Rheologica Acta

, Volume 51, Issue 1, pp 71–80 | Cite as

Time- and temperature-dependent crosslinking behaviour of a silicone resin

  • Friedrich Wolff
  • Christoph Kugler
  • Helmut Münstedt
Original Contribution

Abstract

The crosslinking behaviour of a silicone resin which is interesting from a technical point of view was investigated by means of rheology. In order to accelerate the crosslinking process, zinc acetylacetonate and aluminium acetylacetonate were applied as latent catalysts. The effect of the type of catalyst, its concentration, and the temperature on crosslinking was determined by isothermal dynamic-mechanical measurements. A radial gradient in crosslinking causes the gel point to be reached earlier at the outer edge of the sample in the rheometer. This radial gradient is averaged when measuring G′ and G″. Therefore, since the physically well-defined state of critical gelation (gel point) could not be obtained from the data, the time at which a distinct crosslinking state is reached was determined by the crossover of the moduli G′ and G″. For this distinguished point, the denotation gelation index GI is introduced. The gelation indices measured at different temperatures follow an Arrhenius-type relationship. Activation energies between 89 and 126 kJ/mol were determined. They were found to be dependent on the type of catalyst used but independent of its concentration. The activation energies of the crosslinking processes enable the calculation of the gelation index at temperatures not measured directly.

Keywords

Silicone resin Crosslinking behaviour Viscoelasticity Catalysts Temperature dependence 

References

  1. Arii T, Kishi A (2006) Humidity controlled thermal analysis. The effect of humidity on thermal decomposition of zinc acetylacetonate monohydrate. J Therm Anal Calorim 83:253–260CrossRefGoogle Scholar
  2. ASTM D 4473-08 (2008) Standard test method for plastics: dynamic mechanical properties: cure behaviorGoogle Scholar
  3. Balan C, Riedel R (2006) Rheological investigations of a polymeric precursor for ceramic materials: experiments and theoretical modeling. J Optoelectron Adv Mater 8:561–567Google Scholar
  4. Chambon F, Winter HH (1985) Stopping the crosslinking reaction in a PDMS polymer at the gel point. Polym Bull 13:499–503CrossRefGoogle Scholar
  5. Chambon F, Winter HH (1987) Linear viscoelasticity at the gel point of a crosslinking PDMS with imbalanced stoichiometry. J Rheol 31:683–697CrossRefGoogle Scholar
  6. Chambon F, Petrovic ZS, MacKnight WJ, Winter HH (1986) Rheology of model polyurethanes at the gel point. Macromolecules 19:2146–2149CrossRefGoogle Scholar
  7. Dunstan PO (1999) Thermochemistry of adducts of bis(2,4-pentanedionato)zinc with heterocyclic amines. J Chem Eng Data 44:243–247CrossRefGoogle Scholar
  8. Greil P (1995) Active-filler-controlled pyrolysis of preceramic polymers. J Am Ceram Soc 78:835–848CrossRefGoogle Scholar
  9. Greil P (2000) Polymer derived engineering ceramics. Adv Eng Mater 2:339–348CrossRefGoogle Scholar
  10. Ismail HM (1991) A thermoanalytic study of metal acetylacetonates. J Anal Appl Pyrolysis 21:315–326CrossRefGoogle Scholar
  11. Man Z, Stanford JL, Dutta BK (2009) Reaction kinetics of epoxy resin modified with reactive and nonreactive thermoplastic copolymers. J Appl Polym Sci 112:2391–2400CrossRefGoogle Scholar
  12. Rudolph G, Henry MC (1964) The thermal decomposition of zinc acetylacetonate hydrate. Inorg Chem 3:1317–1318CrossRefGoogle Scholar
  13. Scanlan JC, Winter HH (1991) Composition dependence of the viscoelasticity of end-linked poly(dimethylsiloxane) at the gel point. Macromolecules 24:47–54CrossRefGoogle Scholar
  14. Smith JDB (1981) Metal acetylacetonates as latent accelerators for anhydride-cured epoxy resins. J Appl Polym Sci 26:979–986CrossRefGoogle Scholar
  15. Takahashi T, Colombo P (2003) SiOC ceramic foams through melt foaming of a methylsilicone preceramic polymer. J Porous Mater 10:113–121CrossRefGoogle Scholar
  16. Takahashi T, Kaschta J, Münstedt H (2001) Melt rheology and structure of silicone resins. Rheol Acta 40:490–498CrossRefGoogle Scholar
  17. Tung CYM, Dynes PJ (1982) Relationship between viscoelastic properties and gelation in thermosetting systems. J Appl Polym Sci 27:569–574CrossRefGoogle Scholar
  18. Winter HH (1987) Can the gel point of a cross-linking polymer be detected by the G′–G″ crossover? Polym Eng Sci 27:1698–1702CrossRefGoogle Scholar
  19. Winter HH, Chambon F (1986) Analysis of linear viscoelasticity of a crosslinking polymer at the gel point. J Rheol 30:367–382CrossRefGoogle Scholar
  20. Winter HH, Mours M (1997) Rheology of polymers near liquid–solid transitions. Adv Polym Sci 134:165–234CrossRefGoogle Scholar
  21. Wolff F, Münstedt H (2011) Continuous direct melt foaming of a preceramic polymer using carbon dioxide: extrusion device and first results. J Mater Sci 46:6162–6167CrossRefGoogle Scholar
  22. Wolff F, Kugler C, Münstedt H (2010) Viscoelastic properties of a silicone resin during crosslinking. Rheol Acta (in press). doi:http://10.1007/s00397-010-0513-2
  23. Zhang Z, Wong CP (2002) Study on the catalytic behavior of metal acetylacetonates for epoxy curing reactions. J Appl Polym Sci 86:1572–1579CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Friedrich Wolff
    • 1
  • Christoph Kugler
    • 1
  • Helmut Münstedt
    • 1
  1. 1.Institute of Polymer Materials, Department of Materials ScienceFriedrich-Alexander-University Erlangen-NürnbergErlangenGermany

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