ASTM D689-03 pdf free.Standard Test Method for lnternal Tearing Resistance of Paper.
The work done in tearing a number of sheets of paperincludes a certain amount of work to bend the paper continuously as it istorn, to provide for the rubbing of the torn edges of the specimen together,and to lift the paper. The number of plies torn at one time and their sizecan affect the test result with some papers. Empirical requirements forboth the apparatus and the test method are therefore necessary to keep theadditional work not used for tearing to a definite quantity. For this reason,in making comparisons between two or more sets of paper of the sametype and grammage,use the same number of plies for each set.If a single-ply test specimen gives a reading higher than75 on the standard 1600-gf instrument (75 % of full scale onother instruments), use the next higher capacity instrumentswith one ply or, if necessary, a still higher capacity instrument.9.6.1 For weaker papers,the standard 1600 gf instrumentmay require that 16 or more plies be torn together under theprocedure specified in 6.3. For these papers，and providedlower capacity instruments are available, the number of pliesmay be restricted to four and the next lower capacity instru-ment may be used whenever the reading falls below 20 % offull scale. ISO 1974 provides for testing fourply specimenswith multiple pendulum instruments.If this alternative proce-dure is used, state in the report. Make only one test per specimen，each specimen con-sisting of the specified number of plies. For each specimenkeep the wire sides of all plies facing the same way. Make testsalternately with the wire sides ofall plies toward the pendulumand with the wire sides of all plies away from the pendulum.Make certain that the specimen leans toward and not awayfrom the pendulum by gently creasing the specimen at theclamp if necessary, but in doing so avoid affecting the relativehumidity of the test area.Record the number of plies and the scale reading to thenearest half division.
Note and report if the line of tear fails to pass throughthe top edge of the specimen but deviates to one side. Do notuse the reading obtained. If more than one third of the testsexhibit this behavior,this test method should not be used forthe material concerned.
Compute the average of the ten scale readings. Determine by Practice E 178 or by other suitable statistical test,whether a value that appears to be excessively high or lowshould be included in the average.ASTM D689 pdf download.