Elongational Viscosity in Quality Control. Manfred Stadlbauer Raw Material Characterization 13.2

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1 Elongational Viscosity in Quality Control Manfred Stadlbauer Raw Material Characterization 13.2

2 Content Performance Polyolefins for Extrusion Coating Selected Resins QC Parameters vs. EC Performance Summary Paper 13.2 Manfred Stadlbauer 2

3 Performance Positioning of Borealis Polyolefins for Extrusion Coating High Chemical resistance Heat resistance Stiffness Medium Convent. PP Convent. HDPE mlld Daploy TM HMS PP HDPE CG8410 Borstar mlld Barrier Sealing LDPE Low Bad Good Excellent Processability Paper 13.2 Manfred Stadlbauer 3

4 Overview of high performance polyolefins for extrusion coating Polyethylenes LDPE Tailored LLDPE Tailored HDPE Polypropylenes PP-H/HMS-PP Compounds PP-R/HMS-PP Compounds PP-I/HMS-PP Compounds Key characteristic is strain hardening elongational viscosity and melt elasticity. Paper 13.2 Manfred Stadlbauer 4

5 Rheological characteristics Melt Elasticity lg G'' 2 G''=500Pa lg G''= lg G' Paper 13.2 Manfred Stadlbauer 5

6 Rheological characteristics Melt Elasticity G G =500Pa from the Cole-Cole plot is easy to access allows assessing draw-down and neck-in Lot-to-lot deviations can be captured Application is restricted to homologous systems (e.g. HMS-PP series) NI DD [m/min] 0,35 0,30 0,25 0,20 10g/m², 300m/min 20g/m², 200m/min 20g/m², 300m/min 0, G' [cn] G' [Pa] Paper 13.2 Manfred Stadlbauer 6

7 Rheological characteristics Melt Strength and Melt Extensibility PP-homo HMS MFR = 22 Melt Strength [cn] PP/PE modified MFR = 25 PP-copo HMS MFR = 16 Conventional PP MFR = 20 Drawability [mm/s] Paper 13.2 Manfred Stadlbauer 7

8 Rheological characteristics Melt Strength and Melt Extensibility Melt strength and melt extensiblity require dedicated equipment (Rheotens, preferrably in Wagner-setup) needs 1kg material data acquisition takes ca. 2hr time Neck-in can be assessed well Melt extensibility is not a sensitive measure to describe extrusion coating performance NI DD [m/min] 0,35 0,30 0,25 0,20 10g/m², 300m/min 20g/m², 200m/min 20g/m², 300m/min 0, F max [cn] v max [mm/s] Paper 13.2 Manfred Stadlbauer 8

9 Interrelation of Melt Elasticity, Melt Strength and Melt Extensibility For homologous systems (e.g. HMS-PP blends), melt extensibility correlates with melt elasticity v max [mm/s] For homologous systems, melt strength correlates with zeroshear-viscosity G' G''=500Pa [Pa] branched F max [cn] 3 2 linear η 0 [Pa s] Paper 13.2 Manfred Stadlbauer 9

10 Focus on SER Paper 13.2 Manfred Stadlbauer 10

11 Rheological characteristics Strain Hardening Viscosity LDPE (MFR 190/2.16 =20) can be measured accurately with strain rates up to 10s -1 3s -1 1s -1 Pronounced strain hardening is detected (DD=500m/min) 10s -1 Elongational viscosities of ~10 4 Pa s measureable Paper 13.2 Manfred Stadlbauer 11

12 Rheological characteristics Strain Hardening Viscosity HMS-PP (MFR 230/2.16 =12) can be measured accurately with strain rates up to 10s -1 Pronounced strain hardening is detected (DD=300m/min) -1 10s 3s-1 1s-1 0.3s -1 Elongational viscosities of ~10 4 Pa s measureable Paper 13.2 Manfred Stadlbauer 12

13 Strain Hardening versus Rheotens Parameter lcb MFR F 30 v 30 SHI g/10 cn mm/s % HDPE , LLDPE - 1,2 6, LDPE +++ 4,5 9, ipp --- 2, <0 25% HMS + 75% ipp + 2, % HMS + 75% ipp + 2, % HMS + 25% ipp ++ 3, HMS-PP +++ 2, Paper 13.2 Manfred Stadlbauer 13

14 SER vs. Rheotens (Isothermal stressing vs. fibre spinning) Advantages of SER Advantages of Rheotens Isothermal Experiment Strain Hardening Index (SHI) independent of MFR Very accurate Little amount of material needed Short measurement time Homogenisation of the sample in the extruder (Wagnersetup) Large polymer libraries available Melt strength well accepted in industries Paper 13.2 Manfred Stadlbauer 14

15 Summary High-performance extrusion coating resins require advanced product specifications Elongational flow properties are key in assessing the performance of polyolefins in extrusion coating Novel extensional stressing experiments allow rapid and accurate measurement of transient elongational viscosity of (high-flow) extrusion coating resins Paper 13.2 Manfred Stadlbauer 15