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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.
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.
Improved controlled relative humidity dynamic mechanical analysis of artists’ acrylic emulsion paints
Part II. General properties and accelerated ageing
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.
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.
Abstract
An understanding of the mechanisms by which water molecules are held within a substance or at its surface, either by physical or chemical processes, is of importance in the formulation, preparation and storage of a wide variety of substances. The traditional experimental techniques which have been used to make measurements on samples exposed to specific levels of relative humidity, (e.g. using desiccators containing saturated salt solutions), are slow, laborious, inaccurate, and provide a limited amount of data. This paper describes the conception, operation, and facilities of a new system which by employing recently developed electronic components and transducers, significantly advances the performance capability for moisture sorption analysis.
Abstract
The effect of different relative humidity (RH) on the response of a six-polymer coated Quartz Crystal Microbalance (QCM) sensor based electronic nose (EN) was investigated, RH 30 and 50% respectively. Increases in the sensor responses were observed for an increase in RH. A stainless steel pre-concentration tube (PCT) containing Porapak-S and a nichrome heating element was developed to minimise the effect and allow for chromatographic pre-separation. Breakthrough times of chemical compounds through the PCT were experimentally determined and used to select a mixture of water and toluene as a suitable sample for pre-separation. The PCT was capable of separating the water from the toluene and the EN was competent at evaluating the concentration of toluene in the solution.
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
Abstract
The amorphous content of different Desferal samples was quantified by recording its recrystallization using isothermal microcalorimetry in a static as well as in a flowing humid atmosphere. Furthermore water vapor sorption gravimetry was performed for the same purpose. These analytical methods result in a quantitative signal directly dependent on the content of the amorphous phase (recrystallization, water sorption equilibrium). Their sensitivity allows the detection of amorphous content below 1%. Methods are compared and advantages and disadvantages are discussed.
temperature and relative humidity (RH) conditions: 25 ± 2 °C, 60 ± 5% RH (climate chamber Binder KBF 720) and 40 ± 2 °C, 75 ± 5% RH (climate chamber Binder KBF 240). Samples were packed into polyethylene bags. The bags were closed with a clamping tape and
1 704 – 704 . 16 Staniforth , S. , Hayes , B. and Bullock , L. , “ Appropriate Technologies for Relative Humidity Control for Museum Collections housed in Historic
