New Material: Comprehensive Experiment Purpose And Requirements Of Cellulose Cationic Modifier

1、 Purpose and requirements of the experiment

1. Understand the synthesis method of cationic modifier;

2. Understand the principle and modification method of the interaction between cationic modifier and cellulose;

3. Understand the determination method of dyeing properties of cellulose fabrics;

4. Master the method of determining tertiary amine content by potentiometric titration;

5. Master the use of spectrophotometry to measure the dye uptake of fabrics

II Experimental principle and significance The hydroxyl group in cellulose can be partially ionized in water, making cellulose negatively charged. When dyeing it with reactive, direct and other anionic dyes, because the dyes have the same charge with cellulose, there is a certain repulsive force, and the dyes are not easy to bond with cellulose. Therefore, when dyeing cellulose with these dyes, the utilization rate of dyes is not high, This will not only increase the consumption of dyes, but also aggravate environmental pollution. Grafting cationic groups onto cellulose will make cellulose positively charged, which will undoubtedly improve dye uptake. The method of synthesizing cationic modifier in this experiment and the modification principle of cellulose are as follows:

3、 Experiment content

1. Determination of tertiary amine content:

(1) Prepare 200ml of 0.2mol/L hydrochloric acid (isopropanol glycol 1:1) standard solution.

(2) Use the reference substance sodium carbonate to calibrate the prepared HCl solution, and use methyl orange as the indicator

　　(3) Determination of total amine: weigh 1.0~1.1g+dialkyldimethyl tertiary amine, add 50ml isopropanol to dissolve it, stir it evenly on a magnetic stirrer, add 0.2mol/L isopropanol hydrochloride ethylene glycol standard solution dropwise under stirring state, measure the relationship between the pH value (or potential mV value) of the solution and the amount of HCl added (Vml) with an acidimeter, draw a pH (mV)~V diagram, calculate the titration end point, and calculate the content of total amine (mol/g).

　　(4) Determination of dodecyl dimethyl amine content: weigh 1.0-1.1g of melted+dialkyl dimethyl tertiary amine sample (accurate to 0.1mg) into a 100ml beaker, slowly add 10ml of acetic anhydride (if there is solid in the sample, it needs to be heated and melted in a mild electric furnace), shake up and place at room temperature for 15min. Then add 50ml of isopropyl alcohol solution, put in the stirring magnet, insert the electrode, turn on the magnetic stirrer, conduct potentiometric titration with hydrochloric acid isopropyl alcohol glycol solution, and draw the titration curve. Calculate the content of tertiary amine (mol/g).

2. Synthesis of modifier

　　:

　　(1) Take 15g of dodecyl dimethyl amine into a three necked bottle, add 45ml of isopropanol, shake it up, drop concentrated HCl to the solution pH=7, then add epichlorohydrin (total amine: epichlorohydrin=1.0:1.1mol ratio), shake it up, install a condenser tube and thermometer on the three necked bottle, and heat the three necked bottle in a water bath to keep the temperature of the reaction solution at 80~90 ℃, react for 3h, cool the discharge, and obtain the modifier.

3. Determination of tertiary amine conversion;

Weigh a certain amount of synthetic modifier, and measure its surfactant content (mol/g) with bromocresol green indicator two-phase reverse titration method. See the appendix for the determination method. Calculate the conversion of tertiary amine.

4. Cation modification of cellulose fabric:

(1) Preparation of modifier Add 2.5g NaOH in three beakers, then add water to dissolve, then add 3ml, 6ml, 9ml of modifier respectively, and finally add water to 150ml.

　　(2) Modification method: take three pieces of fabrics weighing about 5g and immerse them in the above modification solution respectively, stir them, heat them to 70~80 ℃, keep them warm for 1h, stir them frequently during this period, then take them out, wash them with water, immerse them in 2g/L HAc solution, stir them for 3~5min, take them out, wash them with water, and squeeze them dry.

5. Dyeing of fabric and determination of dye uptake:

(1) Dyeing process

80 ℃, 40min, 10min to 50 ℃, NaCO310g/L * NaCl 20g/L shall be added when the unmodified fabric is dyed

(2) Methods

　　a. Preparation of dye solution: accurately weigh 1.3g of dye, add water to dissolve it, and dilute it to 500ml

　　b. Determination of dye solution absorbance: Dilute 5.00ml of the above dye solution 80~100 times and measure its absorbance A1

　　c. Dyeing: add 25.00ml dye solution and 125ml water into four beakers respectively, stir evenly, put four pieces of fabric (one of which is unmodified fabric) into the dye cup, dye according to the dyeing process, and stir from time to time during the dyeing process. After dyeing, take out the fabric and wash it with a small amount of water, combine the washed water with the dye solution, dilute it to 500.00ml, and measure its absorbance A2 after appropriate dilution

　　d. Calculation of dye uptake: dye uptake=(1-A2 × (dilution ratio of dye solution)/(A1 × dilution ratio of dye solution) × 100%