Overview
ISO 28343:2010 specifies a standardized laboratory method to determine the glass transition temperature (Tg) of process oils used in rubber compounding by differential scanning calorimetry (DSC). The standard defines the sample preparation, DSC instrument requirements, temperature program, data evaluation (point of inflection), calibration and reporting necessary to obtain consistent and comparable Tg results for process/extender oils used with natural and synthetic rubbers.
Key topics and technical requirements
- Scope: Measurement of Tg of process oils by DSC; same oils often used as extender oils for synthetic rubbers.
- DSC instrumentation: Heat-flow or power-compensation analysers with a liquid‑nitrogen cooling system capable of around −150 °C. Use aluminium sample pans (~40 µl) and a press to seal lids.
- Gases: Dry helium (>99.999%) recommended; dry nitrogen acceptable if helium unavailable. Typical purge flow 20–50 ml/min.
- Sample mass & balance: 5–15 mg test sample; analytical balance accurate to 0.1 mg.
- Temperature program (recommended):
- Heat to 60 °C at 30 °C/min to remove thermal history
- Cool to −140 °C at 10 °C/min, hold 5 min
- Record thermogram from −140 °C to 60 °C at 20 °C/min
- Evaluation: Tg is defined as the point of inflection of the recorded DSC curve (maximum of the first-derivative). The midpoint method may be used by agreement. If crystallization occurs after Tg, Tg is still taken from the point of inflection.
- Calibration & conditions: Temperature calibration per instrument manufacturer or ISO 11357-1. Use same heating rate and purge gas for calibration and testing. Maintain recommended laboratory storage and sample-preparation conditions.
- Reporting: Test report must reference ISO 28343, identify the oil, sample mass, instrument and analyser type, purge gas and flow, Tg (°C) with DSC curve, deviations from the method and test date.
Practical applications and users
ISO 28343:2010 is used by:
- Rubber chemists and formulation scientists to characterize process/extender oils.
- Quality control (QC) laboratories for incoming raw-material verification.
- R&D teams evaluating plasticizer/oil compatibility and low-temperature performance.
- Raw material suppliers and certifying bodies for material data sheets and specifications.
- DSC instrument vendors and lab auditors ensuring method compliance.
Key benefits include improved reproducibility of Tg data for compounding decisions, low-temperature performance prediction and standardized reporting for procurement and regulatory compliance.
Related standards
Keywords: ISO 28343:2010, glass transition temperature, Tg, differential scanning calorimetry, DSC, process oils, rubber compounding, extender oils, DSC method.