How to titrate the vinyl content of silicone oil by iodine dometry?

The principle is very simple, the use of vinyl reducibility and iodine solution reaction, resulting in the discoloration of iodine solution, the final test solution with the color of iodine solution is the end point of the titration, the rest of the operation instrument according to the titration, the steps are good.

1. Experimental principle.

A part of iodine bromide (IBR) plays an addition role with silicone oil, and the remaining part reacts with potassium iodide to release iodine, and the released iodine is titrated with sodium thiosulfate.

The reaction process is as follows:

1) Bonus:

r-ch=ch-r + ibr→rbrch-chir

2) Release of iodine from the remaining iodine bromide.

ibr + ki→i2 + kbr

3) Titration of the released iodine with sodium thiosulfate.

i2 + 2na2s2o3→2nai + na2s4o6

2. Instruments and medicines.

1. Instrument. 1) Iodine measuring flasks (or Erlenmeyer flasks with glass stoppers).

2) Brown burette.

3) Pipettes.

4) Graduated cylinders. 5) Rubber tip dropper.

6) Analyze the balance.

2. Medicines. 1) Iodine bromide solution.

2) Standard sodium thiosulfate solution.

3) Pure carbon tetrachloride.

4) 1 starch solution (dissolved in saturated sodium chloride solution).

5) 10 potassium iodide solution.

6) Silicone oil. 3. Experimental procedures.

1. Use a graduated cylinder to measure 20ml of pure carbon tetrachloride in an iodine measuring flask.

2. Weigh the silicone oil with an analytical balance (weigh by reduction method, take about 25 drops from the rubber head dropper), dissolve it in the iodine measuring flask, and be accurate.

3. Use a pipette to measure 10ml of iodine bromide solution and add it to the iodine measuring flask. Shake well and let stand in a dark place for 1-12 hours.

4. Add 40ml of distilled water and 5ml of KI solution and shake for 2-3 minutes. Rinse the glass stopper and the liquid on the neck of the bottle with a small amount of distilled water.

5. Titration with sodium thiosulfate standard solution (brown burette). During the titration, it must be violently shaken so that all the iodine elements in carbon tetrachloride enter the aqueous solution. Rinse the glass stopper and the liquid on the neck of the bottle with a small amount of distilled water.

6. Titrate until light yellow, add about 1ml of 1% starch solution, and continue to titrate until the blue color disappears, that is, the end point of titration is reached.

4. Data Processing.

The iodine value indicates the number of grams of iodine that can be absorbed by 100g of silicone oil, so the iodine value of the sample is calculated as follows:

Iodine value = (a-b)c m-like

Vinyl content = (a-b)c m sample

where a is the number of ml of sodium thiosulfate solution removed for titration blank;

b is the number of ml of sodium thiosulfate solution used for titration of the sample;

c is the molar concentration of sodium thiosulfate solution.

The accurate determination of the content should be done by chemical titration, which can be referred to the iodometric method for determining the content of double bonds.

This aspect is briefly introduced in the "Quantitative Analysis of Organic Functional Groups", and it is not difficult to understand the relevant knowledge of redox. In addition, there are national standards that clearly stipulate the operation of the iodine dosing method.

First of all, it should be noted that the welding wire will not stick to the contact tip during the welding process. Your so-called adhesion is actually sintered, that is, the welding wire caused by the code contained in the poor wire feeding during the welding process is melted on the contact tip, so that the welding wire and the contact tip are sintered together. If you want to avoid this situation, first of all, you must ensure that the wire feeding performance of the welding wire is good, the copper is not dropped, the mouth is not gagged, and there is a certain stiffness and strength; The second is to clean the wire feeding hose frequently, so as not to affect the wire feeding effect due to the garbage stored in it.

As for the welder, the welder can be adjusted between self-locking and non-self-locking until it can be operated proficiently.

In fact, in the final analysis, you must be able to practice more often, so that practice makes perfect and avoid many failures.

By the way, you must do a good job of protection when carrying out welding operations, because the damage intensity of gas shielded welding to the human body is far greater than that of manual welding.

The dosage is increased by 5%-10% when it is used for feeding or modification, and the dosage is increased by 50%-100% when it is used for base glue.

Each milliliter of sodium thiosulfate titration solution is equivalent to potassium dichromate.

There is a difference, vinyl content refers to how much vinyl head is contained in silicone oil, and the iodine value is just a description and characterization of vinyl content during the analysis.

Viscosity (25, can be customized according to customers.)

Vinyl early closure.

Content (%) can be customized according to customers.

End vinyl silicone manuscript oil.

Technical Indicators: Appearance Colorless transparent liquid, no mechanical impurities Viscosity MPA·s 200 30 500 50 1000 100 5000 500 10000 1000 20000 2000 60000 6000 Vinyl mol% Volatile % The above is a typical index, and our company can also customize end vinyl silicone oil with various viscosity specifications and high vinyl silicone oil according to customer requirements.

Technical indicators: Appearance colorless transparent liquid, no mechanical impurities Viscosity MPA·s 3000 300 10000 1000 85000 85000 8500 Vinyl mol% 10 Volatile content % is a typical index, our company can also customize a variety of viscosity gauge Lubige and vinyl content high vinyl silicone oil according to customer requirements.

Polyisobutylene and vinyl silicone fluids can be blended.

Polyisobutylene has good thermal stability, can be processed at 140-200, and the molecular weight is basically unchanged. When processed at low temperatures, macromolecules are prone to mechanical degradation, and the higher the molecular weight of polyisobutylene, the more intense the degradation. When the processing temperature is 120-150, the degradation of broken chains can be reduced to a minimum.

However, at temperatures above 300, high molecular weight polyisobutylene can be degraded or depolymerized by mechanical shear, radiation or organic peroxides, resulting in a decrease in average molecular weight, with the oxidation reaction being the most prominent. Therefore, during processing, 250 10 -500 10 antioxidant 264 or 1% of the stabilizer butylhydroxymetholben are usually added. If processing stability and anti-aging properties are specifically required, it is recommended to add the antioxidant IRGANOX1010 to further stabilize it.

In addition to vulcanization, the processing of high molecular weight polyisoene can be carried out in equipment suitable for rubber processing (such as double-roll mixers, internal mixers) for mixing, kneading, plasticizing, and mixing with fillers, exacergers, other polymers and other materials.

Polyisobutylene is so tough and resilient that it cannot be extruded and calendered alone. Polyisobutylene is blended with carbon black, calcium silicate, diatomaceous earth, cyclic oak macronucleus, polyethylene, polystyrene or phenolic resins to reduce toughness and resilience. High molecular weight polyisobutylene can be plasticized by adding petroleum, paraffin, coal tar, pine and cedar oil, or similar materials.

The use of plasticizers with limited compatibility, such as trimethylphenol phosphate, can improve the processability and roll stripping properties of polyisobutylene.

Like other viscous materials, low-molecular-weight polyisobutylene is miscible with oils, paraffins, solvents and other polymers and is processed in high-power mixers with impellers.

Shanghai Silicon Friends New Materials.

Vinyl silicone oil is used as a base material for the production of high-temperature vulcanized silicone rubber (HTV), and is mixed with crosslinker, reinforcing agent, colorant, structural control agent, anti-aging agent and other high-temperature vulcanized silicone rubber raw rubber. 2. It is used to make liquid silicone rubber, which is the main material of injection thermoforming silicone rubber; 3 This product is organic with polyurethane, acrylic and other products.