ASTM D528-97 pdf free.Standard Test Method for Machine Direction of Paper and Paperboard.
Float a specimen on tap water in a panand note or mark with an indelible pencil, the final axis of curl.Observe the curl before water penetrates completely throughthe specimen.Place two specimen strips to-gether, one on top of the other, making sure they are aligned atone end. Grasp the two between the thumb and forefinger andhold them so that they are free to bend of their own weight.Repeat,placing the bottom specimen on top. Note whichspecimen bends more when it is placed on the bottom.
Bursting Test-Perform a bursting test onthe test unit sheet in accordance with Test Method D 774.Remove the test unit sheet from the bursting tester and observethe principal line of rupture.Perform tensile tests on thespecimens in accordance with Test Method D 828.Procedures A and C are recommended when the testunit is not in square cut sheet form or where it is not certain thatthe edges of the test unit are parallel to the machine and crossdirections.Procedure A may not be applicable to unsized papers.8.5.3 A modification of Procedure D can be also used wherethe test unit is not square cut or where it is not certain that theedges of the test unit are parallel to the machine and crossdirections.Cut consecutive test specimens at 0,30,60,90,120,and 150°from an arbitrarily selected reference line. The specimen having the greatest tensile strength can be consideredto have its length parallel to the machine direction. This willnot apply to extensible papers.
The axis of curl in Procedure A will be parallel to themachine direction of paper. Papers with a high degree ofdried-in strain may first exhibit an axis of curl in the crossdirection. After strain relaxation，the curl axis changes andparallels the machine direction.The specimen in Procedure B cut with its length parallelto the cross direction,will bend more because of the lessercrossdirection stiffness and will，when on the bottom，fallaway from the specimen cut with its length parallel to themachine direction.
The principal line of rupture in Procedure C (withapproximately perpendicular fractures at either end) will beperpendicular to the machine direction.The bursting test is convenient for papers with a normaldistribution of tensile and stretch characteristics; however,there arenumerous exceptions to this. The principal line of rupture is parallel to thedirection with the higher stretch. In those papers where there is nosignificant difference in the stretch for the two directions, the rupture tendsto be more random and less positive.The specimen in Procedure D, cut with its length in themachine direction,will normally have the greater tensilestrength and the lesser stretch.
No information is presented about either the precisionor bias of this test method since the test result is nonquantitative.ASTM D528 pdf download.