Effects of Nanoclay Structure on the Mechanical Properties of EPDM

1. PJ Yoon*, Marcus Goss Southern Clay Products Gonzales, TX Carl McAfee McAfee Consulting LLC Kennedale, TX Fall 170th Technical Meeting of the Rubber Division, American Chemical Society Effects of Nanoclay Structure on the Mechanical Properties of EPDM *pyoon@scprod.com

2. Objectives and Outline Objectives • Current nanoclays performance in rubber, i.e., EPDM • Synergetic role of nanoclays with CB or silica Outline • Nanoclay structure and chemistry • Cure behavior of nanoclay • Nanoclay performance in EPDM • Nanoclay compatibilization in EPDM • Nanoclay and silica performance in EPDM • Summary • Acknowledgements

3. Nano Tool Benefits • Reinforcing filler • Increase modulus and tensile strength • Improve barrier properties • Increase dimensional stability • Widen processing window • Yield lower density

4. 10 microns Microscopy Smectite Clays SEM Bentonite RockTEM Montmorillonite 1 micron

5. ~100 nm Key Properties of Montmorillonite • High Modulus: ~170 GPa • Shape: Platelet with high aspect ratio • Size: 1nm thick, 75-150 nm across • Surface Area: >750 m2/g (12g/football field) • Charge: unit cell 0.5-0.75 charge; 92 meq/100g clay • Swellability Montmorillonite & Surface Treatment _ _ _ _ _ _ _ _ Exfoliation _ _ _ -OH _ Polymer Matrix Processing

6. Treatment Chemistries * Variations: Quaternary Ammonium Salt, Loading 2M2HT2MBHT 2MHTL8 Investigated in this presentation HT: Hydrogenated Tallow (~C18) T: Tallow (partially unsaturated C18) HTL8: - ethylhexyl no treatment MT2EtOH M2HT

7. The Processing Challenge 8µmParticle >1 Million Platelets

8. The Challenge & Benefit If the aspect ratio increased from 10 to 30 at 3% volume fraction, the permeability reduction improved from 84% to 68%.

9. Nanoclay in EPDM

10. Cure Behavior of Organoclay Peroxide Cure • GEO Specialty • Inert to peroxide, little change in T90 Standard Package ZnO: 5 SA: 2 ZDEC: 1.5 Sulfur Cure • Surface adsorption - activator - accelerator • Need to adjust curative

11. Compounding and Cure Compounding (Brabender, 15 min) EPDM (G8450, G5450) 100 EPDM-MA (Royaltuf 498) Variable Organoclay (C15A, C20A, C10A) Variable Antioxidant (Agerite D) 1 * Organoclay : EPDM-MA = 1 : 1 Peroxide Cure (170 C, 18 min) Peroxide (VulCup 40KE ) 5 Coagent (SR-708) 2 Retarder (Ethanox 703) 0.3

12. Tensile Properties of EPDM Nanocomposites MMT = 5.4 wt% • C15A > C20A > C10A in strength & elongation • Two long alkyl chains, higher loading favored for EPDM • - Maleated EPDM increased strength

13. Tensile Balance of EPDM Nanocomposites With EPDM-MA • - Maleated EPDM increased modulus • Maleated EPDM made no difference in elongation • Homogeneous & higher aspect ratio tactoids

14. Tensile Balance as FMMT * EPDM-MA included • - Steep increase in strength as MMT% • C15A max strain is higher than C20A • Modulus is increased linearlyand • identical. • - High loading of surfactant favored

15. XRD for EPDM Nanocomposites MMT = 5.4 wt%  • Current surfactant yieldedintercalated structure in EPDM • insignificant change before and after cure • insignificant change with maleated EPDM

16. TEM Dispersion Quality * EPDM-MA included C15A C20A - Overall dispersion is excellent - No significant difference between C15A and C20A

17. TEM Dispersion Quality C10A 2 platelets 5 platelets • For C10A, larger and thicker particle lead to fewer # of reinforcing filler • Final particle of 2-5 platelets with ~170 nm length leads to 10-30 aspect ratio

18. Aspect Ratio for Intercalated Particle d001 = 35 A

19. Model Fits Rod-like Filler Disk-like Filler Guth Eq.: aspect ratio ~ 17 Halpin-Tsai Eq.: aspect ratio ~15 Chow Eq.: aspect ratio ~ 40 (Chow Eq. for nylon 6: ~ 100) (~ 30 % reduction in Permeability)

20. 100 nm Pre-dispersed Organoclay • Maleated EPDM as host • 100 phr masterbatch • Homogeneous dispersion • Can utilize TSE & other • T process < 200 C needed

21. Pre-dispersed Organoclay in EPDM 5.4% MMT • For C15A • TSE low temp favored • but not much different 5.4% MMT • For C10A • TSE low temp favored • Significant improvement *TSE: Twin Screw Extruder INT: Internal Mixer H: high shear config. L: low shear config.

22. Nanoclay+Silica in EPDM

23. Compound and Cure counted EPDM-MA as rubber phase Silica: Hi Sil 233 (BET 150 m2/g) ) Method 1: Silica masterbatch Method 2: Direct Method 3: Silica masterbatch, C15A masterbatch

24. TEM Dispersion Quality CSi-1 (MMT : Silica = 0: 14.3) Strong aggregate and network

25. TEM Dispersion Quality CSi-5 (MMT : Silica= 3.3 : 11.0)

26. Cure Behavior of C15A + Silica - MH Gradually decrease - T90 little change

27. Tensile Behavior of C15A + Silica • - Strength increase up to 6wt% MMT • - M100 little change • Elong. at break increase up to 4wt%

28. Dynamic Fatigue Behavior of C15A + Silica De Mattia Method 1 (silica MB) Method 2 (direct) • Exponential increase to over 250 k cycles

29. Summary • For EPDM, two tail surfactant (2M2HT) was favored in dispersion of • organoclay, and tensile properties. High loading of 2M2HT was • also favored for EPDM; more organophilic nanoclay is suitable • to EPDM. • For less compatible organoclay, pre-dispersion in maleated EPDM • was greatly effective in enhancing tensile properties. It may be • related to loosen tactoid aggregates by maleated EPDM molecule. • For mixed C15A and silica fillers, organoclay improved tensile • and fatigue properties in EPDM. Apparently, it seems optimum • composition exists. • Dynamic mechanical test is in progress to understand silica • network as a function of MMT. Black and nanoclay also in progress.

30. Acknowledgements • Prof. Donald Paul at UT • Dr. Peter Dluzneski of GEO Specialty Chemicals • Steve Henning of Sartomer • Steve Chase of Excel Polymers for masterbatches • Lanxess, Crompton for providing the material • SH Bum at UA, Dr. DH Kim at UT • SCP