Effect of Degree of Substitution on the Adhesive Propterties of Methyl Cellulose Derived from Waste Bitter Orange [Citrus Aurantium (Linn.)] Mesocarp

Cellulose was extracted from waste bitter orange mesocarp and chemically modified by etherification in propan-2-ol as solvent with varying amount of methyl chloride and the degree of substitution (DS) of the methyl group for H of the native cellulose calculated by acid-base titration. Nine pastes (seven etherified cellulose (methyl cellulose) and the native cellulose (control) were prepared by dispersing them in distilled water (35% w/v) and heating the eight dispersions to 45°C with continuous agitation for 15min. The solutions were then cooled to room temperature and allowed to gel. The effect of DS on the adhesive properties of the pastes (tack strength, rolling ball test, gelation time, drying time, optical clarity, relative viscosity, syneresis) was comparatively investigated. The results showed that the DS in the etherified cellulose ranged from 1.31 to 1.98 with the methyl cellulose giving higher values of viscosity and tack strength with increase in DS. However, lower values of syneresis, gelation time, optical clarity, drying time and rolling ball distance were recorded with increase in DS. Increase in desirable adhesive properties of the methyl cellulose is attributed to its relatively higher molecular weight compared to the native cellulose. Production and use of etherified cellulose, in place of petroleum-based synthetic adhesives, in remoistening applications such as envelope flaps, postage stamps, labels and other paper works in Nigeria and other developing economies is recommended from the viewpoints of economy, environment, health and safety.