Production and Characterization of Bio-Adhesive from Euphorbia Tirucalli Latex
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Date
2019-06-14
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Addis Ababa University
Abstract
Adhesive 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.
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Keywords
bio-adhesive, viscosity, lap shear strength, Euphorbia tirucalli