Determination of the mechanical properties of single calcium alginate microbeads loaded gallic acid

Abstract

The mechanical properties of biocompatible microparticles including calcium alginate microbeads loaded gallic acid were determined by a micromanipulation technique using a Brookfield Texture Analyzers. Single calcium alginate microbeads of a regular size distribution with a mean diameter in the range of 700– 750 µm prepared by the ionotropic gelation technique were compressed to rupture with a constant speed of 0.5 mm.s−1. The corresponding force imposed on them was measured simultaneously by a force transducer. Results showed that the force imposed on these particles increased when they were compressed, but relaxed significantly when they were ruptured and the increasing alginate concentration led to the improvement of mechanical strength (microcapsules). The exploitation of the linear character of the stresses and deformation allowed us to calculate the creep function. Calculations show that the microbeads are subjected to delayed elasticity (or entropy elasticity) governed by the Kelvin-Voigt analog model. This model is then confronted with the experiment and allowed us to find the modulus of Young of the microbeads which is in agreement with our direct experimental measurements as well as the determination of the delay time and viscosity for a concentration of (3%, w/v).