Paper Characteristics Influencing the Deep Drawing Ability of Paper

The mechanical properties of handsheets made from differently treated pulps were determined in uniaxial tensile tests and by a biaxial bulge test method. The bulge test system, which was specially adjusted for paperboard testing, is introduced in the first part of this paper. Experimental investigation showed that the bulge test method was technically feasible and produced reproducible results. Comparison of bulge test and tensile test flow curves proved the theory that biaxial load leads to higher breaking strains. A hydroforming processes for paperboard was designed. Wet handsheets made of beaten, curled kraft pulp showed the best overall forming ability while freely shrunken samples reached the highest breaking strain. Tests revealed that besides the elongation the level of yield stress considerably influenced the forming results