ASTM D412:16e1 pdf free download – Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers- Tension.
10.4.2 Grips for testing straight specimens shall be constant pressure pneumatic, wedged, or toggle type designed to transmit the applied gripping force over the entire width of the gripped specimen.
11. Specimens
11 . I Dumbbell Specimens—Prepare live specimens for testing.
11.1.1 The test specimens may he injection molded or cut from a flat sheet not less than 1.3 mm (0.05 in.) nor more than 3.3 mm (0.13 in.) thick and of a size which will permit cutting a specimen by one of the standard methods (refer to Fig. 2 for the standard methods). Refer to 7. 1 regarding thermoplastic rubber or thermoplastic elastomer specimens.
11. 1.1.1 Sheets may he prepared directly by processing or from finished articles by cutting and huffing. If obtained from a manufactured article, the specimen shall be free of surface roughness, fabric layers, etc. in accordance with the procedure described in Practice D3183.
11.1.2 The preferred method of preparing specimens is by compression molding. The mold shall have cavities in depth and of a configuration described in subsection 8.2.2 of Practice D3182.
11.1 .2.1 The specimens may be die-cut from the molded piece using Die C (refer to Fig. 2) unless otherwise specified. Cut the specimens from the sheet with a single impact stroke (hand or machine) to ensure smooth cut surfaces.
I I. 1.3 All specimens shall be cut so that the lengthwise portion of the specimens is parallel to the grain unless otherwise specified. Refer to 7.1.1 regarding anisotropy or grain directionality.
11.1.4 An alternative method of preparing dumbbell specimens is to mold them directly in the form of the dies described in Fig. 2 to the depth and of a configuration described in subsection 8.2.2 of Practice D3182.
11. 1 .5 Marking Dumbbell Specimens—Dumbbell specimens shall be marked with the bench marker described in 10.2, with no tension on the specimens at the time of marking. Marks shall be placed on the reduced section. equidistant from its center and perpendicular to the longitudinal axis. The between bench mark distance shall be as follows: for Die C or Die D of Fig. 2, 25.00 ± 0.25 mm (1.00 ± 0.01 in.); for any other Die of Fig. 2. 50.00 ± 0.5 mm (2.00 ± 0.02 in.).
11. 1 .6 Measuring Thickness of Dumbbell Specimens— Three measurements shall be made for the thickness, one at the center and one at each end of the reduced section. The median of the three measurements shall be used as the thickness in calculating the cross sectional area. Specimens with a difference between the maximum and the minimum thickness exceeding 0.08 mm (0.003 in.), shall be discarded. The width of the specimen shall he taken as the distance between the cutting edges of the die in the restricted section.
11.2 Straight Specimens—Straight specimens may be prepared if it is not practical to cut either a dumbbell or a ring specimen as in the case of a narrow strip, small tubing or narrow electrical insulation material. These specimens shall be of sufficient length to permit their insertion in the grips used for the test. Bench marks shall be placed on the specimens as described for dumbbell specimens in 1 1.1.5. To determine the cross sectional area of straight specimens in the form of tubes, the mass, length, and density of the specimen may he required. The cross sectional area shall be calculated from these measurements as follows.