A 21 st Century Toolbox for Characterizing Next Generation Extrusion Coating Resins

Transcription

1 A 21 st Century Toolbox for Characterizing Next Generation Extrusion Coating Resins A. Willem degroot Peter Arnoudse Sjoerd De Vries Session 13 Paper 4 Registered Trademark of The Dow Chemical Company

2 Introduction Plastics Characterization A global, business aligned Characterization Capability, part of Basic Plastics R&D Complement Corporate Analytical Sciences Capability Roles: High-Quality, Low-Cost Testing Service Project & Problem-Solving Support Develop new measurement technology for product and process characterization Benefit to the Plastics Business Faster Speed of Response due to close partnership, product specific knowledge & experience, flexible allocation of resources Paper 13.4 A. Willem degroot 2

3 Overview of Capabilities Internal Capabilities Separations Science molecular weight, comonomer distribution, long-chain branching analytical and preparative scale separations Rheology/Thermal capillary, rotational, & extensional rheology DSC, TGA, TMA Fabrication & Physical Testing variety of fabrication capabilities and full range of mechanical testing; weathering capabilities Analytical structural and compositional analysis additives, decomposition, contamination Sensory Testing Taste & Odor, Appearance, Haptics Manufacturing On line analytical tools Paper 13.4 A. Willem degroot 3

4 Separations Science s Role Materials Science Product Development Separations Science TS&D Catalyst Development Manufacturing Competitive Analysis Paper 13.4 A. Willem degroot 4

5 Resources and Leveraging Internal Corporate Analytical Sciences Computer science and modeling Robotics External Universities Government laboratories Consultants Paper 13.4 A. Willem degroot 5

6 Separations Science Toolbox Mw, Mn, Mz etc. High temperature GPC, Triple detector GPC, GPC-MALLS LCB, LCBd Triple detector GPC, GPC-MALLS, NMR CD (comonomer content and distribution) ATREF, CRYSTAF, DSC, GPC-IR, NMR Paper 13.4 A. Willem degroot 6

7 Extrusion Coating Process The forces acting on the extruded web need to be in balance. Neck-in Drawdown The drawdown force relates to the melt strength. The neck-in force relates to stored energy or elasticity. Paper 13.4 A. Willem degroot 7

8 Molecular Structure LLDPE LDPE Fast Extension Rate Slow Paper 13.4 A. Willem degroot 8

9 Gap in Capabilities Detailed Long Chain Branch Structure Information Comonomer distribution as a function of molecular weight Molecular weight distribution as a function of comonomer content Sensitive analysis of the highest molecular weight components Paper 13.4 A. Willem degroot 9

10 Three New Tools for our Toolbox Fast Cross Fractionation Combination of Triple detector GPC and ATREF Forward or reverse mode Triple Detector - Asymmetric Flow Field Flow Fractionation (AF4) Characterizes long chain branches Characterizes high molecular weight component Molecular Topology Fractionation New Dow developed technique for fractionating long chain branched polymers Paper 13.4 A. Willem degroot 10

11 Triple Detector Cross-Fractionation Unit ATREF + 3DGPC IR Detector (PolymerChar) Viscometer LS Detector GPC Columns ATREF Column Ovens Waters 150C High Temperature Chromatograph High Temperature Autosampler Paper 13.4 A. Willem degroot 11

12 Cross-Fractionation Separation by Molecular Weight GPC Elution Volume (cc) Elution Volume (cc) Elution Volume (cc) Elution Volume (cc) ATREF Temperature ( C) Paper 13.4 A. Willem degroot 12 Separation by Short-chain Branching Dowlex 2056A (0.920 Density)

13 3D Cross Fractionation Data ATREF Temperature Paper 13.4 A. Willem degroot Weight Fraction Log M

14 Asymmetrical Flow Field-Flow Fractionation (AF4) The separation takes place in a channel cut out of a plastic spacer, which is subsequently sandwiched between a solid top wall and a porous bottom wall. The porous wall is overlaid by a membrane that is permeable for the solvent but not for the sample. Cross-flow pump AF4 flow scheme Inlet pump Injector Focus pump SS top plate AF4 channel Trapezoidal-shaped channel cut from spacer Flow in Focus in Flow out Inflow Focus flow Outflow Spacer (height: 350 µm) AF4 channel Waste Detectors SS bottom plate (acc wall) 30 cm 6 cm Cross flow Solvent is pumped through the channel from Inlet to Outlet. The cross-flow pump generates a second flowstream perpendicular to the axial solvent flow. Membrane Porous frit (determines min Mw cutoff) SCM-3Paper 13.4 A. Willem degroot 14

15 Inflow Outflow HTAF4 channel x Parabolic flow profile z AF4 separation mechanism Sample zone Cross-flow Diffusion Top wall w = 350 µm Porous accumulation wall Separation occurs because polymers with different sizes form layers of different thicknesses close to the accumulation wall. The differential displacement along the channel is the result of the parabolic profile of the axial flowstream. The average elevation of the polymer cloud above the wall determines the migration speed and the retention time. l Distance from accumulation wall Concentration Exponential conc. distribution SCM-3Paper 13.4 A. Willem degroot 15

16 HTAF4/HTGPC dual mode set-up Waste Waters GPCV2000 Temperature: 145 C GPC columns Visc GPC pump Waters Alliance 0.7 / 1 ml/min Solvent: 1,2,4-TCB AF4 pump Injector V ini : 200 µl C inj : mg/ml 3 PL mixed B/ 4 PL mixed A Waters RI Waters MALS Wyatt DSP Focus pump Cross-flow pump Postnova AF2000 AF4 channel (ceramic membrane) IR Polymer Char Focusing: Elution: Time: 240 s Flow out: 0.7 ml/min Flow in: 0.7 ml/min Several gradients Focus flow: 2 ml/min Switch from one mode to the other without the need to cool down the instrument Continuous flow through the instrument SCM-3Paper 13.4 A. Willem degroot 16

17 LDPE analysis: HTAF4 vs. HTGPC Shoulder as a result of exclusion effects HTGPC RMS Radius vs. Volume Late elution of branched material Borealis LDPE A CA7230 LDPE PG7014 B 5 LDPE PG7014 C 6 R.M.S. Radius (nm) High Mw is cut-off No separation of ultrahigh Mw material Volume (ml) The distribution of the high Mw species is distorted due to exclusion and late elution SCM-3Paper 13.4 A. Willem degroot 17

18 LDPE analysis: HTAF4 vs. HTGPC RMS Radius vs. Volume No shoulder at high Mw end is detected HTAF4 LDPE A LDPE B LDPE C R.M.S. Radius (nm) Low Mw fraction (< ) is lost through the membrane Volume (ml) Significant difference between samples in the high Mw range HTAF4 allows us to quantify the differences HTAF4 shows a better separation of the high Mw components SCM-3Paper 13.4 A. Willem degroot 18

19 MTF Concept GPC Instrument System Equipped with a Unique Column Designed to Provide Tortuous Channels of roughly Molecular Dimensions The more branching, the later the elution Branched Mixture In Branched Fractions Out Paper 13.4 A. Willem degroot 19

20 Tortuous channels via a packed bed of spheres Direct visualization of macromolecules via microscopy Unpublished results: Professor David A. Hoagland and Chad DeLong, University of Massachusetts Paper 13.4 A. Willem degroot 20

21 Fluorescently Labeled DNA Flowing Through a Packed Bed of Spheres Professor D. A. Hoagland and Chad DeLong University of Massachusetts Paper 13.4 A. Willem degroot 21

22 MTF Elution Reversal -- Flowrate Dependence Effect of Flow Rate on Elution Profile Small Pore Monolithic - PS Standards ml/min ml/min ml/min ml/min ml/min 6 log M Elution Volume (ml) Meunier, D. M.; Smith, P. B.; Baker, S. A. Macromolecules 2005, 38, Paper 13.4 A. Willem degroot 22

23 Ultra Violet Response (mv) ;03;17_3_Arm_Star_02.vdt Method: UV 3ArmStar 4M Retention Volume (ml) Method : UV 3ArmStar 4MixedB WF / dlog MW x x10 6 Mn Mw Mz Log Molecular Weight x10 6 log IV Polystyrene 3-Arm Star GPC and Mark Houwink Plot vcm Star and Linear PS log M log IV (star) log IV (linear) Log Molecular Weight Paper 13.4 A. Willem degroot

24 Separation of Star Branched Polymers by MTF Data File: _04;47;32_3arm_04.vdt Method: areaonly-0000.vcm ,500 kg/mol Right Angle Light Scattering Response (mv) ,250 kg/mol 3,750 kg/mol 5,000 kg/mol Retention Volume (ml) Near baseline resolution of all species Separation of linear from branched and branched based on topology Paper 13.4 A. Willem degroot 24

25 MTF Retention of PS Stars Versus Linear Chains 8 Linear Chains Stars log M Relative Elution Volume Paper 13.4 A. Willem degroot 25

26 Conclusion Today s resins with complex molecular structural designs require the polymer analytical chemist to continue to add new capabilities to their characterization toolbox. Dow continues to develop new advanced tools to aid in new advanced resin, catalyst and process. Paper 13.4 A. Willem degroot 26

27 Acknowledgements Dave Meunier Ted Stokich Pat Smith Edwin Mes Hans De Jonge David Gillespie Colin Li Pi Shan Lonnie Hazlitt Jeff Weinhold Paper 13.4 A. Willem degroot 27