GB/T 6669-2008 in English

《GB/T 6669-2008软质泡沫聚合材料 压缩永久变形的测定》由TC48（全国塑料制品标准化技术委员会）归口，TC48SC2（全国塑料制品标准化技术委员会泡沫塑料分会）执行，主管部门为中国轻工业联合会。
本标准代替GB/T 6669-2001《软质泡沫聚合材料　压缩永久变形的测定》。
本标准规定了测定软质泡沫聚合材料压缩永久变形的三种方法。
本标准适用于厚度大于2mm的乳胶泡沫和聚氨酯泡沫塑料。
本标准与GB/T 6669-2001相比主要变化如下：
―――删除了6.2“如果样品的泡孔结构具有方向性，压缩方向应由供需双方协定”；
―――删除了6.4中“（20±2）℃，相对湿度（65±5）％”的状态调节环境；增加了6.4部分内容；
―――增加了压缩量、压缩时间和恢复时间的偏差要求；
―――式（1）中用“CS”代替“P”表示压缩永久变形；
―――增加了试验报告部分内容。

1 Scope

This standard specifies three methods for determining the compression set of flexible cellular polymeric materials.

This standard applies only to latex and polyurethane foams of thickness greater than 2mm.

2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.

GB/T 6342-1996 Cellular plastics and rubbers - Determination of linear dimensions (idt ISO 1923: 1981)

3 Term and definition

For the purpose of this standard, the following term and definition apply.

3.1

compression set

the difference between the initial thickness and the final thickness of a test piece of the flexible cellular polymeric material after compression for a given time at a given temperature and after a given recovery time, the difference being referred to the initial thickness

4 Principle

Foreword i
1 Scope
2 Normative references
3 Term and definition
4 Principle
5 Apparatus
6 Test pieces
7 Test procedure
8 Calculation and expression of results
9 Test report