Thermoreversible crosslinking of maleic anhydride-grafted ethylene-propylene copolymers

1. Thermoreversible crosslinking of maleic • anhydride-grafted ethylene-propylene copolymers • An evaluation of hydrogen bonded and ionic networks Sun Chunxia March 2005 Coaches: Mark van der Mee Han Goossens

2. Contents • Introduction: crosslinking of rubbers • Objectives • Modification with alkylamines • - Preparation • - Results • - Conclusions • Modification with metal acetylacetonates • Preparation • Results • Conclusions • Future work

3. Crosslinking of rubbers • Crosslinking of rubbers • Crosslinking transforms non-elastic base material into an elastic material • Two main commercial technologies: • 1) Sulphur vulcanisation: • 2) Peroxide curing Why? How?

4. Crosslinking of rubbers Problems: х • Prevents processing in the melt • Complicates recycling of scrap & • used products

5. heating cooling Thermoreversible crosslinking • Thermoreversible crosslinking of rubbers: Low temperature: crosslinked material High temperature: crosslinks weaken or disappear Result: A crosslinked elastomer at service temperature that can be processed at elevated temperatures!

6. Crosslinking of rubbers • Microphase separation into MAn-rich domains • Driving force is strong attraction between MAn groups and strong repulsion between polar MAn groups and apolar EPM chains • Domains act as physical crosslinks, increasing network density

7. Thermoreversible crosslinking Several thermoreversible crosslinking techniques Multiple Hydrogen Bonding Ionomer Metal-Ligand complex Diels-Alder reaction Triple Hydrogen Bonding unit Reversible amide XL formation Quadruple Hydrogen Bonding unit Reversible ester XL formation

8. Thermoreversible crosslinking Previous work in this project So far, pure HB is very weak !

9. Thermoreversible crosslinking How to improve it ? • Combination with ionic interactions • Arrays of HB: Ureidopyrimidinones (UPy’s) (E.W. Meijer et al.)

10. Objectives • Modification of MAn-g-EPM with primary amines to an amide-salt • Significantly improves properties with NH3, which is highly volatile DECREASE IN PROPERTIES • Imide formation will occur at elevated temperatures • DECREASE IN PROPERTIES • 2) Addition of metal acetylacetonates (MeAA) to MAn-g-EPM based imides • Modification of MAn-g-EPM with 3-amino-1,2,4-triazole (ATA) only slightly improves the properties • Addition of different MeAA to the ATA-imide introduces ionic interactions Objectives  Use less volatile primary amines (C3, C6, C10, C18) • Study the mechanism for different metals (Co & Zn) and different imides ATA

11. Results (I)-Alkylamines Modification of maleic anhydride-grafted EPM with alkylamines Preparation Solution in THF at R.T. Compression moulding at 180 ºC for 20 minutes

12. Results (I)- Alkylamines Synthesis 1 eq Alkylamine

13. Results (I)- Alkylamines Different ratios FTIR spectra hexylamine modified MAn-g-EPM FTIR spectra octadecylamine modified MAn-g-EPM

14. Results (I)- Alkylamines Tensile tests • Significant improvement in • tensile properties • Trends in TS and modulus not • consistent with alkyl length • Two competing effects: • Long tails disturb aggregate formation • - poor properties • Long tails can crystallize • - improved properties 1 eq Alkylamine C10 > C18 > C3 > C6

15. Results (I)- Alkylamines • Modulus and TS increase with increasing • amount of alkylamine • C18 > C6 crystallization? Different ratios hexylamine octadecylamine

16. Results (I)- Alkylamines Imide of alkyl-amide acids • Imide formation gives poor properties • Poor properties of C18-imide: • No significant crystallization!

17. Results (I)- Alkylamines • FTIR spectroscopy can be used to study reaction of MAn-g-EPM with amines • Modification with different primary amines improves the tensile properties • significantly • Modulus and TS increase with increasing amount of alkylamine • Imide formation leads to poor properties Conclusions

18. Results (II)- Metal acetylacetonates HB with ionic interaction systems • Metal acetylacetonate (CoAA or ZnAA) added to imide (ATA or • C3) in THF at RT • Definition of 1 eq and 2 eq MeAA: • 1 eq MeAA: adding enough metal to coordinate with all the oxygen atoms from the imide groups, assuming a fourfold coordination • 2 eq MeAA: adding the double amount of metal Preparation

19. Results (II)- Metal acetylacetonates • 1 eq MeAA to ATA-imide 2 eq MeAA to ATA-imide Tensile tests

20. Results (II)- Metal acetylacetonates • 1 eq of MeAA to propylimide 2 eq of MeAA to propylimide Tensile tests

21. Results (II)- Metal acetylacetonates Mechanism for coordination propylimide ATA-imide ATA-imide : 1eq Co >> 1eq Zn; 2 eq Zn ≈ 2 eq Co; 2 eq Zn > 1 eq Zn C3-imide : Co ≈ Zn; 1 eq > 2 eq

22. Results (II)- Metal acetylacetonates • Following mechanism was proposed to explain the results: • In propylimide, Co and Zn can only weakly coordinate with O, • leading to comparable properties • In ATA-imide, additional strong coordination with N from the ATA-ring is • possible. Two different situations: • Co likes to coordinate with N, so good properties are obtained for both low and high amounts • Zn likes to coordinate with O, so an excess of Zn has to be added to force strong coordination with N to get good properties. Conclusions

23. Future work Future work • The effect of the tail length and the amount of the primary amines on the properties will be further investigated • The influence of temperature and amount of octadecylamine on crystallization and mechanical properties will be studied • Other systems of HB combined with ionic interactions will be prepared and evaluated, trying to avoid imide formation • The exact coordination mechanism of MeAA modified MAn-g-EPM will be further investigated by EXAFS • EXAFS can get information about coordination around metals

24. Acknowledgements • Otto van Asselen • Jules Kierkels • All other colleagues of SKT Acknowledgement Thanks

25. Structures and Names

26. Mechanism of 4 fourfold coordination ATA-imide +2 eq CoAA ATA-imide +1 eq CoAA

27. Mechanism of 4 fourfold coordination ATA-imide + 1 eq ZnAA ATA-imide+ 2 eq ZnAA

28. Future work