Strength Properties Of Handsheets Research Articles

The Importance of Xylan for the Strength Properties of Spruce Kraft Pulp Fibres

Summary In this work the role of xylan in spruce kraft pulp fibres was investigated by selectively removing the pulp fibre xylan and also by sorbing xylan onto the pulp fibres. The effects of xylan removal and sorption on fibre properties were measured and the chemical composition of the fibres and also that of the selectively removed xylans was analyzed. According to the results the xylanase could act on both sorbed and native xylan located on accessible fibre surfaces. Xylan was found to affect the strength properties of handsheets. The location and the charge of xylan had a considerable impact on the formation of interfibre bonds. Scott Bond-values correlated with the amount of surface xylan on fibre surfaces, whereas tensile strength was affected by the total amount of xylan and particularly by the total charge of the fibres. The fracture energy was determined by the combined effect of interfibre bonding ability and effective fibre length.

Effects of Different Microorganisms on Pulp and Paper Properties

Abstract Pretreatment of wood chips with some microorganisms including white-rot fungi and streptomyces improves the strength properties of mechanical pulps. We studied the effect of these white-rot fungi and streptomyces on the mechanical properties of handsheets. Strength and optical properties were compared in handsheets prepared from mechanical pulp of treated and untreated wood chips. The fungal pretreatments resulted in handsheet strength properties better than the control and also better than streptomyces when compared at an equivalent freeness. Fungal pretreatments decreased brightness and light-scattering coefficients but did not adversely affect opacity. Lignin content of the chips was reduced by fungal pretreatments.

Paper from kenaf fibre

Samples of kenaf ( Hibiscus cannabinus) grown in Nigeria were examined to determine the kraft pulp and papermaking properties of their bast fibres. The average length of kenaf bast fibre was 2·66 mm while the kraft pulp yield was 58·1%. The strength properties of hand sheets were better than those of hardwood pulp but similar to those of softwood. Kenaf is considered promising for production of high-grade printing, writing and specialyy papers.

紙・板紙の諸特性に及ぼす放射線の影響 第３報 等級の異なる板紙・段ボールの強度特性に及ぼす放射線照射の影響および照射シートに対するリサイクルの影響

Effect of gamma-irradiation on the strength properties of various paperboards and corrugated fiberboards with different grades and effect of recycling on those irradiated sheets were investigated.Results obtained are summarized as follows : 1) Postradiational changes in the strength properties of AA-, A- and C-grade linerboards showed approximately same tendency.2) After 25 kGy irradiation (usual sterilizing dosage), AA- and A-grade liner boards reduced the ranking to A- and B-grade respectively, however, C-grade liner and A-grade medium remained in each grade.3) Corrugated fiberboard composed of AA-liner and A-medium remained the rank of S-4 (JIS Z 1516) even after 25 kGy irradiation. Corrugated fiberboard composed of A-liner and A -medium also remained the rank of S-3 after 25 kGy irradiation.4) Canadian standard freeness of recycled stock from the irradiated samples decreased with increasing dosage, and the increase of short fiber fractions by the irradiation was observed.5) The strength properties of handsheets recycled from the irradiated samples were lower than those from unirradiated samples except the wet tensile strength. Lowering degree of the strength properties was given in the following order : Folding endurance>Tearing>Bursting>Dry tensile.

アルカリ性サルファイト・キノン蒸解におけるリグニンの挙動

The sulfite-quinone cooking has been investigated as an alternative to the kraft process in terms of delignification, pulp yields, and pulp qualities. However, behaviors of lignin in this cooking have not been clarified, and there are few studies in which delignification selectivity and pulp qualities were compared at given delignification rates and H-factors with those of the soda-quinone and the kraft-quinone cookings. In this study, yezo spruce/saghalien fir mixed chips and beech chips were cooked by the three kinds of cookings under the conditions where the delignification at a given H-factor (cooking temp. : 170°C cooking time : 2 h) were equal. Pulp yields, handsheet strength properties, and characteristics of lignins in those pulps and black liquors were compared, and behaviors of lignin and mechanism of delignification in the sulfite-quinone pulping were discussed. In these experiments, 1, 4-dihydro-9, 10-dihydroxyanthracene sodium salt (DDA) was used as a quinone additive, and this sulfite-quinone cooking was called the alkaline sulfite-DDA cooking because sodium hydroxide, sodium sulfite, and DDA were used as cooking chemicals. The results are summarized as follows : (1) The alkaline sulfite-DDA cooking of yezo spruce/saghalien fir wood gave pulp of almost the same kappa no. 50 as the soda-DDA and the krart-DDA cookings. At kappa no. 50, the total pulp yields of the former were higher than those of the latter. However, the screened pulp yields of the alkaline sufite-DDA cooking were almost the same as those of the kraft-DDA cooking and slightly lower than those of the soda-DDA cooking because of its higher yields of screen rejects.(2) This cooking of beech wood gave pulp of kappa no. 26.4, but it had no advantage of pulp yields compared with the soda-DDA and the kraft-DDA cookings.(3) The contents of sulfonic acid group of lignin in pulps given by this cooking were about 0.1-0.2/phenyl propane unit.(4) Handsheet strength properties of this cooking were almost the same as those of the kraft-DDA cooking.(5) Gel chromatography indicated that the dissolved lignin of this cooking was richer in low-molucular lignin fractions than those of the other cookings.(6) Alkaline nitrobenzene oxidation of screened pulps and black liquors of this cooking gave higher yields of vanillin (soft wood) or vanillin and syringaldehyde (hard wood) than those of the others.(7) In the alkaline sulfite-DDA cooking, the condensation of lignin was depressed by the addition of sodium sulfite. This must be a reason why delignification is accelerated together with the increase of solubilyty of lignin with the cleavage of β-ether linkages by quinone compounds and the sulfonation by sulfite.