ANSI SCTE 13-2018 pdf free download – Test Procedure for Determining the Thermal Oxidative Stability of Foamed Polyethylene.
Discussion—Other components in the foam material may cause secondary effects. The OIT value for insulation may be significantly altered by contamination or additives such as pigments, fillers, and processing aids as well as catalyst residues from the cable, wire, insulation, or resin manufacture. The OIT value may increase or decrease depending on whether these additives and residues act as oxidation inhibitors or promoters at the test temperature. At typical test temperatures (for example, ANSI/SCTE 74 requires 180 °C), compounds present in the polyolefin material may decompose and change the polyolefin oxidation mechanism and thereby the OIT value. If the oxidation mechanism is so altered, then the OIT value may not correlate to aging at normal use temperatures. Before using the OIT value to predict field performance and lifetimes, additional studies may be required to establish a correlation between the OIT value measured at high temperature and the performance of the polyolefin under typical field conditions. The OIT value is useful as a product performance test and quality control parameter, or a research and development tool for polyolefin materials.
7. Apparatus, Reagents and Materials Calorimeter—This OIT Test is performed using commercial analyzers known as Differential Scanning Calorimeters (DSC) similar to the Perkin Elmer DSC8000 or equivalent which measures heat flow as a function of time and temperature. A DSC with isothermal control and specimen temperature precision of at least ± 0.1 °C is required. See Note 1
Nitrogen—Use cylinder nitrogen (99.9% purity or better) for purging of cells. See Note 2
Oxygen—Use cylinder oxygen (99.9% purity or better) during the oxidation stage. See Note 2
Pans—Standard aluminum DSC pans (6 mm in diameter) are required to hold specimens during testing.
The pans should be open and not sealed. See Note 3
Degreasing—To degrease pans, wash in reagent grade acetone for 1 minute and dry in a stream of dry nitrogen. Use sufficient acetone to thoroughly wash the pans, that is, 200mL/100 pans. Ultrasonic cleaning of the pans in acetone is acceptable. In addition, it is also acceptable to use a muffle oven at 120 °C for 12 hours.
Temperature Standards—Use pure (>99.9%) indium and tin as temperature calibration standards. See Table 1.
Balance—An analytical balance to weigh specimens with a sensitivity of ± 0.1 mg or better.
8. Instrument Calibration
Instrument Preparation—Clean instrument cells between testing of different material formulations.Follow the instrument manual procedure for cleaning cells or hold the cells at 700 C for 10 minutes inoxygen.Care must be taken to remove the aluminum pan from both the sample and reference position.Temperature Calibration—Follow the instrument manual procedures for temperature calibration of theinstrument using the following heating programs and calibration criteria.
Indium-The experimental sequence for the indium calibration is:
1.Equalize at 50 C (in nitrogen).
2. Heat at 10 C/minute from 50 C to 145 C.
3.Heat at 1 C/minute from 145 C to 165 C.
4. Cool specimen to below 50 ℃.
5. Repeat steps 1) through 4).
6. Use melting temperatures and heat of fusion from second scan for calibration purposes.Tin——The experimental sequence for the tin calibration is:
1.Equalize at 50 C(in nitrogen).
2. Heat at 10 C/minute from 50 C to 220 C.
3.Heat at 1 C/minute from 220 C to 240 °C.
4. Cool specimen to below 50 °℃.
5. Repeat steps 1) through 4).
6. Use melting temperatures and heat of fusion from second scan for calibration purposes.
Melting Temperature—For calibration purposes, define the melting temperature as the extrapolated onsetof the melting peak, not the peak maximum (see Figure 1).ANSI SCTE 13 pdf download.