Mechanical and chemi-mechanical pulps such as CMP, due to the weaker STRENGTH PROPERTIES, have found limited application in the production of high quality PAPERs as compared with chemical pulps. Therefore, appropriate modification of such fibers could be used to overcome such deficiencies. This study investigated the effect of cationic pretreatment of the CMP fibers to improve the potential of the fibers in PAPER production. First, fibers were treated by 20% sodium hydroxide, and then the fiber surface was cationized by grafting with one of the dosages of 5, 10 and 15% EPTMAC, based on fiber oven dry weights. The cationized fibers were mixed with 100, 20 and 40 % non-cationized fibers and the mixture was used to make hand sheets. The tensile and burst indices of the hand sheets were measured. The highest tensile and burst indices were measured on hand sheets produced containing either 20 or 40% fibers grafted with 10% cationic agent.

In order to simultaneously improve wet and dry STRENGTHs of PAPER and decrease environmental issues related to the wet STRENGTH resins, in this study effect of application method of wet STRENGTH additives on PAPER PROPERTIES was investigated. Wet STRENGTH resins were applied in four methods including spraying an aqueous glyoxal solution on to the surface of wet PAPER, addition of aminated polyacrylamide (PAa), glyoxylated polyacrylamide (GPAM) and polyamide-epichlorohydrin (PAE) to the pulp suspension, and spraying of aqueous glyoxal solution on to the surface of wet PAPER containing PAa. The results showed that wet STRENGTH of PAPER increased significantly after glyoxal spraying, which had high correlation with the amount of applied glyoxal. The glyoxal spraying had insignificant effect on the dry STRENGTH of PAPER, however tensile energy absorption (TEA) of PAPER decreased and stiffness of PAPER with increasing glyoxal spraying. Addition of PAa to the pulp suspension slightly increased wet STRENGTH, while dry STRENGTH and TEA of PAPER increased significantly. Glyoxal spraying on the wet PAPER containing PAa distinguished as the best method improving PAPER PROPERTIES while simultaneously increased wet and dry STRENGTHs without increasing effect on the stiffness of PAPER. By this method, the best results obtained in the PAPER contained 0.4% PAa and 1% glyoxal spraying which was optimum compared to the PAPER treated commercial GPAM and PAE resins.

Surface sizing of PAPER by anionic starch was carried out to study its concentration effect on physical and STRENGTH PROPERTIES of recycled PAPER. For this, hand sheets (100 GSM) of mixed recycled pulp containing 1% cationic starch were prepared and treated by the sizing agent on the sheet surface at various concentrations (0, 3-10%). Application and concentration increment of the starch solution resulted in a higher retention on the surface and lesser penetration into the PAPER structure (Z direction), contributing to a better hydrophobicity of sized PAPER and a significant reduction in water absorption of the PAPER; with the highest reduction in the Cobb test up to the solution concentration of 5%. Also, the results revealed that STRENGTH PROPERTIES of bending stiffness, burst and tensile indices increased due to the anionic starch treatment, its consequent absorption and penetration into the PAPER thickness. The improvement rate was more predominant using up to the 5% concentration. Penetration of a part of sizing agent into the porous structure of PAPER and resulted improvement in fiber bonding are possible and probable. However, higher concentration and viscosity of the starch solution contributed to the lesser penetration and bonding formation with higher retention on the PAPER surface which resulted in continuous improvement in PAPER smoothness. With the sizing solution thickening, tear index decreased due to starch film formation on the PAPER surface with brittle character. In general, increasing of the anionic starch solution up to the 5% could be reported as an optimum level.

One of the problems of PAPERs and cardboards in the packaging industry is the poor resistance to water, gas, and oil penetration. Nowadays, much research have been done on the use of biodegradable films and coatings based on polysaccharides to solve this problem. Chitosan is one of these polysaccharides that can be used as a biodegradable coating in packaging PAPERs. In this study, the effect of chitosan on the STRENGTH and barrier PROPERTIES of coated liner PAPER was investigated. Chitosan was used in three levels 10, 15, and 20 g/L acetic acids (1%) and with two softener ratios (glycerol) of 0.5 and 1 (based on dry weight of chitosan) for PAPERs coating. STRENGTH PROPERTIES including tensile, burst and tear index and barrier PROPERTIES including water absorption, air resistance, and oil absorption in the coated samples were investigated. The Statistical analysis of results showed that the barrier PROPERTIES increased significantly. Also, the effect of increasing the concentration of softener in the coating solution on the PROPERTIES of air resistance and oil absorption was positive but negative for water absorption. The basis weight, burst and tear index of the coated samples increased with increasing coating weight, on the other hand the tensile STRENGTH decreased. Moreover, increasing the concentration of softener in the coating solution showed a negative effect on the PROPERTIES of the samples. The results of the scanning electron microscope images showed that formation of chitosan film and the increase in the uniformity of the liner PAPER surfaces, especially in higher consumption amounts.

This research down with aim. of study of substitution possibility of bagasse neutral Sulfite semi chemical (NSSC) instead of division of wood pulp for production of newsprint PAPER in Mazandaran wood and PAPER complex. Cooking of pulp with use of chemicals of Mazandram wood and PAPER factory equal to 20 percent (in dry material basis) in 40 minutes time and 170oc heat. After that bagasse pulp refined with (PFI Mill) refiner to 400±25 CSF Freeness and mixture with CMP pulp of Mazandaran and PAPER factory. Bagasse pulp in ratio 20%, 30%, 40% and 100% of (pure bagasse).Mixture with CMP pulp of Mazandaran wood and PAPER factory with 350±15 CSF Freeness. Bleached long fiber pulp (import) with 550±15 Freeness in 20% level mixture with CMP pulp of factory as blank. One hand sheet with 60 gr/m2 basic weight make from each pulp. Finally: STRENGTH PROPERTIES of hand sheet were determined with used of TAPPI standard. Studies show that, with increasing bagasse pulp, the STRENGTH index like Tensile STRENGTH, Burst STRENGTH and Breaking length increased, The only exception was tear STRENGTH, probably the reason of this subject can related to the 20% long fiber pulp in blank sample because long fiber is one of the major factor that influence tear STRENGTH and increase it.

Zein is one of the important proteins that can be used as a biodegradable coating in packaging cardboards. In this study, the effect of coated zein on the STRENGTH and barrier PROPERTIES of liner cardboard was investigated. Zein was used in three levels of 50, 100, and 150 g/L in ethanol acid (95%) with two softener (glycerol) ratios of 0.5 and 1 (based on the dry weight of the zein) to coat cardboards. The results showed that the increasing of softener concentration in the coating solution had a positive effect on the air resistance and oil absorption but it had negative effect on water absorption. The basis weight, tensile and burst index of the coated samples were enhanced with increasing coating weight while the tear STRENGTH decreased. Moreover, the effect of increasing the softener concentration in the coating solution on the basis weight and tear index was positive but negative for tensile and burst indices and the results showed positive effect on the air and oil.

In this research, the mechanical and barrier PROPERTIES of hand-sheets made of virgin and recycled fibers coated by chitosan and poly (vinyl alcohol) polymer blends were studied. In order to evaluate the coating effects on the barrier PROPERTIES, water vapor transmission rate (WVTR), water absorbance, air resistance and grease proof of coated PAPERs were determined. Mechanical STRENGTH including tensile STRENGTH and burst STRENGTH were also measured. According to the results, the barrier PROPERTIES and mechanical STRENGTH of coated PAPERs improved dramatically compared to uncoated samples. The best results in WVTR and mechanical STRENGTH tests were obtained for coatings with the equal ratio of polymers. On the other hand, coating with 75%chitosan - 25% poly (vinyl alcohol) composition exhibited excellent resistance against the grease penetration and water absorption.

Background and objectives: The collection and consumption of recycled PAPER in addition to helping environment protection, causes more economical PAPER production. Since the consumption of recycled pulps causes low quality PAPER production, so determination of OCC pulp quality can be useful for the better fluting PAPER PROPERTIES prediction For OCC production, it is possible to use all types of PAPERboard and cartons from different sources. Because of using different recycled PAPERboard and cartons for OCC production, the OCC pulps quality are difference. As the fiber length distribution and variation have the important role in PAPER STRENGTH quality, the aim of this study is the determining of different OCC pulp's fiber length variations effect on fluting PAPER quality.Methods and materials: From the four types of recycled PAPER with different quality and with different sources, the OCC pulp was prepared. The NSSC pulp and recycled pulp samples fiber length classification were done by Bauer McNett fiber classification system based on Tappi standard method, T 233 cm - 82, in Mazandaran Wood and PAPER industries (MWPI) mill laboratory. The NSSC pulp prepared from wood of Iranian hardwoods in MWPI used as the control sample. The 127 grams handsheets, were prepared according to Tappi standard method, T 205om-88 for measuring structural (density) and STRENGTH PROPERTIES (tear STRENGTH, burst STRENGTH, breaking length and corrugated medium test) of fluting PAPER.Results: The results have shown that, OCC pulps from different recycled PAPER, have different long fibers and different fines. Among the different OCC pulps, the pulps with the higher amount of long fibers, have more PAPER STRENGTH PROPERTIES (tensile (breaking length), burst, tear), and the pulps with the higher amount of fines and lower amount of long fibers, have the least PAPER STRENGTH PROPERTIES. The corrugated medium test (CMT) of fluting PAPER is one of the important PROPERTIES and the results showed that this STRENGTH also depends to long fibers and fine contents in OCC pulps. The OCC pulps with the higher amount of long fibers and lower amount of fines, have more CMT.Conclusion: OCC pulps produced from different PAPER sources have different fiber length distribution that have a significant impact on the fluting PAPER STRENGTH PROPERTIES Therefore, with doing the fiber length distribution tests it is possible to predict fluting PAPER STRENGTH PROPERTIES OCC pulps with higher amounts of long fiber and lower amounts of fines has good STRENGTH PROPERTIES (tensile STRENGTH, burst STRENGTH and tear STRENGTH) for producing fluting PAPER.

Various kinds of chemicals are used in PAPERmaking to enhance PAPER PROPERTIES and to improve efficiency of the production process. In the presence of cationic starch as an anionic charge catcher, effects of Nano silica/cationic Polyacrylamide complex on retention, drainage time, water volume drained by Dynamic Drainage Jar and PROPERTIES of PAPER recycled from old corrugated container were investigated. The results revealed that individual addition of CPAM is more efficient than the individual addition of anionic nano silica, regarding to the investigated PROPERTIES, increase all characteristics compared to the situation without these addition. Higher volume of drained water (up to 6%) and lesser time needed for the sheet formation (up to 10%) combined with retention increment (> 2%) have been achieved by flocculation and consolidation of fines and fibers via bridging and network flocculation of pulp ingredients and contributing to charge neutralization of anionic surfaces, more and more, resulted in bigger flocs which could be retained by PAPERmaking wire. The mentioned mechanism contributed to better bonding of PAPER network resulted in tensile and burst indicates improvement up to > 45% and >50%, respectively. Influence of silica anionic nanoparticle on STRENGTHening of the flocs formed by CPAM, made higher energy requirements (> 12%) for PAPER tearing. In addition to higher yield of production, application of CPAM/nano silica complex resulted in a PAPER with higher value from quality and application point of view.