Dissertations in Forestry and Natural Sciences

More documents

Recommendations

Info

Taneli Väisänen: Effects of Thermally Extracted Wood Distillates on the Characteristics of Wood-Plastic Composites dimensions specified in the ISO and ASTM standards. In other words, it is possible that the stress required to fracture the WPC sample is relatively lower at smaller sample dimensions than it would be at the dimensions of the final applications because wood fibers are larger in relation to the cross-sectional area of the sample and thus undergo fractures more easily. According to BS EN 15534-1, WPC samples should be conditioned in a standard atmosphere at 23 ± 2 °C and relative humidity (RH) of 50 ± 10% before mechanical testing. An atmosphere of 20 °C and 65% RH may also be used but those conditions should be declared. When determining flexural, tensile, and impact strength of WPCs, the preferred test specimen according to ISO standards should be 80 ± 2 mm in length, 10.0 ± 0.2 mm in width, and 4.0 ± 0.2 mm in thickness. The corresponding specimen dimensions for WPCs in ASTM standards are 125 mm × 12.7 mm × 3.2 mm. In total, a set of 10 specimens should be tested unless the coefficient of variation has a value less than 5%. In that case, a minimum number of five specimens may be sufficient. 3.1.1 Tensile strength Tensile strength is the measure of the maximum amount of tensile stress that a material can withstand while being stretched before breaking. It is defined as a stress and expressed as force per unit area. The most important parameters for tensile testing include testing speed, force capacity, precision, and accuracy. The testing speed is expressed as mm/min, and according to ISO 527-1, it can vary between 0.125–500 mm/min depending on the sample type. At the start of the measurement, the machine slowly extends the sample until it breaks. The elongation of the sample is measured against the applied force. With the measured elongation, it is possible to calculate the strain, , using the following equation: = L-L 0 L 0 , (3.1) 50 Dissertations in Forestry and Natural Sciences No 222
Characterization of wood-plastic composites where L is the final length of the gauge and L0 is the initial gauge length. The applied force is used to calculate the stress, , using the following equation: = F A , (3.2) where F is the tensile force (N) and A is the cross-sectional area of the sample. The relationship between the stress and strain of a material can be displayed on a stress-strain curve (Figure 8). The curve also provides the fracture strength of a material, which is the final recorded point. Figure 8. A typical stress-strain curve for WPCs. Tensile properties of WPCs can be determined according to ISO 527-1 and ASTM D638-14 standards. Although the testing procedures presented in these standards are rather similar, there are some differences that can significantly influence the results obtained. In ISO 527-1, it is stated that the specimens must not be pre-stressed considerably prior to testing. Pre- Dissertations in Forestry and Natural Sciences No 222 51
Page 1: PUBLICATIONS OF THE UNIVERSITY OF E
Page 4 and 5: 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 54 and 55: 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 102 and 103:
Taneli Väisänen: Effects of Therm
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
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
show all

Dissertations in Forestry and Natural Sciences

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?