Properties of hemp fibre polymer composites -An optimisation of ...

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The curves for composite stiffness versus fibre volume fraction were also steeper for the hemp fibres produced by cultivation of P. radiata (Figure a) than the curves for raw hemp bast and water retted hemp (Figure b). The raw hemp bast and the water-retted hemp fibres had therefore lower stiffness of 78 GPa and 88 GPa, respectively than the hemp fibres produced by cultivation of P. radiata (94 GPa) (Table 4). The highest composite stiffness obtained using raw hemp bast, water retted hemp or P. radiata defibrated hemp, as reinforcement were 20 GPa, 26 GPa and 30 GPa, respectively without consideration of porosity (Ec). Cultivation of P. radiata for defibration of hemp fibres resulted thereby both in the highest composite strength and highest composite stiffness. Based on obtainable composite strength and stiffness, the best defibration method was cultivation of P. radiata followed by water retting and then by cultivation of C. subvermispora. It was determined that the hemp fibres tensile strength and stiffness were affected by the defibration methods at 90% probability using analysis of variance (F-test with number of samples = 4 and number of repetitions = 23 for F0.1). V p [% v/v] 10 5 0 Raw hemp bast Water retted hemp C.sub. treated hemp Hemp yarn P.rad. treated hemp 0 10 20 30 Vf [% v/v] Figure 5. Porosity content in the composites versus fibre volume fraction. 134 Risø-PhD-11 40
Figure 6. Effect of composite fabrication (a), fibre length (a), fungal defibration (a) and water retting (b) on composite tensile strength after correction for porosity plotted as a function of fibre volume fraction. Risø-PhD-11 135
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Risø-PhD-11(EN) Properties of hemp
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Contents Preface 6 1 Resumé 7 2 Li
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PhD thesis: Properties of hemp fibr
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1 Resumé Karakterisering af hampef
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2.4 Oral presentations Anders Thyge
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4 Introduction Hemp (Cannabis sativ
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4.2 The outline of the thesis The f
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The only fertilizer used was 360/48
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Temperature [ o C] 35 30 25 20 15 1
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A B Figure 7. A: Model of transvers
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Figure 8. Lignin (a), pectin (b) an
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Figure 11. Microfibril angles (MFA)
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Teleman, 1997). The crystal structu
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to the computing effort and the sub
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Figure 15. The structure of hemicel
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fibre mats, which are made by air-d
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Figure 18. From fibre filament to a
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A B C D Figure 20. Chemical structu
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water vapour and air are removed fr
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7 Defibration methods Defibration m
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Table 5. Fibre yield and cellulose
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a b c Composition [% w/w] 100 Compo
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8 Fibre strength in hemp The streng
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8.2 Effect of pre-treatment of hemp
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E-modulus [GPa] 90 80 70 60 50 40 3
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Second mode: Failure is controlled
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structure, which made much higher f
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Table 7. Porosity factors determine
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Thereby, the effective fibre streng
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a b Composite tensile strength σcu
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Table 9. Mechanical properties in a
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a σ c/ρ c [10 3 m 2 /s 2 ] b Ec/
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Fibre strength σ f [MPa] Fibre sti
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11 References Andersen TL, Lilholt
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Kaar WE, Cool LG, Merriman MM, Brin
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Stowell EZ, Liu TS, 1961. On the Me
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Appendix A: Comprehensive composite
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The porosity constants can now be d
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Appendix D: Density and mechanical
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Paper I Changes in chemical composi
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Risø-PhD-11 81
Page 83 and 84: Risø-PhD-11 83
Page 89 and 90: Paper II Hemp fiber microstructure
Page 91 and 92: ABSTRACT Characterization of hemp f
Page 93 and 94: METHODS AND TECHNIQUES Treatment of
Page 95 and 96: 2000) and their orientation gave th
Page 97 and 98: By TEM microscopy, the single fiber
Page 99 and 100: Table 1. Chemical composition of th
Page 101 and 102: Table 2. Tensile strength (σ) and
Page 103 and 104: Morvan, C., Jauneau, A., Flaman, A.
Page 119 and 120: Paper IV Comparison of composites m
Page 121 and 122: ABSTRACT Aligned epoxy-matrix compo
Page 123 and 124: the calculation of volume fractions
Page 125 and 126: solution (pH 4) for 4 h at 85°C. L
Page 127 and 128: E ⎛ dσ c ⎞ = ⎜ ⎟ ⎝ dε
Page 129 and 130: Table 2. Chemical composition, stru
Page 131 and 132: transverse section of the small hem
Page 133: Long fibres that pass through the e
Page 137 and 138: DISCUSSION The defibration of hemp
Page 139 and 140: This investigation showed that the
Page 141 and 142: Bos, H.L., Molenveld, K., Teunissen
Page 143 and 144: Thygesen, A., 2006. Properties of h
Page 147: Risø’s research is aimed at solv
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