Measurement of intrinsic viscosity of nylon

1. Scope of application:

This method is suitable for the measurement of intrinsic viscosity of dilute nylon solution with sulfuric acid as solvent.

2. Reference standard:

ISO 307

3. Reagents and equipment:

Solvent: (96 ± 0.15)% sulfuric acid

A magnetic stirrer

IVS automatic viscometer

UBV, type II, k = 0.1

G2 sintered glass sand filter funnel

4. Operation method:

a. Preparation of dilute sulfuric acid solution of nylon: weigh 0.125g (accurate to 0.0002g) of nylon sample cut into 1 mm particles into a sample dissolving bottle with a magnetic stirring rod, add 25ml (96 ± 0.15)% sulfuric acid (concentration of 0.005g / ml) into the magnetic stirrer, and adjust the stirring speed to make the solution produce a vortex of about 10 mm. Stir for 30 minutes to completely dissolve the nylon particles. Use G2 sintered glass sand filter funnel for filtration and standby.

b. Kinematic viscosity measurement of sulfuric acid: install the type II USV viscosity tube with 15-17 ml (96 ± 0.15)% sulfuric acid on the automatic measuring platform, input the sample name, operator name, test temperature of 25 ℃ and parameters of the viscosity tube; set the prediction twice, main measurement three times, the maximum allowable standard deviation of 0.1 second, constant temperature of 15 minutes. Select the kinematic viscosity measurement mode and start the measurement.

c. Measurement of intrinsic viscosity of dilute sulfuric acid solution of nylon: add 15-17 ml filtered dilute sulfuric acid solution of nylon to Ubbelohde viscosity tube for measuring kinematic viscosity of persulfate and install it on the automatic measuring platform. Input the batch number of the sample, the name of the operator, the test temperature of 25 ℃ and the parameters of the viscosity tube; set the prediction for 2 times, the main measurement for 3 times, the maximum allowable standard deviation of 0.2 seconds, and the constant temperature of 15 minutes. Select the corresponding intrinsic viscosity measurement method, input the sample concentration, the blank viscosity of the corresponding viscosity tube and the constant of the corresponding evaluation formula. To calculate the molecular weight, enter the corresponding K, a values. Start measurement. After the measurement, the instrument automatically evaluates and gives the test report.

5. Precautions:

a. Sulfuric acid is very corrosive. You must wear protective glasses, gloves and clothes when operating!

b. Viscosity pipe must be cleaned and dried before use.