GB/T 3401-2007Determination of the viscosity of Poly (vinyl chloride) resins in dilute solution using capillary viscometers (English PDF)

3.1 Reduced viscosity (also known as viscosity)

The ratio of the viscosity ratio increment to the polymer concentration c in the solution.

If the solution concentration is low, the viscosity ratio eta/eta0 can be given by the efflux time ratio t/t0, then the reduced viscosity can be expressed as.

The dimension of reduced viscosity is L3M-1.

The unit of reduced viscosity is m3/kg.

In practical applications, it is more convenient to use its 1/1000 (10-3m3/kg), that is, mL/g. The so-called viscosity number refers to the reduced viscosity (viscosity number) of this empirical unit.

The reduced viscosity is usually measured at a low concentration (less than 5 kg/m3, i.e., 0.005 g/mL) unless the concentration is increased for a polymer having a low molecular mass.

3.2 K-value

A constant which is independent of the concentration of polymer solution and is unique to the polymer sample, which is a measure of average degree of polymerization.

Where.

9.1.1 Method A

WEIGH (0.250±0.005)g of resin, accurate to 0.0001 g; and TRANSFER it quantitatively to the 50 mL volumetric flask (6.2.1). ADD about 40 mL of cyclohexanone to the flask, swirling the flask by hand to prevent coagulation or the formation of lumps. Continue dissolution by agitating for 1 h between (80~85)°C using the agitator (6.4). CHECK visually that dissolution is complete.

If gelatinized particles are still visible, START again with a new portion of the resin. COOL the solution to (25±1)°C and make up to the mark with cyclohexanone at the same temperature. MIX the solution thoroughly by shaking.

9.1.2 Method B

WEIGH (0.125±0.0025)g of resin, accurate to 0.0001 g; and TRANSFER it quantitatively to the 25 mL volumetric flask (6.2.2). ADD about 20 mL of cyclohexanone to the flask, swirling the flask by hand to prevent coagulation or the formation of lumps. Continue dissolution by agitating for 1 h between (80~85)°C using the agitator (6.4). CHECK visually that dissolution is complete.

If gelatinized particles are still visible, START again with a new portion of the resin. COOL the solution to (25±1)°C and make up to the mark with cyclohexanone at the same temperature. MIX the solution thoroughly by shaking.

9.1.3 Alternative methods

In addition to preparing the solution according to the above two methods, alternative methods for the preparation of the solution may be used, for example the addition of a measured volume of solvent to a measured mass of test portion, provided that the values obtained for the reduced viscosity and K-value can be shown to be equivalent to those obtained with the method of solution preparation described above. Such alternative methods of solution preparation will require the amounts of solvent and test portion taken to be determined by experiment, and may also require compensation for loss of solvent by evaporation during the dissolution process (Appendix D gives the method of solution preparation by conical flask).

9.2 Determination of efflux times

9.2.1 Determination of efflux times of solvent

9.2.1.1 The temperature of the temperature-regulated bath (6.6) shall be set such that the temperature which is measured by the thermometer (6.7) lies in the range (25±0.5)°C. The measured temperature shall be stable to ±0.05 °C around the temperature at which the temperature-regulated bath has been set.

9.2.1.2 On the viscometer tube M and tube N, CONNECT the latex tube; and PLACE the viscometer vertically in the temperature-regulated bath, so that the liquid level exceeds the viscometer D ball by about 20 mm.

9.2.1.3 USE the filter funnel (6.3) to filter approximately 15 mL of cyclohexanone

into the viscometer through the L tube, at constant temperature for about 10 min.

9.2.1.4 When the temperature is balanced, CLOSE the M tube, SUCK the N

tube or PRESSURIZE on the L tube, so that the solvent, through the capillary, slowly enters the C ball. When the liquid level rises to about 5 mm above the E-line, STOP sucking or pressurizing. OPEN the M tube; and MEASURE the efflux time of the liquid through the E-line to the F-line.

9.2.1.5 The efflux time first read is discarded, and it is repeatedly measured three times. The arithmetic mean thereof is taken as the efflux time t0 of the solvent. Efflux times with the control solvent cyclohexanone shall remain constant to within 0.2 s for a given viscometer. If the difference between the two successive average efflux times measured of the solvent is greater than 0.4 s, the viscometer shall be cleaned (SEE Appendix E).

9.2.2 Determination of efflux times of solution

9.2.2.1 ASPIRATE the above solvent; USE the filter funnel (6.3) to filter

approximately 10 mL of solution into the viscometer through the L tube, so that the solution is washed three times through the C ball and then the solution is aspirated. Then, FILTER about 15 mL of the solution through the L tube into the viscometer, at constant temperature for about 10 min.

9.2.2.2 According to 9.2.1.4, DETERMINE efflux times of the solution.

9.2.2.3 DISCARD the first efflux time reading. REPEAT the measurement of the efflux time until two successive measurements differ by less than 0.25%. The arithmetic mean thereof is taken as the efflux time t of the solution.

Note. The above is a manual procedure. Proprietary equipment is available which will organize the charging of the viscometer with solution and solvent and measure the respective efflux times automatically. The use of such equipment is included in the scope of this Standard provided that all the procedures and verification checks described above are followed by the automated procedure.

10.1 Reduced viscosity

Appendix A

(Informative)

Comparison between the chapter-clause number of this Standard and the chapter-clause number of ISO 1628-2:1998

Table A.1 gives the comparison between the chapter-clause number of this

Standard and the chapter-clause number of ISO 1628-2:1998.

Table A.1 -- Comparison between the chapter-clause number of this

Standard and the chapter-clause number of ISO 1628-2:1998 Chapter-clause number of this Standard Corresponding chapter-clause number of the international standard

1 Paragraphs 1, 2, and 3 of 1 3.1 -3.2 -5 5.1

Figure 1 -

6.2.1 6.2

6.2.2 -

- Paragraph 1 of 9.1

9.1 Paragraphs 7 and 2 of 9.1

9.1.1 Paragraph 3 of 9.1 - Paragraphs 4 and 5 of 9.1 9.1.2 -

9.1.3 Paragraph 6 of 9.1 9.2.1 -- Paragraph 1 of 9.2

9.2.1.1 Paragraph 2 of 9.2 9.2.1.2 -9.2.1.3 -9.2.1.4 -

9.2.1.5 Part content of paragraph 4 of 9.2 Appendix B (Informative) Technical differences between this Standard and ISO 1628-2:1998 and their causes

Table B.1 gives the technical differences between this Standard and ISO 1628-

2.1998 and their causes.

Table B.1 -- Technical differences between this Standard and ISO 1628-

2.1998 and their causes Chapter-clause number of this Standard Technical differences Causes Cover MODIFY the standard's name. The current national standard number does not correspond to the various parts of ISO 1628. This revision still uses the former standard number and cannot correspond to the international standard name.

1 DELETE paragraphs 4 and 5 of Chapter 1 of ISO 1628-2:1998.

Does not meet the provisions of GB/T 1.1 for the content of scope.

CITE Chinese standards which adopt international standards.

DELETE other standards cited.

To adapt to China's national conditions.

Other standards cited have not been translated into Chinese national standards. To facilitate standard application, the reference content is added to the corresponding position in the text.

The content for which ISO 1628-2:1998 cites ISO 1628-1 is listed as 3.1 and 3.2.

MAKE standard applications more convenient.

5 CHANGE 5.1 of ISO 1628-2:1998 to a paragraph.

Does not match China's national standard format.

ADD the specific content of the referenced part in 6.1 of ISO 1628-2:1998.

ADD Figure 1.

MAKE standard applications more convenient.

MAKE standard applications more convenient.

Appendix C

(Informative)

Determination of the kinematic viscosity of cyclohexanone C.1 Materials C.1.1 Cyclohexanone, SEE Chapter 5.

C.1.2 Standard liquid of viscosity. The kinematic viscosity is similar to that of cyclohexanone, such as GBW 13601.

C.2 Apparatus

SEE Chapter 6 for other apparatus.

Ubbelohde viscometer, model 1. The capillary diameter is 0.58 mm, with a relative error of ±2%. The dimensions of other parts are shown in Figure 1.

C.3 Determination of the kinematic viscosity of cyclohexanone C.3.1 Calibration of the coefficient of Ubbelohde viscometer in a (20±0.05)°C constant temperature water bath, USE the model 1 Ubbelohde viscometer to measure the efflux time t0 of the standard liquid of viscosity. The coefficient of the Ubbelohde viscometer is calculated by the equation (C.1).

Where.

c - The coefficient of the Ubbelohde viscometer, in square meters per square second (m2/s2);

nu0 - The kinematic viscosity of the standard liquid of viscosity, in square meters per second (m2/s);

t0 - The efflux time of the standard liquid of viscosity, in seconds (s).

C.3.2 Determination of the kinematic viscosity of solvent cyclohexanone in a (25±0.05)°C constant temperature water bath, USE the model 1 Ubbelohde viscometer to measure the efflux time t1 of solvent cyclohexanone. The kinematic viscosity of solvent cyclohexanone is calculated by the equation (C.2).