Odor, coated surface

Figure 18.1.10. Test approach for the determination of VOC and odorant concentration in coated surfaces.

A specific test method has been developed for determining the VOC and odorant concentration of coated surfaces," "" as shown schematically in Figure 17.1.10. Similar to formaldehyde determination, sample testing is done using a test chamber approach. After some atmospheric conditioning, of the varnished furniture, the samples are stored in a test chamber (typically 1 m ) xmder the following conditions 23°C 0.5 45 3% relative... 

Modem furniture pohshes are designed for a wide variety of surfaces, eg, plastics, metals, and synthetic and natural resin coatings. Furniture pohshes impart shine and provide protection from abrasion, marring, and spills. The formulations clean weU in many cases. In common with most other pohshes, furniture pohshes are characterized by ease and speed of apphcation and of buffing, and by either the absence of objectionable odors or the addition of pleasing ones. 

T-wash pretreatment This acid-mordant solution turns the surface black when correctly treated. Problems can occur with use of such an acid solution in situ and from its pungent odor. It must be applied to zinc in a bright condition without corrosion products on its surface. The paint manufacturer s advice must be sought before using under thick coats of two-pack epoxy or urethane. 

Advances in the production, immobilisation and characterisation of mammalian olfactory receptors led to the development of biosensors where isolated olfactory binding proteins were deposited on the surface of QMBs [102, 103] or were connected to nanoelectrodes [104]. Although still at the development stage, such an array-type device coated with different olfactory receptors will be a powerful and useful tool for detecting and discriminating odorants in the future. 

Microbiological action in starch dispersions results in a drop in pH, loss of viscosity and the development of odor. Retrogradation may be accelerated by the drop in pH or especially if butanol, which complexes with amylose, is generated via starch fermentation. Sulfate-reducing bacteria will cause black deposits due to reaction with iron in the process water. For quality control, preservatives are added to starch slurry, cooked starch, surface size and coating color. 

An earlier off-odor problem that surfaced was the presence of 4-phenyl-cyclohexene in styrene-butadiene coated paper (Koszinowski et al. 1980). This compound was created by a Diels-Alder condensation reaction involving a molecule of styrene and butadiene and is differentiated by its odor from the isomeric 3 and 1-phenyl-cyclohex-ene compounds which cannot be formed by such a condensation reaction. The recognition threshold of this compound in the headspace over an aqueous solution lies around a concentration of 10 pg/kg (10 ppb). The typical odor of this compound at concentrations of 4-phenyl-cyclohexene in paper over 4 mg/kg (4 ppm) is easily identified. AGC determination in this concentration range is also possible without difficulty and its identification with MS using the relative molecular mass of 158 and one of the retro Diels-Alder decomposition product fragments at m/e = 104 (styrene) and mJe = 54 (butadiene) is definitely possible. 

The primer, defined in the first part of this paper as a cut-back of the same or a compatible, unfilled, oxidized asphalt dissolved in a high flash petroleum fraction, should be scrubbed into the concrete surface with a broom or stiff brush (roller or spray application is not recommended) and allowed to dry to permit the solvent to evaporate. This usually takes about 3 to 4 hours, at which time the odor of the solvent will have become faint. This leaves a black deposit of the asphalt in the pores and on the surface of the concrete. If the black color fades away, or becomes gray, the concrete is porous, and another coat of primer is necessary. Repeat until the surface remains black. 

Polymer films have been very widely applied to modify the surfaces of chemical sensors both for solution and gas phase measurements. Solution coating has been used to coat quartz crystal oscillators [91-93, 112] and SAW devices [113, 114] with various polymeric adsorbates and polymer/lipid mixtures [90, 94] to prepare arrays of sensors for use in gas sensing and odor evaluation and discrimination. 

The extrusion aid must easily coat the resin yet be readily removable from the extrudate. It should also not leave a residue which could alter the color of the product. The volatilization temperature of the lubricant should be lower than the sintering temperature of the polymer. The other requirements of lubricants include high purity, low odor, low polar components, high auto-ignition temperature, low surface tension, and low skin irritation. Common lubricants are synthetic isoparaffmic hydrocarbons available in a wide boiling range. Some of the commercial lubricants include Isopar solvents (available from Exxon Corp.), mineral spirits, and VM P Naphtha (available from Shell Corp.). 

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