Dissertations in Forestry and Natural Sciences

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Taneli Väisänen: Effects of Thermally Extracted Wood Distillates on the Characteristics of Wood-Plastic Composites should last for at least 30 ± 2 min. ASTM D1037-12 specifies two methods to determine water absorption of WPCs. In method A, the WPCs are first immersed for two hours in fresh water (20 ± 1 °C) and then weighed. After weighing, the sample is submerged in water for an additional 22 hours and then weighed again. Method B is similar to the 24-hour immersion procedure described in ISO 62. 3.3 VOC EMISSIONS There are several methods available for the determination of VOC emissions from solid products. If the product is primarily intended for indoors use, the emissions are commonly determined according to ISO 16000-6. In this standard, the emissions are analyzed by thermal desorption/gas chromatography with flame ionization detector and mass spectrometry (TD-GC-FID/MS) using a Tenax TA ® absorbent tube as a collector for VOCs. Proton-transfer-reaction mass-spectroscopy (PTR-MS) is another way to determine and compare VOC emissions between different samples. This is an online monitoring technique using gas phase hydronium ions as the ion source reagents. This technique is used in food science, medicine, and biological and environmental research. (Schripp et al. 2014) 3.3.1 TD-GC-FID/MS The guidelines for determination of VOC emissions from building products using emissions test chamber system are given in ISO 16000-9. In this procedure, the air flow transfers the emitted compounds from the chamber to a Tenax TA ® absorbent tube. After reaching the tube, the compounds of interest are adsorbed onto the surface of the material. When the compounds are being analyzed, the tube is heated to a temperature over 250–300 °C and the adsorbed compounds are released into the flow of carrier gas that transfers the compounds to the GC-MS. 56 Dissertations in Forestry and Natural Sciences No 222
Characterization of wood-plastic composites The measurements are conducted under controlled conditions as defined in the standard. This states that the products should be tested at a temperature of 23 ± 2 °C and RH of 50 ± 5%, with an air velocity in the range 0.1–0.3 m/s. In addition, the temperature should not vary by more than ± 1.0 °C during the measurements, and RH and air flow rate can fluctuate by only ± 3%. Before the measurements, the test chamber must be cleaned with alkaline detergents and then rinsed twice with distilled water. In addition, cleaning by thermal desorption is also allowed. To eliminate the possible effects of background emissions, an air sample of the empty emission chamber is taken before the actual measurements. When the sample is placed in the chamber, it should be positioned in the center of the chamber to ensure that the air flow is evenly distributed over the emitting surface. The measurements should be carried out at predefined sampling times that depend on the objective of the test. However, duplicate air samples should be taken at least at 72 ± 2 h and 28 ± 2 days after the start of the test. For TD-GC-FID/MS, the analysis of VOCs is optimal for the range of VOCs eluting between and including n-hexane and n-hexadecane (Woolfenden 2009). However, when the tube is heated, the adsorbed compounds are released slowly from the tube. This may lead to low sensitivity and wide chromatographic peaks. In addition, this system is not capable of measuring the emissions of certain VOCs, such methane and formaldehyde. Modern TD-GC-MS systems avoid wide peaks by using cold traps to focus the samples before they reach the column, but the properties of column also affect the wideness of the peaks. Overall, the sensitivity of TD-GC-MS is highly dependent on the absorbent material, system parameters and the amount of the sample. 3.3.2 PTR-MS PTR-MS is an easy-to-use online VOC monitoring system with high sensitivity and rapid time response. In PTR-MS, the VOC trace gases in the sampled air are ionized in proton-transfer Dissertations in Forestry and Natural Sciences No 222 57
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PUBLICATIONS OF THE UNIVERSITY OF E
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Grano Oy Jyväskylä, 2016 Editors:
Page 7 and 8: ABSTRACT The use of raw materials d
Page 9: Universal Decimal Classification: 6
Page 12 and 13: Finally, I am grateful to my wife A
Page 14 and 15: TD-GC-FID/MS Thermal desorption/gas
Page 17 and 18: LIST OF ORIGINAL PUBLICATIONS This
Page 19 and 20: Contents 1 Introduction ...........
Page 21 and 22: 1 Introduction The finiteness of cr
Page 23 and 24: Introduction A new and environmenta
Page 25 and 26: 2 Wood-plastic composites By defini
Page 27 and 28: Wood-plastic composites additives u
Page 29 and 30: Wood-plastic composites Cellulose i
Page 31 and 32: Wood-plastic composites The propert
Page 33 and 34: Wood-plastic composites Figure 3. T
Page 35 and 36: Wood-plastic composites of lubrican
Page 37 and 38: Wood-plastic composites roughness a
Page 39 and 40: Wood-plastic composites Hosseinaei
Page 41 and 42: Wood-plastic composites the accessi
Page 43 and 44: Wood-plastic composites However, WP
Page 45 and 46: Wood-plastic composites A typical s
Page 47 and 48: Wood-plastic composites to fill the
Page 49: Wood-plastic composites absorption.
Page 52 and 53: Taneli Väisänen: Effects of Therm
Page 63 and 64: 4 Thermal processing of wood Therma
Page 65 and 66: Thermal processing of wood Figure 9
Page 67 and 68: Thermal processing of wood counterp
Page 69 and 70: Thermal processing of wood and the
Page 71 and 72: Thermal processing of wood and Miet
Page 73 and 74: 5 Aims and significance Despite the
Page 75 and 76: 6 Materials and methods Two types o
Page 77 and 78: Materials and methods heat energy f
Page 79 and 80: Materials and methods with the untr
Page 81 and 82: Materials and methods 6.2.1 Tensile
Page 83 and 84: Materials and methods 6.3 WATER ABS
Page 85 and 86: Materials and methods The emissions
Page 87: Materials and methods where Evoc is
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Taneli Väisänen: Effects of Therm
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9 Summary and conclusions In the pr
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Bibliography Abdolvahaba E, Lashgar
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Bibliography Ayrilmis N, Jarusombut
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Bibliography Cernansky R. State-of-
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Bibliography polypropylene composit
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Bibliography with odor assessments
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Bibliography La Mantia FP, Morreale
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Bibliography Mohan D, Pittman CU, a
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Bibliography Rinne J, Taipale R, Ma
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Bibliography Stark NM and Rowlands
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Bibliography Yeh S and Gupta RK. Im
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