C1: Multi-Functional Polymeric Materials


Thermotropic glazings for overheating protection. I. Material preselection, formulation, and light-shielding efficiency
Journal of Applied Polymer Science 131 (4), 2014, doi: 10.1002/app.39950
February 2014
By: Weber, A., Resch, K.
Publisher: Wiley Periodicals, Inc.
--- This article presents a systematic strategy for formulation and optimization of thermotropic layers for overheating protection purposes. Specifically, thermotropic systems with fixed domains (TSFD) which consist of a thermotropic additive finely dispersed in a matrix material are considered. Based on systematic material (component) preselection regarding thermoanalytical characteristics and refractive indices, numerous thermotropic layers were formulated. [....]
Thermotropic glazings for overheating protection. I. Material preselection, formulation, and light-shielding efficiency
Thermotropic glazings for overheating protection. II. Morphology and structure-property relationships
Journal of Applied Polymer Science 131 (4), doi: 10.1002/app.39910
February 2014
By: Weber, A., Schmid, A., Resch
Publisher: Wiley Periodicals, Inc.
--- This article completes a systematic strategy for formulation and optimization of thermotropic systems with fixed domains (TSFDs) for overheating protection purposes. Focus was on characterization of morphology and on revealing optimization potential. A comprehensive characterization of scattering domain size and shape was done applying optical microscopy and scanning electron microscopy. In general, scattering domains exhibited inappropriate size and/or shape for optimum overheating protection performance ...
Thermotropic glazings for overheating protection. II. Morphology and structure-property relationships
Thermotropic Overheating Protection Glazings: Effect of Functional Additives and Processing Conditions on Light-Shielding Efficiency
Journal of Polymer Engineering 2014 Vol: 34(2):161-172. DOI: 10.1515/polyeng-2013-0275
February 2014
By: Weber, A., Resch, K.
Editor: Grizzuti, Nino
Publisher: Walter de Gruyter GmbH
--- Within this study, the effect of functional additives and processing conditions on the overheating protection performance of thermotropic systems with fixed domains (TSFD) for overheating protection purposes was evaluated. The focus was on improving the overheating protection performance of a prototype TSFD based on a UV curable acrylate resin by optimization of the material constitution (addition of functional additives like surfactants and nucleating agents) and the processing conditions (temperature conditions during manufacturing, annealing). For the evaluated system, an effect of the nucleating agent on the overheating protection performance was ascertained. Furthermore, omission of an annealing step improved the overheating protection performance slightly.
ISBN: ISSN (Online) 2191-0340
Thermotropic Overheating Protection Glazings: Effect of Functional Additives and Processing Conditions on Light-Shielding Efficiency
Thermotropic systems with fixed domains exhibiting enhanced overheating protection performance
Journal of Applied Polymer Science 131 (12), doi: 10.1002/app.40417
February 2014
By: Weber, A., Resch, K.
Publisher: Wiley Periodicals, Inc.
--- Within this study, a time saving photo-initiated miniemulsion polymerization process (duration of polymerization was 15 min) was established in order to encapsulate a paraffin wax with an acrylate polymer shell. The obtained freeze-dried latex was an off-white powder exhibiting spherical particles with mean diameters around 400 nm and a concentration of paraffin wax around 56% ...
Thermotropic systems with fixed domains exhibiting enhanced overheating protection performance
A Model of the Optical Properties of a Non-absorbing Media with Application to Thermotropic Materials for Overheat Protection,
Energy Procedia 30 (2012) 116-124
November 2012
By: A. Gladen, J.H. Davidson, S, Mantell, J. Zhang, Y. Xu
Publisher: Elsevier Ltd.
--- Thermotropic materials offer the potential to provide overheat protection for polymer absorbers. These materials are composed of a matrix material in which a second material, referred to as the scattering domain, is dispersed. Temperature control is accomplished by a reduction in transmittance at a desired temperature corresponding to the phase change temperature of the scattering domain. The phase change is accompanied by a change in refractive index. This paper describes a numerical model to predict the transmittance and reflectance of a polymer based thermotropic material as a function of the relative index of refraction m between the matrix and scattering domains, the scattering domain size and volume fraction fv, and the sheet thickness ...
A Model of the Optical Properties of a Non-absorbing Media with Application to Thermotropic Materials for Overheat Protection,
Thermotropic glazings for overheating protection
Energy Procedia 30 (2012) 471-477
November 2012
By: A. Weber, K. Resch
Publisher: Elsevier Ltd.
--- In this paper, the effect of material composition on the overheating protection performance of thermotropic systems with fixed domains (TSFD) is studied. Several thermotropic layers were formulated by variation of both, matrix material and thermotropic additive. Refractometry was applied in order to obtain refractive index data as a function of temperature of all material constituents and to screen wether material combinations are promising to formulate or not. Investigations concerning optical properties, switching temperature and switching process were carried out applying UV/Vis/NIR spectrometry. Morphological analysis was conducted with a Scanning Electron Microscope (SEM). Several TSFD showed reasonable light-shielding efficiency. Nevertheless further optimization of scattering domain size and shape is necessary to improve the light shielding performance.
Thermotropic glazings for overheating protection
Smart Windows - Smart Collectors, Entwicklung und Charakterisierung von Überhitzungsschutzverglasungen für Gebäudeverglasungen und thermische Solarkollektoren
BHM 156 (2011) 11, S. 429 - 433
December 2011
By: Katharina Resch, Andreas Weber
Publisher: Springer Science+Business Media
--- Thermotropic glazings change their light transmittance from transparent to opaque upon reaching a certain threshold temperature reversibly. Such functional glazings can provide effective overheating protection for building façades or solar thermal collectors. The overall objective of the present study is to produce tailor-made thermotropic overheating protection glazings by systematic material pre-selection and formulation ...
Smart Windows - Smart Collectors, Entwicklung und Charakterisierung von Überhitzungsschutzverglasungen für Gebäudeverglasungen und thermische Solarkollektoren
Coil-coated spectrally selective coatings on copper or aluminium with pigments modified by aminosilanes
WIPO Patent Application WO 2010/133693
May 2010
By: Koželj M, Orel B, Jerman I, Steinbücher M, Vodlan M, Peros D.
--- The invention relates to TSSS and TISS coatings applied by coil-coating onto substrates of copper or aluminum. Inorganic pigments functionalized by aminosilane are used for making paints, which after the coil-coating onto the substrate form the coatings. For the functionalization the pigment is dispersed in a solution of an aminosilane in a solvent or a mixture of a solvent and a binder without an addition of a non-aminosilane dispersing agent with or without subsequent grinding and use of 0.05-30 % of aminosilane on pigment. An aromatic, aliphatic, cycloaliphatic, ketone, ester, ether or alcohol compound or a mixture thereof can be used as the solvent. A silicone-polyester, polyurethane or fluoropolymer can be used as the binder.
The effect of polyhedral oligomeric silsesquioxane dispersant and low surface energy additives on spectrally selective paint coatings with self-cleaning properties.
Solar Energy Materials and Solar Cells (94) 2, pp. 232-245
February 2010
By: JERMAN, Ivan, KOŽELJ, Matjaž, OREL, Boris
--- Thickness-Insensitive Spectrally Selective (TISS) paint coatings were made of fluoropolymer resin binder (Lumiflon (LF), Asahi Glass Co., Ltd., Japan) and their water- and oil-repellent properties were obtained by the addition of Polyhedral Oligomeric Silsesquioxane (POSS) characterized by amino (AP), isooctyl (IO) and perfluoro (PF) groups attached on the silsesquioxane cube. Paint dispersions were made by modifying of black spinel pigment with trisilanol isobutyl POSS dispersant and with a single-capped silane isobutyltrimethoxysilane (IBTMS). Infrared and 29Si NMR spectra measurements were used for the identification of the structural characteristic of the corresponding POSS compounds ...
The effect of polyhedral oligomeric silsesquioxane dispersant and low surface energy additives on spectrally selective paint coatings with self-cleaning properties.
Geeignete Polymere für Innovationen in der Solarthermie
2. Solarthermie-Technologiekonferenz, Berlin, Germany
January 2010
By: Völkel, Mark (BASF SE)
Presentation is available as PDF-file and online video. Image: © Creventis Services 2010
Geeignete Polymere für Innovationen in der Solarthermie
Morphology of phase-separated thermotropic layers based on UV cured acrylate resins Polymers for Advanced Technologies
Polymers for Advanced Technologies Vol. 20, Issue 12, 1163–1167, Dec. 2009
December 2009
By: Katharina Resch, Gernot Wallner
--- In this paper, relationships between the scattering domain parameters (size and shape) and the light-shielding properties of thermotropic systems with fixed domains (TSFD) are established. Specific focus is given to the effect of additive type on the formation of scattering domain size. Various functional layers are prepared by a variation of thermotropic additives. Scattering domains are investigated applying high resolution Atomic Force Microscopy (AFM) in a phase imaging mode. Thermotropic layers formulated with additive types exhibiting a short chain length display roughly spherical scattering particles with dimensions between 0.5 and 3?µm and a moderate reduction in hemispheric solar transmittance along with a significant increase in diffuse solar transmittance above the switching threshold ...
Morphology of phase-separated thermotropic layers based on UV cured acrylate resins Polymers for Advanced Technologies
Corrosion protection of Sunselect, a spectrally selective solar absorber coating by (3-mercaptopropyl) trimethoxysilane.
Solar Energy Materials and Solar Cells (93) 10, pp. 1733-1742.
October 2009
By: KOŽELJ, Matjaž, ŠURCA VUK, Angela, JERMAN, Ivan, OREL, Boris.
--- The formation of a protective layer from (3-mercaptopropyl)trimethoxysilane (MPTMS) on commercial Sunselect, cermet-based spectrally selective coating (Alanod, DE), was studied by non-electrochemical (infrared reflection–absorption—IR RA, X-ray photoelectron spectroscopy—XPS), electrochemical (cyclic voltammetry (CV) in the presence of a redox probe (Cd+2), and potentiodynamic (PD)) techniques. By simple immersion and subsequent dip coating of the Sunselect substrate in the MPTMS sol, the hydrolyzed MPTMS precursor was adsorbed on the substrate, forming a protective layer imparting corrosion stability to Sunselect in a salt spray chamber for at least 20 days, outperforming any other sol–gel coating used so far for the corrosion protection of Sunselect ...
Corrosion protection of Sunselect, a spectrally selective solar absorber coating by (3-mercaptopropyl) trimethoxysilane.
Phase separated thermotropic layers based on UV cured acrylate resins – Effect of material formulation on overheating protection properties and application in a solar collector
Solar Energy (83) 9, pp. 1689-1697
September 2009
By: Resch, K., Wallner, G.M. and Hausner, R.
--- This paper focuses on the effect of material composition on the overheating protection properties of thermotropic systems with fixed domains for solar thermal collectors. Numerous functional layers were prepared by a variation of base resin (polyester-, epoxy- or urethane–acrylate) and of thermotropic additives (non-polar and polar waxes) as well as by additive concentration (5 and 7 wt%). A detailed investigation of optical properties, switching temperature and switching process was performed applying UV/Vis/NIR spectroscopy. Thermal transitions of both the thermotropic layers and the additives used were determined by Differential Scanning Calorimetry (DSC). The capability of the produced thermotropic layers to reduce stagnation temperatures in an all-polymeric flat plate collector was evaluated by theoretical modeling. The thermotropic layers showed a hemispheric solar transmittance between 76% and 87% in clear state. Above the switching threshold this transmittance changed by 1–16% to values between 62% and 85% ...
Phase separated thermotropic layers based on UV cured acrylate resins – Effect of material formulation on overheating protection properties and application in a solar collector
Adhesion and thermal stability of thickness insensitive spectrally selective (TISS) polyurethane-based paint coatings on copper substrates
Solar Energy Materials and Solar Cells (93) 5, pp. 630-640
May 2009
By: Kunic, R., Kozelj, M., Orel, B., Šurca Vuk, A., Vilcnik, A., Slemenik Perse, L., Merlini, D., Brunold, S.
--- Thickness insensitive spectrally selective (TISS) paint coatings based on a polyurethane polymeric binder deposited on copper substrates were investigated to obtain information about their service lifetime. The degradation of TISS paint coatings was performed according to the methodology worked out within Task 10 of the IEA's Solar heating and the cooling programme. The activation energy (Ea) for the degradation process was derived from vibrational band changes of the polyurethane binder recorded in the infrared hemispherical reflectance spectra of TISS paint coatings exposed to different thermal loads. The results of the vibrational band analysis were correlated with cross-cut tests, showing that the coatings started to lose integrity at 190 °C but protected the copper substrate against oxidation perfectly even at 200 °C (15 days). An accelerated test procedure confirmed that TISS coatings could be safely used in solar collectors for at least 45 years.
Adhesion and thermal stability of thickness insensitive spectrally selective (TISS) polyurethane-based paint coatings on copper substrates
Thermotropic layers for flat-plate collectors - A review of various concepts for overheating protection with polymeric materials
Solar Energy Materials and Solar Cells (93) 1, pp. 119-128
January 2009
By: Resch, K. and Wallner, G.M.
--- Within this paper a comprehensive review of the developments of thermotropic hydrogels, thermotropic polymer blends and thermotropic systems with fixed domains for overheating protection purposes is given. In addition, performance properties for thermotropic layers to prevent overheating in solar collectors are defined. The different thermotropic material classes are discussed as to their ability to meet these requirements. The review shows that thermotropic layers developed so far need to be adapted as to switching temperature and long-term stability for applicability in solar thermal collectors.
Thermotropic layers for flat-plate collectors - A review of various concepts for overheating protection with polymeric materials
Spectroscopic investigations of phase-separated thermotropic layers based on UV cured acrylate resins
Macromolecular Symposia (2008)
December 2008
By: K. Resch, G.M. Wallner, R.W. Lang
--- In this paper spectroscopic techniques were adapted and applied to characterize the optical and morphological properties of thermotropic resins. Thermotropic films were prepared by variation of resin base and thermotropic additives. By UV/Vis/NIR spectroscopy the solar optical properties, the switching temperature, the switching process and the residual transmittance in the opaque state were determined. To control the sample temperature from ambient to 100?°C a conventional UV/Vis/NIR spectrophotometer equipped with an Ulbricht-sphere was adapted by a heating stage. Additive content, distribution and scattering domain size were characterized by Differential Scanning Calorimetry, Attenuated Total Reflectance spectroscopy and microscopic techniques ...
Document Number: 265, 49-60
Property and performance requirements for thermotropic layers to prevent overheating in an all polymeric flat-plate collector
Solar Energy Materials and Solar Cells (92), pp. 614-620
June 2008
By: Resch, K., Wallner, G.M. and Hausner, R.
--- Within this study the potential of thermotropic layers to prevent overheating of an all-polymeric solar collector is evaluated by theoretical modeling. The investigations show that collector stagnation temperatures can be reduced to temperatures between 80 and 90 °C by using thermotropic layers either in the glazing or on the absorber. For overheating protection to a maximum temperature of 80–90 °C a residual solar transmittance of the thermotropic layer below 0.25 in the opaque state (>0.85 in clear state) is effectual. The required switching temperature is dependent on the collector configuration.
Property and performance requirements for thermotropic layers to prevent overheating in an all polymeric flat-plate collector