How to test the viscometer with Capillary tube GBGB17931-2003

A . 1 RangeThis method suits for testing the viscosity of  PET polymer and copolymer-determination.

A 2 Principle

Under 25±0.02 ℃ ,Determination Solvent and concentration of 0. 005 g/ml, PET resin solution flow out of time, then work out the viscosity of known concentration .

A . 3 Reagents
Unless other stated, only in the analysis using  pure  grade reagents.
A . 3. 1 Phenol
A . 3. 2  1.1.2.2-Tetrachloroethane
A . 4  Instrument
A . 4. 1 Constant temperature water bath:  (25± 0.02) ℃。
A. 4. 2 Ubbelohde viscometer:ISO 1628-1:1998 1B type Capillary Viscometer (Φ= 0. 88 mm ) ; or other type viscometer

Remarks: ISO 1628-1 :1998 1B type capillary viscometer (Φ= 0. 88 m m ) can make sure the Solution  of flow time from 80 s to 200 s.

A . 4. 3

Heating device: to control the temperature at(110± 10) ℃  oil bath or other heating(1 10 ±1 0) ℃ device.

A. 4. 4 Magnetic stirrer or other stirrer device.

A . 4. 5

Diameter (63-90) μm stainless steel filter or micro-pores diameter for (40^-1 00) μm glass filters
A . 4. 6 Analytical balance: minimum Division value of 0.1 mg,
A. 4. 7 Stopwatch: minimum Division value of 0.1 s Or automatic timing stopwatch.

4. 8 Pipette: 25 m l. Automatic  liquid  filling  apparatus  can be used.

A .4. 9 Erlenmeyer flask: 50 m l, 100 m l, with  glass stopper.

4. 10 Density Meter: range (1.200^ 1.300) g/cm 3

A . 5  Prepare Solvents and  sample solution
A . 5. 1  Preparation of solvents
A . 5. 1. 1  Put the reagent bottle containing phenol (A. 3. 1) into a hot water bath at about 60 ℃ to melt the phenol
A . 5. 1. 2  Wipe the water out of the phenol reagent bottle，The phenol and 1, 1, 2, 2-tetrachloroethane (A. 3.2) were weighed at a mass ratio of 60:40 (Accurate to 1%) after loading another reagent bottle and shake to mix well.
A . 5. 1. 3  The prepared solvent was filtered through a stainless steel filter (A. 4. 5) or a glass filter (A. 4.6) into a stoppered brown glass. Place it 24 h for using.
A . 5. 1. 4  Test the density of prepared solvent in a constant tepperature water bath (A . 4. 1)  at （25 ±0.02）℃。 The solvent density should be controlled in the range of (1.235士0.003) g/cm3
For the solvent in using,pls measure the average outflow time at A.6.4.

If the average time exceeds 1% of the initially data,this solvent should be discarded and a new solvent should be prepared

 

A. 5. 2  Preparation of Sample solution

5. 2. 1 Weighed (0.1250±0.0010g) sample in 50 ML or 100 ML Cone bottle(a.4.9).

A. 5. 2. 2 Using Pipette (A.4.8) or Automatic pipetor measuring 25 ml phenol/ 1.1.2.2 Tetrachloroethane Solvent(A.5.1) into cone bottle.
A . 5. 2. 3 Placed the cone bottle contains solvent on a heating device (A.4.3) at the temperature of (110 ±10)℃.Provided constant heating and stirrer（A.4.4）,make the sample dissolved completely. The dissolution time controlled within 30 minutes. If this time is exceeded, it needs to be re-dissolved.

When the sample dissolving finished, cool to room temperature.
A . 6 Steps

A . 6. 1 Preparation
A . 6. 1. 1  The sample solution is filtered through a stainless steel filter or glass funnel then added to an Ubbelohde viscometer (A.4.2). The liquid level of the solution should be between the markings.
A. 6. 1. 2  Place the viscometer vertically in a constant temperature water bath (A. 4. 1) at (25 ± 0. 02) ° C. The upper scale of the viscometer is lower than the constant temperature water surface at least 30 mm. The viscometer should be placed in a constant temperature water bath for about 20 m in order to reach a temperature of (25 ± 0. 02) ℃
A . 6. 2  Determination of flow time of the sample solution

Measuring 3 times of effluent under the circumstances of not emptying and reloading the new solution. Make sure the max value and minimum values does not exceed 0.2s.Take average of 3 flow time as the sample solution flow time t.
A . 6. 3 Determination of flow time of the solution

Take about 17 ml of solvent, using the same method as A . 6. 2 5 times , and make sure the max and minimum values does not exceed 0.1s. Take average of 3 flow time as the sample solution flow time t0. For the solvent in use measure the average flow time a least one time a day.If the difference in the average outflow time of two consecutive measurements is greater than 0.2s,the viscometer should be cleaned..

Remarks: Cleaning the viscometer：Put the viscometer in the solution of sulfuric acid- potassium dichromate(i, 1 by volume) more than 12 h before using or measured value is not parallel
Remove the concentrated sulfuric acid and potassium dichromate,

washed with water first then washed with ionized wate (or Distilled water) at least 5 times, and then cleaned with acetone 1 time. At last dry the viscometer in less than 100 ℃.When the viscometer is in use,washed the test solution first,then washed with Trichloromethane, at last dry it.
A . 7  Calculation results

I represent for viscosity of PET solution. using the formula (A.1),In milliliters per gram (m L / g),

Remarks :

t0---Solvent outflow time, in seconds (s)
t- Flow time of the solution, in seconds(s) ,
c — Solution concentration，in units of grams per milliliter (g/m l) .

Take the average of the two parallel determinations as the test result. And fix the four significant digits according G B / T 81 70- 1987.

Note: ISO 7792-1: 1997 provides that the viscosity number is one of the characteristic properties of PET resin naming

The intrinsic viscosity of the PET resin solution is expressed [η] in terms of the amount indicated by the formula (A. 2) in units of dl / g 

Remarks:
c— The concentration of the solution in grams per minute (g / dL):
ηr—The relative viscosity

Take two parallel determination average as the test result and take three decimal places according GB/T 8170-1987