Preliminary results for biological degumming of decorticated hemp fibre show that bacteria occuring naturally on the fibre have the ability to degum fresh decorticated fibre under alkaline, unsterile conditions (Tab. 1). Treatment lasting 4 days showed no damage of the fibre. Based on the molecular weight of cellulose, the quality of biologically degummed fibres seems to be better than the quality of chemically treated hemp.
The uronic acid content could be reduced to 18.57 % and the pentose content to 44.14 % compared to fresh decorticated hemp. Thus the uronic acid and the pentose content of the biologically degummed fibre is around 10 % lower than in ultrasonic treated fibre.
Tab 1: Uronic acid, pentose, lignin, fibre content and molecular weight of cellulose of fresh decorticated fibre and other primary fibre (BaFa / ATB), chemically (chemical / ultrasonic / steam explosion) treated fibre and biologically degummed fibre (*-preliminary results)
|
uronic acid content |
pentose content |
lignin index * |
fibre content |
molecular weight of cellulose |
|
% |
% |
|
% |
|
fresh decorticated hemp |
4.34 |
5.54 |
0.05 |
67.60 |
1'597'110 |
BaFa |
2.86 |
4.1 |
0.03 |
74.91 |
1'595'432 |
ATB |
3.24 |
3.23 |
0.06 |
76.66 |
1'592'015 |
chemical |
1.33* |
2.02* |
0.03 |
90.75* |
1'379'126 |
ultrasonic |
1.24 |
3.02 |
0.05 |
80.63 |
1'419'487 |
steam explosion |
1.52* |
|
|
84.15* |
1'404'261 |
biologically degummed |
0.81 |
2.45 |
0.03 |
82.15 |
1'580'685 |
|
