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Heat and moisture treatments were shown to affect restoration of the capillary-porous structure of paper folders that was lost during drying. Thermodynamic functions of cellulose water of hydration were calculated for hydrothermal treatment over broad ranges of time and temperature. The effects of saturated vapor with high state parameters on paper strength were demonstrated. [ABSTRACT FROM AUTHOR]

High-resistance paper was manufactured by laccase-grafting of carboxymethyl cellulose (CMC) and chitosan (CPX) on Kraft pulp fiber. The reaction was mediated in the presence of laccase by one of the following polyphenols in the presence of air: gallic acid (GA), vanillic acid (VA) and catechol (1,2-DHB). Enzyme was added at constant loading (24 kg ton-1), 1% pulp consistency, 0.005% CMC, pH = 6.3 ± 0.5 and 2 mM of mediator. CPX content was assessed at two levels (0% and 0.005%). Treated pulps were analyzed by different mechanical tests (ring crush, mullen, corrugating medium test (CMT) flat crush of corrugating medium test and tension). An improvement in these parameters was obtained by biopolymer coupling and selected mediator. When using GA, three parameters increased more than 40%, while ring crush increased 120%. For the case of VA, properties were enhanced from 74% to 88% when CPX was added. For 1,2-DHB, there was not found a statistically significant difference between the results in the presence of CPX. Scanning electron microscopy, confocal microscopy, FTIR and 13C NMR were used in all papers in order to evaluate grafting. Hence, it was possible to correlate polymerization with an improvement of paper's mechanical properties. [ABSTRACT FROM AUTHOR]

Water soluble cationic chitosan (C-Ch) and surface-modified microfibrillated cellulose (C-MFC) were prepared and characterized. C-MFC was prepared by reaction of MFC (microfibrillated cellulose) with β-chloroethyldiethylamine followed by quaternization using methyl iodide while C-Ch was prepared by reaction of a commercial chitosan (Ch) with 2,3-epoxypropyltrimethyl ammonium chloride. C-Ch and C-MFC were characterized by elemental analysis (nitrogen content), Fourier transform infrared spectroscopy (FTIR) and surface charge determination. The prepared C-Ch and C-MFC were used with bentonite in order to improve drainage and filler retention in paper handsheets made from softwood and bagasse pulps. Dosage rates were 0.05–0.2% (w/w, weight of additive by weight of fibres) and 0.05–1% (w/w) for C-Ch and C-MFC, respectively. When used alone, these polymers did not induce any noticeable effect on drainage but they improved the retention of ground calcium carbonate (GCC). The effect of C-MFC/bentonite and C-Ch/bentonite systems on filler retention was more pronounced in case of bagasse pulp than for softwood pulp. The use of C-Ch improved filler retention more than C-MFC did. Comparisons with a commercially available cationic polyacrylamide (CPAM) showed that CPAM was the most efficient additive regarding both drainage and GCC retention, followed by Ch, C-Ch, and finally C-MFC. [ABSTRACT FROM AUTHOR]

Abstract: The effects of glycerol concentration and coating weight on biopolymer-coated paper properties were investigated using response surface methodology. Tests were run on the coated papers to determine water vapor barrier and mechanical properties. Coating weight was the most important parameter affecting water vapor permeability (WVP). Conversely, increasing coating weight led to a decrease in WVP and to an increase in tensile strength (TS) of the resulting coated papers. The papers coated with sodium caseinate (NaCAS) exhibited lower WVP values than those coated with other biopolymers. The TS of the papers coated with hydroxypropylmethylcellulose (HPMC) and chitosan was not affected by the glycerol concentration. HPMC-coated papers were higher in TS and %E than the other coated papers. For all types of coated paper, a maximum level of coating weight and level of glycerol concentration within range of 18.72–26.11% were found to be optimum for minimum WVP and maximum TS and %E. [Copyright &y& Elsevier]

Recently, an environmental criteria was required for every product and process. The great amount of pollution caused by the paper and cellulose industry effluents, especially those produced from nonwood fibrous materials, e.g., rice straw and bagasse. Using new technologies or redesigning products to meet new environments criteria is necessary. The production of cellulose by microorganisms is considered as one of the most beneficial sources for environment requirements. Microbial polysaccharides are valuable commodities, since they display many useful properties and can be produced in large quantities. This article reviews previous research on the biosynthesis of bacterial cellulose, structural features, properties, as well as potential applications as new industrial materials, i.e., paper industry, wastes treatment, sewage purification, food, medicine, etc. Suggestions for an economic production process for bacterial cellulose and cellulose derivatives also were reported. [ABSTRACT FROM AUTHOR]