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The hybrid films of reinforcing the aged papers have been employed via layer-by-layer (LBL) assembly deposition of the chitosan lactate/carboxymethyl cellulose complex previously modified with metal oxide. In order to reinforce the films, a vacuum infiltration was adopted in the LBL process. The mechanical properties and structure of the aged papers in relation to fiber morphology were investigated using SEM, FTIR, XPS, and tensile test. The well-dispersed coatings resulted in an excellent improvement in mechanical properties of the modified paper. After only three bilayers deposited, the measured tensile strength and folding endurance for modified aged newspaper samples increased up to 100% and 450%, respectively, as compared to the control sample. This high efficiency was kept even when the modified paper samples exposed to the moist-heat accelerated aging and UV irradiation. The pH of the paper rose to alkalescence rapidly, and the paper samples maintained their coloration close to the original after treatment. [ABSTRACT FROM AUTHOR]

Inorganicfillers, the second largest component of the papermakingprocess, have poor bondability with cellulosic fibers, interfere ininterfiber bonding, and reduce paper strength. Filler preflocculation/modificationis a practical method for enhancing interactions between the fillerparticles and fibers. This article reports on the effects of fillercontent and preflocculation on the filler bondability factor calculatedbased on first-pass ash retention and paper strength properties suchas the tensile, Z-direction tensile, and compositetensile indexes. Talc filler preflocculated using 0.1–0.8%dosages of cooked cationic starch based on the dry weight of fillerwas loaded in paper to obtain varying filler contents of 15–24%.The filler bondability factor (FBF) and various tensile propertiesof paper were calculated and analyzed for all experiments. FBF andpaper strength were reduced with increasing filler content in paper,whereas they were improved upon addition of preflocculated fillerin paper. Noticeably, preflocculated filler resulted in increasesin FBF and composite tensile index of 13–24% and 7–15%,respectively, at a 24% filler content in paper. [ABSTRACT FROM AUTHOR]

The improvements of adding sodium borohyride to the alkali sulfite–anthraquninone (AS–AQ) pulping process on properties of pulp and paper sheets was investigated. These properties were compared to those of the AS–AQ and the ethanol addition to AS–AQ (ASAE) pulping processes. The screened yield increased with alkali sulfite–antraquinone–sodium borohyride (ASAB) pulping process and kappa number decreased with respect to the AS–AQ process. Tensile and burst index of paper sheets improved with the ASAB pulping process, and the tear index for the ASAB pulping process was slightly decreased compared to that of the AS–AQ and ASAE pulping processes. It was determined that whiteness and brightness of papersheets decreased by adding sodium borohyride to the AS–AQ pulping process, whereas the opacity of papersheets did not change clearly compared to AS–AQ and ASAE pulping processes. [ABSTRACT FROM AUTHOR]

The surface properties of paper depend not only on the fibrous matrix but also on the final treatment of the paper surface. The present work compares paper samples with two different surface sizing treatments by using AFM and profilometry to assess topography and roughness parameters as well as to evaluate the spreading of the sizing formulation and to estimate sizing agent particle sizes. The results were confronted with dynamic light scattering measurements regarding particle size. This work shows that AFM is a valuable technique to visualize and quantify the effects of sizing on the paper surface. Due to the small amount of surface sizing applied, no significant differences between the surface sized samples and the reference sample (without surface treatment) could be detected in terms of the surface roughness parameters. Nonetheless, those of sample B1 are systematically smaller than those of sample A1. [ABSTRACT FROM AUTHOR]

A new approach to the measurement of x−yuniformity of the surface of a paper sheet is described. Scanning electron micrographs are taken of both the top and bottom surfaces of a paper sheet and image-analyzed. The images were converted to grayscale, and the standard deviation of the pixel brightness was called the “SEM roughness index” and calculated for each surface. Both commercial newsprint sheets and handsheets made with kraft, TMP, and recycled fibers were examined. Debonders and cationic polymers were added to some sheets. The addition of debonders increases the index on the top side of the sheet but decreases it on the bottom. This is caused by the movement of fines from the top to the bottom side. The addition of cationic polymers increases the SEM roughness index by increasing the degree of microfloc formation. Samples taken across a reel from a commercial paper machine tend to show a mirror image relationship between the top and bottom surfaces. The SEM roughness index is able to detect subtle changes in sheet structure caused by differences in the mode of addition of polymers used for retaining fines in the sheet. [ABSTRACT FROM AUTHOR]

The main purposes of filler addition in papermaking are to improve paper properties and reduce cost. The cost reduction is attributed to the low cost of the filler itself and to the energy savings that occur during the papermaking process. In this work, the effects of clay filler addition on the energy savings during the papermaking process, including water drainage, pressing, and drying, were systematically investigated. Experimental results indicated that the addition of filler could dramatically increase the drainage rate and the water removal rates during pressing and drying. With 20% filler addition, the drainage time decreased by 20% compared to the unfilled paper. At a filler content of 23%, the solids content of the handsheets after pressing increased at least 5 absolute points, and the drying rates increased by 20%. All these improvements can offer considerable benefits for paper mills, including enhanced machine speeds and large energy savings. [ABSTRACT FROM AUTHOR]

To increase the filler content in paper without sacrificing paper properties, clay−starch composites, made from a simple precipitation method, were used in papermaking. Compared to untreated clay, the clay−starch composite filled paper improved paper tensile strength up to 100−200%. Contrary to untreated clays that usually reduce the ZDT (z-directional tensile strength) of papers, the clay−starch composite actually increases the ZDT. The significant improvements in the paper strengths are attributed to the formation of a fiber−starch−filler sandwich structure, which avoids direct contact between filler and fiber. The specific shear bond strengths (expressed as specific bond strengths) between fillers and fibers were measured and used as the main variables for the modeling. It was also found that the fiber−fiber specific strength is weaker than the fiber−starch specific bond strength. The tensile strength (expressed as breaking length) was modeled by using a modified Page equation. The experimental results agreed very well with the modeling results. [ABSTRACT FROM AUTHOR]