ASTM D2176-16(R2021) pdf free download

ASTM D2176-16(R2021) pdf free download.Standard Test Method for Folding Endurance of Paper and Plastics Film by the M.I.T. Tester
1. Scope
1.1 This test method describes the use of the M.I.T.-type folding apparatus for determining folding endurance of paper and plastics film. The M.I.T. tester can be adjusted for samples ofany thickness; however, ifthe outer layers thicker than about 0.25 mm (0.01 in.) rupture during the first few folds, the test loses its significance. The procedure for the Schopper-type apparatus is given in Test Method D643. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for informa- tion only and are not considered standard 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. Apparatus
5.1 Folding Tester, consisting of: 5.1.1 A spring-loaded clamping jaw constrained to move without rotation in a direction perpendicular to the axis of rotation of the folding head specified below and having its clamping surfaces in the plane of this axis. The load is applied by a spring attached to the jaw assembly which is easily adjustable to provide any desired tension on the specimen within range of 4.9 to 14.72 N (500 to 1500 gf). The deflection of the spring when loaded shall be at least 17 mm (0.67 in.)/9.81 N, which is achieved by using a weight of 1 kg mass. 5.1.2 An oscillating folding head supporting two smooth, cylindrical folding surfaces parallel to, and symmetrically placed with respect to, the axis of rotation. Each of the two folding surfaces shall have a radius of curvature of 0.38 mm (0.015 6 0.001 in.) and a width of 19 mm (0.75 6 0.04 in). The distance separating the folding surfaces is greater than the uncompressed thickness of the specimen being tested by no more than 0.25 mm (0.010 in.). The position of the axis of rotation is midway between the common tangent planes of the two folding surfaces. The folding head is provided with a clamping jaw with its nearest edge not less than 9.5 mm (0.375 in.) beyond the axis of rotation. The rotary oscillating move- ment of the head is such as to fold the specimen through an angle of 135 6 2°, both to the right and to the left of the position of the unfolded specimen. 5.1.3 Various size folding heads are required for testing different thicknesses of specimens. Heads available will ac- commodate thicknesses from 0 to 0.25 mm (0 to 0.01 in.), 0.25 to 0.50 mm (0.01 to 0.02 in.), 0.50 to 0.75 mm (0.02 to 0.03 in.), 0.75 to 1.02 mm (0.03 to 0.04 in.), and 1.02 to 1.25 mm (0.04 to 0.05 in.). 5.2 Power Driven Device, for imparting a rotary oscillating motion of 175 6 25 cycles/min to the folding clamp. 5.3 Counter, for registering the number of double folds required to break the specimen and a device to stop the instrument when the specimen breaks. 5.4 Strip Cutter, to cut 15-mm wide parallel strips within 60.02 mm with clean edges. 5.5 A means for controlling the temperature of the folding head so that, during folding, it does not increase more than 0.5°C. Temperature rises of this magnitude will reduce the relative humidity at the fold by more than 2 % and the number offolds by as much as 10 %. Acommon method for controlling the temperature of the folding head is by allowing an exhaust fan to draw conditioned room air from air rapidly over both the specimen and head. The fan shall be of the centrifugal type not less than 50 mm in diameter, mounted so that its inlet is adjacent to the folding head. Other methods that prevent heating of the folding head within the tolerances specified are acceptable.