Application of Enzyme for Improvement of Acacia APMP Pulping and Refining of Mixed Pulp for Printing Papermaking in Vietnam

This study assesses the influence of commercial enzyme (FibreZyme? LBR) treatment applied to APMP pulp and to the mixture of 55 % Acacia CTMP75 pulp, 30 % soft-wood bleached chemical pulp (LBKP 90 from Chile) and 15 % hard-wood bleached chemical pulp (NPKP 90 from Indonesia). The treatment was conducted at different temperatures, reaction times and enzyme dosages. The APMP and mixed pulp treated with the enzyme showed a significant decrease of refining time to achieve the same refining degree (Schopper–Riegler freeness, °SR) and better mechanical–physical properties due to the development of fibrillation. The fibre morphology difference between before and after treatment was revealed by the microscopic observations performed by a scanning electron microscope (SEM). The SEM analysis showed that the surface of the enzyme-treated fibre had some swelling and fibrillar phenomenon that lead to strong paper properties such as tear index, tensile index and burst index.     

Dendronized Cellulose Nanocrystals as Templates for Preparation of ZnS and CdS Quantum Dots

Cellulose nanocrystals (CNC) isolated from bleached bagasse pulp were modified with a second-generation isocyanate dendron (G2-dendron) to prepare dendronized cellulose nanocrystals (DCN). Transmission electron microscopy (TEM), elemental analysis for nitrogen, Fourier transform infrared (FTIR) and ¹³C magic angle spinning nuclear magnetic resonance (¹³C MAS NMR) proved occurrence of the modification of cellulose nanocrystals surfaces. The dendronized cellulose nanocrystals were used as templates for formation of ZnS and CdS quantum dots with uniform diameter at low temperature in water. The prepared DCN/QDs were highly soluble in water. TEM images showed that the size of the prepared quantum dots was about 5 nm in diameter. UV-Visible and fluorescence spectroscopy showed absorption and emission at wavelength values lower than that reported for bulk ZnS and CdS.     

The effect of eucalypt pulp xylan content on its bleachability,refinability and drainability

Currently, bleached eucalypt pulps are largely used for printing and writing (P&W) and sanitary (tissue) paper grades. Among the many pulp quality requirements for P&W and tissue paper production the xylan content is one of the most significant. For P&W papers, increasing xylans improve pulp refinability and strength properties but negatively affect bulk and drainability. For tissue paper, xylans are purportedly advantageous during paper drying in the Yankee cylinder but negatively affect paper bulk and may increase dusting during paper manufacture. On the other hand, bleachability is a very important parameter for both P&W and tissue grade pulps since bleaching cost is the second most significant in eucalypt bleached kraft pulp production. The aim of this study was evaluating the influence of eucalyptus pulp xylan content on its bleachability, refinability and drainability. A sample of industrial unbleached eucalyptus kraft pulp containing 15.6?% xylans was treated with various alkali charges at room temperature in order to obtain materials with different xylan contents. The pulps were bleached to 90 % ISO brightness with the O–D_HT–(EP)–D sequence and evaluated for their refinability and drainability. By increasing the alkali concentration in the range of 10–70 g/L pulps of 14.5–5.9 % xylans were produced with no significant impact on cellulose crystallinity. The decrease of xylan content significantly decreased pulp bleaching chemical demand, water retention value and refinability and increased pulp drainability.     

Bleachability and characterization by fourier transform infrared principal component analysis of acetosolv pulps obtained from sugarcane bagasse

Sugarcane bagasse Acetosolv pulps were bleached by xylanase and the pulps classified by using Fourier transform infrared (FTIR) spectroscopy and principal component analysis (PCA). Pulp was treated with xylanase for 4–8 h with stirring at 30°C. Some samples were further extracted with NaOH for 1 h at 65°C. FTIR spectra were recorded directly from the dried pulp samples by using the diffuse reflectance technique. Reduction in kappa number of 69% was obtained after sequence xylanase (4 h)-alkaline extraction. During bleaching the viscosity decreased only 12%. FTIR-PCA showed that the first three principal components (PCs) explained more than 90% of the total variance of the pulp spectra. PC2×PC1 plot showed that the points related to pulps from sequence xylanase (4 h)-alkaline extraction are different from the other. This group isenlarged by plotting PC3×PC1 or PC3×PC2 containing all pulps submitted to alkaline extraction. PC2 and PC3 are the principal factor for differentiation of the pulps. These PCs suffer influence of the ester bands (1740 and 1244 cm⁻¹). On the other hand, the pulps bleached only with xylanase could not be differentiated from the nonbleached pulps.     

Influence of recycling and temperature on the swelling ability of paper

Hornification is the loss of fiber wall swelling which is detrimental to subsequent recycling resulting from drying. It is known that dried fibers lose their conformability and swelling capacity. The effect of recycling treatment on the swelling ability of hardwood bleached kraft pulp fibers was determined. Modelling paper recycling, sheets were recycled using heat treatment (23°C, 60°C, 100°C). The results were compared with those for natural fibers from bleached kraft pulp. Swelling kinetics of sheets was measured by a modified method monitoring interactions of pulp with water. Swelling ability decreased during the recycling in comparison with never-recycled pulp at all temperatures. Recycling of sheets caused only small changes in the cupri-ethylene-diamine viscosity, however, the water retention value decreased considerably.     

Synthesis and characterization of microcrystalline cellulose powder from corn husk fibres using bio-chemical route

In the present study low cost microcrystalline cellulose (MCC) powder was prepared from cornhusk fibres, extracted chemically followed by anaerobic consortium treatment. Cornhusk fibres were treated with 10% alkali at 120 °C for 60 min followed by anaerobic consortium treatment for 3 days. It was then bleached with hydrogen peroxide and finally washed. Bleached pulp was hydrolysed using 4 N HCl to get the MCC. In the present investigation, we have characterized the MCC prepared from cornhusk fibres thoroughly for its physico-chemical properties and compared with Avicel^®-PH 101, a commercial grade MCC. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Powder Diffraction (XRD) and Differential Scanning Calorimetry (DSC) were used for characterization of samples. Similarly the powder and flow properties of the MCC prepared from cornhusk fibres were also investigated and the results were compared with Avicel^®-PH 101. Our results showed that various properties and the purity of MCC prepared from cornhusk fibres are comparable to the commercial grade MCC. Since, cornhusk is an agricultural waste product, MCC obtained from cornhusk fibres will be from cheaper raw materials than current market MCC.     

Improving Accessibility and Reactivity of Celluloses of Annual Plants for the Synthesis of Methylcellulose

Pretreatments (water-soaking, pre-mercerization, mercerization under a pressure of 15 bars and steam explosion) were used to improve the accessibilities and reactivities of celluloses of bleached flax, hemp, sisal, abaca and jute pulps for the synthesis of methylcellulose. Degrees of crystallinity were determined by X-ray Diffraction (XRD) spectra. The iodine adsorption accessibilities of pulps were low and accessible fractions ranged from 1.3 to 5.2%. Accessible fractions in amorphous cellulose were calculated in the 5–18% range. The accessibilities of these pulps were hemp pulp > flax pulp > sisal pulp > jute pulp > abaca pulp. Fourier Transform Infrared (FTIR) spectra showed that mean hydrogen bond strengths were weakened and relative crystallinity indexes were decreased by pretreatments. The accessibility and reactivity of the abaca pulp were improved by water soaking, mercerization under 15 bars pressure, steam explosion and preliminary mercerization, of which steam explosion and pre-mercerization were the best treatments. Species was the main factor for the accessibility and reactivity.     

Synthesis of high-performance superabsorbent glycerol acrylate-cross-linked poly (acrylic acid)

Glycerol acrylate (GA) is synthesised by an acryloylation reaction with acryloyl chloride. An ester was used as a cross-linking agent at varying proportions in the synthesis of poly acrylic acid (PAA). The amount of cross-linking density in the product (GA-PAA) and degree of neutralisation determine the absorbency of the polymer samples. A sample of GA-PAA containing 0.8 % GA was discovered to absorb 395 and 66 g/g of water and saline solution, respectively. Different solvent uptakes were tested with the sample showing varying capacity for different solvents. The temperature of the reaction was maintained at 60 °C and a reaction time of 2½ h. FTIR, TGA, SEM and XRD analyses were used to characterise the products.     

Preparation,characterization, and properties of fast‐responding bulk hydrogel and treated bleached banana pulp

The reaction between bleached banana pulp and pure maleic anhydride (MA) was investigated. The reaction was conducted in a reactor in the presence of xylene used as a solvent and sodium hypophosphite as catalyst. The appearance of infrared absorption bands at 1891 and 1708 cm^?1 indicated that MA chemically reacted by esterification with bleached banana pulp. However, evidence of an esterification reaction was obtained between cellulose and MA. The production of fast‐responding bulk hydrogel with a high swelling ratio was also investigated. This hydrogel was synthesized first by the formation of maleated acrylamide particles and then by the graft copolymerization of the particles with cellulose. The maleated acrylamide particles were characterized with mass spectroscopy, and the formed hydrogl was characterized by FT‐IR. The esterification reaction between bleached banana pulp and maleated acrylamide was also studied. Steam absorption for bulk hydrogel, maleated acrylamide‐treated bleached banana pulp, MA‐treated cellulose and bleached banana pulp is higher than the steam absorption for untreated cellulose and bleached banana pulp. Compared with treated bleached banana pulp and cellulose, the hydrogel had very high swelling ratios and much faster swelling rates attributed to the collaboration of the ionized particles and bulk hydrogel. The number of ionic maleated acrylamide groups in the hydrogel affected the swelling behavior. Copyright © 2004 John Wiley & Sons, Ltd.     

Spectroscopic characterization of oxidized nanocellulose grafted with fluorescent amino acids

A hardwood bleached kraft pulp was oxidized by sodium hypochlorite using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and sodium bromide in water as catalysts to produce oxidized fibers. These oxidized fibers were mechanically disintegrated into oxidized nano-elements which were separated from the coarse components by centrifugation to obtain oxidized nanocellulose (ONC). The ONC was then coupled with fluorescent amino acids using a two step coupling procedure. First, the ONC was activated by N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide hydrochloride, forming a stable active ester in the presence of N-hydroxysuccinimide. Second, the active ester was reacted with the amino groups on the amino acids, forming an amide bond between the ONC and amino acids. The products (ONC-amino acids) were characterized by transmission electron microscopy and by different spectroscopic techniques such as absorption, emission, FTIR and XPS.     

Composite polyphosphazene membranes doped with phosphotungstic acid and silica

Poly（bis（phenoxy）phosphazene） （SPBPP）/phosphotungstic acid （PWA）/silica composite membranes for fuel cells were prepared. The composite membranes were characterized by using FTIR, TGA and SEM techniquies. Incorporation of PWA particles and silica particles into the SPBPP polymer matrix and a specific interaction between them were confirmed by FTIR spectra. TGA results showed that the composite membranes had high thermal stability. Homogeneous distribution of PWA and silica particles within the SPBPP matrix was verified by SEM micrographs. The doped membranes showed increased water uptake and proton conductivity.     

Carboxymethylcellulose obtained by ethanol/water organosolv process under acid conditions

Sugar cane bagasse pulps were obtained by ethanol/water organosolv process under acid and alkaline conditions. The best condition of acid pulping for the sugarcane bagasse was 0.02 mol/L sulfuric acid at 160 degrees C, for 1 h, whereas the best condition for alkaline pulping was 5% sodium hydroxide (base pulp) at 160 degrees C, for 3 h. For the residual lignin removal, the acid and alkaline pulps were submitted to a chemical bleaching using sodium chlorite. Pulps under acid and alkaline conditions bleached with sodium chlorite presented viscosities of 3.6 and 7.8 mPa x s, respectively, and mu-kappa numbers of 1.1 and 2.4, respectively. The pulp under acid condition, bleached with sodium chlorite was used to obtain carboxymethylcellulose (CMC). CMC yield was 35% (pulp based), showing mass gain after the carboxymethylation reaction corresponding to 23.6% of substitution or 0.70 groups -CH(2) COONa per unit of glucose residue. The infrared spectra showed the CMC characteristic bands and by the infrared technique it was possible to obtain a substitution degree (0.63), similar to the substitution degree calculated by mass gain (0.70).     

Characterization of Starch/Acrylic Acid Super‐Absorbent Hydrogels Prepared by Ionizing Radiation

Copolymerization of acrylic acid (AAc) and gelatinized maize starch in aqueous medium using γ‐irradiation, followed by neutralization with alkali solution was carried out. The preparation conditions, such as irradiation dose and starch/AAc compositions were investigated. The higher the irradiation dose, as well as the AAc content in the feed solution, the higher the gel content. The copolymers were characterized by FTIR spectroscopy, thermo‐gravimetric analysis (TGA) and scanning electron microscopy (SEM). SEM revealed that the higher the dose, the lower the copolymer pore size. Starch/AAc copolymers have thermal stability higher than that for starch and poly acrylic acid individually. The swelling of starch/AAc hydrogels reduced as the gel content increases. The maximum water absorption obtained for starch/AAc hydrogels in distilled water was 200 g/g, and for neutralized starch/AAc hydrogels was 350 g/g. The swelling ratio of starch/AAc hydrogels of different compositions in NaCl solution is lower than that obtained in distilled water. The results suggest that the neutralized starch/AAc hydrogels have a high swelling property, and can be used in a variety of commercial applications.     

Triazole-forming waterborne polyurethane composites fabricated with silane coupling agent functionalized nano-silica

In the research work, "click" chemistry was used to modify waterborne polyurethane (WPU) with silane coupling agent (SiCA) functionalized nano-silica. The modified WPU (CWPU) was characterized by FTIR, scanning electron microscope (SEM), thermogravimetric analysis (TGA) and contact angle measurement. The experiment results show that the modification can improve the thermal stability, hardness, and water or weather resistance of CWPU.     

Preparation and characterization of water-redispersible nanofibrillated cellulose in powder form

Water-redispersible, nanofibrillated cellulose (NFC) in powder form was prepared from refined, bleached beech pulp (RBP) by carboxymethylation (c) and mechanical disintegration (m). Two routes were examined by altering the sequence of the chemical and mechanical treatment, leading to four different products: RBP-m and RBP-mc (route 1), and RBP-c and RBP-cm (route 2). The occurrence of the carboxymethylation reaction was confirmed by FT-IR spectrometry and ¹³C solid state NMR (¹³C CP-MAS) spectroscopy with the appearance of characteristic signals for the carboxylate group at 1,595 cm⁻¹ and 180 ppm, respectively. The chemical modification reduced the crystallinity of the products, especially for those of route 2, as shown by XRD experiments. Also, TGA showed a decrease in the thermal stability of the carboxymethylated products. However, sedimentation tests revealed that carboxymethylation was critical to obtain water-redispersible powders: the products of route 2 were easier to redisperse in water and their aqueous suspensions were more stable and transparent than those from route 1. SEM images of freeze-dried suspensions from redispersed RBP powders confirmed that carboxymethylation prevented irreversible agglomeration of cellulose fibrils during drying. These results suggest that carboxymethylated and mechanically disintegrated RBP in dry form is a very attractive alternative to conventional NFC aqueous suspensions as starting material for derivatization and compounding with (bio)polymers.     

Development of continuous process enabling nanofibrillation of pulp and melt compounding

Microfibrillated cellulose (MFC), a mechanically fibrillated pulp mostly consisting of nanofibrils, is a very attractive material because of its high elastic modulus and strength. Although much research has been done on composites of MFC and polypropylene (PP), it has been difficult to produce such composites at an industrial level because of the difficulties in using MFC in such composites are not only connected to the polarity (that can be improved with compatibilizers), but also with the challenge to make a homogeneous blend of the components, and also the low temperature stability of cellulose that could cause problems during processing. We developed a new processing method which enables continuous microfibrillation of pulp and its melt compounding with PP. Never-dried kraft pulp and powdered PP were used as raw materials to obtain MFC by kneading via a twin-screw extruder. Scanning electron microscopy showed nano to submicron wide fibers entangled in the powdered PP. MFC did not aggregate during the melt compounding process, during which the water content was evaporated. Maleic anhydride polypropylene (MAPP) was used as a compatibilizer to reinforce interfacial adhesion between the polar hydroxyl groups of MFC and non-polar PP. We investigated the effect of MAPP content on the mechanical properties of the composite, which were drastically improved by MAPP addition. Needle-leaf unbleached kraft pulp (NUKP)-derived MFC composites had better mechanical properties than needle-leaf bleached kraft pulp (NBKP)-derived MFC composites. Injection molded NUKP-derived MFC composites had good mechanical and thermal properties. The tensile modulus of 50 wt% MFC composite was two times, and the tensile strength 1.5 times higher than that of neat PP. The heat distortion temperature of 50 wt% MFC content composite under 1.82 MPa flexural load was increased by 53 °C, from 69 to 122 °C. This newly developed continuous process using powder resin has the potential for application at an industrial level.     

Synergistic effects of cerium phosphate and intumescent flame retardant on EPDM/PP composites

An intumescent flame retardant system composed of ammonium polyphosphate (APP) and pentaerythritol (PER) was used for flame retarding ethylene–propylene–diene‐modified elastomer (EPDM)/polypropylene (PP) blends. Cerium phosphate (CeP) was synthesized and the effect on flame retardancy and thermal stability of EPDM/PP composites based on intumescent flame retardant (IFR) were studied by limiting oxygen index (LOI), UL‐94, and thermogravimetic analysis (TGA), respectively. Scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR) were used to analyze the morphological structure and the component of the residue chars formed from the EPDM/PP composites, and the mechanical properties of the materials were also studied. The addition of CeP to the EPDM/PP/APP/PER composites gives better flame retardancy than that of EPDM/PP/APP/PER composites. TGA and RT‐FTIR studies indicated that an interaction occurs among APP, PER, and EPDM/PP. The incorporation of CeP improved the mechanical properties of the materials. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and characterization of biodegradable sugarcane bagasse nano reinforcement for polymer composites using ball milling operation

The present work includes the processing and characterization of nano-based natural reinforcement for polymer composite materials. Sugarcane bagasse has been collected and the fibers were extracted using manual striping process. Undesirable materials present in the extracted fibers were removed by 1% NaOH-based chemical treatment. The macrofibers were reduced to nano scale by using high-energy ball milling process. Nanoparticles from bagasse fibers were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The degree of crystallinity of nano bagasse is 55.2% and it was reported by using XRD. A FTIR spectrum confirms the presence of cellulose functional groups in nano bagasse. The nano bagasse dimensions and morphology were investigated using SEM. The average length and diameter of the nano bagasse is 51.2 and 46.1 nm, respectively. Thermal stability of the nano bagasse was revealed by TGA analysis. The chemical composition of cellulose, lignin, and hemicellulose contents was also investigated.     

Cellulose Nano Whiskers (CNWs) Loaded-Poly(sodium acrylate) Hydrogels. Part-I. Effect of Low Concentration of CNWs on Water Uptake

In this work, de-watered cellulose pulp(DCP), obtained from a paper mill, have been acid-hydrolyzed to yield cellulose nano-whiskers (CNWs). As revealed from FESEM measurements, these CNW were found to possess a median length of 258.5 nm, diameter of 35.2 nm, and an aspect ratio of 7.3. The CNWs were also characterized by TGA, XRD and FTIR analysis. The CNWs were found to possess a fairly high Crystallinity Index (CI) of 0.925. The addition of cellulose at low concentration range, i.e., from 25 to 125 mg (nearly 1.25 to 6.25 weight percent of polymer sodium acrylate) caused an enhancement in water uptake of resulting hydrogels .The CNWs-loaded poly(SA) hydrogels showed chain relaxation controlled swelling in the medium of pH 7.4 as was confirmed from the swelling exponent ‘n’ values obtained using power function law‥ The second order kinetic model was found to fit well to the kinetic water uptake data. However, all the samples, when prepared in the form of films, did not show any remarkable increase in their mechanical strength.     

The impact of resorcinol bis(diphenyl phosphate) and poly(phenylene ether) on flame retardancy of PC/PBT blends

Flame retardancy of bisphenol A polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends was improved by the addition of resorcinol bis(diphenyl phosphate) (RDP) and poly(phenylene ether) (PPO). A PC/PBT blend at 70/30 weight ratio obtained a V‐0 rating by the addition of 10 wt% RDP and 10 wt% PPO. The combination of 5 wt% methyl methacrylate‐butadiene‐styrene tercopolymer (MBS) with 3 wt% ethylene‐butylacrylate‐glycidyl methacrylate tercopolymer (PTW) causes a remarkable increase in toughness of the PC/PBT/RDP blend while maintaining a high rigidity. A detailed investigation of the flame‐retardant action of PC/PBT/RDP and PC/PBT/RDP/PPO blends was performed using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), TGA‐FTIR, temperature‐programmed pyrolysis/gas chromatography/mass spectrometry (TPPy/GC/MS), and scanning electron microscopy/energy dispersive spectrometer (SEM/EDS). The results demonstrate that RDP induces a higher char yield at ca. 450 °C and synchronously increases the thermal stability of the blend with PPO. The flame‐retardant role of RDP in the condensed phase was discerned from TGA, FTIR, and SEM/EDS of the residues. Copyright © 2010 John Wiley & Sons, Ltd.