INDEX tensile

Chemically pretreated chips, for example with sodium sulphite in the well established CTMP process, require more energy to produce pulps of comparable freeness than corresponding TMP pulps (Table 13.3). On the other hand most softwoods CTMP pulps generally require less energy to reach a given level of strength (for example tensile index) than corresponding TMP pulps. The reasons for such differences include ... 

Fig. 5 Tensile index of the pulps for different refining levels...

Back and Anderson [68] have found that at a surface tan-perature of 150°C, both the tensile index and the modulus of elasticity remain at high levels in the range of 39%-70% initial solids content, but decreases sharply at higher solids content. They used press-dried paper made from 60%-yield softwood Kraft pulp. 

Fig. 5.15 Tensile index of the new composite and reference samples. Commercial copy is a geometric mean value. Abbreviations-. C new composite handsheets. Fibre components euca eucalyptus unrefined, reg. cellulose regenerated cellulose, w fractionated refined softwood...

Fig. 9 Tensile index, i.e. the stress at break of paper sheets from HBK fibres subjected to chemical treatment (PAE or PAE/PEC), mechanical beating or a combination of both. From Gardlund et al. [54]...

As previously discussed in Sect. 2, salt plays an important role in the performance of a PEC. Figure 12 shows the increase in wet and dry tensile index after the adsorption of one layer of PAE and thereafter the adsorption of anionic PECs with different charge ratios prepared from PAE and CMC. From these results, it is obvious that, although there was a clear effect of the PEC addition in deionized water, the effect was much greater in the presence of 0.01 M NaCl. PAE is a commonly used wet-strength additive in the paper industry, with the ability to bond covalently to the cellulose in the pulp fibres [55]. CMC is also commonly used in papermaking. 

Fig. 13 (a) Tensile index and slrain-at-break of sheets made of fibres treated with PECs prepared from PAA of molecular weight 5000 and PAH of molecular weight 15,000 at a charge ratio (anion/ cation) of 0.8 as a function of PEC dose, (b) Tensile index of PEC-treated sheets (filled triangles) as a function of adsorbed amount of PAH [59] in comparison with the tensile index data for sheets made of fibres treated with PEMs after adsorption of layers 1, 3,5 and 7 (open squares) [57]... 

Chemical pulps have a higher strength potential (tensile index) but lower light scattering ability. 

Changes of tensile index of different paper grades vs. relative air humidity. 0%—initial tensile index value measured under standard conditions [51],... 

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