Development of High Quality Printing Paper Using Kenaf (Hibiscus Cannabinus) Fibers

Kenaf (Hibiscus cannabinus) is an annual non-wood plant which has shown great potential as an alternative source of papermaking fiber. The purpose of this research was to investigate the suitability of Malaysian cultivated kenaf fibers in the production of high quality printing paper. The first part of the research characterized the chemical, morphological and pulping properties of kenaf fractions. The bast fibers had a lower lignin content, higher cellulose content, and lower hemicellulose content compared to the core fibers. The whole stem kenaf had lower lignin and cellulose content, and hemicellulose and ash content was comparable to softwood. Fiber morphology results showed that kenaf bast fibers were long and slender, while the core fibers were much shorter and wider. Morphology and chemical analysis indicated that bast and core fibers were significantly different. In this part, the pulping properties of different fractions of kenaf were also studied. The pulping experiments led to the conclusion that bast fibers are relatively easy to delignify during pulping, followed by the whole stem and the core kenaf fractions. An unbleached whole kenaf pulp with high viscosity, good bleaching characteristics and relatively good yield could be produced with the kraft pulping process. The second part of the research investigated the production of bleached pulp using environmentally-friendly method, TCF. Conventional Elemental Chlorine Free (ECF) bleaching sequences were also used to compare the results with the TCF sequences. The results indicated that in contrast to unbleached kraft wood pulps, kraft kenaf pulps can be easily bleached to a brightness of 91.4% using a 4-stage TCF [Q1(PO)Q2P] bleaching sequence. This will be a significant advantage for kenaf over wood. The third part of the research studied the polymer deposition, surface topography and printability. The utilization of chitosan in sizing improved the paper strength and surface properties significantly, but its effectiveness was strongly dependent on the method of addition and concentration. Spray deposition application gave superior strength properties followed by equilibrium adsorption. It is less effective under alkaline conditions. The effect of chitosan was compared with cationic starch and polyvinyl alcohol (PVA). Sizing quality of cationic starch fairly matched with the sizing quality of chitosan, however, it was able to reduce the water absorption potential of paper more than chitosan at a same concentration (i.e. 2%). The final part of study demonstrated that the use of chitosan in optimum dosage could improve the printability and print quality of kenaf paper in terms of surface roughness, water and oil absorption, ink penetration, print density, ink set-off and gloss contrast for offset printing. The overall conclusion is that whole stem kenaf is an attractive raw material that is suitable for use in the production of high quality printing paper in areas where forest resources are inadequate to supply a kraft mill of economic size. Chitosan is recommended as an additive in conventional surface sizing to enhance strength and surface properties for printing paper

Effects of hot water pre-extraction on surface properties of bagasse soda pulp

In this work, the effects of hot water pre-extraction of depithed bagasse on the soda pulping and surface properties were studied. The conditions of hot water pre-extraction were: maximum temperature 170 °C, heat-up time 90 min, time at maximum temperature 10 min, and solid to liquor ratio (S:L) 1:8. Consequently, the pre-extracted and un-extracted bagasse chips were subjected to soda pulping at 160 °C for 1h with 11, 14 and 17% active alkali charge and an S:L of 1:5. The results showed that the hot water pre-extraction increased bagasse surface texture porosity by hemicellulose degradation. Therefore, the delignification was faster for pulping of pre-extracted samples. At a certain charge of alkali, pre-extracted samples showed higher screened yield and lower Kappa number. For instance, at 17% alkali charge, pre-extracted bagasse gave 11.3% higher pulp yield compared with the un-extracted ones. Inverse gas chromatography (IGC) results showed that the hot water pre-extraction changed the active sites on the bagasse surface, decreasing the dispersive energy and the basicity character, and affected the particle morphology. The pulping process decreased the hydrophobicity and the basicity of the bagasse surface. The surfaces of un-extracted and pre-extracted bagasse pulps had similar properties but different morphology. The pulps present higher surface area and permeability with more reactive capacity.info:eu-repo/semantics/publishedVersio

Effect of chitosan-epoxy ratio in bio-based adhesive on physical and mechanical properties of medium density fiberboards from mixed hardwood fibers

Abstract Chitosan and bio-based epoxy resins have emerged as promising formaldehyde-free replacements for traditional urea–formaldehyde (UF) adhesives in engineered wood products. This study evaluated five chitosan-to-epoxy weight ratios (3:1, 2:1, 1:1, 1:2, 1:3) as adhesives for hot-pressing medium density fiberboards (MDF) using mixed hardwood fibers. Increasing the epoxy ratio reduced viscosity and gel time, facilitating spraying and fast curing. The density of the formulated MDFs increased with higher epoxy ratios, ranging from 679 kg/m3 for the 3:1 ratio to 701 kg/m3 for the 1:3 formulation, meeting the 500–900 kg/m3 density range specified in EN 323. The 1:3 epoxy-rich formulation enhanced modulus of rupture (MOR) to 31 MPa and modulus of elasticity (MOE) to 2392 MPa, exceeding the minimum requirements of 16 MPa and 1500 MPa set out in EN 310 and EN 316, respectively. Dimensional stability peaked at 5% thickness swelling for the 1:3 formulation after 24 h water soaking, fulfilling the < 25% requirement per EN 316. Internal bond strength reached a maximum of 0.98 MPa for the 3:1 chitosan-rich formulation, satisfying the 0.40 MPa minimum per EN 319. One-way ANOVA tests showed the adhesive ratio had a significant effect on mechanical properties and dimensional stability at 95–99% confidence levels. Duncan's multiple range test revealed the 1:3 ratio boards exhibited statistically significant improvements compared to untreated group. Overall, tailoring the ratios achieved well-balanced properties for MOR, MOE, and dimensional stability, demonstrating potential to replace UF resins

Chemical modification of cellulose nanofibers with phthalimide air filter to adsorb carbon dioxide

The applications of renewable nanomaterial’s, such as cellulose nanofibers (CNFs), have recently been of great interest due to their unique properties, including high surface area, high aspect ratio, biodegradable, easy access and reactive hydroxyl groups on the surface. The purpose of this study was to fabricate refined air nano filters using phthalimide- modified CNFs. Because phthalimide contains amine groups that are needed to adsorb carbon dioxide. In this study, a freeze drying method was used for direct removal of water from pure CNFs gel and phthalimide -modified. Also, the properties of pure CNFs aerogels and phthalimide-modified (containing amine groups) were investigated to adsorption carbon dioxide. Modification of CNFs with phthalimide in 4% (v/v) acetic acid, with ratios of CNFs to phthalimide 1: 0, 1: 0.5, 1: 1 and 1: 1.5 wt %. Chemical properties and morphology of modified CNFs were investigated using various techniques including SEM, FTIR-ATR, XRD and TGA. Based on the results, the SEM test did not show any change in the size and structure of the modified CNFs. The presence of phthalimide was confirmed by the creation of new pitches NH2, C-N and ester 〖COO〗^- on modified CNFs using the ATR-FTIR spectroscopy test. Also, the results of TGA indicated that increasing the amount of phthalimide reduces the thermal stability, indicating the reactivity of the functional groups of phthalimide with CNFs. In addition, the highest carbon dioxide adsorption of 1.5% phthalimide was about 50%

Influence of mild alkaline treatment on the cellulosic surfaces active sites

Agro-residues fibers are inexpensive environmentally friendly alternatives to synthetic fibers in fiber reinforced polymer composites. The natural fiber properties and bondability with adhesive can be modified by subjecting the fibers to a pre-treatment procedure. The knowledge ofthe modified fibers sur face properties is essential to explain and predict their applications. The present study is focused on the effect of alkaline treatment on the surface characteristics of stalk fibers from rapeseed, tobacco, cotton, lemon balm and kiwi. The chemical composition of fibers and Fourier transform infrared spectroscopy show components extraction and the X-ray diffraction show improvement in the crystallinity index of the treated fibers. But only the IGC analysis allows us to know in detail the alterations on the fiber surface and the effect on the adhesion of the fibers. IGC shows that alkaline treatment produces changes in the nature and number of the active sites, responsible for the physico-chemical activity of the surface of the fibers. The fiber hydrophobicity was improved by the increase of more energetic and active sites in the surface. Also,the creation of new basic active sites and removal of acidic active sites from the fiber surface due to alkaline treatment has been clearly shown.info:eu-repo/semantics/publishedVersio

Effect of Cationic Starch and Chitosan on Dry Strength of Bleached Soda Pulps Made of Pre-Extracted and Non-Extracted Bagasse

This study focused on the properties of alkaline pulp obtained from the soda pulping of pre-extracted bagasse and the effects of dry strength polymers on mechanical properties of paper in comparison to a paper obtained from nonextracted bagasse. Hot-water pre-extraction was carried out at 135°C for 30 min. Consequently, soda pulping and ECF bleaching were performed on pre-extracted and un-extracted bagasse, under similar conditions. It was found that pre-extraction of about 50% of hemicelloluse of the bagasse decreased total pulping yield, kappa number and increased bleachability of pulps and resulted in a significant loss in tensile and burst strengths of hand-sheets. Then, reinforcing effect of the pulps with chitosan and cationic starch applied in the wet-end were investigated. The results obtained with suitable amounts of chitosan and cationic starch were encouraging, because comparable strengths were obtained from pre-extracted and un-extracted bleached soda bagasse pulps with 1% chitosan and 1.5% cationic starch. According to the results, drop in paper strength due to hemicellulose pre-extraction of the bagasse could be compensated using suitable dry strength polymer. E     Effect of Cationic Starch and Chitosan on Dry   Strength of Bleached Soda Pulps Made of   Pre-Extracted and Non-Extracted Bagasse   Zeinab Khorasani 1, Yahya Hamzeh1*, Alireza Ashori2, and Mohammad Azadfallah 1   1. Faculty of Natural Resources, Department of Wood and Paper Sciences and Technology, University of Tehran, P.O. Box: 31585-4314, Karaj, Iran 2. Department of Chemical Technologies, Iranian Research Organization for Science and Technology (IROST), P.O. Box: 15815-3538, Tehran, Iran Received 2 April 2012, accepted 17 December 201