SIST EN ISO 2578:2000 PDF

EN ISO 2578:1998 - Overview

EN ISO 2578:1998 (identical to ISO 2578:1993) defines procedures for evaluating the thermal endurance or time‑temperature limits of plastics after prolonged exposure to heat. The standard describes how to measure changes in selected mechanical, electrical or optical properties caused by thermal ageing; all measurements are made after specimens have returned to ambient conditions. The method assumes an Arrhenius‑type relationship between log(time to failure) and reciprocal absolute temperature to derive a temperature index (TI) and relative temperature index (RTI).

Key topics and technical requirements

• Scope and principle
  • Evaluates thermal ageing in air (thermal endurance), excluding other stresses.
  • Uses changes in chosen properties to determine time to failure and extrapolate limits.
• Test selection and end‑point
  • Choose properties relevant to service (destructive or non‑destructive).
  • Agree threshold (often 50% of initial value) and extrapolation time (commonly 20 000 h).
• Test specimens and conditioning
  • Prepare specimens per relevant test methods. Thermosets conditioned 48 h at lowest exposure temperature; thermoplastics may require annealing.
• Exposure temperatures
  • Use at least three temperatures (recommended 3–4) to establish an Arrhenius plot.
  • Lowest temperature should give time to threshold ≥ 5 000 h; highest should not be