Method of Modification of Okra Bast Fiber

Method of Modification of Okra Bast Fiber

Vinyl monomer (Acrylonitrile) was dissolved in cold distilled water. Initiator and catalyst solutions were also prepared with cold distilled water. The modifying baths were prepared by adding required amount of monomer, initiator and catalyst. The fibre-liquor ratio was maintained at 1:50. Modification was started at 30°C and then the temperature was slowly increased upto 90°C with 30 min and continued for 240 min with occasional stirring by a glass rod and allowed for further 30 min as the bath cools down. Hot distilled water was added to the modifying baths in order to maintain the fibre-liquor ratio 1:50 throughout the experiment. After modification the fibres were washed with hot distilled water to remove the suspended homopolymer on the okra bast fibre sample and dried at room temperature.

Percentage of grafting was calculated according to the following formula:
A-B
Percentage of grafting = ---------- 100
B
Where,
A = The weight of the okra bast fibre after modification
B = The weight of bleached okra bast fibre before modification

Selection of Optimum Modification Conditions

In order to select the optimum conditions of modification of okra bast fibre, monomer concentration, initiator concentration, catalyst concentration, modification time and modification temperature were selected accordingly.

Selection of Monomer Concentration

Ten baths were prepared with 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M and 0.1M acrylonitrile monomer. Keeping constant all other parameters (Initiator 0.1M, catalyst-0.1M, time 90 min, temperature 70°C, fibre-liquor ratio1:50), the monomer concentration which gave the maximum percentage of grafting was selected for modification.

Selection of Initiator Concentration

The selected monomer concentration and other parameters (catalyst 0.1M, time 90 min, temperature 70°C, fibre-liquor ratio 1:50) were kept constant and the ten modifying baths were prepared with 0.001M, 0.005M, 0.01M, 0.015M, 0.02M, 0.025M, 0.03M, 0.035M, 0.04, and 0.045M potassium persulphate (K2S2O8) initiator solution. The initiator concentration which gave the maximum grafting was selected for modification.

Selection of Catalyst Concentration

The selected monomer and initiator concentration and other parameters (time 90 min, temperature 70°C, fibre-liquor ratio 1:50) were kept constant and then ten modifying baths were prepared with 0.001M, 0.002M, 0.003M,
0.004M, 0.006M, 0.007M, 0.008M, 0.009M, 0.01M,and 0.02M ferrous sulphate (FeSO4) as catalyst to catalyse the initiator. The catalyst concentration which gave the maximum grafting was selected for modification.

Selection of Modification Time

Eight modifying baths each containing selected monomer, initiator and catalyst concentrations were prepared and the fibres were modified at 70°C for 30, 60, 90, 120, 150, 180, 210 and 240 min. The time of modification which gave maximum grafting was selected for modification.

Selection of Modification Temperature

Seven modifying baths, each containing selected monomer, initiator and catalyst concentrations were prepared and then the okra fibre were modified at 30° (room temperature), 40°, 50°, 60°, 70°, 80° and 90°C for selected time. The temperature, which gave maximum grafting, was selected for modification.