Advertisement

Effect of temperature-cycling on the morphology of polymeric thermotropic glazings for overheating protection applications

  • Andreas WeberEmail author
  • Katharina Resch
Original Paper

Abstract

In this paper, the morphology of thermotropic systems with fixed domains (TSFD) was evaluated applying high resolution Atomic Force Microscopy (AFM) also upon heating and cooling. Furthermore nano-mechanical characteristics of the samples were determined by means of Force/Distance spectrometry. TSFD formulated with additive types exhibiting a short chain length displayed roughly spherical scattering particles with dimensions between 0.6 μm and 4 μm. By means of Force Distance spectroscopy stiffness values of 0.6 N/m and 7.8 N/m were determined for the scattering domains and the matrix, respectively. Upon heating, melting and deliquescence of the additive along with migration was ascertained. After cooling to ambient temperature the formation and growth of terrace-like additive domains on the surface was recorded. Additive types with long-chain molecules developed anisotropic scattering domains resembling distorted disks without predominating orientation. Diameters up to 50 μm and a thickness between 200 nm and 600 nm were ascertained. Determination of stiffness yielded values of 0.9 N/m and 13.1 N/m of the scattering domains and the matrix, respectively. Upon heating, swelling and deliquescence of the additive were detected. After cooling to ambient temperature a partial recovery of swelling was observed. Force-Distance spectroscopy yielded a 5 to 10 nm thick additive layer which coated wide areas of the surface after the heating cycle for all samples investigated.

Keywords

Thermotropic systems with fixed domains Atomic force microscopy Scattering domain size Force distance curve Phase imaging 

Notes

Acknowledgments

The research work of this paper was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the Kplus-program of the Austrian Ministry of Traffic, Innovation and Technology with contributions by the University of Leoben. The PCCL is funded by the Austrian Government and the State Governments of Styria and Upper Austria.

The investigated samples were obtained from a project of the non Kplus-program, which is funded by the State Government of Styria, Department Zukunftsfonds Steiermark. The authors wish to express their acknowledgements to Cytec Surface Specialties (Drogenbos, BEL), Sasol Germany GmbH (Hamburg, GER) and Chemson Polymer Additive AG (Arnoldstein, AUT), for providing the materials. Special thanks go to the Austrian Center for Electron Microscopy and Nanoanalysis (Graz, AUT) for sample preparation. The authors are grateful to Franz Schmied (Institute of Physics, University of Leoben, Austria) for technical support on the Atomic Force Microscope.

References

  1. 1.
    Nitz P, Hartwig H (2005) Solar control with thermotropic layers. Sol Energy 79:573–582CrossRefGoogle Scholar
  2. 2.
    Nitz P, Wagner A (2002) Schaltbare und regelbare Verglasungen. BINE Themeninfo I/02:1–12Google Scholar
  3. 3.
    Seeboth A, Schneider J, Patzak A (2000) Materials for intelligent sun protecting glazing. Sol Energy Mater Sol Cells 60:263–277CrossRefGoogle Scholar
  4. 4.
    Resch K, Wallner GM (2009) Thermotropic layers for flat-plate collectors—A review of various concepts for overheating protection with polymeric materials. Sol Energy Mater Sol Cells 93:119–128CrossRefGoogle Scholar
  5. 5.
    Yao J, Zhu N (2012) Evaluation of indoor thermal environmental, energy and daylighting performance of thermotropic windows. Build Environ 49:283–290CrossRefGoogle Scholar
  6. 6.
    Resch K, Hausner R, Wallner GM (2007) All polymeric flat-plate collector — potential of thermotropic layers to prevent overheating. In: Goswami DY, Zhao Y (eds) Proceedings of ISES Solar World Congress 2007. Solar energy and human settlement. Tsinghua University Press/Springer, Beijing/Berlin, pp 561–565Google Scholar
  7. 7.
    Wallner GM, Resch K, Hausner R (2008) Property and performance requirements for thermotropic layers to prevent overheating in an all polymeric flat-plate collector. Sol Energy Mater Sol Cells 92:614–620CrossRefGoogle Scholar
  8. 8.
    Nitz P (1999) Optical modelling and characterisation of thermotropic systems. PhD-Thesis, Albert-Ludwigs-University, FreiburgGoogle Scholar
  9. 9.
    Resch K, Wallner GM, Hausner R (2009) Phase separated thermotropic layers based on UV cured acrylate resins – Effect of material formulation on overheating protection properties and application in a solar collector. Sol Energy 83:1689–1697CrossRefGoogle Scholar
  10. 10.
    Resch K, Wallner GM (2009) Morphology of phase-separated thermotropic layers based on UV cured acrylate resins. Polym Adv Technol 20:1163–1167CrossRefGoogle Scholar
  11. 11.
    Resch K, Wallner GM, Lang RW (2008) Spectroscopic investigations of phase-separated thermotropic layers based on UV cured acrylate resins. Macromol Symp 265:49–60CrossRefGoogle Scholar
  12. 12.
    Resch K, Weber A (2011) Smart Windows - Smart Collectors: Entwicklung von funktionalen Überhitzungsschutzverglasungen für Gebäudeverglasungen und thermische Solarkollektoren. Berg- Huettenmaenn Monatsh 156:429–433CrossRefGoogle Scholar
  13. 13.
    Raghavan D, Gu X, Nguyen T, VanLandingham M, Karim A (2000) Mapping polymer heterogeneity using atomic force microscopy phase imaging and nanoscale indentation. Macromolecules 33:2573–2583CrossRefGoogle Scholar
  14. 14.
    Pickering JP, Vancso GJ (1998) Apparent contrast reversal in tapping mode atomic force microscope images on films of polystyrene-b-polyisoprene-b-polystyrene. Polym Bull 40:549–554CrossRefGoogle Scholar
  15. 15.
    Achalla P, McCormick J, Hodge T, Moreland C, Esnault P, Karim A, Raghavan D (2006) Characterization of elastomeric blends by atomic force microscopy. J Polym Sci B Polym Phys 44:492–503CrossRefGoogle Scholar
  16. 16.
    Hutter JL, Bechhoefer J (1993) Calibration of atomic-force microscope tips. Rev Sci Instrum 64:1868CrossRefGoogle Scholar
  17. 17.
    Weber A (2010) Analyse der Morphologie und des Schaltvorganges von thermotropen Polymeren mittels Rasterkraftmikroskopie. Master Thesis, University of Leoben, LeobenGoogle Scholar
  18. 18.
    Cappella B, Silbernagl D (2007) Nanomechanical properties of mechanical double-layers: a novel semiempirical analysis. Langmuir 23:10779–10787CrossRefGoogle Scholar
  19. 19.
    Domke J, Radmacher M (1998) Measuring the elastic properties of thin polymer films with the atomic force microscope. Langmuir 14:3320–3325CrossRefGoogle Scholar
  20. 20.
    Cappella B, Silbernagl D (2008) Nanomechanical properties of polymer thin films measured by force–distance curves. Thin Solid Films 516:1952–1960CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Polymer Competence Center Leoben GmbHLeobenAustria
  2. 2.Materials Science and Testing of Polymers, Department Polymer Engineering and ScienceUniversity of LeobenLeobenAustria

Personalised recommendations