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

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so higher cellulose content was obtained. Water retting is also a much faster process due to the higher microbial activity at the higher temperature (35°C; Paper IV). Defibration of hemp with the fungus P. radiata Cel 26 resulted in addition to the fibre components degraded in water retting in hemicellulose and lignin degradation, so the cellulose content increased to 86% (Figure 26b). A similar chemical composition has been obtained by wet oxidation (Thomsen et al., 2005; Paper I), which is also an oxidative process. The cultivation resulted in slight cellulose decay, in the large-scale experiments, indicating the presence of cellulose degrading enzymes (Paper IV). However at the smaller scale the cellulose yield was high (96%) and the fibre wall remained intact as confirmed by TEM microscopy (Paper II; Figure 10). The fungus Ceriporiopsis subvermispora degraded cellulose in the hemp fibres and formed much mycelium above the water surface, while stem pieces below the surface were not colonised by the fungus (Table 5, Figure 26b). The fungus grew well at low and medium scale cultivation with reduction of pH from 6 to 4.8 (Paper IV). At large scale, the sterilisation was insufficient resulting in lower fibre yield after 14 days cultivation (27 g/100 stem) and unchanged pH (Paper IV). Lignin degradation was obtained by the treatment with P. radiata Cel 26 by peroxidase enzymes, confirmed as presence of H2O2 in the cultivation broth (Paper IV). Smaller fibre bundle transverse sections were therefore obtained by defibration with P. radiata Cel 26 (3⋅10 3 μm 2 ) than by water retting and by C. subvermispora defibration (Paper IV), due to degradation of the lignin rich middle lamellae between the fibres. Table 6. Fibre yield and cellulose recovery for the hemp fibres treated with the biotechnological methods presented in Figure 26 (Paper I; Paper IV). Treatment Fibre yield [% w/w] Cellulose recovery [% w/w] Water retting 68 79 Fungal defibration C.sub. treated 14 days 75 85 C.sub. treated 31 days 65 83 P.rad. treated 14 days 70 85 P.rad. treated 31 days 72 96 Enzymatic defibration using pectinex solution 1 g/kg fibres 88 95 10 g/kg fibres 88 95 100 g/kg fibres 83 93 10 g/kg fibres followed by STEX 67 87 Note: Conditions are shown in Figure 26. The treatment of hemp fibres with pectin degrading enzymes (Pectinex) resulted in moderate increase in the cellulose content of the fibres and in high cellulose recovery (93-95%, Table 6, Figure 26c). Neither pectin nor lignin was degraded during the treatment. Thereby it seems like that the enzyme mixture was insufficient for effective defibration. If the enzyme treatment was followed by steam explosion, pectin and hemicellulose degradation were also obtained resulting in more cellulose rich fibres (78% w/w). 42 Risø-PhD-11
a b c Composition [% w/w] 100 Composition [% w/w] 80 60 40 20 0 100 80 60 40 20 0 60 63 65 64 15 15 17 14 10 12 7 3 5 7 7 7 4 7 4 5 3 5 5 1 1 3 4 1 2 1 2 3 2 2 Raw fibres sep-oct sep-apr Raw fibres 4 days 64 Field-frost retting of Uso-hemp 72 78 15 14 13 74 Water retting of Felina-hemp 7 4 6 6 4 5 4 6 1 2 1 2 2 2 3 1 3 2 3 1 2 1 2 2 2 2 1 Felina-hemp C. Sub P. Rad C. Sub P. Rad 14 days cultivation 31 days cultivation Cellulose Hemicellulose Lignin Pectin Water soluble Wax Ash Enzyme treatment: 1-100 g Pectinex / kg Felina or Uso hemp fibres; 40°C; pH 5; 24 hours. Steam explosion conditions: 50 g Uso hemp fibres/batch; 185°C; 2 min. Composition [% w/w] 100 80 60 40 20 0 68 70 71 15 15 15 16 12 5 6 3 3 0 5 5 3 2 0 4 5 3 3 0 6 4 4 2 2 4 3 1 1 1 1 g pec 10 g pec 100 g pec 10 g pec 10 g pec +STEX Pectinex on Felina-hemp [g/kg fibres] Pectinex on Uso-hemp [g/kg fibres] Figure 26. Chemical composition of hemp fibres treated with biotechnological methods. a: Frost treatment of Uso hemp and water retting of Felina hemp (Unpublished data; Paper IV). b: Fungal treatment of hemp (Paper IV). c: effect of pectin degrading enzymes (g pectinex solution/kg hemp bast, Paper I; Unpublished data). Risø-PhD-11 43 82 66 86 78
Page 1 and 2: Risø-PhD-11(EN) Properties of hemp
Page 3 and 4: Contents Preface 6 1 Resumé 7 2 Li
Page 5 and 6: PhD thesis: Properties of hemp fibr
Page 7 and 8: 1 Resumé Karakterisering af hampef
Page 9 and 10: 2.4 Oral presentations Anders Thyge
Page 11 and 12: 4 Introduction Hemp (Cannabis sativ
Page 13 and 14: 4.2 The outline of the thesis The f
Page 15 and 16: The only fertilizer used was 360/48
Page 17 and 18: Temperature [ o C] 35 30 25 20 15 1
Page 19 and 20: A B Figure 7. A: Model of transvers
Page 21 and 22: Figure 8. Lignin (a), pectin (b) an
Page 23 and 24: Figure 11. Microfibril angles (MFA)
Page 25 and 26: Teleman, 1997). The crystal structu
Page 27 and 28: to the computing effort and the sub
Page 29 and 30: Figure 15. The structure of hemicel
Page 31 and 32: fibre mats, which are made by air-d
Page 33 and 34: Figure 18. From fibre filament to a
Page 35 and 36: A B C D Figure 20. Chemical structu
Page 37 and 38: water vapour and air are removed fr
Page 39 and 40: 7 Defibration methods Defibration m
Page 41: Table 5. Fibre yield and cellulose
Page 45 and 46: 8 Fibre strength in hemp The streng
Page 47 and 48: 8.2 Effect of pre-treatment of hemp
Page 49 and 50: E-modulus [GPa] 90 80 70 60 50 40 3
Page 51 and 52: Second mode: Failure is controlled
Page 53 and 54: structure, which made much higher f
Page 55 and 56: Table 7. Porosity factors determine
Page 57 and 58: Thereby, the effective fibre streng
Page 59 and 60: a b Composite tensile strength σcu
Page 61 and 62: Table 9. Mechanical properties in a
Page 63 and 64: a σ c/ρ c [10 3 m 2 /s 2 ] b Ec/
Page 65 and 66: Fibre strength σ f [MPa] Fibre sti
Page 67 and 68: 11 References Andersen TL, Lilholt
Page 69 and 70: Kaar WE, Cool LG, Merriman MM, Brin
Page 71 and 72: Stowell EZ, Liu TS, 1961. On the Me
Page 73 and 74: Appendix A: Comprehensive composite
Page 75 and 76: The porosity constants can now be d
Page 77 and 78: Appendix D: Density and mechanical
Page 79 and 80: Paper I Changes in chemical composi
Page 81 and 82: Risø-PhD-11 81
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 105 and 106:
Risø-PhD-11 105
Page 107 and 108:
Risø-PhD-11 107
Page 109 and 110:
Risø-PhD-11 109
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Risø-PhD-11 111
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Risø-PhD-11 113
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Risø-PhD-11 115
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Risø-PhD-11 117
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 and 134:
Long fibres that pass through the e
Page 135 and 136:
Figure 6. Effect of composite fabri
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 145 and 146:
Risø-PhD-11 145
Page 147:
Risø’s research is aimed at solv
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