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DSC determination of PE pipeline oxidation induction time (OIT)

Dec 13, 2017

DSC determination of PE pipeline oxidation induction time (OIT)


Brief introduction:

Polyethylene (PE) pipe with excellent chemical stability, non-toxic, at room temperature resistant to hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid, amines, sodium hydroxide, potassium hydroxide and other chemicals. Polyethylene pipe is flexible and lightweight, and is widely used in all areas of life, such as water supply, gas supply, heating and other fields.

Polyethylene pipe itself is the thermal oxygen stability of the pipe qualitative change, brittle failure caused by one of the main reasons that it directly affects the pipe shelf life and service life; identification of polyethylene material life is usually measured oxidation induction time ( OIT), the so-called oxidation induction time is to use the pipe environment (oxygen, nitrogen, room temperature) to be artificially changed to improve oxygen and nitrogen density and pressure and improve the ambient temperature of about 10 times (200 degrees Celsius) as a means, Under extreme conditions, to see how long it takes for the polyethylene to undergo thermal oxidative stability changes, that is, the time required for the autocatalytic oxidation of the polyethylene material, this time is to evaluate the resistance of the material during forming, storage, welding, and use The most appropriate indicator of thermal degradation. The longer the oxidation induction time OIT, the longer the service life of the pipe; on the contrary, the service life of the pipe is shorter.


Test preparation

      a) Instruments: DSC-100 heat flow-type differential scanning calorimeter;

    aluminum crucible; photon; knife.

b) Sample: PE pipe sample; oxygen, nitrogen

    c) The main test conditions: sample weight: 15 ± 5mg

     Sample Pan: Aluminum crucible

      heating rate: 20 / min

       Ambient flow: 100ml / min

Test Steps:

The PE sample was cut into about 0.2mm3 size, placed in an aluminum crucible, another take an empty aluminum crucible as a reference, the two aluminum crucible were placed in the DSC-100 differential scanning calorimeter furnace Sample holder and reference holder. The temperature of the sample is raised to 200 under the protection of air or nitrogen atmosphere. When the sample temperature reaches 200 the atmosphere immediately converted to oxygen, the determination of the sample at a temperature of 200 at the start of decomposition time in the oxygen atmosphere time required, this time is the polyethylene pipe Of oxidation induction time.