ISO 1126:2015

Overview

ISO 1126:2015 specifies laboratory methods for determining the loss on heating of carbon black used as a rubber compounding ingredient. The loss on heating measures primarily moisture content (and traces of other volatiles) and is a key quality parameter for carbon black used in the rubber industry. The standard defines three accepted test methods - gravity‑convection oven (method 1), moisture balance (method 2), and infrared irradiation (method 3, rapid) - and identifies method 1 as the preferred procedure.

Key topics and technical requirements

• Scope & limitations
  • Applies to carbon blacks for rubber compounding; not applicable to treated carbon blacks that contain added volatile materials.
• Three test methods
  • Method 1 - Gravity‑convection oven (preferred):
    • Heat sample at 125 °C for 1 hour in a gravity‑convection oven; weigh before and after cooling in a desiccator to calculate percent loss on heating.
    • Typical test portion ~2 g; analytical balance accuracy to ±0.1 mg.
  • Method 2 - Moisture balance:
    • Indirect heating with a moisture balance at ≤125 °C; record mass loss when change is <1 mg over 30 s.
    • Sensitivity 0.1 mg; typical test portion ~2 g.
  • Method 3 - Infrared irradiation (rapid):
    • Direct infrared heating using an infrared moisture meter; typical sample 5 g, sensitivity 1 mg.
    • Reading taken when change falls to 0.05% per minute and holds for an additional 2 min.
• Apparatus & measurement accuracy
  • Oven temperature control ±1 °C at 125 °C; uniformity ±5 °C or better.
  • Analytical balance and desiccator requirements are specified.
• Reporting
  • Test report shall include reference to ISO 1126, method used, sample identification, result to the nearest 0.1%, any deviations/unusual features and test date.
• Precision
  • Precision data and inter‑laboratory reproducibility are provided in Annex A.

Applications and practical value

• Ensures consistent moisture control and quality in carbon black powders used in rubber compounding (tire, hose, belt and general rubber goods manufacture).
• Useful for incoming quality control, batch release testing, supplier comparison and specification compliance.
• Enables laboratories and manufacturers to select a method balancing speed (method 3) and accuracy/reliability (method 1) depending on operational needs.

Who uses this standard

• Rubber compounders, carbon black producers, third‑party testing laboratories, quality assurance teams and material specification engineers working in the rubber and polymer industries. National standards bodies and regulatory labs may also reference ISO 1126 for harmonized testing.

Related information

• Developed by ISO/TC 45 (Rubber and rubber products), Subcommittee SC 3 (raw materials). For consistency in raw material testing, consult other ISO standards covering rubber compounding ingredients and laboratory practices.