GB/T 12027-2004Plastics -- Film and sheeting -- Determination of dimensional change on heating (English PDF)

Foreword

This standard is identical to the international standard ISO 11501:1995 Plastics - Film

and sheeting - Determination of dimensional change on heating.

This standard replaces GB/T 12027-1989 Test method for dimensional stability of

plastic films.

Compared with GB/T 12027-1989, the main changes in this standard are as follows:

-- Revision of the name: The English name is the same as ISO 11501, and the

Chinese name is "Plastics - Film and sheeting - Determination of dimensional

change on heating".

-- Revision of the scope: The scope of application of this standard includes plastic

sheet products, and clearly stipulates that this test method is a test method for

determining dimensional changes under heating conditions.

-- The chapter "Principle" is added (see Chapter 3).

-- The chapter "Apparatus" is added (see Chapter 4).

-- The specimen size is 120 mm×120 mm, and the marking length is 100 mm×100

mm (see 5.1 of the 1989 edition; see Figure 1 of Chapter 6 of this edition).

-- The following test steps are added: a. Put the metal container with the kaolin bed

into the oven and heat it to the test temperature; b. Place the sample flat on the

kaolin bed and cover it with a thin layer of kaolin (see Chapter 6).

-- The chapter "Precision" is added (see Chapter 8).

-- Appendix A is added (see Appendix A).

Appendix A of this standard is an informative appendix.

This standard replaces GB/T 12027-1989 from the date of implementation.

This standard was proposed by China National Light Industry Council.

This standard shall be under the jurisdiction of the National Technical Committee on

Plastic Products of Standardization Administration of China.

This standard was drafted by the Institute of Plastic Processing and Application of Light

Industry.

Main drafters of this standard: Chen Qian.

Plastics - Film and sheeting - Determination of dimensional

change on heating

1 Scope

This standard specifies test methods for the determination of longitudinal and transverse

dimensional changes in plastic films and sheets when heated. This method is suitable

for the determination of dimensional changes in thermo-shrinking or non-thermo-

shrinking plastic sheets with a thickness of less than 1 mm.

2 Normative references

The provisions in the following documents become the provisions of this standard

through reference in this standard. For the dated references, the subsequent amendments

(excluding corrections) or revisions do not apply to this standard, however, parties who

reach an agreement based on this standard are encouraged to study if the latest versions

of these documents are applicable. For undated references, the latest editions of the

referenced documents apply to this standard.

GB/T 2918-1998 Plastics - Standard atmospheres for conditioning and testing (idt

ISO 291:1997)

3 Principle

Tests include:

a) Separate determination of the initial length between two specified length

marks in the longitudinal and transverse directions of each specimen;

b) The specimen is placed on the kaolin bed in the oven and heated according to

the specified temperature and time;

c) After the specimen is cooled, the lengths between the longitudinal and

transverse marks are measured again and then the dimensional changes are

calculated.

4 Apparatus

5 Specimens

Before specimen preparation and measurement, the sample shall be conditioned in a

standard environment specified in GB/T 2918-1998 for at least 2 hours.

Prepare three specimens. Take a specimen of about 120 mm×120 mm from the middle

and both sides of a film or sheet. When the specimen is cut, it shall be at least 50 mm

away from the edge of the film or sheet.

6 Test steps

The metal container (4.2) containing the kaolin bed is placed in the oven (4.1), and the

temperature is controlled such that the kaolin bed is within the specified temperature.

Mark the longitudinal (or machine) and transverse directions of the specimen as shown

in Figure 1, and mark the initial longitudinal and transverse lengths (L0 and T0) in the

middle of the specimen. Measure separately with a measuring tool (4.4), accurate to 0.5

mm.

The specimen is laid flat on the kaolin bed, covered with a thin layer of kaolin, and

maintained at the specified temperature during the time required by the material.

Appendix A is an example of test temperatures and heating times for various film and

sheet materials.

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