Sintayehu, Nibret (PhD)Mengsteab, Nugusse2020-03-082023-11-102020-03-082023-11-102019-06-14http://etd.aau.edu.et/handle/12345678/20997Adhesive is bonding material most widely used in manufacturing sectors like shoe, wood, textile, papers, and others. Most of these manufacturing sectors rely on using petroleum-based adhesives such as urea formaldehyde, fevicol, polyvinyl acetate, and phenol formaldehyde resins. As these adhesives are produced from non-renewable resources and they are also carcinogenic to human beings due to formaldehyde emission, it is necessary to prepare adhesives from bio-based sources. In this research bio-based adhesive was produced using Euphorbia tirucalli latex as a renewable feedstock. The process of bio-adhesive production includes extraction of latex from branches of Euphorbia tirucalli using water as a solvent and mixing the extracted latex with silica to formulate the adhesive. 21.6 percentage yield of liquid latex was obtained from the extraction section. Before the preparation of the bio-adhesive the extracted latex was characterized in terms of total solid content, pH, viscosity, density and FTIR. Design Expert® version11.1.0.1 with full factorial was applied to investigate the effect of experimental variables such as latex concentration (30, 40 and 50%), silica load (10, 20 and 30parts per hundred rubber) and mixing time (15, 30, and 45 minutes) on the viscosity and bonding strength of the bio-adhesive. Significances of the experimental variables were analyzed by analysis of variance. Maximum lap shear strength (3.28MPa) with a corresponding viscosity of 567.2mPa.s was obtained when 50% latex concentration was mixed with 20phr silica for 30 minutes and minimum lap shear strength (1.2MPa) with a corresponding viscosity of 398mPa.s was observed when 30% latex concentration mixed with 10phr silica for 15 minutes. Finally, the prepared bio-adhesive was characterized in terms of bonding strength, thermal stability, viscosity, pH, and foam length by taking a sample from the experimental run which gave maximum lap shear strength. The results obtained confirmed that the prepared bio-adhesive is comparable with commercial synthetic adhesives and met the minimum requirements except with limited thermal stability.en-USbio-adhesiveviscositylap shear strengthEuphorbia tirucalliThesis