Mechanical and water-absorption properties of composites made from sisal fiber and polyester matrix have been investigated. Test specimens were prepared with untreated fiber and treated with alkaline solution of sodium hydroxide. The amount of fiber content in the composites varied with values of 10%, 20%, and 30% by volume. The test results indicate that the alkaline treatment has improved the tensile, compressive, and impact strength of the composite with the added benefit of low water absorption. The impact strength is found to increase with an increase in the fiber content. However, the tensile and compressive strengths have decreased; water-absorption rate has increased with an increase in the fiber content.

The inferior mechanical and water absorption properties of natural fibers are massive challenges to utilizing them for industrial applications. The study aims to enhance tensile strength, impact strength, water absorption, and degradation of sisal/polyester composites using glass and carbon fillers. Four fillers proportions (2.5 wt.%, 5 wt.%, 7.5 wt.%, 10 wt.%) and two sisal fiber proportions (20 wt.% and 30 wt.%) were taken to fabricate the composites. Experimentations were performed according to the ASTM standards. The fillers improved tensile and impact strength, water absorption, and degradation of the composites. Carbon-filled composites displayed better results than the corresponding glass-filled composites. Carbon fillers showed a maximum increment of 24.2% in tensile and 78.5% in impact strength for the dry 20/80 composites, and 14.7% in tensile and 57.3% in impact strength for the dry 30/70 composites. Moreover, carbon fillers reduced water absorption by 55.4% for the 20/80 composites and by 53.6% for the 30/70 composites. The highest values of tensile and impact strengths were obtained for the 5 wt.% carbon-filled 30/70 composite; whereas, the lowest water absorption was for the 10 wt.% carbon-filled 20/80 composite. The lowest degradation of 2% in tensile and impact strengths was exhibited for the 7.5 wt.% carbon-filled 20/80 composites.

This paper has presented the enhancement of tensile and impact strength of continuously aligned sisal fiber reinforced polyester composites through chemical treatment and hybridization. Sodium hydroxide (NaOH) and baking soda (NaHCO₃) were used for sisal fiber treatment. Comparisons on the effect of sodium hydroxide and baking soda treatments on tensile and impact strength of the composites were performed. Unidirectional glass and carbon fibers were selected as hybrid fibers. Nineteen laminates were prepared as per the standards. The laminates were made of pure sisal fiber and hybridized with glass or carbon fibers at different stacking sequence, orientation, and volume fraction. The effects of glass and carbon fibers hybridization on tensile and impact strength of the composites were studied and compared. Further enhancements on the tensile and impact strength of the composites were investigated through alterations on the stacking sequence, orientation, and volume fraction of the hybrid fibers. Symmetric hybrid composites which avoided sisal/sisal plies interface have shown more than 95% and 130% rise in their tensile strength by adding about 8% volume of glass and carbon fibers respectively. Moreover, with only about 8% carbon fiber inclusion in the laminates, almost 60% improvements in the impact strength were discovered.

Background: Injera is food consumed daily by Ethiopians like bread and rice in other parts of the world. Biomass stoves are used to bake Injera in most rural households. The unsustainable use of fuelwood causes deforestation. Improved cook stoves such as Mirt (name in local language) were introduced to replace traditional stoves and save fuel wood. This study presents a performance comparison of three newly developed prototype biomass stoves with traditional and Mirt stoves. The prototype stoves were made with a clay pan (designated MUC: Mekelle University prototype with clay pan), with a glass pan (MUG) and with an aluminum pan (MUA). Controlled cooking tests were conducted for each type of stove to determine the thermal efficiency and specific fuel consumption. Results: The thermal efficiencies of the traditional, Mirt, MUC, MUA and MUG stoves were found to be 14%, 17%, 21%, 29% and 32%, respectively. Similarly, the percentage fuel wood savings by Mirt, MUC, MUA and MUG compared to the traditional stove were 32%, 48%, 64% and 67%, respectively. The results indicate that the prototype stoves had significantly better performance compared to the traditional and Mirt stoves. Conclusion: The prototype stoves have the potential to reduce fuel wood consumption by more than half of that currently consumed employing traditional stoves. In addition to the economic benefit of saving fuel wood, the improved stoves will have significant environmental implication. Based on the fuel saving figures, it is estimated that 0.4, 0.5 and 0.52 tons/year of fuel wood may be saved per household adopting MUC, MUA and MUG stoves, respectively.

This research aims to reduce the degradation of sisal fiber-reinforced polyester composites due to water absorption through chemical treatments and hybridizations. Sisal fibers were treated using sodium hydroxide (NaOH) and baking soda (NaHCO3). Unidirectional glass and carbon fibers were chosen as hybrid fibers. Thirteen laminates of pure sisal fibers, hybridized with glass or carbon fibers at different stacking sequences and volume fractions, were prepared using the hand layup technique. The laminates were examined for tensile and impact strength at dry and wet conditions. The effects of baking soda and sodium hydroxide treatments, glass and carbon fibers hybridization, and the sequence and volume of the hybrid fibers on the tensile strength, impact strength, water absorption, and degradation of the laminates were studied and compared. Chemical treatments and hybridizations have enhanced the tensile and impact strength of the composites. Significant reduction in the water uptake rate and degradation of the laminates were observed. Almost 166% and 87%, respectively, improvements were obtained in the tensile and impact strength of the dry samples. Moreover, more than 74% reduction in water uptake, and 84.7% and 91.7%, respectively, improvements in the degradation of the tensile and impact strengths were discovered.

The 2030 sustainable development goal (SDG7) target progress indicators show that developing countries are off track. Ethiopia’s low performance to the SDG7 has endangered its economic, societal, and environmental sustainability. The performance in clean cooking has contested its policy, institutional setup, and R&D. The objective of this paper lies in evaluating four improved cook stoves against a traditional stove based on fuel consumption, cooking time, and emission. The study would contribute to solving the clean-cooking challenges by giving scientific evidence on the technological status of these stoves. The evaluation results show that the TCS consumed 2.7 kg of fuel, had a cooking time of 1:30 h, and used 4.3 kg CO₂ per cooking period. Similarly, the ICSs required: 1.2 kg, 2 h, and 1.9 kg (EZY); 1.5 kg, 3 h, and 2.4 kg (Tikikkle); and 1.4 kg, 5 h, and 3.2 kg (Lakech), respectively. In addition, these stoves registered a thermal efficiency of 25, 17, and 19%, respectively. The metal body, insulation, and air inlet caused EZY to perform better. However, these technologies are low-order technologies, and their performance is found to be a major locking factor in ICS adoption. This evidence would help ICS actors to understand where to intervene for better adoption. Furthermore, the authors gave implementation fix recommendations to improve ICS programs.