Materials Science Forum Vol. 1122

Abstract: PMMA is used in dentistry as the main matrix for denture manufacture. Dentures are a substitute for natural human teeth which must have mechanical properties and are biocompatible to withstand mastication in the oral cavity. However, PMMA has poor mechanical properties, so it is necessary to add filler to the PMMA matrix. In this study zirconium oxide (ZrO₂) was used as a filler because it has good mechanical properties and aesthetics. The aim of this study was to study the effect of adding ZrO₂ filler on the hardness and compatibility of denture composites at concentrations ( 0%, 1%, 3%, 5%, and 7%). The bulk composite polymerization method used in the manufacture of dental composites is by mixing powdered materials in the form of PMMA, BPO as an initiator, and ZrO₂ filler which has been silanized with liquid materials in the form of MMA monomer and cross-linking agent Ethylene Glycol Dimethacrylate (EGDMA). Mixing powder liquid in this method uses hand mixing in a stainless steel container until it reaches the dough phase and is packed into a mold according to ASTM for Vickers hardness tests. Heat cured polymerization technique was used for the curing process in a water bath at 74°C for 90 minutes and continued at 100°C for 30 minutes. The results obtained in this study, the addition of ZrO₂ filler to a concentration of 5% showed an increase in the hardness value up to 37.6 VHN. Keywords: Denture Teeth, Composite Bulk Polymerization, Heat cured Polymerization, Zirconium Oxide

Abstract: Activated carbon (AC) is an adsorbent material used for the removal of pollutants from wastewater. Unfortunately, these materials used by the industry are very expensive. This is why research is being conducted to produce low-cost activated carbons from natural biomass. The objective of this work is to study the effect of activation by orthophosphoric acid on the quality of activated carbons. The different techniques used for the characterization are: the Iodine number and the Methylene Blue Index. For activated carbons prepared in a single activation step, iodine number of 609.12 and methylene blue value of 102.48 mg/g were obtained. For those prepared in two activation steps, iodine number of 951.75 mg/g and methylene blue value of 115.14 mg/g were obtained.

Abstract: Typha australis is an invasive plant from Senegal also found in wetlands. In order to limit its proliferation, typha australis is used in the energy sector but also in construction. This study contributes to the valorisation of typha australis in the field of biocomposites. For this purpose, typha fibres were used. The fibres were extracted manually using a plastic comb, then subdivided into three zones, namely the bottom, middle and top, and dried. The resulting fibres were characterised physically by measuring density, water content and absorption coefficient, and morphologically by determining the morphology but also of the section of the fibres. many respects, the physical property results concerning density show an average of the three areas of 1.53 g/cm³ with a water content between 6 and 10% and an absorption coefficient showing two main absorption phases. As for the tomography results, we directly notice the presence of fibre bundles and not of individual fibres due to the manual extraction method used. Nevertheless, the results obtained suggest a behaviour comparable to that of the most commonly used natural fibres, namely flax.

Abstract: Anaerobic digestion or anaerobic digestion is a biological process of degradation of organic matter in an anaerobic environment. It involves the degradation and stabilization of complex organic matter by a consortium of micro-organisms leading to methane-rich biogas that can be used as an alternative energy to fossil fuels. In addition, the use of biogas allows for the preservation of the environment and the sustainable development of rural areas and landlocked regions, as well as the diversification of energy resources, but also contributes to the development of agriculture through the production of organic fertilizer. In 2018, Senegal was ranked as the 15th world exporter of cashew nuts with a production of around 18,000 tons per year according to a study by PADEC (Support Program for the Development of Casamance). Four regions mainly invest in it: Kolda, Ziguinchor, Sédhiou, and Fatick. However, in the natural region of Casamance ( Kolda, Ziguinchor, and Sédhiou), each year, after the cashew nut campaign, more than 342,000 tons of cashew apples, pressed or not, are rejected without any recovery, thus degrading in the environment. In addition, rice is traditionally grown in Casamance and in some Diola circles, it had become one of the criteria of wealth, which explains why it occupied most of the cultivated areas and each year thousands of tons of rice husk are burned for elimination/reduction without any recovery. These immense annual productions of waste, without any recovery, in a context dominated by a deficit in cooking and lighting energy constitutes a form of energy resilience and motivates us to study the co-digestion of the rice husk (with a report of C/N equal to 101.317) on cashew apple pulp (having a C/N ratio of 23.201 ). The study of the co-digestion of rice husk and apple pulp at the laboratory scale with the inoculum reveals, that the co-digestion with pH correction contains 39.40% methane and 51.50% carbon dioxide after 49 days of production and 64.04% methane (CH₄) and 25.86% carbon dioxide (CO₂) on the 96th day. For co-digestion without adjustment, production stopped on the 49th day with a production of 23.68% methane and 45.65% carbon dioxide.

Abstract: Natural fibers have garnered considerable attention from researchers and academics alike due to their eco-friendly nature and sustainability. These fibers are being explored for their potential use in polymer composites. The use of natural fiber-reinforced polymer composite materials is rapidly increasing in both industrial and fundamental research applications due to their renewable, low, and biodegradable properties. In order to reduce the CO₂ emissions, the building energy consumption and preserve the natural sand. The present study involved conducting an analysis of the results obtained from the experimental investigation where five mixtures of typha fiber sand, and cement (MHC0, MHC5, MHC10, MHC15 and MHC20)) were utilized to make Typha-concrete. The experimental mixtures being examined and the results indicate that the density of the samples diminishes in proportion to the incorporation of typha fiber, while the thermal conductivity is enhanced. In addition, the characteristics of lightweight structures can be attributed to the generated specimens, which have been determined by their documented compressive strength. Based on the results of RILEM's functional classification analysis, it can be concluded that Typha-concrete meets the mechanical and thermal requirements of construction materials, making it a feasible option for both structural and insulating concrete applications.

Abstract: The production of the jute fibers and yarns in enormous amounts and their use in different fields requires an overall comprehension of the evolution of their performance during their use and before their end life. Exposing the jute yarns to the extreme environmental conditions, such as high humidity, severe weathering, severe environments, freezing environments and others can degrade the mechanical properties jute yarns. Besides, the use of these jute yarns on the appropriate applications immersed in normal water may be accelerated them to reach their end-of-life. In this work, the thermal and mechanical properties of the jute yarns immersed in normal water for different duration were evaluated. This environmental condition was selected owing to the high probability to the exposing of yarns to the immersing in normal water on outdoors which affect their performance. The thermal stability of the jute yarns was effectuated in order to explain the chemical and physical changers occurred and linked to the mechanical properties. Results show that the mechanical properties of the jute yarns degraded by along immersion in water compared to the raw one. The tensile stress and the tensile modulus are dropped by 47 % (from 52 to 28 MPa) and 46 % (from 2.28 to 1.24 GPa), respectively for the samples immersed in water along duration (9 months) compared to the raw samples. Besides, the thermal stability of the immersed samples shows that there are no significant changes except a slight high residue for the immersed ones.

Abstract: Wood waste biomass has emerged as an abundant source of alternative energy. This alternative energy source holds significant potential in the industrial sector, particularly in the field of metal casting. The development of aluminum melting equipment aims to provide invaluable support to aluminum craftsmen by harnessing wood waste as an easily accessible fuel source. The approach employed in this research involves the design of a wood waste combustion chamber capable of reaching the aluminum melting point. Two types of wood, Ulin (Eusideroxylon zwageri) and Gelam (Melaleuca cajuputi), were utilized in the study. The research achieved a temperature of 863°C in 28 minutes with Ulin wood, whereas with Gelam, a temperature of 821°C was reached in 29 minutes. This study makes a significant contribution to the efficient utilization of wood waste biomass in the aluminum casting industry, offering remarkable environmental and economic benefits.