Marta Malíková

Assessing the Progress of Degradation in Polyurethanes by Chemiluminescence

The thermooxidative and thermal stabilities of polyurethanes synthesized from polyisocyanate and polyol were assessed by chemiluminescence and thermogravimetry. The effect of varying heating rates, synthesis procedures (i.e., with or without a crosslinking catalyst), atmospheres and long‐term ageing under laboratory conditions were examined and a mechanism of oxidative degradation was proposed based on comparisons of the—separately determined—oxidizability of polyisocyanate and polyol to that of polyurethane.

Insolation of Interiors: The Dead Angle Analysis

Quality of the indoor environment is determined by physical and psychophysical factors. People spend in the interiors most of the time during the day. Therefore indoor visual, thermal and acoustic effects are important for their health and work productivity. Visual environment can be evaluated in term of daylight availability, spatial luminance distribution and access to sunlight. Unless availability of sky/diffuse light can be considered for window design because of low intensities, the direct sun radiation with its original wavelength composition and high intensity is important for health and stimulation of human body organs in moderate climatic zones. To evaluate access to sunlight, there is necessary to determine the sun position on the sky, dimensions of envelops and windows as well as orientation of significant apertures and potential impact of external obstructions. Sun rays reaching the window surface can or cannot penetrate into the interior. This depends on the angle of sun beam incidence, orientation and dimensions of the aperture, thickness and structure of the envelope. Angle in which incident rays penetrate in the interior is so called acceptance angle. Angle in which incident rays are not causing insolation of interiors or cannot penetrate through the window glazing is so called dead angle. This paper analyses and discusses the meaning and dimensions of the dead angle.

Modelling of Daylight Sources in the Artificial Sky

Daylight in nature is characterized by daily permanent changes of sunlight and skylight. Real measurements of daylight availability are showing that different daylight exterior illuminance for building interiors can be expected each minute. This brings some complications in the window design and the choice of criteria for daylight evaluations. There are several ways how to find basic conditions and typical relations combining sunlight beam with diffuse skylight from the whole sky vault. The older assumption considered that interiors have to be sufficiently illuminated under the worst overcast conditions. The newer approach is based on the utilization of daylight in specific localities and the determination of changes in sunlight and skylight occurrence probability. Therefore, both daylight sources are researched in detail specifying sky luminance distributions and sun influences to find conditions for their simulation in laboratory facilities. The most sophisticated equipment to study daylighting in exterior and interior architectural spaces are artificial skies with the artificial sun. These have to be precisely calibrated with a verified zenith luminance and horizontal illuminance levels by theoretical calculations and checked by experimental measurements. Reference daylight conditions defined in the ISO/CIE 15469:2004 standard have to be respected with trials to determine natural sun and sky as sources of daylight in the real environment and modelling these in the artificial sky in a certain intensity scale. This paper presents the method and results of modelling daylight applying electrical light sources in artificial sky which is installed in the Institute of Construction and Architecture, Slovak Academy of Sciences (ICA SAS) and discusses possibilities of their simulation in laboratory conditions.

EN Criteria for Evaluation of Daylight in Interiors

Daylighting in buildings is commonly designed and evaluated after the Daylight Factor criterion which is required also by the Slovak standard STN 73 0580. The model of the overcast sky representing the worst daylight conditions is the basis of all standard daylight calculations in many countries. Currently, the prEN standard Daylighting of buildings is elaborated by the CEN TC 169 WG11. A new climatological criterion for evaluation of daylight provision is proposed to reflect various luminous conditions in European localities. This paper informs and discusses the concept of the new standard and presents an example of daylighting evaluation in an interior applying STN and new EN criteria.

THE EFFECT OF OXYGEN CONCENTRATION ON OXIDISABILITY AND CHEMILUMINESCENCE FROM ISOTACTIC POLYPROPYLENE

It has been shown that the linear plot of maximum chemiluminescence intensity on concentration of oxygen in surrounding atmosphere does not correspond with negligible changes of oxidation induction time. Four‐parametric “master equation” used in [1] has been applied for interpretation of chemiluminescence—time runs in both the oxygen and nitrogen.