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Volatile Organic Compounds (VOC) are ubiquitous in the indoor air since they are emitted from materials used indoors. Investigations of these materials are mostly carried out in emission test chambers under controlled climatic conditions. Reference materials are an important tool for quality assurance/Quality control of emission test chamber measurements but so far they are not commercially available. In this study, a new approach was tested to develop an appropriate reference material with homogenous and reproducible emission of the VOC with well measurable air concentrations in emission test Chambers larger than 20 L at air change rates of 0.5 - 1 /h.
Thermoplastic Polyurethane (TPU) was selected as Matrix material which was impregnated with 2,2,4- trimethyl-1,3-pentanediol monoisobutyrate (texanol) as test VOC using compressed carbon dioxide. An optimization of the impregnation parameters such as temperature, pressure, time, VOC injection volume and TPU sample size was performed until the targeted area specific Emission rate (SERa) value was reached. Further aspects like process control, storage effects and correlation of the sample size to the emission rate were investigated. It was found that the SERa immediately after sample preparation were not reproducible between the batches but became unified 10 days after loading into the test chamber indicating the necessity of aging before use. SERa between 13,000 and 18,000 mg m-2 h-1 were obtained, and the impregnated materials could be well stored in aluminum-coated polyethylene foil for at least seven weeks without significant losses. Furthermore, the impregnation of styrene and the SVOC 2,6-diisopropylnaphthalene was tested.
Volatile Organic Compounds (VOC) are ubiquitous in the indoor air, since they emit from materials used indoors. Investigations of these materials are mostly carried out in test chambers under controlled climatic conditions. Quality control of these test chamber measurements is important but there is a lack of commercially available homogenous reference materials as required for round robin tests or quality assurance of laboratories. The approach of the present study is the impregnation of a supporting material with VOC, which are reproducibly released in measurable chamber air concentrations under standardised test conditions. A polymer made of Thermoplastic Polyurethane (TPU) was chosen as carrier material. It was impregnated with the VOC trimethyl pentanediol isobutyrat (texanol).
Recent research into emissions of (semi-)volatile organic compounds [(S)VOC] from solid materials has focused on the development of suitable reference materials for quality assurance/quality control of emission test chamber measurements, which fulfill requirements such as homogenous and reproducible (S)VOC release. The approach of this study was to find a method for preparation of a material with predictable (S)VOC emission rates. AVOC (styrene) and an SVOC (2,6-diisopropylnaphthalene, DIPN), loaded into either vacuum grease or a 1:1 mixture of paraffin/squalane, have been tested. For the prediction of the emission rates, a model using the finite element method (FEM) was created to simulate the (S)VOC emission profiles. Theoretical and experimental results obtained in a Micro-Chamber/Thermal Extractor (μ-CTE™) and in 24 L emission test chamber measurements were in good agreement. Further properties were investigated concerning the material applicability, such as shelf life and inter-laboratory comparability. The maximum relative standard deviation in the inter-laboratory study was found to be 20%.
Correlation of aldehyde emissions and fatty acids content in pine wood and oriented strand boards
(2011)
Indoor air quality is important for human health and comfort. To ensure good indoor air quality contamination by volatile organic compounds (VOC) should be minimised. The aim of the project is the reduction of unsaturated aldehydes which can emit from oriented Strand boards (OSB): These aldehydes have an impact on the health based evaluation of emissions from products for indoor use according to the AgBB (Ausschuss zur gesundheitlichen Bewertung von Bauprodukten, Committee for Health Evaluation of Building Products) scheine (AgBB 2010). The model OSB were produced in a pilot plant using well known raw materials (Pinus sylvestris at different trunk heights) under using various processing parameters (Wilke et al. 2011).
OSB emit predominantly monoterpenes and aldehydes. Aldehydes are oxidation products of fatty acids in wood. The conditions which affect the oxidation process are the fatty acid concentration and composition, the oxygen content, the sample surface and the presence of compounds which indicate, inhibit or stop the oxidation respectively. The oxidation rate rises with an increasing number of double bounds in the fatty acid, e.g. the oxidation rate between oleic, linoleic and linolenic acid correspond to 1:12:24. One of the most important products of fatty acid oxidation is hexanal. It is generated during the oxidation of linoleic acid. This study shows a direct correlation between aldehyde emission and oxidation, hexanal can be used as an indicator for oxidation.
With a gas mixing system (GMS) developed in our laboratory we created a gas mixture of
four substances. Adsorptive wall materials of four different compositions were exposed to this
gas mixture, consisting of 1-pentanol, hexanal, butyl acetate and n-decane. Aim of this study
was to scrutinize the ability of these samples to reduce the concentration of the supplied gas.
This capacity is expressed in the sorption flux F or area specific adsorption rate respectively.
The test was performed referring to a draft of ISO 16000-24.