Materials Science Forum Vol. 1160

Abstract: Polymer Electrolyte Membranes (PEM) is an important component in a Direct Methanol Fuel Cell (DMFC) system that has a primary function as a proton conductor and separator between a cathode and anode. Due to the awareness of the comprehensive methanol crossover issue in the commercially available Nafion membrane, however, the main parameter of PEM for DMFC is low methanol permeability. The chitosan-based inorganic hybrid membrane is a promising organic–inorganic hybrid for the development of high-performance PEM. The study of composite membranes as PEM was initiated with the synthesis of silica from POFA (palm oil fuel ash). Using the phase inversion technique, the chitosan was mixed with silica filler in an acetic solution to produce Ch/Silica composite membrane. Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDX) analysis shows that pure silica has been successfully synthesized from POFA and can interact with chitosan in the layer of the membrane structure which is supported by the Fourier Transform Infrared Spectroscopy (FTIR) spectra results. Water uptake shows a value of 75%, while methanol uptake with a low value of 52%. The addition of silica gives the membrane the ability to reduce methanol crossover as indicated by the low value of methanol permeability of 0.00027 mg cm²s^-1. However, this membrane has good proton exchange performance as indicated by the Ion Exchange Capacity value of 1.56 mmol g^-1. These results indicate that the composite membrane of chitosan with silica from POFA has the potential as PEM in direct methanol fuel cell applications.

Abstract: The use of biodegradable materials from renewable natural resources helps to reduce the percentage of plastic waste. In this study, we used banana peel starch (Musa Paradisiaca L.) and shrimp shell chitosan as the basic material for bioplastic by adding glycerol. In this process, additives in the form of carboxymethyl cellulose (CMC) are also used. to increase the biodegradability level of the bioplastic. The composition of chitosan and glycerol used were 1 gr and 1%, respectively. Starch variations were 1, 2, and 3 grams, while CMC were 0.5, 1, and 1.5 grams. The results of this study, namely the Optical Microscope test showed that the bioplastic structure still contained pinholes (air bubbles), indentations, and non-homogeneous starch. In the tensile test conducted on samples G and C, the average tensile strength was 0.01063 MPa, the average elongation was 2.65% and the average Young's modulus was 2.159 MPa. The results of the Biodegradation Test showed that variations in the addition of CMC composition to bioplastics significantly affect the percent degradation value, where the greater the CMC composition, the higher the percent degradation value.

Abstract: Silver nanoparticles (AgNPs) are very useful in biomedical applications, especially for the development of anti-infection implants. For biomedical applications, AgNPs that were fabricated by green synthesis approach are more favorable than conventional approach using toxic reducing agent such as NaBH₄ or N₂H₄. In this study, AgNPs were prepared through green synthesis approach using extract of Seminyak leaves and pH were varied (5; 8 and 11) to know the influence of pH on formation of AgNPs. Visual observations reveal that increasing pH led to faster color change of samples (yellow to black) suggesting that pH is directly proportional to reaction kinetics. UV-Vis spectroscopy results unveil that strong peak at 422 nm was observed in sample with pH 11, while low and broad peak were observed in sample with pH 5 and 8, implying the presence of nano-sized particles in sample with pH 11 and larger particles in sample with pH 5 and 8. Transmission electron microscopy (TEM) characterization results shows that dispersion of nano-sized particles with particle size 15.4 ± 4.1 nm were observed in sample with pH 11, while aggregation of nano-sized particles with particle size 29.2 ± 7.2 nm and 20.8 ± 7.0 nm were observed in sample with pH 5 and 8 respectively. X-ray diffraction (XRD) results show that the intensity of Ag’s peak in sample with pH 11 is at least two times higher than other samples, indicating formation of AgNPs in sample with pH 11 is more favorable than other samples. The results suggest that formation of dispersed and uniform AgNPs in the presence of extract of seminyak leaf as capping and reducing agent were favorable at high pH conditions.

Abstract: Ramie fibers as a natural fiber are frequently utilized in fiber-reinforced polypropylene composite preparation due to their remarkable mechanical properties, renewable, and sustainable materials. This research investigated the effect of ramie fiber addition at various compositions on the tensile and impact properties of ramie fiber-reinforced waste polypropylene composites (RFRWPC). Furthermore, a comparative analysis was conducted to assess the potential of ramie fiber as a green reinforcement. In this research, ramie fiber was treated in a 10% NaOH solution at 100 °C for two hours. The treated ramie fiber with a volume fraction of 5, 10, and 15% was blended with waste polypropylene using an extruder at 180 °C to produce an RFRWPC pellet. The pellet obtained was used to prepare tensile and impact tests through an injection molding machine at 195 °C. The tensile and impact properties of RFRWPC were measured according to ASTM D638 and ASTM D256, respectively. The results showed that the polypropylene composite reinforced with 10% ramie fiber has a tensile strength 4.61% higher than glass fiber reinforced waste polypropylene composite (GFRWPC). RFRWPC with equivalent reinforcement percentages to commercial GFRWPC have nearly identical impact strength. The research findings demonstrated the excellent potential of ramie fiber as a green reinforcement as a substitute for glass fiber in enhancing the mechanical properties of polypropylene composites.

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 investigates the utilization of corn cob ash as a partial replacement for cement in the production of sandcrete bricks. This was necessitated due to the high cost of cement and the eco-friendly alternative to cement potentials the corn cob ash may possess. The corn cob was obtained from locals in Uselu, Benin City and was washed, dried for 24 hours then burnt in the furnace at 700 °C for 12 hours to obtain the ash at Engineering Faculty Workshop, University of Benin, Benin City. The corn cob ash substitution with cement, were done in weighted percentages, between 10 % and 20 %, cured for 3 days, 16 days and 28 days in a laboratory controlled environment using varying water/cement ratios and fine aggregates. Response surface methodology in Design- Expert 7.0 software was used to produce the experimental designs. The results obtained, reveal that corn cob ash can replace cement, up to 10 % weighted percentages in sandcrete brick, without reducing its compressive strength below 2.5 N/mm² and it also had 11.98 % of water absorption, which satisfied the standards for non-load bearing sandcrete bricks. The quadratic model formulated for the blended sandcrete brick was significant possessing a p-value of 0.02 and 0.047 with an adjusted R² value of 0.65 and 0.56 for the compressive strengths and water absorption properties respectively.

Abstract: This study explored using Burnt Brick Waste (BBW) to partially replace sand in mortar production, aiming to enhance strength, durability, and performance in flood-prone areas. BBW, a byproduct of brick production, was tested at replacement levels from 0% to 50% in 10% increments. A 1:6 mix ratio was used to produce 450 × 225 × 150mm hollow blocks with a web thickness of 37.5 mm, meeting the Nigeria Industrial Standard for 6-inch load-bearing blocks. Tests on 72 block samples evaluated compressive strength at various ages, 54 blocks for water absorption, and 18 cylindrical specimens for sorptivity. SEM-EDX analysis was employed to understand performance mechanisms. Results showed that higher BBW replacement increased compressive strength but also increased water absorption and sorptivity rates compared to control samples, though these rates decreased with age. SEM-EDX analysis indicated increased pore sizes with lower BBW replacement, enhancing strength but reducing durability due to the clay's high-water affinity in burnt bricks. Flood simulation tests revealed that mortar units with 10% and 20% BBW had reduced compressive strength compared to controls after a 10-day simulation. The study recommends limiting BBW replacement to 10% for optimal strength and durability in flood-prone areas. It also suggests reusing burnt bricks from house renovations in mortar, reducing construction costs, improving strength without affecting durability, and decreasing waste at brick factories. This practice also offers ecological benefits by reducing dependence on sandy soil for construction, mitigating environmental damage.

Abstract: Increase in the rate of generation of household waste (i.e Municipal Solid waste, MSW) in Nigeria necessitated the growing demand for a safe way to dispose MSW. When MSW comes in contact with water, it generates leachates, a poisonous fluid, that are harmful to humans. The use of landfill system for disposal of MSW has been a good approach for waste disposal. This study evaluated the effect of some hydraulic conductivity (H) parameters (i.e void ratio, degree of saturation and microbial suspension) and permeating fluids on the interaction of lateritic soil subjected to varying steps of treatments with Bacillus coagulans (B. coagulans) and subject to leachate environment for landfill application. Soil was mixed with 0 to 2.4 × 10⁹ cells/ml of B. coagulans. After mixing and compaction, Calcium solution was introduced by gravity on the compacted soil samples and were permeated to percolate to a point of partial saturation. After application of Calcium solution, compacted samples were saturated in water for 24 to 48 hours up until fully saturated, thereafter subjected to H test using water as well as leachate as permeating fluids for a period of 91 days. Results show that void ratio values varied in the ranges 0.550-0.471 and 0.481- 0.485 for specimens where water and leachate were used as permeation fluids. Degree of saturation varied meaningfully with permeation fluids. H values varied in the ranges 1.51 x 10^-9 -1.71 x 10^-9 m/s and 6.84 x 10^-10 - 8.27 x 10^-10 m/s for specimens where water and leachates were used as permeation fluids. Soil-leachate interaction study and micro structural investigations revealed that the modified soil is well-matched with leachate and met the regulatory H value of 1.0 × 10^-9 m/s for used in landfill applications.

Abstract: This research investigates the impact of various environments and material conditions on the residual flexural strength of corroded reinforced concrete beams. Parameters such as corrosion rate (R), potential (E_corr), corrosion current density (I_corr), polarization resistance (R_P), curing age (t), and acid concentration (C_a) from 0.0 M to 0.3 M were used to evaluate the residual strength of the beams. The combination of Python software version 3.11 and IBM SPSS version 25 was used to develop, train, and analyze the necessary variables for the model. The regression model was developed using 64 data points and 15 predictors, resulting in 48 degrees of freedom for the residuals. The Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) values are 897.9 and 932.5, respectively, functioning as metrics for assessing this model's quality of fit in comparison to others. A decreased AIC or BIC indicates a more optimal model fit. The Log-Likelihood value of -432.97 objectively evaluates this model's fit, with higher values indicating a better match. The regression results were further analyzed using polynomial terms to demonstrate the influence of the factors on the residual strength of corroded reinforced concrete beams. The findings indicate that the model sufficiently aligns with the data, as shown by a high R-squared value of 0.946, which indicates that 94.6% of the variability in residual strength is due to the independent variables. The adjusted R- squared score of 0.920 substantiates the model's robustness after accounting for the number of predictors. The investigation revealed that these factors significantly influence the residual strength of the reinforced concrete beams as established by the formulated model.