Physical Properties Of Handsheets Research Articles

Fiber Evolution during Alkaline Treatment and Its Impact on Handsheet Properties

To understand the swelling effects of alkaline treatment on the morphological properties of fibers and physical properties of handsheets, bleached softwood kraft pulp was treated with NaOH at different concentrations. The results showed that the fiber swelling increased, but the shrinkage and elongation of the paper at a NaOH concentration of 6% or higher did not improve. Dissolution of amorphous material occurred during the treatment together with peeling reactions. The fiber length and shape factor decreased and the fines content increased with an increasing alkali concentration. The cellulose crystallinity decreased with an increasing NaOH concentration. This was confirmed by X-ray diffractometry, which also showed that some cellulose I was converted to cellulose II, especially at higher NaOH concentrations (> 9%). The fiber curl and kink indices increased and the handsheet density decreased with an increasing NaOH concentration. However, the tensile index decreased more steeply than the density with an increasing NaOH concentration, possibly because of the lower number and strength of the interfiber bonds, increased kinks, and reduced fiber strength and length. The handsheet extensibility first increased and subsequently decreased as the NaOH concentration increased, which indicated that well-controlled NaOH treatment could be used to improve the extensibility of paper.

Physical Properties of Handsheets with MFC-PCC Hybrid

Physical Properties of Handsheets with MFC-PCC Hybrid

Improved Bleached Chemical Reed Pulp Properties Using Atmospheric High Consistency Refining

The influence of atmospheric high consistency refining (AHCR) on the properties of bleached chemical reed pulp was investigated. Fiber quality, water retention value (WRV), dynamic drainage, and physical properties of handsheets were determined. The results showed that compared with low consistency refining (LCR), AHCR maintained reed pulp fiber length, had lower fines generation, produced more fiber curl and kink, and improved WRV and dynamic drainage. Compared with LCR pulp, the tear index, folding strength, and tensile energy absorption (TEA) of AHCR pulp were increased, while tensile index was maintained at the same value. A mill trial was performed to demonstrate the benefits of using AHCR, which was to improve machine runnability and to enhance the performance of the paper made from reed pulp.

Effects of shrimp chitosan on the physical properties of handsheets

The effects of shrimp chitosan as an additive were determined on the physical properties of handsheets, especially: their brightness, opacity, surface roughness and surface water absorptiveness. Commercial, hardwood, bleached kraft pulp was beaten to attain 390 mL Canadian standard freeness and then made into four sets of handsheets by mixing each part of the beaten pulp slurry with shrimp-chitosan solution to obtain 0.00%, 0.25%, 0.50% and 0.75% (oven dry weight (o.d. wt.) of pulp), respectively, in accordance with standard test methods. All the sets of handsheets were conditioned for 1 wk and then tested for their mechanical and physical properties at 50 ± 2% relative humidity and 23 ± 1 °C. The results indicated that even though there were some substantial decreases in some physical properties of shrimp-chitosan-treated handsheets (brightness, surface roughness and surface water absorptiveness), their opacity was slightly increased. Most of the mechanical properties of shrimp-chitosan-treated handsheets such as the bursting index, folding endurance, tensile index, modulus of elasticity and tensile energy absorption were greatly increased with the addition of shrimp chitosan at 0.25% o.d. wt. of pulp to 0.50% o.d. wt. of pulp. However, there was no effect on the tearing strength by adding shrimp chitosan to the handsheets.

Performance enhancement of poly(butylene succinate)/chemithermomechanical pulp fiber composites by debonder treatment

Debonder, a kind of weak combination reagent usually used in the production process of fluff pulp, was used as interfacial modifier in poly(butylene succinate)/chemithermomechanical pulp fiber composites. Physical properties of handsheets prepared by treated fibers indicated that the bonding strength between fibers was sharply decreased by the debonder treatment. The mechanical performance of composites prepared from treated fiber showed significant enhancement. In comparison with untreated one, the tensile strength, impact strength, and bending strength of composite containing 40 wt% of chemithermomechanical pulp fiber treated with 0.5 wt% debonder increased by 21.9, 22.3, and 35.4%, respectively. Furthermore, the data of rheological behavior measurement exhibited that the incorporation of debonder lowered the shear viscosity of composite and favored the processing process of composite. Besides, debonder played a role of hydrophobic agent in composites. A significant increase in storage modulus (E’) was observed upon the incorporation of treated chemithermomechanical pulp fiber. Scanning electron microcopy images showed that the interfacial bonding between treated fibers and poly(butylene succinate) matrix was improved.

Modifying cellulose fibers by adsorption/precipitation of xylan

Xylan was precipitated on bleached and unbleached softwood kraft pulps (SKPB and SKPUB), a bleached sulfite pulp, and viscose fibers to investigate the influence on physical properties of handsheets as well as to gain more detailed information of the distribution of adsorbed xylan on cellulosic surfaces. The adsorption step was carried out at constant conditions. The values of the parameters were chosen after a series of different adsorption steps (as presented elsewhere) also in regard as a possible industrial application. Afterwards, suspension and physical strength properties of unrefined and refined samples were determined. Refining resulted in a stronger increase in the beating degree of the pulps with additional xylan than the reference samples. The water retention value was not significantly changed. Comparing the tensile index of the handsheets versus the beating degree a remarkable increase in the strength properties was not observed. The investigation of the surface of the SKPB fibers via ATR suggests that precipitated xylan is heterogeneously and nonuniformly distributed. On cellulose model films, particles could be detected via atomic force microscopy. Phase images recorded with OH-functionalized tips suggested that these particles consist of xylan. An inhomogeneous distribution of xylan could be a reason that there is no measurable influence on the strength properties of the handsheets.

Effect of commercial cellulases and refining on kraft pulp properties: Correlations between treatment impacts and enzymatic activity components

The importance of enzymes as biotechnological catalysts for paper industry is now recognized. In this study, five cellulase formulations were used for fibre modification. The number of PFI revolutions decreased by about 50% while achieving the same freeness value (decrease in CSF by 200mL) with the enzymatic pretreatment. The physical properties of handsheets were modified after enzymatic pretreatment followed by PFI refining. A slight decrease in tear strength was observed with enzymes C1 and C4 at pH 7 while the most decrease in tear was observed after C2, C3, C5 treatments. C1 and C4 which had xylanase activity improved paper properties, while other enzymes had a negative impact. Therefore, the intricate balance between cellulolytic and hemicellulolytic activity is the key to optimizing biorefining and paper properties. It was also observed that C1 impact was pH dependent, which supports the importance of pH in developing an enzymatic strategy for refining energy reduction.

Oxidized Fiber from Dissolved Air Flotation Rejects and its Influences on Paper Properties

Fibers obtained from dissolved air flotation rejects were oxidized using a TEMPO oxidation system to prepare oxidized recovered fibers. The effects of oxidization time on carboxyl content, water retention value, and physical properties of handsheets were evaluated. The effects of pH, amount of oxidized recovered fibers, and aluminum sulfate on paper properties were also considered. The results showed that carboxyl content and water retention values increased with the increasing of oxidized time. FTIR analysis indicated that carboxyl groups were connected to the surface of fibers. SEM micrographs showed that fibers were integrated more closely in the paper sheet, benefiting from the addition of the oxidized recovered fibers. Tensile index, burst index, and folding endurance were respectively increased by 71.7%, 38.5%, and 600% when 3% of oxidized recovered fibers was added to the pulp at pH 5, with 0.5% aluminum sulfate addition, based on the original pulp. Tensile index and folding endurance were increased by 40.2% and 433.3%, respectively, when 1% oxidized recovered fibers (the oxidized time was 60 min) were added into pulp for recycled pulp. This finding may lay the foundation for greater re-use of fiber obtained from dissolved air flotation rejects.

The Preparation and Application of the Cationic Biopolymer Based on Xylan-Rich Hemicelluloses from Agricultural Biomass

During the last few years increasing attention has been paid to the exploitation of hemicelluloses as biopolymer resources because they are available in very large amounts in organic wasters from renewable forest and agricultural biomass. The efficient method to prepare the cationic biopolymers based on xylan-rich hemicelluloses from agricultural biomass has been developed in this paper. These biopolymers with cationic functional groups, having many good properties such as solubility, bio-degradation, cationic or ampholytic polymers, were synthesized by the chemical modification of sugarcane bagasse xylan-rich hemicelluloses with CHMAC and preferably with ETA in different media. These biopolymers based on xylan-rich hemicelluloses with the degree of substitution (DS) up to 0.55 could be obtained by varying the molar ratio of ETA or CHMAC to anhydroxylose units in hemicelluloses from 0.5 to 3.0. 13C NMR confirmed that cationic groups were grafted onto the backbone of hemicelluloses. In addition, their applications in papermaking as dry strengthen agent were investigated. It was found that these biopolymers could obviously improve the physical properties of hand sheets formed from old corrugated container pulp fibres. These results mentioned above highlight the remarkable potential for using the hemicelluloses-based biopolymers as wet end additives in papermaking.

Influence of hemicellulosic derivatives on the sulfate kraft pulp strength

In this work the application of different hemicellulosic derivatives including different degrees of substitution (DS) cationic hemicelluloses and carboxymethyl hemicelluloses in sulfate kraft pulp were investigated in detail. It was found that cationic hemicelluloses and carboxymethyl hemicelluloses could improve the physical properties of hand sheets, while the cooperation of cationic hemicelluloses and carboxymethyl hemicelluloses could enhance sharply the physical properties of hand sheets. When the dosages of cationic hemicelluloses with DS of 0.37 and carboxymethyl hemicelluloses with DS of 0.35 were 1.0% and 1.0% (based on dry pulp weight), respectively, the physical properties of hand sheets was significantly improved, breaking lengthen and tear index of hand sheets increased by 21.1% and 54.6% compared with the control hand sheets without any additives added. The fiber intertexture of the hand sheets was observed by SEM. The results indicated that hemicelluloses could be used as the source for the production of wet-end additives in papermaking, which might represent an important strategy for sustainable use of the agricultural residue.

電子線照射の紙質に及ぼす影響

Low energy electron beam irradiating instruments are applied for surface treatment and paint cure because of their compactness compared with corresponding high energy instruments. As electron beam has higher transmittance than UV light, it is supposed to be suitable for high-speed curing of relatively thick ink film such as intaglio ink film.However, electron beam irradiation causes degradation of organic high-polymer induced by radical reaction, involving the main chain scission and crosslinking reaction of the polymer. In the case of paper, electron beam irradiation decreases degree of polymerization of cellulose and sheet strength.In this paper the effects of electron beam irradiation on the physical and chemical properties of handsheets were studied.Following results were obtained.(1) The fiber strength of the handsheets, given by the wet zero-span breaking length, decreased with electron beam irradiation, while the fiber bonding strengths, as given by Pulmac B factor, wet breaking length and Young's modulus, increased. Besides, the microphotographs of the fractured areas of the handsheets showed that the sheet fracture pattern shifted from the inter-fiber bond breakage mode to the fiber breakage mode.(2) The contributions of the fiber strength and fiber bonding strength to the double folds and tensile strength were determined by multiple regression analysis using the equation T=kFaBbLc (T : Physical property of handsheet, F : Fiber strength, B : Fiber bonding strength, L : Fiber length, k, a, b, c : Parameter). It was found that the decreases of double folds and tensile strength caused by electron beam irradiation are mainly attributed to the decrease of fiber strength.(3) The GPC analysis of the irradiated handsheets showed that the decrease of fiber strength is caused by the decrease of degree of polymerization of cellulose.(4) With high dose of irradiation different kinds of pulp sheets showed similar values of probability of main chain scission, while with low dose of irradiation each pulp sheet showed different value of that.(5) Amount of chemical groups such as aldehyde and carboxyl groups and copper number of the handsheets increased with irradiation.

Physical properties of handsheets containing amorphous cellulose.

Mechanical and optical properties of handsheets prepared from mixture of bleached kraft pulp and either microcrystalline cellulose powder (MCP), freeze-dried amorphous cellulose (FAC), or hydrated amorphous cellulose gel (HAC) were studied in terms of crystallinity of the additives and interaction between pulp fibers and the cellulose additives. X-ray diffraction patterns and moisture content of the handsheets showed that both FAC and HAC behaved as amorphous cellulose in handsheets. However, mechanical and optical properties such as Young's modulus, tensile index, tearing resistance, opacity, and scattering coefficients of handsheets showed that MCP and FAC behaved like fillers, and that HAC behaved like strength resins for improving interfiber bonding of pulp fibers. The handsheets had the maximum tensile strength and Young's modulus around 12% HAC content. Effects of the addition of HAC to pulp suspension on physical properties of handsheets seemed to be similar to those of beating of chemical pulp on physical properties of paper. These results and scanning electron micrographs of handsheets indicated that hydrated amorphous cellulose gel can form strong interfiber-bonding with pulp fibers, whereas little interaction is present between pulp fibers and MCP or FAC.

The topochemistry of black spruce sulphonation: A TEM/EDXA study

Pulps produced by mechanical defibration of sulphite treated black spruce wood chips contain large amounts of lignin. The degree of sulphonation of this lignin has a significant influence on the physical properties of handsheets made from the resulting pulps In earlier work we have described the factors affecting the sulphonation of black spruce.The aim of the present investigation was to determine the differences in reactivity of sulphite towards lignin in the middle lamella and cell wall of black spruce.Black spruce wood chips were well impregnated with sodium base sulphite solutions having pH 7, and then heated at 140° and 80°C for known times. The resulting sulphonated wood chips were cut into small sticks and embedded in Vestopal. Transverse sections, 150 nm thick, were placed on a carbon grid having a single 1 mm hole bearing a collodian film which had been carbon coated. Sulphur contents in the middle lamella and cell wall were determined with a Philips 400 TEM coupled with an EDAX 9100/60 analyser. The concentration of sulphur was taken to be proportional to the x-ray counts in the sulphur Kα window after background subtraction, as shown in Figure 1.