Adhesives. Determination of the colour and/or colour changes of adhesive coats under the influence of light

1998 ◽  
Keyword(s):  
Colour Changes

scholarly journals The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones

Buildings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 18 ◽  
Author(s):  
Jeanette Orlowsky ◽  
Franziska Braun ◽  
Melanie Groh
Keyword(s):  
Water Absorption ◽  
Water Uptake ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Absorption Determination ◽  
Colour Changes ◽  
Uptake Velocity ◽  
Outdoor Weathering

The durability of eleven different water repellents applied on one sandstone type was studied after a long-term weathering at seven different locations in Germany. By measuring colour changes, it could be shown that the formation of black crusts, the deposition of particles and biogenic growth caused a gradual darkening as well as significant changes in total colour over time. Additionally, the water absorption behaviour was investigated with two different methods: applying a low pressure using the pipe method and capillary water absorption measurements from a wet underlay. Afterwards, the test results were analysed with four different evaluation methods: calculation of the protection degree from pipe method and capillary water absorption, determination of the velocity of water uptake during capillary water absorption and calculation of the damaged depth of the stone surface using single-sided NMR technique. The growing damaged depth leads to an increase of the water uptake velocity and to a decrease of the protection degree of the applied hydrophobing agents. Three protective agents based on isobutyltrimethoxysilane showed already after two years of outdoor weathering a clear loss of performance, which significantly increased after 30 years of exposure.

scholarly journals The Efficacy of Polymer Coatings for the Protection of Electroless Copper Plated Polyester Fabric

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1277 ◽  
Author(s):  
Alenka Ojstršek ◽  
Natalija Virant ◽  
Daryl Fox ◽  
Latha Krishnan ◽  
Andrew Cobley
Keyword(s):  
Screen Printing ◽  
Base Material ◽  
Polyester Fabric ◽  
Polymer Coatings ◽  
Mechanical Characterisation ◽  
Polyurethane Resin ◽  
Colour Changes ◽  
Acrylate Resin ◽  
Photo Stability

The selective metallisation of textiles is becoming a very important process in the development of electronic or e-textiles. This study investigated the efficacy of polymer coatings for the protection of copper (Cu) conductive tracks electroless plated on polyester (PES) fabric against laundering and rubbing, without essentially affecting the physical-mechanical and optical properties of the base material. After the electroless deposition of a consistent layer of Cu onto PES, four polymers were applied individually by screen-printing or padding. The physical-mechanical characterisation of coated textiles revealed that polyurethane resin (PUR) and modified acrylate resin (AR) had little effect on the air permeability, tensile strength and breaking tenacity of the PES, as compared to silicone elastomer polydimethylsiloxane (PDMS) and epoxy resin (ER). On the other hand, PUR and PDMS had higher abrasion resistance and photo-stability under prolonged UV irradiation, as compared to AR and ER. In addition, freshly Cu plated samples were coated with polymers, washed up to 30 cycles and characterised by measuring their electrical resistivity, determination of colour changes and the examination of the surface morphology. Based on these results, PUR presented the most suitable protection of Cu tracks on PES, with the lowest impact on physical-mechanical properties. ER is not recommended to be used for protection of Cu tracks on fabrics, due to its rigidity, low photo-stability, washing and wear durability.

550. Colour changes in heated and unheated milk: I. The browning of milk on heating

1954 ◽  
Vol 21 (2) ◽  
pp. 194-203 ◽  
Author(s):  
H. Burton
Keyword(s):  
Visible Spectrum ◽  
Colour Changes

Methods for measuring the reflectance of milk are described. The effect of heating is to reduce the reflectance of whole and separated milk progressively towards the blue end of the visible spectrum. The reflectance of cream is almost unaffected. The measurement of reflectance at the blue end of the visible spectrum is shown to be a useful method for the determination of the brownness of milk. The variation of rate of browning with temperature and with pH and the effect of storage on brownness are given.

scholarly journals Properties and cleanability of new and traditional surface materials in cattle barns - a field study

2008 ◽  
Vol 17 (3) ◽  
pp. 227 ◽  
Author(s):  
R. KUISMA ◽  
H-R. KYMÄLÄINEN ◽  
M. HELLSTEDT
Keyword(s):  
Field Study ◽  
Laboratory Experiments ◽  
Laboratory Studies ◽  
Surface Materials ◽  
Colour Changes ◽  
The Difference ◽  
Coated Surfaces ◽  
One Year ◽  
The One

In this study surface properties and cleanability of new and traditional surface materials in cattle barns were examined in a field test. The concrete and plastic-coated samples were placed on a walking path on the floor and on a feeding table in a cattle barn. The surfaces were characterized using colorimetric and gloss measurements and determination of topography. In most cases, the colour of the surfaces placed on the floor darkened during the one year study period, whereas the colour changes of the samples placed on the feeding table did not show a similar trend. However, in both locations the plastic-coated surfaces were generally the easiest to clean, and the highest colour changes indicating soil residues were detected on the uncoated and silane-impregnated concrete surfaces. The difference between the locations was also seen in the gloss values, which increased in the samples placed on the floor during the one-year test period but varied considerably between the different materials on the surfaces placed on the feeding table. This field study confirmed the observation from earlier laboratory studies that plastic coatings improved the cleanability of concrete cattle barn surfaces. Silane impregnation was not functionally competitive with the plastic coatings. In general, the cleanability results were in accordance with the results of previous laboratory experiments but the field study provided practical information about the behaviour of the surface materials examined.;

Spectrophotometric Determination of Fluoride in Groundwater Using Complexes of Flavonoid Chrysin

2013 ◽  
Vol 1 (1) ◽  
pp. 16-20
Author(s):  
Zaher Barghouthi ◽  
Sameer Amereih ◽  
Saed Khayat
Keyword(s):  
Drinking Water ◽  
Detection Limit ◽  
Visible Region ◽  
Free Ligand ◽  
Molar Absorptivity ◽  
Reliable Determination ◽  
Limit Value ◽  
Quantitation Limit ◽  
Colour Changes

A simple spectrophotometric method is developed for determination of fluoride in drinking water by using complexes of chrysin. The method is based on the reaction of the coloured complexes with fluoride where its colour changes, due to the formation of the colourless fluoride complex and liberating of the free ligand, is dependent on the concentration of fluoride in water samples. The molar absorptivity for the complexes at the wavelength of maximum absorption in the visible region, 371 nm is 2.75 × 103 L mol-1 cm-1. The method allows a reliable determination of fluoride in the range 0.3─3.0 mg L-1 which is compatible to WHO limit value of 1.5 mg L-1. The sensitivity, detection limit, quantitation limit, and correlation coefficient for the method were found to be 0.211 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 0.9914 respectively. The percentage recovery of 1.5 mg L-1 fluoride is 101.3.

scholarly journals Measurement of potato tubers resistance against mechanical loading

2008 ◽  
Vol 54 (No. 1) ◽  
pp. 22-31 ◽  
Author(s):  
V. Mayer ◽  
D. Vejchar ◽  
L. Pastorková
Keyword(s):  
Mechanical Loading ◽  
Mechanical Load ◽  
Potato Tubers ◽  
Potato Varieties ◽  
Agricultural Engineering ◽  
Measurement Results ◽  
Web Camera ◽  
Colour Changes ◽  
Vertical Vibrations

The contribution presents a method for the determination of the potato tubers resistance against mechanical loading, the measurement results obtained with the selected potato varieties, and the comparison of the latter. For testing the potato varieties samples, the method developed in Agrartechnik (ATB) Bornim (Germany) was verified and utilised. The potato samples were exposed to vertical vibrations with adjustable amplitude in the device constructed at the Research Institute of Agricultural Engineering, (RIAE) Prague, for testing tuber samples for mechanical loading. The potato samples cutting pictures were scanned by a web camera or a scanner, and the colour changes on the cuttings were evaluated by means of a computer program. In the paper are presented the results of two different measurements. Significant differences were found between four varieties regarding their resistance against equal mechanical load, and in one variety in different degrees of mechanical load for both early and late potatoes.

Spectrophotometric Determination of Fluoride in Groundwater Using Complexes of Flavonoid Chrysin

2013 ◽  
Vol 1 (1) ◽  
pp. 16-20
Author(s):  
Zaher Barghouthi ◽  
Sameer Amereih ◽  
Saed Khayat
Keyword(s):  
Drinking Water ◽  
Detection Limit ◽  
Visible Region ◽  
Free Ligand ◽  
Molar Absorptivity ◽  
Reliable Determination ◽  
Limit Value ◽  
Quantitation Limit ◽  
Colour Changes

A simple spectrophotometric method is developed for determination of fluoride in drinking water by using complexes of chrysin. The method is based on the reaction of the coloured complexes with fluoride where its colour changes, due to the formation of the colourless fluoride complex and liberating of the free ligand, is dependent on the concentration of fluoride in water samples. The molar absorptivity for the complexes at the wavelength of maximum absorption in the visible region, 371 nm is 2.75 × 103 L mol-1 cm-1. The method allows a reliable determination of fluoride in the range 0.3─3.0 mg L-1 which is compatible to WHO limit value of 1.5 mg L-1. The sensitivity, detection limit, quantitation limit, and correlation coefficient for the method were found to be 0.211 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 0.9914 respectively. The percentage recovery of 1.5 mg L-1 fluoride is 101.3.

scholarly journals An Optical Method for the Determination of the Cholesteric Pitch in Liquid Crystals

1995 ◽  
Vol 50 (6) ◽  
pp. 589-594 ◽  
Author(s):  
Ingo Dierking ◽  
Frank Gießelmann ◽  
Peter Zugenmaier
Keyword(s):  
Liquid Crystal ◽  
Crystalline Phase ◽  
Optical Method ◽  
Liquid Crystalline ◽  
Vries Equation ◽  
Band Model ◽  
Colour Changes ◽  
Crystal Cells ◽  
Cholesteric Liquid Crystalline

Abstract Preparation of a cholesteric liquid crystalline phase in planar orienting liquid crystal cells exhibits discontinuous colour changes with temperature when viewed between crossed polarizers. The trans­ mission spectra of such a system can be described by a modified de Vries equation, with the birefringence dispersion included in a simplified single-band model. With a suitable choice of the cell gap as compared to the cholesteric pitch, the procedure can be used as a new method to determine the temperature dependence of the cholesteric pitch.

scholarly journals Spectroscopic Determination of Two Beta-Blockers – Atenolol and Propanolol by Oxidative Derivatization Using Potassium Permanganate in Alkaline Medium

2020 ◽  
Vol 39 (1) ◽  
pp. 56-64
Author(s):  
Edebi N. Vaikosen ◽  
Jeniffer Bioghele ◽  
Ruth C. Worlu ◽  
Benjamin U. Ebeshi
Keyword(s):  
Alkaline Medium ◽  
Beta Blockers ◽  
Molar Absorptivity ◽  
Pharmaceutical Dosage Forms ◽  
Bluish Green ◽  
Relative Standard ◽  
Colour Changes ◽  
Tablet Formulations ◽  
Assay Conditions

AbstractA simple, rapid, sensitive, cheap and accurate oxidative method for two beta-blockers in pharmaceutical dosage forms was developed and evaluated. The method involved the oxidimetric treatment of atenolol and propanolol with 2 x 10-3 mol L-1 KMnO4 in alkaline medium (pH ≥ 9). Scanned spectra of oxidized complex showed distinctive absorptions at 460, 520, 540 and 570 nm. Arrays of colour changes were observed - from violet to blue; blue to bluish-green and yellow. Exhibited colours were due to ligand-metal charge transfer. An indirect spectrophotometric determination of atenolol and propranolol was done after 12-15 minutes at 520 nm. The optimum assay conditions showed linearity ranged from 0 – 15.0 μg mL-1 for both beta-blockers (R= 0.9997 – 0.9999). Molar absorptivity values were 4.79 x 103 and 4.88 x 103 L mol-1 cm-1 for atenolol and propanolol respectively, with corresponding Sandell’s sensitivity values of 0.056 and 0.053 μg cm-2. Limits of detection and quantification were 0.50 and 1.65 μg mL-1 for atenolol respectively and 0.58 and 1.91 μg mL-1 for propanolol, while relative standard deviation for intra-and inter-day precision were < 2.0%. The applicability, accuracy and reliability of the method were demonstrated by the determination of atenolol and propanolol in tablet formulations. The recovery studies ranged from 93.33 - 103.00% for both beta-blockers and the amounts in brands were from 97.53 ± 2.68 to 100.84 ± 1.82%.

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