NATIONAL FOREWORD

This Indian Standard (Part 6/Sec 1) (Second Revision) which is identical with ISO 306 : 2013 ‘Plastics — Thermoplastic materials — Determination of Vicat softening temperature (VST)’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on recommendation of the Methods of Sampling and Test for Plastics Sectional Committee and approval of the Petroleum, Coal and Related Products Division Council.

This standard was originally published in 1992 and subsequently revised in 1999. The first revision of this standard was identical with ISO 306 : 1994. The second revision of this standard has been undertaken to align it with the latest version of ISO 306 : 2013.

The major changes in this revision are as follows:

a) New apparatus, namely heating equipment consisting of a fluidized bed;

b) Precision data based on round robin testing performed in 2009; and

c) Comparison data for tests with liquid-filled and fluidized bed.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminologies and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker, while in Indian Standards, the current practice is to use a point (.) as the decimal marker.