Search Results

You are looking at 1 - 10 of 492 items for :

  • All content x
Clear All

Abstract  

Indoor radon and thoron concentrations were dominated with their exhalation rate from building materials. Thus, the evaluation of exhalation rate with highly precise is important. This paper presented a new technique to measure the dependence radon/thoron exhalation rate, from building materials used in Japan, on absolute humidity. The measurement technique consisted of a solid state alpha detector equipped a ventilation-type chamber and humidity control system in a flow through method. The exhalation rate of dried samples (Indian red granite and Japanese gray granite) was measured at various absolute humidity levels in the range of 1–20 g cm−3. It was found that exhalation rate increased exponential with increasing of absolute humidity for both samples. Furthermore, the dependence of radon emanation coefficient on building material’s temperature was also studied using an accumulation chamber equipped with scintillation cell alpha detector. The emanation coefficient of dry sample increased proportionally with increasing the material’s temperature with a correlation factor of 0.88.

Restricted access

Humidity controlled thermal analysis

The effect of humidity on thermal decomposition of zinc acetylacetonate monohydrate

Journal of Thermal Analysis and Calorimetry
Authors: T Arii and A Kishi

Abstract  

The low temperature formation of crystalline zinc oxide via thermal decomposition of zinc acetylacetonate monohydrate C10H14O4ZnH2O was studied by humidity controlled thermal analysis. The thermal decomposition was investigated by sample-controlled thermogravimetry (SCTG), thermogravimety combined with evolved gas analysis by mass spectrometry (TG-MS) and simultaneous differential scanning calorimetry and X-ray diffractometry (XRD-DSC). Decomposition of C10H14O4ZnH2O in dry gas by linear heating began with dehydration around 60C, followed by sublimation and decomposition above 100C. SCTG was useful because the high-temperature parallel decompositions were inhibited. The decomposition changed with water vapor in the atmosphere. Formation of ZnO was promoted by increasing water vapor and could be synthesized at temperatures below 100C. XRD-DSC equipped with a humidity generator revealed that C10H14O4ZnH2O decomposed directly to the crystalline ZnO by reacting with water vapor.

Restricted access

Abstract  

Part II covers the most common methods of measuring the humidity of solid material. State of water near solid surfaces, gravimetric measurement of material humidity, measurement of water sorption isotherms, chemical methods for determination of water content, measurement of material humidity via the gas phase, standardisation, cosmonautical observations are reviewed.

Restricted access

content of wheats as a function of temperature and humidity. J. Soc. Chem. Industry 60 :44–46. Gane R. The water content of wheats as a function of temperature and humidity

Restricted access

Abstract  

Part I of the short survey covers definitions of air humidity and the respective measuring methods such as hygrometry, psychrometry, dew point measurement, LIDAR hygrometry and humidity sensors. Techniques based on property changes of matter with adsorbed moisture from air are reviewed.

Restricted access

Abstract  

The use of dataloggers in food engineering is discussed in two examples. The first example describes the measurement of temperature and humidity in a bulk tank car during transport and unloading. In the case of wheat flour the relative humidity in the air raises from about 80% r.h. to values near 100% r.h. at the air compressors for pneumatical unloading start working. The second example shows the use of the datalogger in education on heat transfer. The device was fixed in an ice cream sample which was placed in a store at –25°C. The measured hardeningtime agrees well to theoretical heat transfer calculation.

Restricted access

Abstract  

Atmospheric humidity in the surroundings of A-1 atomic power station is taken off by means of an absorption equipment in order to measure natural tritium concentration in atmosphere. Atmospheric water is reduced with Mg at 580°C, and hydrogen obtained is used for catalytic hydrogenation of acetylene. Optimum conditions of ethane preparation in dependence of temperature, molar ratio of the components, flow rate and the number of hydrogenation cycles when using the new selective nickel catalyst 40-01 are reported.

Restricted access

Abstract  

Effects of humidity and light conditions /fluoroscent light, sunlight and diffuse sunlight/ on the response of 2 mm thick clear polymethylmethacrylate /PMMA/ dosimeter during irradiation and during postirradiation storage were determined spectrophotometrically at 305 and 314 nm. The results showed that irradiation of dosimeters at 12–97% relative humidity did not result in any change in the response upto 2 weeks of post-irradiation storage. However, there is some decrease in the response at higher humidities />76%/ for longer storage time. Post-irradiation storage and dosimeters at constant relative humidity conditions between 35 and 97% had no effect on the response up-to 3 weeks. Post-irradiation storage at lower relative humidity /12%/ showed some decrease in the response for longer periods. The response of dosimeter is not very sensitive to short time exposure to diffuse sunlight and fluorescent light. However, a significant increase in the optical density was observed during exposure of dosimeters to direct sunlight.

Restricted access

Abstract  

Issues encountered with dynamic mechanical analysis of artists’ acrylic emulsion paint films are presented alongside modifications to improve controlled relative humidity (RH) experiments using isothermal and thermal scanning conditions. Free films of titanium white (PW6) artists’ acrylic emulsion paints were cast as free films and their viscoelastic properties measured using the tensile mode of the dynamic mechanical analyser (DMA). Artists’ acrylic emulsion paints are within their glass transition temperature region at room temperature and are highly responsive to changes in ambient temperature and relative humidity, hence controlling relative humidity during analysis is vital to the successful analysis of these paints.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: B. Ormsby, G. Foster, T. Learner, S. Ritchie, and M. Schilling

Abstract  

After improvements were made to a modified Polymer Labs MkIII DMTA instrument to facilitate repeatable controlled humidity (RH) experiments using isothermal and thermal scanning conditions, the viscoelastic properties of titanium white pigmented artists’ acrylic emulsion films were measured in tensile mode. The effects of temperature, relative humidity and accelerated ageing regimes on two brands of titanium white paints were explored. These paints are highly responsive to changes in temperature and relative humidity, formulation differences affect properties slightly, and while light ageing had a negligible effect, thermal ageing resulted in decreased storage modulus and increased film density.

Restricted access