1、BRITISH STANDARD CONFIRMED FEBRUARY 1991 BS 2782-6: Method 641A: 1983 Incorporating Amendment No. 1 Methods of testing Plastics Part 6: Dimensional properties Method 641A: Determination of dimensional stability at 100 C of flexible polyvinyl chloride sheet IMPORTANT NOTE. Before reading this method
2、it is essential to read BS 2782-0, issued separately. UDC 678.5/.8:678.01:620.179.7 97C100:678.743.22 41BS2782-6:Method 641A:1983 This British Standard, having been prepared under the directionof the Plastics StandardsPolicy Committee, waspublished under the authorityof the Board of BSIandcomes into
3、 effect on 28 February 1983 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference PLC/40 Draft (reference 82/52804) announced in BSI News September 1980 ISBN 0 580 13177 7 A British Standard does not purport to include all the necessary provisions of a con
4、tract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 and 2, an inside back
5、cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue Comments 6282 February 1991 Indicated by a sidelin
6、e in the marginBS2782-6:Method 641A:1983 BSI 12-1999 i Contents Page 0 Introduction 1 1 Scope 1 2 Principle 1 3 Form of test specimen 1 4 Number of test specimens 1 5 Procedure 1 6 Expression of results 1 7 Report 1 Publication referred to Inside back coverii blankBS2782-6:Method 641A:1983 BSI 12-19
7、99 1 0 Introduction This method has been prepared under the direction of the Plastics Standards Policy Committee. Method 641A is an editorial revision of method106F of BS2782:1970, which is being withdrawn. WARNING NOTE. This method does not necessarily detail all precautions necessary to meet the r
8、equirements of the Health and Safety at Work etc. Act1974. Attention should be paid to any appropriate safety precautions, and the method should be operated only by trained personnel. 1 Scope This method describes a procedure for assessing the relative amount of moulded-in strain in flexible PVC she
9、et, a factor affecting the dimensional stability of the material at room temperature. NOTEThe title of the publication referred to in this standard is given on the inside back cover. 2 Principle Method 641A determines the reduction in length of a rectangular piece of flexible polyvinyl chloride shee
10、t when it is heated at100 C for15min. 3 Form of test specimen The test specimen shall be a piece250mm long and6mm to7mm wide cut from a sample taken from a roll or a sheet. Immediately after the sample has been taken it shall be kept at a temperature not exceeding30 C and then kept at23 2 C for not
11、less than2h immediately before the test specimen is cut and measured. 4 Number of test specimens The number of test specimens and the positions within the sheet or roll of sheet under test from which they shall be cut shall be as specified in the relevant British Standard for the material. 5 Procedu
12、re Measure the length (L 1 ) of the test specimen to the nearest0.5mm. Take care that the test specimen remains flat and straight when its length is measured. NOTEA convenient method of ensuring that it does, is to place the test specimen in a rectangular groove approximately300mm long,7mm wide and
13、1.5mm deep in a block of wood or other suitable material with a flat upper surface. Measurements of length may be made with a transparent rule suitably graduated and fitting into the groove. When the test specimen has been measured, immerse it for a period of151min in a water bath at a temperature o
14、f100 1 C. Ensure that the test specimen does not touch the sides or bottom of the water bath. NOTEA cage of metal gauze with feet is a suitable means of achieving this. On removal from the water, allow the test specimen to cool in air at23 2 C for at least15min. Take care to avoid stretching the tes
15、t specimen in handling it. Then measure the length (L 2 ) of the test specimen to the nearest0.5mm. Calculate the change in length of the test specimen as follows: percentage change = where Repeat the above procedure for remaining test specimens. 6 Expression of results Express the dimensional stabi
16、lity at100 C of the material under test as the percentage change in length of the test specimen that shows the greatest change. 7 Report The report shall state: a) a complete identification of the material tested including type, source, manufacturers code number etc.; b) a reference to this British
17、Standard method, i.e.BS 2782:Method 641A:1983; c) the dimensional stability at100 C of the material; d) the individual test results and the positions of the test specimens relative to the roll or sheet under test; e) the conditioning, if any, of the test specimens. L 1 is the initial length of the t
18、est specimen, and L 2 is the length of the test specimen after heating and cooling in air. L 1 L 2 L 1 -100 2 blankBS2782-6:Method 641A:1983 BSI 12-1999 Publication referred to BS 2782, Methods of testing plastics. BS 2782-0, Introduction. BS 2782-6: Method 641A: 1983 BSI 389 Chiswick High Road Lond
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