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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.

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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.

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Vitreousness is an important quality characteristic that affects the yield of semolina during milling of durum wheat. It has been observed that kernel vitreousness seems to be lower when durum is exposed to damp conditions just before harvest. The main objective of this research was to determine the effect of high relative humidity (RH) on kernel vitreousness of ten durum wheat cultivars. Spikes were exposed to 88% RH at room temperature for 1 and 3 days. This resulted in increased spike moisture, kernel moisture and kernel size. Vitreous kernel content (vitreousness) decreased 23.6% after spikes were exposed to high relative humidity for 3 days. Exposure to 88% RH caused the greatest decline in vitreousness with the cultivar ‘Ben’.

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Abstract  

A description is given of modifications to a dynamic mechanical analyser (DMA) to allow controlled relative humidity (RH) experiments to be performed under isothermal or thermal scanning conditions. Free film samples of polyester melamine paints (under-cured, normal-cured and over-cured) were supplied and the viscoelastic properties measured in the tensile mode of the DMA. A reduction in the glass transition temperature (T g) of up to 10C was found as the controlled RH was increased.

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All building materials can be affected by microbiological agents during their lifecycle. The presence of microorganisms changes the appearance of the surface, degrading it, and they can even cause health problems to the residents. The biological susceptibility is dependent on the content of nutrient based on organic compounds. Thus one of the most susceptible of those materials are earthen construction materials. The degree of fungal growth is influenced by the chemical composition and plant fibres additives as well as the external conditions such as temperature and relative humidity.

The earth plastering mortar has started to gain more attention recently as it is considered to have a low environmental impact and to increase the indoor air quality. Mechanical and physical characteristics of earth materials were studied by a number of authors but the knowledge about the biological resistance of the material is scarce.

This study intends to look into the issue of the biological colonisation of earth plasters depending on the relative humidity. The samples, made of four types of earth plasters with different plant fibres, were placed to an environment of the relative humidity ranging from 33% to 100%. During a period of 4 weeks the extent of fungal growth was observed.

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Abstract  

Growth of mould fungi is one of the main causes of deterioration of foodstuffs, building materials and textiles. A new microcalorimetric technique has been developed for the study of mould activity as a function of water activity, temperature and atmospheric composition. This paper describes the method, in particular how to measure mould activity as a function of relative humidity.

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Abstract  

Knowledge of the dynamics of HTO in leafy plant–soil system is required to verify models, such as the NORMTRI code, which predict environmental tritium following its release. Tritium concentrations in plants has been evaluated using the code NORMTRI and experimentally by collection of samples of different plants and their soils samples. In the present study, major seasonal crop plants i.e. wheat, mustard, sugar cane, coriander, spinach, potato, were collected beyond Narora Atomic Power Station site boundary and gular, arandi, neem, ashok, amaltas, csuarina leaf samples within NAPS site boundary for analysis of HTO content. Data analysis indicated that HTO in leaf is strongly influenced by atmospheric relative humidity and type of the plant.

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Green buildings are more comfortable than conventional buildings; thereby making them more satisfying and productive workplaces, there is little empirical evidence to support this belief. The aim of the case study was to test the hypotheses that indoor parameters in green buildings in dependence on building materials and structures are more suitable than in buildings with conventional materials and structures. These hypotheses will be test for comparing the green buildings and conventional buildings in term of the comfort and satisfaction of the occupants.

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saturated aqueous solutions of CH 3 COOK, NaI (samples of TAA·H 2 O), NaBr, KBr, KNO 3 and K 2 SO 4 (samples of TAA) in order to produce relative humidity values of 0, 22, 38, 58, 81, 94 and 97, respectively [ 5 ]. The control of relative humidity was

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Abou-Elella, G. M. (2003): Effect of eriophyid prey species and relative humidity on some biological aspects of the predatory mite, Proprioseiopsis (Amblyseius) lindiquisti (Acari: Phytoseiidae). Egypt. J. Biol. Pest Cont. 13, 31

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