GB/T 20644.2-2025Special environmental condition—Guidance for choosing—Part 2: Polymer materials (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document is Part 2 of GB/T 20644 "Guidelines for the selection of special environmental conditions". GB/T 20644 has been published as follows part.

--- Part 1: Protection of metal surfaces;

--- Part 2: Polymer materials.

This document replaces GB/T 20644.2-2006 "Guidelines for selection of special environmental conditions Part 2: Polymer materials" and Compared with GB/T 20644.2-2006, in addition to structural adjustments and editorial changes, the main technical changes are as follows.

a) The content of "scope" has been changed to include special environmental conditions such as humid heat, humid ocean, and cold (see Chapter 1, 2006 edition). Chapter 1);

b) Added "Terms and Definitions" (see Chapter 3);

c) Deleted "Classification of Polymer Materials" (see Chapter 3 of the 2006 edition);

d) Deleted "Classification of Use Environment" (see Chapter 4 of the 2006 edition);

e) The content of "Requirements for Polymer Materials in the Use Environment" has been modified (see Chapter 4, Chapter 5 of the 2006 edition);

f) The content of Table 1 has been modified, and some evaluation items have been added (see Table 1, Table 1 of the 2006 edition);

g) Added the content of "Biodegradation Test" (see 7.3).

Introduction

GB/T 20644 "Guidelines for the Selection of Special Environmental Conditions" covers my country's dry heat, dry hot desert, plateau, humid heat, humid hot ocean, cold, etc. 6 special environmental conditions. Currently, GB/T 20644 consists of two parts.

--- Part 1: Metal surface protection. The purpose is to give special environments such as dry heat, dry hot desert, plateau, humid heat, humid hot ocean, cold, etc. Guidelines for the selection of metal surface protection under certain conditions;

--- Part 2: Polymer materials. The purpose is to give special environmental conditions such as dry heat, dry hot desert, plateau, humid heat, humid hot ocean, cold, etc. Guidelines for the selection of polymer materials under certain conditions.

1 Scope

This document gives the environmental conditions for polymers used in special environmental conditions such as dry heat, dry hot desert, plateau, humid hot ocean, humid heat, cold, etc. Material requirements, selection of polymer material types, selection of test evaluation items, selection of test methods, etc.

This document is applicable to polymer materials such as plastics, rubber, and coatings, among which plastics include biodegradable plastics and non-biodegradable plastics.

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document.

GB/T 3681.2 Plastics test methods for exposure to solar radiation Part 2: Direct natural weathering and exposure behind window glass Weathering

GB/T 9276 Test method for natural weather exposure of coatings

GB/T 20625-2024 Terminology for special environmental conditions

GB/T 20643.3-2025 Environmental test methods for special environmental conditions Part 3: Artificial simulation test methods and guidelines Molecular Materials

GB/T 22047 Determination of the ultimate aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a closed respirometer or Method for determining released carbon dioxide

3 Terms and Definitions

The terms and definitions defined in GB/T 20625-2024 apply to this document.

4 Requirements of the use environment for polymer materials

The requirements of the use environment for polymer materials are as follows.

---Polymer materials used in dry heat and dry hot desert environments should be resistant to light aging, high temperature and low temperature, and have good adaptability to temperature changes. Materials;

---The polymer materials used in plateau environments should be made of materials with good light aging resistance, low temperature resistance and temperature change adaptability, or materials with added Materials with light stabilizers;

---Polymer materials used in hot and humid marine environments should be resistant to light aging, heat and humidity, and mildew;

---Polymer materials used in cold environments should be selected from materials with high low-temperature toughness and good adaptability to temperature changes;

---While meeting the performance requirements of polymer materials in different environments, materials with good biodegradability should be selected.

5 Selection of polymer materials