Effect Of Sodium Hydroxide Treatment Research Articles

Effect of sodium hydroxide treatment on the fracture toughness of luffa natural fiber reinforced epoxy epikote 828

AbstractMicro‐sized luffa natural fibers (MLNFs) were derived from raw luffa natural fibers from Vietnam by undergoing treatment with sodium hydroxide. This study examined the impact of sodium hydroxide concentration, temperature, and treatment duration on the fracture toughness of epoxy resin 828 reinforced with MLNFs. The results showed that the fracture toughness of the composite, as measured by the critical‐stress‐intensity factor (KIC) and Izod impact strength, was improved after the treatment of the MLNFs with sodium hydroxide. Specifically, with the optimal sodium hydroxide treatment parameters of 6% NaOH at 70 °C for 6 h, the critical‐stress‐intensity factor increased by 93% (from 2.0 to 3.86 MPa m1/2) and the Izod impact strength rose by 44.6% (from 3.81 to 5.51 kJ/m2). The thermal properties and surface structure of MLNFs treated with NaOH were analyzed using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) images.

Effect of Sodium Hydroxide Treatment on Chemical Composition and Feed Value of Common Reed (Phragmites australis) Straw

This research was undertaken with the aim of determining the effect of sodium hydroxide (NaOH) treatment on the chemical composition, in vitro gas production, neutral detergent fiber digestibility (NDFD) and true dry matter digestibility (TDMD), dry matter intake (DMI), and relative feed value (RFV) of common reed (Phragmites australis) straw. Reed straw was treated with 0% (control), 1%, 2%, and 3% NaOH and stored in 1.5-L glass jars in triplicate for 21 days. NaOH treatment had a significant effect on the chemical composition, in vitro gas production, NDFD and TDMD, DMI, and RFV of the reed straw. While it decreased the cell wall content of the reed straw, it significantly increased the NDFD, TDMD, DMI, and RFV. The neutral detergent fiber content of the reed straw decreased with NaOH treatment in a dose-dependent manner and ranged from 56.03% to 65.05%, whereas the NDFD increased and ranged from 53.10% to 59.99%. Metabolizable energy, organic matter digestibility, and TDMD values were improved, ranging from 9.15 to 10.19 MJ/kg DM, 58.46% to 65.05%, and 55.29% to 62.33%, respectively. The estimated RFV and DMI also improved, ranging from 84.70% to 95.58% and from 1.87% to 2.14% of body weight, respectively. The most effective treatment dose of NaOH was 3%. Therefore, it can be suggested that NaOH treatment has the potential to improve the nutritive value of reed straw. However, before large applications, further in vivo investigations are required to determine the effects of NaOH treatment on the feed intake and production of ruminant animals.

Effects of Chemical Treatment on the Physical Properties of Typha

Plant-based concretes are produced from plant aggregates and a binder. Plant fibers are mainly composed of saccharides (sugars) and these sugars can decrease the concentration of Ca2+ ions in the cement pore solution and delay the formation of hydration products. To improve the interfacial bond between fibers and matrix a chemical treatment is widely used. This study investigates the effect of sodium hydroxide treatment on physical and hygroscopic properties of Typha aggregates. In particular, a 5% sodium hydroxide solution is used to treat these aggregates and their bulk and absolute densities, porosity, water content and water absorption are evaluated accordingly. Results indicate that bulk and absolute densities increase after treatment from 56.44 kg/m3 to 122.57 kg/m3 and 541.93 kg/m3 to 555.17 kg/m3, respectively. NaOH treatment reduces porosity of Typha from 89.58 % to 77.92% and decreases water content from 1.4 % to 1%. The treatment with sodium hydroxide reduces substantially the water absorption of the aggregates.

Effect of sodium hydroxide treatment on dry sliding wear behavior of Phoenix sp. fiber reinforced polymer composites

In this work, the effect of various concentrations of sodium hydroxide treatment (5, 10, 15 and 20%) on tribological properties of Phoenix sp. fiber reinforced epoxy composites was investigated for the first time and reported. The composites were fabricated by using compression molding technique with optimized fiber length (20 mm) and fiber volume fraction (40%). The shore D hardness of the untreated and treated fiber reinforced composites was determined. The dry sliding wear test was conducted using pin-on-disk wear testing machine at different loads (10, 20 and 30 N), sliding speeds (1, 2 and 3 m/s) and sliding distances (1, 2 and 3 km). The arithmetic mean surface roughness of the samples was measured before and after the wear test. The outcomes revealed that the concentration of sodium hydroxide treatment significantly influenced the hardness and tribological properties and surface roughness value of the fabricated composites. In particular, the composites reinforced with 15% treated fiber composites showed higher wear resistance at all operating conditions and was suggested for fabricating the friction composites for automobile and machine tool applications. The morphology of the worn surfaces of the samples was examined using a scanning electron microscope to study the wear mechanisms.

Effect of Sodium Hydroxide Treatment on Physico-chemical, Thermal, Tensile and Surface Morphological Properties of Pongamia Pinnata L. Bark Fiber

ABSTRACT Surfaces of Pongamia pinnata L. fiber (PPF) were modified by the 5% (w/v) sodium hydroxide solution with the various immersing period as 15, 30, 45, 60 and 75 minutes. Chemical compositional analysis evidenced that 5% (w/v) sodium hydroxide solution with 60 minute immersing period is optimum treatment. Removal of lignin content from the optimally treated PPF was detected through the chemical analysis as well as Fourier Transform-Infrared spectroscopy. X-ray diffraction analysis outcomes established the enhancement in the crystallinity index (45.31% to 52.43%) and crystallite size (5.43 nm to 8.32 nm) of the optimally surface-modified PPF. Improvement in the maximum cellulose degradation temperature (332°C to 348°C) and kinetic activation energy of the optimally-surface modified fibers (68.642 KJ/mol to 72.563 KJ/mol) were acknowledged from differential thermogravimetric curve and broido plots. Scanning electron microscope and atomic force microscopy investigations visualized the improvement in surface roughness of the PPF after alkalization. All the above findings authorized the suitability of optimally surface modified PPF as reinforcement in lightweight polymer composite applications.

Physico-Mechanical Properties of Pineapple Leaf and Banana Fiber Reinforced Hybrid Polypropylene Composites: Effect of Fiber Ratio and Sodium Hydroxide Treatment

Natural fibers are becoming abundant and viable substitute for the synthetic fibers day by day, as synthetic fibers are expensive and nonrenewable. The main aim of present research is to evaluate the effect of sodium hydroxide treatment and banana and pineapple leaf fiber ratio on mechanical and physical properties of pineapple leaf-banana fiber reinforced hybrid polypropylene composites. Hybrid composites were prepared using a hot press machine. Raw pineapple leaf and banana fiber were chemically treated with 5% sodium hydroxide to increase adhesion between the fibers and polypropylene. Both raw and alkali treated fibers at 5 wt% were utilized during composite preparation. Pineapple leaf and banana fiber ratios were varied in 1:1, 3:1 and 1:3. Morphological analysis (scanning electron microscopy) and mechanical (tensile, flexural and hardness) tests of prepared composites were subsequently conducted. Better adhesion between the fibers and polypropylene was observed in case of treated fiber composites as compared to raw fiber composites. Scanning electron microscopic analysis also showed better bonding between the fibers and polypropylene when pineapple leaf and banana fiber ratio was 3:1. Subsequently thebest set of mechanical properties was attained for that particular fiber ratio.

Effects of Sodium Hydroxide Treatment on LLDPE/DS Composites: Tensile Properties and Morphology

In this research, the effect of different sodium hydroxide (NaOH) concentration (3, 6 and 9 wt.%) on the tensile properties of linear low density polyethylene / date seeds (LLDPE/DS) composites were investigated. The size of DS particles was measured at (125 - 250 μm) and the ratio of LLDPE over DS was fixed at 90/10 wt.%. The samples were prepared using extrusion process (screw speed at 60 rpm and barrel and die temperature at 160°C and 165°C respectively) followed by injection moulding process (from feed to exit die zone temperature at 160, 165, 170 and 175°C respectively). Results suggest that the addition of NaOH particularly 3 wt% has improved the tensile strength. Additionally, the elongation at break has improved as well. However, the high concentration of NaOH, particularly 9 wt.% effects negatively on these properties. In contrast, the Modulus shows different trend, which increased as NaOH concentration increased in the composites. The SEM section shows the improvement on DS surface as low NaOH concentration used (3 wt.%) and deterioration on the DS surface as high NaOH concentration used (9 wt.%).

Effects of Sodium Hydroxide Treatment and Ultrafiltration on the Removal of Humic Contaminants from Archaeological Bone

AbstractThis study compared bone collagen extraction techniques that included treatment with sodium hydroxide and 30 kDa ultrafilters using a set of well‐preserved, humic‐contaminated archaeological marine mammal bones. Treatment with sodium hydroxide was effective at removing humic contaminants from archaeological bone, although yields were significantly decreased. Yields were also significantly decreased by ultrafiltration although this study produced no evidence that 30 kDa ultrafilters were effective at selectively removing humic contaminants from archaeological bone. The combination of sodium hydroxide treatment and ultrafiltration did not produce superior results to the treatment involving only sodium hydroxide. Archaeological samples exhibiting darker colouration indicative of humic contamination should be treated with sodium hydroxide to remove these contaminants. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of sodium hydroxide treatment on microstructure and mechanical properties of lotus fibers

Lotus fibers were prepared from lotus stems through being treated with sodium hydroxide. The lotus fibers were characterized by scanning electron microscopy (SEM), fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and thermal analysis (TG and DTA). The results indicate that the length of lotus fibers ranges from 3.52 cm to 5.80 cm and the width of lotus fibers ranges from 50 μm to 90 μm. Lotus fibers belong to celluloses fiber with cellulose I structure and the crystallinity of lotus fibers is 48.50 %. The lotus fibers consist of cellulose, lignin, hemicellulose, pectin, lipid and water-soluble substances. The effect of concentration of sodium hydroxide, time and temperature of treatment on removal of impurities, fineness and breaking strength of lotus fibers were investigated. The results suggest that the removal of impurities and breaking strength increase with the rise of concentration of the sodium hydroxide, time and temperature of treatment, respectively. However, the fineness of lotus fibers decreases with an increase in concentration of the sodium hydroxide, time and temperature of treatment. The results are expected to provide valuable guidance for preparation of lotus fibers through simple treatment with sodium hydroxide, which can be applied in textile industry.

Effect of Sodium Hydroxide Treatments on the Tensile Strength and the Interphase Quality of Hemp Core Fiber-Reinforced Polypropylene Composites.

The formulation of greener composite materials by substituting glass fibers with natural fibers is a current field of research. If such natural fiber reinforcements come from industrial side streams, as hemp core fibers (HCFs) come from the extraction of hemp strands for the textile industry, an additional advantage can be identified. Nonetheless, such by-product fibers show some drawbacks, such as high lignin contents, which can make it difficult to obtain a good interphase between the fibers and the matrix and to obtain a good fiber individualization. A digestion treatment at different NaOH contents is proposed to eliminate soluble lignin and extractives from the surface of the fibers. At the same time, the use of a coupling agent solves incompatibilities between the fibers and the matrix. The composites were tensile tested and the impact of the proposed treatments is evaluated and discussed. Later, the Kelly-Tyson modified equation and a modified rule of mixtures—the micro-mechanic models—is used to study the impact of such treatments on the quality of the interphase between the polymer and the reinforcement. Both treatments showed a high impact on the tensile strength and the quality of the interphase, obtaining competitive composite materials reinforced with HCFs derived from a by-product.

Acoustical, thermal, and morphological properties of zein reinforced oil palm empty fruit bunch fiber bio‐composites

ABSTRACTIn this research, biodegradable composites were prepared with zein as a polymer matrix and oil palm empty fruit bunch (OPEFB) as fiber reinforcement. The fibers were treated with sodium hydroxide (NaOH). The effects of sodium hydroxide treatment on sound absorption, thermal stability, and fiber‐polymer matrix interaction in composites were examined. The acoustical sound absorption coefficients of the composites were evaluated using two‐microphone transfer function impedance tube method. The spectral, thermal, and morphological studies of the composites were analyzed and characterized using scanning electron microscope (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. It was found that in all the biodegradable composites, the sound absorption coefficients increased as the frequency increased. Increases in fiber loading caused sound absorption coefficients of the composites to increase. The sodium hydroxide treatment showed a better interface adhesion on fiber and zein matrix. It was also found that this treatment increased the sound absorption coefficients. This was supported by qualitative analysis on the SEM micrographs and FTIR spectrum. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44164.

Effect of Sodium Hydroxide Treatment on the Mechanical Properties of Crushed and Uncrushed Luffa cylindrica Fibre Reinforced rLDPE Composites

Effect of Sodium Hydroxide Treatment on the Mechanical Properties of Crushed and Uncrushed Luffa cylindrica Fibre Reinforced rLDPE Composites

Effects of sodium hydroxide treatment on the properties of low‐density polyethylene composites filled with chicken feather fiber

The effects of alkali treatment with sodium hydroxide on the tensile properties, morphology, thermal degradation, and mass swell of low‐density polyethylene (LDPE)/(chicken feather fibers (CFF)) composites were studied. The LDPE/CFF composites were prepared by using a Z‐Blade mixer at 180oC and a rotor speed of 50 rpm. The LDPE/CFF‐Treated composites exhibited higher tensile strength, Young's modulus, and final decomposition temperature but had lower mass swell percentage and elongation at break than the LDPE/CFF composites. An SEM morphology study showed that the CFF treatment could significantly improve adhesion at the interface and lead to ingress of the fiber into the LDPE phase. Thermogravimetric analysis indicated that the LDPE/CFF‐Treated composites had higher thermal stability than the LDPE/CFF composites. J. VINYL ADDIT. TECHNOL., 20:36–41, 2014. © 2014 Society of Plastics Engineers

The effect of sodium hydroxide treatment and fiber length on the tensile property of coir fiber-reinforced epoxy composites

The aim of this study is to investigate the effect of surface modification through sodium hydroxide (NaOH) treatment and fiber length on the tensile strength of coir fiber of reinforced epoxy composites. The coir fibers were treated with 2%, 4%, 6%, 8%, and 10% concentration of NaOH separately for 10 days. The tensile strength of untreated and alkali-treated fiber was measured. For each group of the coir fiber, experiments were conducted on different fiber lengths, namely, 10, 20, and 30 mm. The experimental results showed that increasing the NaOH concentration leads to a decrease in fiber diameter in a linear fashion. This reduction in diameter naturally ends up with reduced tensile strength. The treated coir fiber was used as a reinforcement and epoxy as a matrix to fabricate the composites. The tensile strength of different samples of composites was measured. Increased NaOH concentration (up to 4%) in fiber treatment was found to increase the tensile strength, and further increase in NaOH concentration reduces the tensile strength; also, increased fiber length was found to increase in tensile strength. The maximum tensile strength of the composite was observed at 4% NaOH-treated samples. On the basis of the nonlinear regression analysis, the tensile strength equation was proposed for coir fiber-reinforced epoxy composites.

Effect of sodium hydroxide treatment of bacterial cellulose on cellulase activity

The synergistic action between Thermobifida fusca exocellulase Cel6B and endocellulase Cel5A on sodium hydroxide pretreated bacterial cellulose (BC) was determined. The activities of Cel6B and Cel5A were tested singly and both activities were dramatically increased on pretreated BC, especially in the early stage of hydrolysis. Cel5A, which attacks the cellulose chain randomly, showed a larger increase on NaOH treated BC than Cel6B. Mixtures of the two enzymes were also able to degrade NaOH treated BC faster than BC and the kinetics of the mixture differed from that of the individual enzymes. The degree of synergistic effect (DSE) on BC decreased dramatically with time of hydrolysis. However, the DSE on NaOH treated BC was almost constant throughout the incubation, with a smaller effect at higher NaOH concentrations. The change caused by NaOH did not increase the DSE, although each individual cellulase activity increased. This showed that synergistic activity was more effective on recalcitrant cellulose, which requires effective cooperation between the cellulase components for hydrolysis.

The Effect of Sodium Hydroxide Treatment of Rice Straw on In situ Disappearance of Hemicellulose and Lignin in its Cell Wall

In situ disappearance of cell wall constituents of the untreated and NaOH-treated rice straw was examined in detail. In situ cellulose digestion of rice straw was significantly improved by treatment with 4% NaOH. Hemicellulose in the cell walls of rice straw abundantly contained galactose and xylose, followed by arabinose, glucose, and uronic acids. In situ digestion of xylose residues in hemicellulose of the straw was inferior to that of other monosaccharides, but that of the straw was remarkably improved by the NaOH-treatment. The same amount of guaiacyl- and syringyl- lignins was released from the untreated rice straw during in situ digestion. On the other hand, more abundant syringyl-lignin than guaiacyl-lignin was released from NaOH-treated rice straw during the in situ digestion. In situ disappearance of ester-linked p-coumaric and ferulic acids from the untreated rice straw was larger than that of the ether-linked acids. While, in situ disappearance of ether-linked p-coumaric and ferulic acids from the NaOH-treated rice straw was larger than that of the ester-linked acids. The results obtained in this study suggest that the partial destruction of a network structure built up from hemicellulosic polysaccharides and lignin in rice straw cell walls by NaOH-treatment makes it easy for the access of cellulolytic microorganisms and their cellulases to cellulose and accelerates the in situ cellulose digestion of rice straw.

Effect of Sodium Hydroxide Treatment of Rice Straw on the Composition of Lignin of Cell Wall

In order to characterize the features of cell wall lignins of untreated and 4% NaOH-treated rice straw, analyses of phenolics of cell wall were done. And, infrared (IR) spectra of Bjorkman lignins prepared from rice straw were examined. The amounts of nitrobenzene oxidation products of the untreated rice straw was higher than those of the NaOH-treated rice straw and the most abundant phenolic aldehydes and acids released from rice straw by the 4% NaOH treatment which come in the following order were vanillin, p-coumaric acid, ferulic acid and p-hydroxybenzaldehyde. In the untreated rice straw, the total amount of esterified and etherified p-coumaric acids was much more abundant than that of the ester-and ether-forms of ferulic or syringic acids. About 50% of the esterified p-coumaric acid was released from rice straw by the 4% NaOH treatment. Some of the esterified ferulic acid also was released from rice straw by the 4% NaOH treatment. IR spectroscopy showed that both bands at 1, 730cm-1 attributable to cinnamic acid esters and at 1, 270cm-1 due to the methoxyl groups of guaiacyl units clearly decreased in the spectrum of the lignin prepared from NaOH-treated rice straw. These results conclusively indicate that p-coumaric and ferulic acids are covalently linked to carbohydrates and to lignin through ester linkages, and they are mainly released from rice straw by 4% NaOH treatment. Also a considerable amount of hemicelluloses and lignin are solubilized from rice straw by the treatment.

Effect of Sodium Hydroxide Treatment of Rice Straw on Cell Wall Composition and Digestibility of Dry Matter

Effect of Sodium Hydroxide Treatment of Rice Straw on Cell Wall Composition and Digestibility of Dry Matter

Effects of sodium hydroxide treatment on coordination changes of cobalt ions in CoNaY by means of UV/VIS diffuse reflectance spectroscopy

The coordination changes of Co2+ in CoNaY/NaOHs, prepared by cobalt ion-exchange and treatment with NaOH, during dehydration at various temperatures have been investigated by UV/VIS diffuse reflectance spectroscopy. After dehydration of CoNaY/NaOHs at 473 K, the DRS bands show the formation of mixed cobalt oxide species interacted with lattice oxygen. This mixed cobalt oxide species interacted with lattice oxygen decompose during further dehydration at 673 K. The strong intensities of the bands at 660, 575 and 530 nm after dehydration of CoNaY/NaOHs at 873 K indicate that a considerable amount of the cobalt ions remains in the sodalite cage with tetrahedral coordination even after dehydration at 873 K.

Enhancement in reducibility of cobalt ions in CoNaY by treatment with alkali-metal hydroxides

Cobalt-containing Y-zeolites, prepared by ion exchange and treatment with aqueous alkali-metal hydroxide solution, have been investigated. The reducibility of cobalt ions in each site of zeolite Y was investigated by TPR. X-Ray diffraction, FTIR spectroscopy, UV–VIS DRS and Xe adsorption were used to investigate the effect of sodium hydroxide treatment. The cobalt ions in the sites, SI and SI migrated to the sodalite cage and supercage after treatment with aqueous sodium hydroxide. The extent of migration was related to the concentration of sodium hydroxide and the cobalt loading. The amounts of cobalt ions located at various sites were estimated from the area of each TPR peak. The other alkali-metal hydroxides, KOH and LiOH, showed a similar effect. Cobalt species in the supercage and on the exterior surface of the zeolite after treatment with sodium hydroxide solution were shown to be CoO(OH) by the IR band at 3631 cm–1 which was oxidized to Co3O4 during calcination at 623 K. The formation of cobalt metal clusters is facilitated by treatment with sodium hydroxide solution and by subsequent reduction with hydrogen.