ISO 4577:2019

Overview

ISO 4577:2019 specifies an oven method to determine the thermal oxidative stability of polypropylene and propylene-copolymers. The standard describes an accelerated ageing test performed in a forced‑draught oven in air to estimate the resistance of moulded specimens to heat‑induced oxidation and to provide an indication of service life under severe thermal conditions.

Key topics and technical requirements

• Test principle: Accelerated ageing by heat in the presence of air; visual inspection to determine time to failure (localized crazing, crumbling and/or discoloration).
• Recommended test temperature: 150 °C (±1 °C at a single location; ±1.5 °C throughout the oven). If time to failure < 7 days at 150 °C, repeat at 140 °C and lower in 10 °C steps as needed.
• Oven and airflow:
  • Forced‑draught (mechanical convection) oven.
  • Exhaust rate: at least one oven‑chamber volume per 10 minutes.
  • Air velocity at specimen positions: 0.75 m/s to 1 m/s.
  • Temperature control to nearest 1 °C; recording recommended.
• Specimens and preparation:
  • Compression‑moulded sheet per ISO 19069‑2 (injection‑moulded or product specimens allowed by agreement).
  • Typical specimen size: 50 mm × 10 mm × 1.0 mm (±0.05 mm). At least five specimens per test.
  • Clips lined with inert film; avoid contamination.
• Specimen holder: stationary, uniaxial or biaxial rotation - biaxial rotation is reference method for uniform exposure.
• Inspection and results:
  • Visual inspection at least once per day (stop rotation during inspection).
  • Report average and range of time to failure in days at 150 °C (or other temperatures used). Exclude area within 5 mm of clips.
• Optional analyses: For research or dispute, follow oxidation by viscosity number (ISO 1628‑3) or melt flow rate (ISO 1133‑1); Arrhenius plots (100–150 °C, 10 °C intervals suggested) can estimate life‑temperature relationships.

Applications and users

ISO 4577 is used by:

• Polymer manufacturers and compounders for quality control and heat‑stability benchmarking.
• Testing laboratories validating polypropylene grades and stabilizer performance.
• Product designers and materials engineers estimating service life of polypropylene parts under thermal oxidative stress.
• R&D teams comparing stabilizer systems and developing heat‑stable formulations.

Key benefits: standardized accelerated ageing protocol, reproducible comparison of thermal oxidative resistance, and data useful for material selection.

Related standards

• ISO 291 - Standard atmospheres for conditioning and testing
• ISO 19069‑2 - Preparation of test specimens for polypropylene
• ISO 1133‑1 - Melt flow rate (MFR/MVR) testing
• ISO 1628‑3 - Viscosity of polypropylenes

Keywords: ISO 4577, polypropylene thermal oxidative stability, oven method, accelerated ageing, propylene-copolymers, forced draught oven, service life estimation.