Automatic Viscometer And Ubbelohde Viscosity Method Application In Methyl Vinyl Silicone Rubber Industry

Methyl vinyl silicone rubber, referred to as vinyl silicone rubber, is copolymerized by dimethylsiloxane and a small amount of vinylsiloxane. The introduction of a small amount of unsaturated vinyl greatly improves its vulcanization process and finished product performance, especially heat aging resistance and high temperature compression deformation resistance. Methyl vinyl silicone rubber is the most common type of silicone rubber and currently dominates the production of silicone rubber at home and abroad.

Methyl vinyl silicone rubber is widely used as a protective layer for gaskets, sealing materials and fragile and shockproof parts in the aviation industry; in the electrical industry, it can be used as advanced insulating materials such as electronic components, dynamic sealing rings for high-temperature potentiometers, and sealing rings for underground long-distance communication equipment; in medicine, because methyl vinyl silicone rubber has little physiological reaction to the human body and is non-toxic, it is used for surgical plastic surgery, artificial heart valves, blood vessels, etc.

GB/T 28610-2020 standard gives a clear determination scheme for the relative viscosity-average molecular weight of methyl vinyl silicone rubber. The standard states that the viscosity method is a relatively simple method for determining the relative viscosity-average molecular weight of polymers. The intrinsic viscosity is the concentrated viscosity or the logarithmic viscosity of the polymer solution when the concentration approaches zero. This method uses an Ubbelohde viscometer to determine the intrinsic viscosity.

01. Weighing samples

Use a 1/10,000 balance to weigh the methyl vinyl silicone rubber and put it into a volumetric flask. Use a DP25 automatic dispenser (pipetting accuracy ≤ 0.1%) to transfer a quantitative amount of toluene solution into the sample dissolving bottle;

02. Dissolving samples

Put the volume containing toluene into the PV6 rotary sample dissolving device, and dissolve the sample at the specified temperature and time by shaking;

03. Viscosity test

Put the sample dissolving bottle containing the methyl vinyl silicone rubber sample into a water tank with a set temperature (25 ℃±0.01℃) in the IVS800 sample tray, start the test function, and automatically get the test results;

04. Test results

The IVS800 fully automatic viscosity measurement system is connected to the computer, which can automatically get the test results and store the data, which is convenient for diversified viscosity data analysis;

Relative viscosity average molecular weight:

Where:

K—constant, K=9.46x10-3;

M—relative viscosity average molecular weight of the sample;

[η]—characteristic viscosity value,

α—characteristic constant value, α=0.71.

05. Cleaning the viscosity tube

The viscosity tube is fixed in the constant temperature water tank of the IVS800 viscometer. It does not need to be disassembled and taken out, and can be automatically cleaned, automatically discharged, and automatically dried.