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A new preparation technique of cross-section for examining the fine structure of fiber and paper was investigated. A critical point in the structural characterization study of paper is to prepare cross-sections in a way the structure remains unchanged. However, the destruction of internal structure or creation of artifact in the thin sections during their preparation process even in a epoxy resin embedded sample is not avoidable.

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Abstract:Fully restrained fiber-oriented sheets, machine-made paper, and handmade sheet by the standard method were prepared from Manila hemp pulp. Strain-to-failure of the fiber-oriented sheets was almost the same in both the machine (MD) and the cross machine (CD) directions, while a distinct direction-dependence was observed in the machine-made paper. This indicates that a degree of fiber orientation of paper is not a dominant factor controlling strain at break. Furthermore, dried-in shrinkage in CD of the machine-made paper can be simply estimated by comparison of strain-to-failure of this paper with that of the fully restrained fiber-oriented sheet or the handmade sheet prepared. Uneven profile of strain-to-failure in CD of the machine-made paper is observed over the width direction. This profile may possibly be explained by analogy of the geometrical and mechanical conditions of the wet web at the dryer pocket with those of the short span thin body. Notable acoustic emission (AE) from the specimens sampled from both edge and center of the dried web in the elongation test was not observed except at the final stage of plastic region. The result indicates that difference of strain-to-failure between them is attributed to a different degree of dried-in shrinkage since structural breakage like bond failure or fiber breakage which may happen in plastic deformation causes emission of elastic wave.

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