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Taneli Väisänen: Effects of Thermally Extracted Wood Distillates on the Characteristics of Wood-Plastic Composites differences between the raw materials (Schwarzinger et al. 2008). A comparison of the VOCs studied showed that monoterpenes were the compounds being emitted most from the hardwood distillate modified WPCs whereas cyclohexene was emitted most abundantly from the softwood distillate modified WPCs. Surprisingly, monoterpene emissions were higher from the hardwood distillate modified WPCs than from the WPCs containing the softwood distillate. In general, hardwoods mainly contain sterols, triterpenoids, and higher terpenes whereas softwood terpenes possess mono-, sesqui-, and diterpenes together with sterols (Björklund Jansson and Nilvebrant 2009). It was, therefore, assumed that the WPCs treated with softwood distillate would have higher monoterpene emissions than those modified with hardwood distillate. As terpenes are constructed from units of isoprene, it is possible that the higher terpenes in hardwood had thermally decomposed during the slow pyrolysis process, which resulted in the formation of lower terpenes, such as monoterpenes. Yadav et al. (2014) demonstrated that isoprene is one of the products of the thermal decomposition of terpenes. Both hardwood and softwood distillates contained only small amounts of guaiacol and benzene even though guaiacol could be smelled from the distillate modified WPCs. Interestingly, when the softwood distillate content was increased from 1 wt% to 8 wt%, the emissions of acetaldehyde declined. This also affected the odor characteristics of the WPCs as acetaldehyde could not be smelled from the WPCs with 2–8 wt% of distillate. This finding suggested that the distillate contains chemicals that react with acetaldehyde to form other compounds. There are no statutory limits for the material VOC emissions determined with PTR-MS. Thus, no conclusions could be made about whether the emission levels of a certain VOC exceed its safety limits. Due to the extremely high sensitivity of PTR-TOF- MS, the emission rates presented in this thesis may be considerably higher than the levels that would be estimated with the standardized chamber test method. However, the 108 Dissertations in Forestry and Natural Sciences No 222
Discussion comparison of VOC emissions between different material types using PTR-TOF-MS is feasible and sometimes more practical than the traditional chamber test method. 8.5 LIMITATIONS AND FUTURE PROSPECTS In this thesis, the effects of hardwood (birch) and softwood (primarily pine) distillates on the properties of WPCs were determined. Similar studies have not been previously conducted, even though the potential of other types of organic waste and residues as additives for WPCs has been extensively assessed (Hamzeh et al. 2011, Li et al. 2014, Madhoushi et al. 2014, Das et al. 2015a). This thesis focused on the determination of the effects of different wood distillates on the mechanical properties, water resistance and VOC emissions of WPCs. The positive effects of both distillates on the mechanical properties of the WPCs were evident, and the underlying reason for the enhancement was anticipated to be the improvement in the interfacial bonding between the polymer matrix and wood fibers. Further investigations of WPCs with scanning electron microscopy (SEM) and spectroscopic techniques would provide more detailed information on the interactions occurring between WPC constituents before and after the additions of the distillates. The considerably lower water absorption values for the WPCs treated with distillates were attributed to the composition of the distillates and to the ability of the distillates to fill the gaps within the WPCs. It was assumed that the distillates were hydrophobic as they were obtained from the tar phases and all the water-soluble compounds had been extracted from the distillates. However, the exact compositions of the distillates were not characterized. The chemical composition of birch distillates has been determined by Fagernäs et al. (2012a), and it was presumed, based on our other studies, that the distillate used in this thesis would be composed of similar chemical compounds. The composition of softwood distillates Dissertations in Forestry and Natural Sciences No 222 109
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PUBLICATIONS OF THE UNIVERSITY OF E
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Grano Oy Jyväskylä, 2016 Editors:
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ABSTRACT The use of raw materials d
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Universal Decimal Classification: 6
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Finally, I am grateful to my wife A
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TD-GC-FID/MS Thermal desorption/gas
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LIST OF ORIGINAL PUBLICATIONS This
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Contents 1 Introduction ...........
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1 Introduction The finiteness of cr
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Introduction A new and environmenta
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2 Wood-plastic composites By defini
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Wood-plastic composites additives u
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Wood-plastic composites Cellulose i
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Wood-plastic composites The propert
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Wood-plastic composites Figure 3. T
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Wood-plastic composites of lubrican
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Wood-plastic composites roughness a
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Wood-plastic composites Hosseinaei
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Wood-plastic composites the accessi
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Wood-plastic composites However, WP
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Wood-plastic composites A typical s
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Wood-plastic composites to fill the
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Wood-plastic composites absorption.
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Taneli Väisänen: Effects of Therm
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Page 60 and 61: 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
Page 115 and 116: 9 Summary and conclusions In the pr
Page 117 and 118: Bibliography Abdolvahaba E, Lashgar
Page 119 and 120: Bibliography Ayrilmis N, Jarusombut
Page 121 and 122: Bibliography Cernansky R. State-of-
Page 123 and 124: Bibliography polypropylene composit
Page 125 and 126: Bibliography with odor assessments
Page 127 and 128: Bibliography La Mantia FP, Morreale
Page 129 and 130: Bibliography Mohan D, Pittman CU, a
Page 131 and 132: Bibliography Rinne J, Taipale R, Ma
Page 133 and 134: Bibliography Stark NM and Rowlands
Page 135: Bibliography Yeh S and Gupta RK. Im
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