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

2000) and their orientation gave thereby an indication of the microfibril orientation.
SEM observations of P. radiata Cel 26 defibrated and delignified hemp fibers showed
slightly darker intermediate lines on the fiber surface parallel with the cellulose
microfibrils.
Gravimetric plant fiber analysis
The fibers were milled to pass a 1 mm sieve. From the milled fibers, wax was extracted
in chloroform, water-soluble components in water, pectin in EDTA solution, lignin in
solution of chlorite and acetic acid and hemicellulose in boric acid and 12 % NaOH
solution. The residual part was cellulose with less than 1 % of minerals (Browning,
1967).
RESULTS AND DISCUSSION
The original hemp stems were 1.5-2.5 m tall and 5-15 mm in diameter near the soil
surface. The stems contained 35-40 % w/w bast fibers and were organized in layers from
the stem pith towards the surface by 1-5 mm xylem, 10-50 μm cambium, 100-300 μm
cortex, 20-100 μm epidermis and 2-5 μm cuticle. The definition of stem components are
in accordance with Garcia-Jaldon et al. (1998) and aspects of the stems are shown in
SEM micrographs (Figure 1) and modeled in Figure 2A.
Figure 1. Hemp stem shown at increasing magnification using different transverse
sections in SEM: A: Xylem + cambium + cortex + epidermis; B: Primary and secondary
single fibers; C: Major layers in primary single fiber; D: Thin lamellae within the S2
layer.
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