Nehemiah Mengistu Zeleke

Biocomposite materials have brought other possibilities to the manufacturing industry rather than synthetic materials. Biodegradable polymer materials such as polylactic acid (PLA) have attracted various industries’ attention for numerous applications due to their tensile strength (TS), while they have some mechanical weaknesses that prevent them from being utilized for different engineering applications. The amalgamation of microcrystalline cellulose (MCC) at varying percentages (0%, 3%, 6%, and 9%) and montmorillonite (MTT) at the same percentages (0%, 3%, 6%, and 9%) serves as a filler, while sorbitol (S) is used as a plasticizer in concentrations of 10%, 20%, 30%, and 40%. The material is fabricated at different temperatures (Ts) of 100°C, 125°C, 150°C, and 175°C using the melt‐mixing method, and the process is optimized to establish an effective experimental setup. This study prepared 16 samples through Taguchi’s orthogonal array design. The optimal factor level combinations were investigated for flexural strength (FS) at (3% MCC/9% MTT/20% S/175°C); at these levels FS is 96.5 MPa; flexural modulus (FM) at (6% MCC/9% MTT/20% S/175°C); at these control factors FS is 9.8 GPa; TS at (9% MCC/9% MTT/10% S/175°C); at these levels TS is 85.2 MPa; Young’s modulus (YM) at (6% MCC/9% MTT/0% S/150°C); at this experimental run YM is 4.22 GPa; hardness value (HV) at (6% MCC/9% MTT/10% S/175°C); at these levels HV is 138.2; impact strength (IS) at (9% MCC/9% MTT/20% S/175°C); at these factor combinations IS is 54.2 J/m; water absorption (WA) at (0% MCC/0% MTT/0% S/150°C); at this experimental run WA is 2.42%; and density (D) at (9% MCC/9% MTT/30% S/175°C) at this experimental run density is 0.0427 g/mm ³ . Analysis of variance (ANOVA) for the regression model shows the statistical significance of the model and the significance of the factors. The comparison analysis indicated that the quality characteristics of the optimum MCC/MTT/S/PLA material are comparable to the performances of various engineering materials.

Coffee husk (CH) is a sustainable and abundantly available cellulosic waste material. Its fiber consists of cellulose as the major structural part which leads to potential utilization for the manufacturing of microcrystalline cellulose (MCC) products that can be utilized for different industrial applications. In the present study, chemical composition of outer skin-isolated coffee husk was determined and sequential treatments of various untreated (UT) sample, ethanoltoluene treated sample through dewaxed (DW) treatment, sodium hydroxide (NaOH)treated sample through alkali (AT) treatment, and sulfuric acid (H₂SO₄)treated sample through bleaching (BL) treatment have been carried out. The Micro Crystalline Cellulose (MCC) has been extracted through hydrogen peroxide (H₂O₂) after BL treatment. The BL treatment for MCC extraction process was conducted without chlorine and additional harsh acid treatment, respectively. The characterization of chemically treated samples was carried out to investigate their morphological, physico-chemistry, and thermal behavior through a scanning electron microscope (SEM), Fourier transform infraredray (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), and differential temperature analyzer (DTA). From the chemical composition analysis; the cellulose, hemicellulose, lignin, and extractive content were determined and its values were (52.9), (12.5), (24.3), and (9.4), respectively. In the morphological examination, the great untreated (UT) fiber sample was greatly reduced into a micro-sized BL sample, revealing that (from FTIR analysis) the lignin and hemicellulose contents were greatly removed during chemical treatments and the presence of a micro crystalline cellulose region with 54.7 yield. Also, the sample AT and BL showed the lowest amorphous region in X-RD due to the removal of hemicellulose and lignin. The highest crystallinity index has been determined for the BL sample, i.e., 89.9. Additionally, the thermal analysis shows that the AT and BL sample has great thermal stability than other (UT and DW) samples at high temperature. Therefore, the outer skin separated coffee husk was prepared from agricultural waste was subjected to eco-friendly chemical treatments to yield MCC. Thus, the extracted MCC is expected to be reliable for replacing other plant materials for the production of crystalline nanomaterial and reinforcing constituent for the fabrication of bio composite.