝑚 𝑆𝑆 3𝑟𝑟𝑟𝑟𝑟𝑟 Assumptions:𝑆𝑆 1: Fully developed, isothermal,⁄ steady state, and Laminar Flow - 2: No radial/circumferential𝑚𝑚𝑚𝑚 velocity 8 𝑏𝑏 𝑟𝑟𝑟𝑟𝑟𝑟 3: Incompressible𝐷𝐷 fluid - 4: No slip at the𝑚𝑚𝑚𝑚 wall of the die 𝑉𝑉 ⁄ Rheological Calculation from MFR Tester to Online Rheometer

Melt flow rate tester On-line rheometer

System running under pressure control

D: 2.095 mm L/D: 3.818

ASTM D1238/ISO 1133 – Test Method B (Based on melt volumetric displacement)  Melt flow rate ( ): = ×  𝒈𝒈 ( ) : Melt volume-flow𝟏𝟏𝟏𝟏 𝒎𝒎𝒎𝒎𝒎𝒎rate 𝒎𝒎 ⁄ 𝑴𝑴𝑴𝑴𝑴𝑴3 𝑴𝑴𝑴𝑴𝑴𝑴 𝝆𝝆  : Polymer melt density at test𝑐𝑐𝑐𝑐 temperature ( ) 𝑀𝑀𝑀𝑀𝑀𝑀 �10 𝑚𝑚𝑚𝑚𝑚𝑚 ( ) 𝑔𝑔 3  ( ρ𝑚𝑚 ) =  ( �𝑐𝑐𝑐𝑐 ) = ( ) 𝟑𝟑 𝟐𝟐 𝟑𝟑 𝒄𝒄𝒄𝒄 𝟏𝟏𝟏𝟏 𝝅𝝅𝑹𝑹 𝑳𝑳 𝒄𝒄𝒄𝒄   𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏 : Piston𝑴𝑴𝑴𝑴𝑴𝑴 travel distance�𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏 over𝒕𝒕𝑩𝑩 time 𝑴𝑴𝑴𝑴𝑴𝑴: Gear pump� speed 𝟏𝟏𝟏𝟏 𝑺𝑺𝑺𝑺  : Barrel radius  : Pump volume ( ) 𝐿𝐿 𝑐𝑐𝑐𝑐 𝑡𝑡𝐵𝐵 𝑆𝑆 3 𝑟𝑟𝑟𝑟𝑟𝑟 𝑐𝑐𝑐𝑐 9 𝑅𝑅 𝑉𝑉 ⁄𝑟𝑟𝑟𝑟𝑟𝑟 CHALLENGE ! Correlation of Online Rheometer to Standard Condition in MFR Tester = ×

𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂 𝑟𝑟푟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑚𝑚 𝑀𝑀𝑀𝑀𝑀𝑀 = 10( 𝑀𝑀𝑀𝑀𝑀𝑀) (𝜌𝜌 ) 3 𝐷𝐷𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝑀𝑀𝑀𝑀𝑀𝑀𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂𝑂 𝑟𝑟푟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑉𝑉𝑉𝑉𝜌𝜌𝑚𝑚 3 𝒂𝒂𝑻𝑻 Standardized melt flow rate tester 𝐷𝐷 CORRELATION Online rheometer (ASTM D1238) × . = : Standard weight ( ) 𝑴𝑴 𝟗𝟗 𝟖𝟖 Pump pressure : Barrel diameter(9.55 ) e.g.𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷 M: 2.16𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷 kg P: 43.38𝟐𝟐 psi 𝑀𝑀 𝑘𝑘𝑘𝑘 𝝅𝝅𝑫𝑫𝒃𝒃 𝐷𝐷𝑏𝑏 𝑚𝑚𝑚𝑚 : 2.095 Die dimeter correlation : Diameter ( ) : 3.819 : 3.819 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐷𝐷𝐿𝐿 𝑚𝑚𝑚𝑚 𝐿𝐿𝐷𝐷 ⁄𝐷𝐷 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 ( ) ⁄𝐷𝐷

Challenge:𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 Different𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄 temperatures𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄 𝒂𝒂𝑻𝑻 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷 𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 10 Arrhenius relationship for Temperature correlation

( = ( ) T0 −𝐸𝐸𝑎𝑎 1 1 𝑅𝑅 𝑇𝑇𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆− � 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 0 (𝑀𝑀𝑀𝑀> 𝑀𝑀+ 100) 𝑀𝑀𝑀𝑀𝑀𝑀 𝑒𝑒 Calculation of activation energy 𝑇𝑇where𝑇𝑇𝑔𝑔

 : Flow activation energy ( ) ( ) =  R: Universal gas constant (8.314𝑘𝑘𝑘𝑘 × 10 . ) ( ) 𝑎𝑎 𝑚𝑚𝑚𝑚𝑚𝑚 𝐸𝐸 � −3 𝑘𝑘𝑘𝑘 𝒂𝒂 𝜹𝜹 𝒍𝒍𝒍𝒍 𝑴𝑴𝑴𝑴𝑴𝑴  : Standard temperature ( ) 𝑚𝑚𝑚𝑚𝑚𝑚 𝐾𝐾 𝑬𝑬 −𝑹𝑹 � ⁄ 𝑷𝑷  : Processing temperature ( ) 𝜹𝜹 𝟏𝟏 𝑻𝑻 𝑇𝑇𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝐾𝐾 𝑇𝑇0 𝐾𝐾

11 Experimental

Material Off-line measurements  Dynisco® LMI5000 melt flow rate tester  Polypropylene (PP)  Test method: Method B (2.16 kg/230 °C)  manufactured by BRASKEM S.A  Flag length: 6.35 mm  MFR (2.16 kg/230 °C): 35.5 g/10min  Die dimensions: L/D: 3.818, D: 2.095 mm

Human Machine Process Interface (HMI) On-line measurements

 Dynisco® REX single screw extruder  Dynisco® ViscoIndicator Rheometer  Barrel L/D: 20:1  90 degrees heated adaptor  Head pressure: 4.1 MPa Rheological  ½-20 mounting port Sensing Unit  Pump pressure: 43.38 psi (pressure mode)  Barrel temperatures: 230 °C, 250 °C, (RSU) 270 °C, and 290 °C  Dynisco® Vertex Mercury pressure transducer  Collecting about 40 g of extrudates at each temperature Rheological Control Unit (RCU)

12 Calculation of Activation Energy

1 ln = + ln( ) −𝐸𝐸𝑎𝑎 𝑀𝑀𝑀𝑀𝑀𝑀 𝐴𝐴 𝑅𝑅 𝑇𝑇 Linear fitting equation: y = a+b*x Adj. R-Square: 0.99 -4595.4 Slope (b = -Ea/R) (±92.21) Activation energy 38.2 (kJ/mol)

13 Comparison of Online Measurements and Laboratory MFR Measurements

1

1 Harban, A. A., McClamery, R. M. (1963) “Limitations on Measuring Melt Flow Rates of Polyethylene and Ethylene Copolymers by Extrusion Plastometer,” Materials Research and Standards 3: pp. 906. Online rheometer at various processing temperatures Offline MFR test at standard testing condition on extrudates collected at each processing temperature Offline MFR test on raw PP at various testing temperatures Conclusion

 Application and benefits of online rheology measurements

 ViscoIndicator online rheometer design

 Rheological calculations from capillary rheometer (constant rate) and MFR tester (constant stress) to online rheometer

 Temperature correlation and calculation of activation energy ( ) = ( ) 𝜹𝜹 𝒍𝒍𝒍𝒍 𝑴𝑴𝑴𝑴𝑴𝑴 𝑬𝑬𝒂𝒂 −𝑹𝑹 𝜹𝜹 𝟏𝟏⁄𝑻𝑻 𝑷𝑷

 Good agreement between online and offline MFR measurements at standard conditions 15 “Everything Flows”-Heraclitus https://www.beautifulworld.com/north-america/united-states/the-wave/

Thank You !

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