Deformation of liquid-filled calcium alginate capsules in a spinning drop apparatus

Abstract

This paper describes the mechanical properties of thin-walled, liquid-filled calcium alginate capsules by measuring the deformation of these particles in a spinning drop apparatus. By variation of the guluronic acid content of the alginate, the polymerization time and the calcium and alginate concentration we systematically studied the elastic properties of these capsules. In a series of experiments we observed for the first time new types of irreversibly deformed capsules, which can be described by plastic deformation. For comparison purposes, we also investigated liquid-filled calcium alginate particles in squeezing capsule experiments. The qualitative and quantitative results of both experiments in terms of the deformation properties and the surface Young moduli were in good agreement. Furthermore we also investigated liquid-filled calcium alginate particles by NMR microscopy to characterize the capsules in view of their membrane thickness. These results, in combination with the spinning capsule experiments allowed us to measure the kinetics of surface gelation and the mechanism of membrane growing.

Alginate/sodium caseinate aqueous-core capsules: A pH-responsive matrix

“…where d D denotes capsule displacement, F is the measured force, E S is the surface Young modulus, d is the membrane thickness, a is the radius of the capsule and v S the surface Poisson ratio for which a value of 1 3 was assumed according to Leick et al, [16]. Table 2 summarized Young's moduli values of alginate and composite capsules, in function of preparation pH, calculated by linear regression from compression curves at small displacements (data not shown).…”

Determination of the elastic properties of single microcapsules using micromanipulation and finite element modeling

“…Such tests primarily yield two sets of data; (i) force and fractional deformation at failure under compression and (ii) material properties of the capsule wall. Of the latter, only the elastic regime has so far been studied in detail (Leick et al, 2010;Liu, 2006). In order to estimate the elastic modulus of a capsule wall from compression data, experimental data has to be compared with theoretical force curves.…”

Alginate liquid core capsule formation using the simple extrusion dripping method

“…In order to ensure spherical capsules are formed, manipulation of several process variables of the formation process is needed. These variables included the physical properties of alginate solution and liquid core solution, types of alginate, cavity depth, collecting distance, dripping velocity and gelation time [4][5][6][7][11][12][13]. However, the suitable process variables are obtained after many trials and errors, which are tedious and time consuming.…”