Abstract
The in-plane tensile stress-strain properties of two kinds of commercial paper and a kind of paperboard were determined in a compact testing machine equipped with an optical extensometer. Copy paper, sack paper made from unbleached kraft pulp and paperboard were tested at about 25°C and two different relative humidity of 25% and 55%. A dumbbell or dog-bone type specimen specified in the JIS Z 2201for sheet materials was used in the tension tests, instead of a constant-width strip specimen specified in the ASTM D828-97. Tension specimens were cut in three different orientations from each type of paper and paperboard on a paper cutter, following a steel plate. The thickness of paper and paperboard was carefully measured with a high-precision digital micrometer under a constant pressure. The tensile properties were shown to vary greatly, depending on the specimen shape and size, test direction, ambient relative humidity and strain rate. The Ramberg-Osgood equation was used to model the nonlinear stress-strain behavior.
