Industrial methyl methacrylate (two)

4 Test method

Unless otherwise specified, the reagents and water used in this test method are all analytical reagents and distilled water or water of equivalent purity

The standard solutions, preparations and products used in this test method are prepared in accordance with GB601 and GB603 unless other requirements are specified

4.

According to the provisions of GB3143

4.

According to the provisions of Article 2.

4.

The difference between the two parallel determination results is not more than 0.

4.

4.

In ethanol medium, with bromothymol blue as the indicator solution, neutralized with sodium hydroxide standard titration solution

4.

a.

b.

c.

4.

In the Erlenmeyer flask, add 20-50mL ethanol and 2 drops of bromothymol blue indicator solution, use sodium hydroxide standard titration solution to drop to blue, use a pipette to add a sample of the same volume as ethanol, use sodium hydroxide standard The titration solution is titrated to blue, and 15s does not fade as the end point
.

4.
3.
4 Expression of analysis results

The content (X ₁ ) of acid ( calculated as methacrylic acid ) expressed in mass percentage is calculated according to formula (1):

In the formula: V ₁ -the volume of sodium hydroxide standard titration solution, mL;

c—The actual concentration of sodium hydroxide standard titration solution, mol/L;

V ₂ —sample volume, mL;

p—0.
943, sample density, g/cm ² ;

0.
086 — The mass of methacrylic acid expressed in grams, which is equivalent to 1.
00mL sodium hydroxide standard titration solution [(c(NaOH)=1.
000mol/L] .
Take the arithmetic average of two parallel determinations as the result .

4.
3.
5 Tolerance

The relative deviation of the two parallel determination results is not more than 10%
.

4.
4 Determination of moisture

4.
4.
1 Karl Fischer method (arbitration method) is measured in accordance with GB6283 electricity consumption titration method
.

4.
4.
1.
1 Allowable difference

The relative deviation of the two parallel determination results is not more than 10%, and the arithmetic mean is the determination result
.

4.
4.
2 Gas chromatography

Measure in accordance with the regulations of GB2366
.

The quantitative method adopts the peak height-percentage standard curve method
.

4.
4.
2.
1 Preparation of standard samples

The water content of the product is within the range of 0.
05% to 0.
1% using a benzene-water balance solution, which is prepared according to Article 5.
2.
1 of GB2366; the water content of the product is within the range of 0.
1% to 0.
5% using the weighing and sample preparation method, according to the article Prepared in section 5.
2.
2, using methyl methacrylate with known moisture content as the base solution
.

4.
4.
2.
2 Standard curve usage period

Calibrate once every two months.
During this period, when the absolute value of the maximum relative deviation of the four repeated test values ​​is greater than 15%, it should be re-calibrated immediately
.

4.
4.
2.
3 The rest shall be implemented in accordance with the provisions of GB2366, and the instrument part shall be implemented in accordance with the provisions of GB9722
.
Refer to Appendix A for chromatographic test reference conditions and chromatographic diagrams
.

4.
4.
2.
4 Allowable difference

The relative deviation of the two parallel determination results is not more than 10%, and the arithmetic mean is the determination result
.

4.
5 Determination of content

According to the organic impurity content measured by gas chromatography and the acid content and moisture content measured in Article 4.
3.
4.
4, the content of methyl methacrylate is calculated by calculation
.

4.
5.
1 Reagents and materials

a.
Anhydrous methanol ;

b.
Acetone ;

c.
Methyl acrylate ;

d.
Methyl isobutyrate ;

e.
Ethyl methacrylate ;

fa-hydroxyisobutyrate methyl ester: self-made (and calibrated its purity);

g.
Methyl methacrylate: excluding moisture and acid content, purity ≥99.
95%;

h.
Carrier gas: nitrogen with a purity of not less than 99.
8%;

i.
Fuel gas: hydrogen with a purity of not less than 99.
8%;

j.
Combustion gas: compressed air after purification treatment
.

Related Links: Industrial Methyl Methacrylate (1)