Papers by Keyword: Alkali Treatment

Abstract: This study characterized Lygodium circinnatum (Nito), a natural fiber native to the Philippines, using a factorial design of experiments to determine the optimal alkali treatment for enhancing its chemical and mechanical properties. Sodium hydroxide (NaOH) was applied at varying concentrations (2%, 8.5%, and 15%) and soaking times, with conditions evaluated using Minitab 18 software. X-ray diffraction (XRD) was used to assess crystallinity index (CI), identifying 2% NaOH and 0.50-hour soaking as the most effective combination, yielding the highest CI. Fourier transform infrared (FTIR) spectroscopy confirmed a reduction in non-cellulosic compounds after treatment. Morphological changes were observed using scanning electron microscopy (SEM), which revealed smoother surfaces and reduced impurities. Mechanical tests showed increased tensile strength and tensile force, although a slight decrease in cross-sectional area was noted, attributed to the loss of surface material. These results demonstrate that mild alkali treatment significantly improves Nito fiber's structural integrity and performance. The study provides a scientific basis for optimizing natural fiber treatment and highlights the potential of Nito fiber in developing sustainable, high-performance materials for use in various engineering and industrial applications, including composites and biodegradable products.

Abstract: Ramie fibre has been widely utilized, particularly in the textile industry. The application of Ramie fabric-based composites has been increasingly favored for the fabrication of lightweight structures and high-performance products. Polypropylene (PP) is commonly used to reinforce natural fibres due to its superior physical, mechanical, and thermal properties. Proper treatment of ramie fabric is crucial to ensure strong bonding between the ramie and polypropylene (PP). Alkali treatment is commonly employed to address bonding issues. In this study, ramie fabric was treated using different concentrations (5 wt%, 16.7 wt%, 28.6 wt%, and 37.5 wt%) and durations (30 minutes, 1 hour, 20 hours, and 24 hours). Subsequently, a compression molding process was employed to manufacture both the lamina and laminate. The lamina was exposed to a temperature of 170°C and a pressure of 100 kg/cm³ for three minutes, while the laminate was subjected to a temperature of 170°C and a pressure of 210 kg/cm³ for seven minutes. The results revealed an increase in tensile strength compared to pure PP tests. The single and five-layered composites showing an increase of 1.65% and 2.79%, respectively. The optimal tensile strength reached by five-layered composite was 25.82 MPa. Despite the increased strength, fibre failure occurred due to swelling. The occurrence of fibre failure and increased strength when transformed into a composite highlights the potential for further improvement of ramie fabric and polypropylene.

Abstract: This study explores the utilization of areca husk fiber (AHF), a naturally derived agricultural waste product, in enhancing the mechanical properties of natural rubber latex (NRL) composites. Areca husk fibers, treated with sodium hydroxide (NaOH) to improve their surface characteristics, were incorporated into NRL matrices. The objective was to investigate the effect of alkali treatment on the interfacial bonding and overall performance of the resulting composites. Mechanical testing revealed significant improvements in tensile strength, flexibility, and water resistance in the treated AHF composites compared to untreated ones. The findings suggest that alkali-treated AHF can significantly enhance the structural integrity and durability of NRL composites, offering a promising approach for developing sustainable, biodegradable materials from agricultural residues.

Abstract: Fibre reinforced polymer composites are employed instead of metal and wood because they are stronger, more lightweight, have a favourable strength to weight ratio, and are noncorrosive. In the current research, sisal, carbon fibre, and industrial waste tea leaf fibre (WTLF) reinforced hybrid epoxy composites are being examined for their chemical, mechanical and acoustical properties with experimental study. The sisal and WTLF were chemically treated with 5% sodium hydroxide (NaOH) solution. By modifying the weight percentage of sisal and WTLF with a structure of 40 weight percent fibre and 60 weight percent matrix, five different compositions of natural fibre reinforced hybrid composites were fabricated using an automatic compression moulding technique. As per the ASTM standard the manufactured hybrid composites are tested for mechanical, chemical and acoustic characteristics. According to the experimental findings, sisal fibre with a 25 wt% and WTLF with a 5 wt% demonstrated superior mechanical properties, while these materials also demonstrated an excellent acoustic absorption coefficient (AAC) of 0.62 between the frequency range of 2000 to 6300 Hz. The morphology of failure samples revealed the matrix micro crack, void formation, fiber pullout and layers of fractured fibers which are being examined using Scanning Electron Microscopy (SEM). The superior bonding between fibre and matrix was seen in the FTIR study of 5% alkali treated composites.

Abstract: The mechanical properties of natural fiber composites reinforced with rice husk and multi-walled carbon nanotubes are studied. Two different mixing concentrations are prepared: 5 wt.% and 10 wt. % rice husk and 0.5 wt.% and 1.0 wt.% multi-walled carbon nanotubes incorporating with the constant reinforcing phases of the banana fiber is 10 wt.%. (Specimens: NBRME1 and NBRME2, where, N-NaOH; B-Banana fiber; R-Rice husk; M-MWCNT; E-Epoxy). The effect of surface treatment of banana fiber bundles is reacted with a 6% sodium hydroxide solution. The surface-treated reinforcement results indicated higher tensile, bending, and impact strength of the 0.5% MWCNT composite (43.96 MPa, 60.62 MPa, and 46.5 J/m) compared with 1% MWCNT composite. High-resolution optical macroscopic images are revealed a variety of defects, including interface behaviour, fiber stretching, fracture, cracking, and agglomeration. Biodegradable organic rice husk-based epoxy resin composite is valuable for manufacturing electronic parts, chips and circuits.

Abstract: This study aims to investigate the capability of sound absorption coefficient (SAC) of oil palm frond (OPF) composite. Also, to characterize the fiber surface without treatment and with alkali treatment. Two parameters were formulated to characterize the SAC ability of the OPF composite: chemical treatment and density of composite. The composite was manufactured from a waste OPF as a reinforcement and urea-formaldehyde (UF) resin as a matrix. The fibers were blended with UF 10% (weight fraction) and formed by hot-pressing under the pressure of 9 tons at 140°C for 5mn. The SAC was measured by the impedance tube respected with ASTM 1050 (the transfer function method) within the frequency of 125-6400 Hz. Morphological analysis is investigated by scanning electron microscopy (SEM) on untreated and alkali-treated OPF fiber. The measurement data were obtained and compared with different densities and treatments. It reveals that the SAC of OPF composite was proportion to density and alkali-treated. The SAC worsens as the composite becomes dense due to the greater density. The treated fibers have more roughness and friction area than untreated fiber; thereby, the incidence of sound energy rapidly dissipates to thermal energy, causing improved SAC performance

Abstract: This study uses an experimental approach to illustrate the significance of particle size and alkali-treated on the sound absorption coefficient of oil palm frond (OPF) particleboard. Two variables were investigated: Particle size and one hour of NaOH treatment of oil palm frond. The particleboard was manufactured based on OPF material with 10% urea-formaldehyde as the binder and 1% NHCl₄ as the hardener. The mixing of OPF with UF was pressed under hot-pressing of 9 tons at 140°C for 5 minutes to obtain OPF particleboard. 100 mm and 29 mm diameter of OPF particleboard were fabricated with three different particle sizes in the constant density of 0.4 g/cm³ and thickness of 10mm. Three particle sizes were fine, medium, and coarse particle sizes with a diameter of 0.2-0.6, 1-2, 2.4-4.8 mm, respectively. The SAC was determined using a two-microphone impedance tube following ASTM E 1050 at frequencies 50 to 6400 Hz. The single rate number, noise reduction coefficient (NRC), the mean of arithmetical values for the SAC at four-octave bands frequency (250, 500, 1000, and 2000), was determined. The data from experimental and calculation were obtained and investigated.

Abstract: Ongoing studies show that an effective demand for using natural fibers as a substitution of an artificial fiber in fiber-reinforced composites formation has increased their applicability in an industrial area worldwide. The hydrophobic nature of natural fiber makes week adhesion among the cellulose fiber and matrix components; these problems are usually encountered in fiber-reinforced composites production. To overcome such a limitation of a cellulose fiber, specific physical and chemical treatment strategies were advised by researchers around the world for surface modification of natural cellulose fibers. One of the most basic and efficient surface modification approaches adopted today by the researchers was alkali treatment, widely used in natural fiber composites formation. This technique effectively improved the Mechanical property of natural cellulose fiber, such as tensile strength and flexural properties, while the impact strength result was reduced.

Abstract: In the past few decades, concrete has been the most widely used material for structural applications in the world and uses steel reinforcement as aide to meet the flexural, tensile and ductility demands required of concrete structures. Manufacturing of concrete and steel reinforced concrete structures is associated with millions of tons of carbon dioxide emissions and mineral waste. This activity is also responsible for the depletion of a large number of non-renewable resources. Reinforcing steel is also a high cost material, consumes a lot of energy in its production. Consequently, the use of natural fibres as an alternative for steel reinforcement is widely investigated, to promote the use of sustainable concrete structures. This study aims to investigate the effect on durability, flexural, compressive, tensile properties and workability of concrete by incorporating coir fibre at varying fibre content to find the fibre content which gives optimum results. The fibre contents used were 0%, 0.5%, 1.0%, 1.5% and 2.0% by weight of cement. Furthermore, the effect of modifying the surface of the coir fibres by alkali treatment (i.e. 5 wt.% NaOH solution) and coating the fibres with epoxy paint and polyurethane varnish on coir fibre reinforced concrete (CFRC) were also investigated. Tests conducted on the CFRC specimens included slump test and flexural, compressive and tensile strength tests. Water absorption and sorptivity tests were also conducted to investigate the durability. Slump (workability) and unit weight reduced with an increase in fibre content. The surface modification methods used, had resulted in an increased workability and a reduced unit-weight. A coconut fibre content of 1% produced the best combination of flexural, tensile and compressive properties. Water absorption and sorption rate per unit time, increased with an increase of coir fibre content. It is also found that epoxy paint and alkali treatment of the fibres has a positive effect on the mechanical strength properties and also the durability and workability of the CFRC specimens. However, polyurethane varnish coating had a detrimental effect on the mechanical strength properties of the CFRC specimens.

Abstract: In tropical regions such as the Philippines, pineapple leaf fiber (PALF) is abundantly available as a low-cost and renewable source for industrial purposes. In this research, PALF was used as a reinforcing material for cement-based composites to open up further possibilities in waste management. Since natural fibers are not fully compatible with the matrix due to their hydrophilic nature, surface treatment is necessary to enhance the fiber-matrix bonding. Fibers were treated using sodium hydroxide (NaOH) with varying concentrations (4%, 8% and 12%) for 6-hr immersion time at room temperature. PALF was then added at varying content (1%, 4% and 7% w/w cement) to the concrete mixture with a design mix ratio of 2:1 (sand: cement) and a constant water-cement ratio of 0.55. The samples were mechanically characterized after 28 curing days following ASTM C209 and ASTM C473. Full factorial experimental design (FFED) was used to investigate the effects of alkali treatment and the fiber content on the mechanical strengths of the composite. Experimental methods, analysis of variance (ANOVA) and normality test were carried out to evaluate, analyze and validate the results. The best results for tensile strength parallel to the surface and flexural strength at 2.028 MPa and 1.495 kN, respectively, were observed at composites with 1% PALF with 4% NaOH. Meanwhile, composites with 1% PALF with 12% NaOH showed the best result for tensile strength perpendicular to the surface at 1.681 MPa. According to ANOVA results, only the model for the tensile strength perpendicular to the surface showed a curvilinear behavior (p-value=0.012). Results revealed that the factor with the most significant effect was the interaction of the fiber content and alkali treatment on the tensile strength parallel to the surface (p-value=0.000), tensile strength perpendicular to the surface (p-value=0.001) and flexural strength (p-value=0.001).