2.1. Chemical treatment of coir fiber
The Coir fibers were initially collected and cleaned.
For single stage treatment, a solution of 0.5% chromium sulfate with 2/3 drops of HCl was prepared.
An initial pH of 2.5-3 was maintained (during reaction this pH became 8-9).
Coir fiber was taken into the prepared solution and shaken for 3 hours. After 3 hours reaction the fiber is washed properly in distilled water.
For two stages CrSO4 and NaHCO3 treatment,
the same procedure was followed with an addition of 0.02% NaHCO3 solution.
The solution along with coir fiber was shaken for another 2 hours.
Later the fiber was washed properly with distilled water.
2.2. Tensile testing
Tensile testing was performed for the span length of 5mm, 15mm, 25mm and 35mm using a tensile testing machine.
The fibers were glued in between two paper frame (Fig. 1) to conform a good gripping
and straight direction to the test clamps.
Diameter of single fiber was measured using a scanning electron microscope (SEM).
The paper frame was carefully placed in between the jaws of the load cell.
The load cell and cross-head speed used were 50N and 4mm/min respectively.