This study aims to evaluate how age, harvesting seasons, and culm height affect the properties of various bamboo species. The properties of bamboo fibres for composite development in Ethiopia have not been investigated so far. In this study, the properties of Y. alpina and B. oldhamii were scientifically investigated for bamboo culm structural applications and bamboo fibre composite development based on age and the harvesting season. Y. alpina was collected at Injibara and Mekaneselam which are located in east Gojjam and south wollo, whereas B. oldhamii was collected at Kombolcha which is located in south Wollo, Ethiopia. Three representatives of bamboo plants were collected in the three regions, namely from three age groups, across two harvesting months. The highest and lowest moisture content and shrinkage were measured at the ages of one year and three years, respectively, whereas basic densities were measured at the ages of three years and one year. The harvest month of November yields higher moisture content and shrinkage but lower basic densities compared to February. Yushania alpina has a higher moisture content and shrinkage but lower basic densities compared to Bamusa oldhamii. The current research demonstrates that the three-year-old groups and the harvesting month of February produce yields more suited for construction and structural purposes due to the ensuing good dimensional stability after drying. From the highest to the lowest percentage of the degree of crystallinity of the yield, it is that derived from Inj., followed by Meka., and then Kombolcha, respectively. Bamboo fibres have high powder crystals and degradation temperatures which make them suitable for composite development at two year old. Yushania alpina has a higher degree of crystallinity and degradation temperature of cellulose compared to Bambusa oldhamii.

Polyelectrolyte complex membranes (PECMs) were prepared by combining sodium carboxymethyl cellulose (NaCMC) and gelatin (Ge) with variations in the Ge content in the NaCMC matrix. Characterization methods, such as infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), contact angle analysis (CA), and universal testing machines (UTM) were used to investigate the physicochemical studies of the prepared membranes. The pervaporation characteristics of membranes with Ge content were investigated using an azeotropic mixture of water and bioethanol. The obtained data revealed that the membrane with 15 mass% of Ge (M-3) showed a maximum flux of 7.8403 × 10⁻² kg/m²·h with separation selectivity of 2917 at 30 °C. In particular, the total and water flux of PECMs are shown as very close to each other indicating that the fabricated membranes could be employed to successfully break the azeotropic point of water–bioethanol mixtures. Using temperature-dependent permeation and diffusion data, the Arrhenius activation parameters were calculated, and the obtained values of water permeation (E_pw) were considerably smaller than bioethanol permeation (E_pE). Developed membranes showed the positive heat of sorption (ΔH_s), suggesting that Henry’s sorption mode is predominant.

The current studies aim to measure the mechanical strength based on age, harvesting season and bamboo species in Ethiopia. The bamboo fibres are extracted using a roll milling machine, which was developed by the author. The age groups (1, 2 and 3 years), harvesting months (February and November), and bamboo species (Yushania alpina and Bambusa oldhamii) are the parameters of the current research studies. Prepregs and composites were produced from bamboo fibres and polypropylene. The mechanical properties of bamboo fibres and their composites in Ethiopia have not been investigated by researchers for the composite application so far. The tensile strength, Young’s modulus, and impact strength of injibara (Y. alpina) bamboo fibres reinforced PP composites from the ages of 1– 3 years old in November is 111 ± 9–125 ± 8 MPa, 15 ± 0.9–25 ± 0.72 GPa, and 47 ± 5 KJ/m²–57 ± 6 KJ/m², whereas, in February, it is 86 ± 3.86–116 ± 10 MPa, 11 ± 0.71–23 ± 1.5 GPa, and 34 ± 4–52 ± 6 KJ/m², respectively. Moreover, Kombolcha (B. oldhamii), bamboo fibres reinforced PP composites in November are 93 ± 7–111 ± 8 MPa, 7 ± 0.51–17 ± 2.56 GPa, and 39 ± 4–44 ± 5 KJ/m², whereas, in February, it is 60 ± 5–104 ± 10 MPa, 12 ± 0.95–14 ± 0.92 GPa, and 26 ± 3 KJ/m²–38 ± 4 KJ/m², respectively. Furthermore, Mekaneselam (Y. alpina) bamboo fibres reinforced PP composites in November are 99 ± 8–120 ± 11 MPa, 9 ± 0.82–16 ± 1.85 GPa, and 37 ± 4 KJ/m²–46 ± 5 KJ/m², whereas, in February, it is 91 ± 8–110 ± 9 MPa, 8 ± 0.75–14 ± 1.86 GPa, and 34 ± 3 KJ/m²–40 ± 4 KJ/m², respectively. At two years, November and Injibara bamboo have recorded the highest mechanical properties in the current research studies. Bamboo fiber strength in Ethiopia is comparable to the previous study of bamboo fibres and glass fibres used for composite materials in the automotive industry.