Overview
EN ISO 11409:1998 (identical to ISO 11409:1993) specifies a differential scanning calorimetry (DSC) method for determining heats and temperatures of reaction of phenolic resins. The standard covers resols and novolak-based systems (for example, novolaks mixed with hexamethylenetetramine) that show exothermic cure behaviour. The method measures heat flux versus time or temperature; exothermic reactions produce peaks whose integrated area gives the reaction energy (enthalpy), while peak position yields reaction temperatures.
Key topics and technical requirements
- Principle: measure differential heat flux between sample and reference during a controlled temperature program and integrate exothermic peaks to obtain heats of reaction.
- Typical sample types: resols, novolaks + hardeners (e.g., hexamethylenetetramine); small representative powdered/granular samples are required.
- Apparatus requirements:
- Differential scanning calorimeter (DSC) with heat-flow recording and automatic differential signal.
- Heating/cooling capability up to about 10 °C/min; recommended test heating rate 5 °C ± 1 °C/min.
- Temperature resolution to at least ±0.1 °C; operating range preferably 20–300 °C.
- Sensitivity and time-base precision to ensure measurement uncertainty around ±1 %.
- Sample holders: pressure‑tight, inert, high‑conductivity capsules (steel capsules recommended), pressure-tight to 2 MPa to retain volatiles.
- Sample mass and handling:
- Typical sample mass order: 2–10 mg, weighed to 0.05 mg accuracy.
- Discard results if mass loss during scan exceeds 10 %.
- Calibration and measurement:
- Calibrate heat axis and time base (electrical or reference material). Indium is recommended as a reference (melting point 156.6 °C; heat of fusion ~28.42 J/g).
- Construct baselines, measure peak areas (average of repeated integrations or electronic integration), and calculate heat of reaction normalized to sample mass.
- Reporting: include instrument details, sample preparation, heating rate, calibration method, heats (J/g), onset and peak temperatures, mass loss and thermogram copy.
Applications and users
- Practical uses: formulation development, quality control, cure kinetics screening, batch-to-batch comparison and R&D of thermosetting phenolic resins.
- Typical users: polymer scientists, materials labs, QC departments in resin and composites manufacturing, academic researchers working on cure behaviour and thermal characterization.
- Keywords: EN ISO 11409:1998, phenolic resins, differential scanning calorimetry, DSC, heats of reaction, resols, novolaks, hexamethylenetetramine.
Related standards
- ISO 472 (Plastics - Vocabulary)
- ISO 5725 (Precision of test methods)
- ISO 10082 (Phenolic resins - Definitions and test methods)
- IEC 1074 (DSC methods for melting/crystallization)
