The overall goal of this procedure is to improve the tensile properties of ramie fiber, prepared in a hydrogen peroxide oxidation degumming system by using a controlled release alkali source made by partially replacing sodium hydroxide with magnesium hydroxide. This method can help answer key questions in the field of oxidative extraction of natural fibers, such as extraction of ramie and flax fiber prepared in hydrogen peroxide oxidation degumming system. The main advantage of this technique is that pH and thus oxidation ability of the degumming solution can be controlled by adjusting the substitute rate of the magnesium hydroxide.
We first had the idea for this method when we found that if sodium hydroxide was used as a alkaline source, the pH value of the degumming solution dropped quickly, making it difficult to control the hydrogen peroxide reaction speed. First, dissolve hydrogen peroxide, alkali, sodium triphosphate, anthraquinone, and HEDP in 100 milliliters of distilled water to make the degumming solution. Immerse 10 grams of raw ramie in the degumming solution and scour it at 85 degrees Celsius for 60 minutes.
Following this, increase the temperature to 125 degrees Celsius and scour for another 60 minutes. Now, dissolve 0.4 grams of sodium bisulfite in 100 milliliters of distilled water to prepare the reducing solution. After scouring, treat the degummed ramie fiber in the reducing solution at 90 degrees Celsius for 60 minutes.
After reducing the degummed ramie fiber, wash it thoroughly with deionized water. Immerse the fiber in degumming oil at 90 degrees Celsius for 15 minutes, then dry the fiber in an oven at 125 degrees Celsius for four hours. Prepare degumming solutions with magnesium hydroxide substitution rates of zero, 20, 40, 60, 80, and 100%as previously described.
Immerse the raw ramie in the degumming solutions, then scour at 85 degrees Celsius for 60 minutes. Wash the combined ORP electrode with distilled water. After air drying, immerse the combined ORP electrode in the degumming solutions to record the ORP value every 10 minutes.
Immerse the pH electrode in the degumming solutions to record the pH value every 10 minutes. Next, test the hydrogen peroxide content of the degumming solutions every 10 minutes by the potassium permanganate titration method according to the Chinese standard. Degrease the ramie fiber by submerging it in a two to one mixture of benzene and ethyl alcohol.
After allowing the solvent to evaporate, cut the fiber into short pieces using scissors. Place the samples in a weighing container, and keep them in a controlled humidity atmosphere until it reaches equilibrium water content before removing for test purposes. Now, immerse a copper wire in concentrated nitric acid, followed by 98%anhydrous ethylenediamine.
Then, wash the copper wire thoroughly with distilled water. Place the fiber sample and copper wire in a flask. Add 10 milliliters of distilled water and 10 milliliters of one mol per liter cupriethylenediamine solution to the glass bottle.
Add a magnetic stir bar to the flask and stir the mixture for one hour to prepare the ramie fiber cupriethylenediamine solution. Following this, transfer 6.5 milliliters of the ramie fiber solution to an Ubbelohde viscometer to measure its intrinsic viscosity. Finally, set the clamping distance at 20 millimeters, and the descending speed of the bottom clamp at 20 millimeters per minute.
After equilibrating the fiber samples under standard atmospheric conditions, test the tenacity, breaking elongation, and work of rupture of the fiber using the fiber strength instrument under the appropriate conditions. Although the solubility of magnesium hydroxide in degumming solution was higher than distilled water, due to the slight effect of degumming auxiliaries, it was still insufficiently soluble. When a controlled release alkali source was applied, the pH was stable, and decreased with increasing substitution rate.
Decrease of the ORP value was slower under higher substitution rate. Residual gum analysis revealed that the yield of degumming and residual gums of fiber increased with the substitution rate. The DP value, crystallinity, and tensile properties increased with the substitution rate, but decreased with substitution rate higher than 20%The COD value decreased by 20%under the substitution rate of magnesium hydroxide.
In FTIR patterns of the fiber, signals due to the stretching vibration of CH and OH and cellulose were observed. The carbinol peak was attributed to the CO stretching of COH bending and hemicellulose, and this signal was stronger when the substitution rate was lower, which indicates that hemicellulose can be removed more effectively under a lower substitution rate. Although the residual hydrogen peroxide contents increased when using the controlled release alkali source, the substitution rate did not influence the residual hydrogen peroxide content.
Once mastered, this technique can be done in about 200 minutes if it is performed appropriately. While attempting this procedure, it's important to remember to control the substitution rate of the magnesium hydroxide. After its development, this technique paved the way for researchers in the field of oxidation natural fiber extraction, or bleaching.
After watching this video, you should have a good understanding of how to adjust the pH value of working solution, with a controlled release alkali source, and the method of natural fiber extraction. Don't forget that working with cupriethylenediamine can be extremely hazardous, and appropriate precautions should always be taken while performing this procedure.
