Determination of styrene polymer content for industrial use (1)

1 Scope

This section specifies the method for determination of polymer content in styrene for industrial use

The photometric method in this section is applicable to the determination of styrene samples with a polymer content ranging from 1 mg/kg to 15 mg/kg

The visual method of wood part is suitable for the determination of styrene samples with polymer content (mass fraction) not more than 1.

This section does not apply to the detection of dimers and polymers in styrene for industrial use

This section is not intended to explain the safety issues related to its use.

Note: Styrene is flammable.

2 Normative references

The clauses in the following documents become clauses of this part after being quoted in this part of GB/T12688

GB/T 3723 General Rules for Sampling Safety of Industrial Chemical Products (GB/T3723-1999, ISO3165:1976, idt)

GB/T 6680 General Rules for Sampling of Liquid Chemical Products

GB/T 6682 Analytical laboratory water specifications and test methods (GB/T6682-2008, ISO3696:1987, MOD)

GB/T 8170 Numerical Rounding Rules and the Expression and Judgment of Limit Values

3 Principles of the method

3.

Using styrene styrene monomer present in the polymer insoluble in methanol principle, in styrene was added a sample of anhydrous methanol , absorbance was measured at 420nm, the quantified and compared with the calibration curve to determine the content of the polymer

3.

In the styrene is added a sample of anhydrous methanol , solution turbidity visually observed and compared with the standard solution to determine the content of the polymer

4 Reagents and materials

Unless otherwise noted, the reagents used in this section should be of analytical grade

4.

4.

4.

4.

4.
5 Styrene : purity (mass fraction) ≥99.
6%
.

4.
6 Polystyrene: Wash 50 mL of styrene (4.
5) with an equal volume of sodium hydroxide solution 3 times, and then with an equal volume of water 2 times .
After the second water wash, the styrene is quickly filtered through a two-layer pleated filter paper .
Then pour about 20 mL of filtered styrene into a test tube and place it in an oven at 100° C.
to heat for 24 hours to promote polymerization .
At the end, break the test tube, take out the polystyrene , discard all the glass, and grind the polystyrene into a fine powder in an agate mortar .

4.
7 Commercial high-purity polystyrene: high-molecular-weight polystyrene is required
.

Note: The additives contained in the commercial polystyrene particles may affect the absorbance of the standard solution, so care should be taken when choosing.

5 Apparatus and equipment

5.
1 Spectrophotometer: It can measure the absorbance at a wavelength of 420nm, and the sensitivity can meet the determination of styrene polymer with a content of 1mg/kg
.

5.
2 Photometer absorption cell: the length of the optical path is 50mm～150mm
.

5.
3 Pipette: 1mL, 10mL, 15mL
.

5.
4 Pipette: 10mL, 15mL
.

5.
5 Conical flask with stopper: 100mL
.

5.
6 Volumetric flask: 100mL, 1000mL
.

5.
7 Test tube: (25×150)mm
.

5.
8 Fluorescent tube
.

5.
9 Electronic balance: the accuracy is 0.
1mg
.

6 sampling

Take samples according to GB/T3723 and GB/T6680
.