Ricerc@Sapienza

This paper investigates swelling-induced eversion and flattening in curved bilayer gel beams. An explicit formula is produced to evaluate the change in curvature induced by large swelling deformations. The validity is tested against a fully coupled nonlinear three–dimensional stress-diffusion model. Limit situations for nearly-homogeneous and slightly curved beams are discussed.

We investigate the adhesion mechanism between an elastic strip of vinylpolysiloxane bent in a racquet-like shape, and a thick elastomeric substrate with the aim to understand how local swelling modifies adhesion. Using a modified loop–tack adhesion test, we place a droplet of silicone oil in between the two materials, vary the dwell time and measure the force required to separate the two interfaces. The experiments are then compared with an analytical model that describes how the critical peel force is modified as the interfacial surface energy changes over time.

Polymer gels are porous fluid-saturated materials which can swell or shrink triggered by various stimuli. The swelling/shrinking-induced deformation can generate large stresses which may lead to the failure of the material. In the present research, a nonlinear stress–diffusion model is employed to investigate the stress and the deformation state arising in hydrated constrained polymer gels when subject to a varying chemical potential. Two different constraint configurations are taken into account: (i) elastic constraint along the thickness direction and (ii) plane elastic constraint.

We investigated the stress response of hydrogels to multiple and consecutive planar extensions using the standard Flory-Rehner thermodynamics. We show explicitly how the stress relaxation at a given extension depends on both the number and magnitude of incremental steps that lead to such extension. These results have the potential to impact the design of hydrogel-based actuators where a prescribed extension can be achieved through several consecutive extensions.

Sialolithiasis is a non-neoplastic salivary gland disease that rarely affects the minor salivary glands. There are no guidelines in the literature which can suggest which is the best surgical approach to treat Minor Salivary Glands Sialolithiasis (MSGL). The present case was of a 48-year-old male patient complaining of painful swelling localized in the left back-commissural zone which was 0.5 mm in diameter, for which surgical enucleation approach was done and in that some small calcific masses ranging from 0.2 to 4 mm in diameter were found.

In the present study, a 3D finite element model of a single trabecula from the human femur head is developed with the aim of evaluating the dynamics of water diffusion through bone tissue and the subsequent swelling of the specimen due to water uptake. Numerical results in terms of dimensional changes of the trabecula are in good agreement with experimental observations reported in literature. The results show iso-concentration maps at different instants of time.

Interpenetrated polymer network microgels, composed of crosslinked networks of poly(N-isopropylacrylamide) and Polyacrylic acid (PAAc), have been investigated through rheological measurements at four different amounts of Polyacrylic acid. Both PAAc content and crosslinking degree modify particle dimensions, mass and softness, thereby strongly affecting the volume fraction and the system viscosity.

In this study, gellan gum (GG), a natural polysaccharide, was used to fabricate spherical porous beads suitable as sustained drug delivery systems for oral administration. GG was cross-linked with calcium ions to prepare polymeric beads. Rheological studies and preliminary experiments of beads preparation allowed to identify the GG and the CaCl2 concentrations suitable for obtaining stable and spherical particles. GG beads were formed, through ionotropic gelation technique, with and without the presence of the synthetic clay laponite.