Oxidation induction time or OIT is a standardized test performed in a
DSC DSC may refer to:
Academia
* Doctor of Science (D.Sc.)
* District Selection Committee, an entrance exam in India
* Doctor of Surgical Chiropody, superseded in the 1960s by Doctor of Podiatric Medicine
Educational institutions
* Dalton State Col ...
which measures the level of thermal stabilization of the material tested. The time between melting and the onset of decomposition in isothermal conditions is measured. The atmosphere is
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
up to melting and then oxygen. The typical temperature is 190-220 °C.
Oxidation-induction time can be known with the use of
Differential Scanning Calorimetry measurements, which is done with the sample body and a substance that will be heated in a constant rate in an atmosphere of
inert gas
An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. The noble gases often do not react with many substances and were historically referred to ...
. Once the specified temperature is attained, its atmosphere will be replaced by an air atmosphere of the said rate or an
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
atmosphere. The specimen will be then held at a constant temperature up to the indication of oxidative reaction by exothermal deviation of DSC heat flow curve. Time interval in the middle of the start of the air flow and the beginning of the oxidation reaction is called the isothermal OIT. The said method was also mentioned and discussed on several various technical standards like DIN EN ISO 11357-6.
This test is routine when assessing the quality of organic materials or
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
s, such as
polyethylene
Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including b ...
pipes.
References
ISO 11357-6:2018 Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)
Polymer physics
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