BS ISO 247-2:2018 pdf download – Rubber — Determination of ash Part 2: Thermogravimetric analysis (TGA)
This document specifies two methods for the determination of ash from raw rubbers, compounded rubbers and vulcanizates using a thermogravimetric analyser (TGA).
The methods are applicable to raw, compounded or vulcanized rubbers of the M, O, R and U families described in ISO 1629:
— Method A is applicable for the determination of the ash from raw rubbers.
— Method B is applicable for the determination of the ash from compounded or vulcanized rubbers.
The methods are not applicable for the determination of the ash from raw rubbers, compounded or vulcanized rubbers containing chlorine, bromine or iodine.
This document does not cover the interpretation of the ash results from the inorganic chemical contents of compounded or vulcanized rubbers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 248‑1, Rubber, raw — Determination of volatile-matter content — Part 1: Hot-mill method and oven method
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures 3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
A weighed test portion is heated in an atmosphere of nitrogen. After complete decomposition of the polymer, the atmosphere is switched from nitrogen to oxygen or air and the test portion is further heated until all the carbonaceous matter has been burnt off and a constant mass is reached. The mass of the residue represents the ash.
5.1 Dry nitrogen, purity ≥ 99,99 %.
5.2 Dry oxygen, purity ≥ 99,99 %, or air.
6.1 Thermogravimetric analyser, comprising the following elements:
b) Heating furnace;
c) Temperature programmer;
d) Gas flow controller, for controlling the purge gas to the balance and furnace, and keeping a constant flow rate.
6.2 Sample pan, platinum pan or alumina ceramic pan.
6.3 Analytical balance, capable of weighing to the nearest 0,1 mg.
7 Preparation of the test sample
7.1 For raw natural rubber, test samples shall be cut from the homogenized piece prepared in accordance with ISO 1795. For raw synthetic rubber, test samples shall be cut from the dried rubber obtained after carrying out the determination of volatile‑matter content in accordance with the hot‑mill method of ISO 248‑1.
Take a test portion of about 2 g to 5 g from the homogenized sample and cut into pieces by hand.
7.2 Test samples of rubber compounds shall be sheeted on a mill and cut into pieces by hand.
7.3 Test samples of vulcanizates shall be sheeted or crumbed on a mill or comminuted by hand.
7.4 Care shall be taken to ensure that test samples of rubber compounds and vulcanizates are representative of the sample.
Calibrate the thermogravimetric analyser (see 6.1) according to the manufacturer’s instructions.
Temperature and mass calibration should be performed.
To ensure consistent results, the thermogravimetric analyser shall be calibrated periodically. It is recommended to perform mass calibration once a month.
9.1 Method A
9.1.1 Switch on and stabilize the instrument, set the temperature of furnace to 30 °C.
9.1.2 Place an empty sample pan on the platform and tare the sample pan.
9.1.3 Take about 10 mg to 20 mg from the test portion of raw rubber (see 7.1) and weigh to the nearest 0,1 mg. Place it in the sample pan. Position the sample pan on the sample platform and load the sample pan onto the thermo‑balance.
9.1.4 Set the flow rate according to the manufacturer’s instructions. Raise the temperature to 500 °C at a rate of 20 °C/min or 30 °C/min under an atmosphere of nitrogen. Maintain at this temperature for 1 min.
9.1.5 Switch from the stream of nitrogen to a stream of oxygen or air. Raise the temperature to 550 °C. Maintain the temperature at 550 °C for 5 min or until the mass is constant.
9.1.6 Calculate the ash using the apparatus micro‑processor.
9.2 Method B
9.2.1 Switch on and stabilize the instrument, set the temperature of furnace to 30 °C.
9.2.2 Place an empty sample pan on the platform and tare the sample pan.BS ISO 247-2 pdf download.