ASTM D618-21
Standard Practice for Conditioning Plastics for Testing

Standard No.

ASTM D618-21

Release Date

2021

Published By

American Society for Testing and Materials (ASTM)  US  /  ASTM

Replace By

ASTM D618-00

Latest

ASTM D618-13

Introduction

Analysis of the core content of the standard

Adjustment procedure	Temperature and humidity parameters	Applicable thickness	Typical application
Procedure A	23°C/50%RH	≤7mm:40h ＞7mm:88h	General material benchmark test
Procedure B	50°C+desiccant	≤7mm:5h ＞7mm:15h	Thermosetting material rapid test
Procedure C	35°C/90%RH	96h	High Humidity Environment Simulation

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Key Technical Requirements

The standard laboratory environment is defined as 23±2°C and 50±10%RH. When the temperature tolerance is tightened to ±1°C, the humidity tolerance is adjusted accordingly to ±5%. For specimens thicker than 7mm, the conditioning time needs to be extended to 88 hours to ensure osmotic equilibrium.

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Differences with ISO 291

• Adjustment Scheme: ASTM D618 provides 7 procedures, while ISO 291 only specifies 2 basic conditions
• Tolerance Band: ASTM allows dynamic adjustment of humidity tolerance based on test temperature (e.g., ±2°C corresponds to ±10%RH)
• Military Specification: Procedure B is equivalent to Condition E-48/50 in the MIL-P specification

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Implementation Recommendations

1. Procedure A is preferred as the baseline test condition
2. Procedure G (27°C/65%RH) is recommended for tropical climates
3. Procedure D/E water immersion treatment is recommended for electrical performance testing
4. Use Practice E104 Controlling Precision Humidity Environments

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Standard Evolution Analysis

Main changes in the 2021 edition: Added reference to terminology standard D883, clarified that "room temperature" is defined as the range of 20-30°C. Compared to the 2013 edition, the technical description of temperature and humidity coordination has been strengthened.