1989 Volume 43 Issue 7 Pages 697-708
It is useful to have some practical formulas describing a particular strength property of paper as a function of a few easily measurable fundamental sheet and fiber properties. Such formulas will be helpful for designing paper and predicting strength properties of paper before it is made.
In this study, the author tried to determine statistically optimal formulas for tensile breaking length, MIT double folds, burst index and tear index of handsheets based on the extended Clark type formula.
First, eighteen kinds of abaca handsheets were prepared with varying fiber length, beating degree, fiber strength and wet pressing pressure. Multiple regression analysis and Akaike Information Criterion (AIC) were applied to a linear function given by taking logarithm of the extended Clark type formula so as to construct the optimal extended Clark formula for each strength property of abaca as a function of weighted average fiber length, bulk, zero-span breaking length and Z-directional tensile strength. Correlation coefficient of over 0.97 between observed and calculated values was found for each strength property.
Secondarily, modifications of the formulas for abaca by introduction of fiber coarseness as an additional fundamental property were carried out so that the formulas would be applicable to handsheets made of other fibers than abaca fiber. As the result, the generalized formulas for breaking length and burst index were obtained, both of which showed correlation coefficients of over 0.94 between observed and calculated values.
The formulas for abaca and the generalized formulas are expected to be used as the Paper Design Functions.
