GB/T 25254-2022Poly-(tetra methylene ether glycol)(PTMEG) for industrial use (English PDF)

5.1 Appearance

Solid. white waxy; Liquid. colorless and transparent, no visible impurities.

6.2 Appearance

Observe the sample visually under natural light or fluorescent lighting.

6.3 Average molar mass and hydroxyl value

The average molar mass and hydroxyl value are determined according to Appendix A.

6.4 Viscosity

The viscosity is measured according to the method specified in Clause 2 of GB/T 10247-2008, using a precision constant temperature bath and thermometer, and the test temperature is set to 40.00°C. The comparison of specification and density of PTMEG is shown in Table 2.

6.5 Moisture

The measurement shall be carried out in accordance with the provisions of GB/T 6283; and the arithmetic mean of the parallel measurement results shall be taken as the report result. The absolute difference of the parallel measurement results shall be no greater than 25 mg/kg.

6.6 Chroma

The measurement shall be carried out according to the provisions of GB/T 3143, and the sample measurement temperature is 40°C~60°C.

6.7 Acid value

6.7.1 Principle

Dissolve the sample in an alkaline methanol solvent. After neutralizing the acidic substance, titrate the excess alkali with standard hydrochloric acid titration solution.

6.7.4 Determination procedures

6.7.4.1 Instrument settings

Set the control parameters according to the operating instructions of the automatic potentiometric titrator; and set the end point determination method to pH=5.3.

6.7.4.2 Determination

Take 10g of the specimen (accurate to 0.01g) into a 100mL glass beaker; add 50.00mL of methanol solvent; stir until completely dissolved; perform potentiometric titration with standard hydrochloric acid titration solution; record the standard titration solution volume (V1) required when the titration reaches pH=5.3.At the same time, measure the blank solution volume (V10).

6.7.6 Tolerance

The arithmetic mean of the parallel measurement results is the report result; and the relative deviation of the two parallel measurement results is no greater than 20%.

6.8 Carbonyl ratio

Measure according to Appendix B.

6.9 Molar mass ratio

6.9.1 Method summary

The molar mass ratio of PTMEG is calculated by an empirical formula based on the measured viscosity and average molar mass.

6.10 Stabilizer (BHT) content

6.10.1 Method summary

Prepare a standard solution based on the features with characteristic absorption of BHT at 278nm; and establish a standard curve between concentration and absorbance.

6.10.4 Drawing of working curve

6.10.4.1 Add 1.0mL, 2.0mL, 3.0mL, 4.0mL and 5.0mL of standard BHT solution to the 100mL volumetric flask respectively, and dilute to the mark by methanol.

6.10.5 Determination of sample

Weigh 10g of the sample (accurate to 0.01g), add it to a 100mL volumetric flask; dilute to the mark with methanol; and shake well. Use methanol as a blank, use a 10mm cuvette to perform spectral scanning; perform data processing on the spectrum; and calculate the corrected absorbance at 278nm.

7.2 Batching rules

Products are inspected in batches, and the mixing volume in the same storage tank is considered a batch, and the batch size does not exceed 3000t.

7.3 Sampling

Carry out nitrogen replacement and protection sampling according to the provisions in GB/T 6678 and GB/T 6680.The sample size shall be no less than 0.5kg.

7.4 Judgment rules

The inspection results are judged according to the rounding value comparison method specified in GB/T 8170 to determine whether they meet the requirements in Clause 5.

8.1 Marking

PTMEG products shall be accompanied by product marks, including. product name, product standard number, manufacturer name and address, net content, production batch number, certificate of conformity, etc.

9.1 Packaging

PTMEG products shall be packed in clean stainless steel tank trucks or clean, dry, strong steel drums, or other containers that meet the requirements. When packaging, it shall be filled with nitrogen and sealed. The quality requirements of nitrogen include. dew point no greater than - 40°C, oxygen content no greater than 5µg/g.

9.3 Storage

PTMEG shall be stored and sealed with dry nitrogen (nitrogen quality requirements are the same as 9.1). The suitable temperature for storage in the storage tank is 45 °C ~ 80 °C. Barrel products shall be stored in a dry and ventilated environment. The product can be molten by hot air or steam heating during use. PTMEG product shelf life. in solid state, the shelf life is 12 months; in liquid state, the shelf life is 6 months.