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

Table 1. Chemical composition of the structure on hemp stem level and single fiber level
based on qualitative evaluation (Content: +++ = high, ++ = medium, + = low and 0 =
none).
Stem level Epidermis Parenchyma
Single fibers
Cell part
cells
ML+P S1 + outer S2 Inner S2
Cellulose + 0 + ++ +++
Lignin 0 0 +++ ++ +
Pectin ++
+++ ++ 0 0
Wax ++ 0 + 0 0
Figure 6. Lignin shown as red colour in transverse sections of hemp stem after the
Wiesner reaction (A) and the Mäule reaction (B) (arrows = strongly lignified part of the
cell wall).
Pectin was stained with Ruthenium Red by reaction with carboxylic acid side groups
(Table 1, Figure 7A). Both the parenchyma cells and the single fiber compound middle
lamellae contained pectin, while the secondary wall appeared to lack pectin. Wax was
found in the epidermis with highest content in the cuticle layer according to the
hydrophobic red staining with Sudan IV (Figure 7B).
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