Barbara Calcagno

• University of Puerto Rico System

The Lunar Exploration and Access to Polar Regions (LEAPR) project proposes a conceptual architecture that enables human access to the surface of the Moon through the use of the future cis-lunar space station known as the Gateway. The Karaya Transport Vehicle (KTV) is the vessel that has been designed to perform crewed missions to different location...

The effect of varying electrospinning parameters is reported for the production of collagen nanofibers from acetic acid with controlled fiber diameter, orientation, and mechanical properties. Nanofibers with a range of diameters of 175–400 nm are obtained by varying either the voltage or the flow rate. An increase in nanofiber alignment is observed...

Recently, liquid crystalline elastomers (LCEs) have been proposed as active substrates for cell culture due to their potential to attach and orient cells, and impose dynamic mechanical signals through the application of external stimuli. In this report, the preparation of anisotropic and oriented nematic magnetic-sensitized LCEs with iron oxide nan...

The process of calendering, or cold rolling, is relevant to geologic processes and industrial applications, ranging from food processing to thin film transistor manufacturing. When dissimilar materials are sandwich stacked and then subjected to extrusion-like deformation between rollers, several factors influence the outcome of the product composit...

Liquid crystalline elastomers (LCEs) are materials that reveal unusual mechanical, optical and thermal properties due to their molecular orientability characteristic of low molar mass liquid crystals while maintaining the mechanical elasticity distinctive of rubbers. As such, they are considered smart shape-changing responsive systems. In this work...

We report on the magnetothermal repair of a thermoplastic magnetic nanocomposite consisting of iron oxide nanoparticles embedded in poly(methyl methacrylate) (PMMA). The nanoparticles responded to an applied alternating magnetic field by dissipating heat, raising the nanocomposite temperature to above the glass transition temperature and resulting...

Liquid crystalline elastomers (LCE´s) are liquid crystal polymers that combine the mechanical properties of rubbers with the ordered structure and mobility of LC phases. They have unique optical, mechanical and piezoelectric properties, which can be modified in response to external stimuli. The latter allows for potential applications such as mecha...

Cold rolling of a sandwich composite with a metallic strip inclusion in a polymeric matrix can produce a range of outcomes, including deformation and fracture of the inclusion. Using different material combinations under the same processing parameters, the results ranged from minor deformation, to folding and/or loss of adhesion, and fracture of th...

A load applied to a composite is transferred from the matrix to the dispersed phase through their shared interface. The performance of the composite depends strongly on the interfacial adhesion between the constituents. Shear strength, resistance to delamination, and effective load transfer between the matrix and the inclusion are improved when the...

This research uses both experimental and analytical mechanics approaches to understand the roles that stiffness, strength and interfacial adhesion play in the deformation and fracture of an inclusion material sandwiched between layers of dissimilar material. These results have application beyond the experimental calendering problem considered here,...

The viscoplastic behavior of high density polyethylene, polypropylene, and polycarbonate under uniaxial tensile loading at constant strain rate and large strains was studied. Standard ASTM samples of the polymers cast by injection molding were tested at room temperature and constant crosshead speed; testing was conducted in the range of 5 to 300 mm...

Metal inclusions in polymeric composites exhibit different fracture patterns under a process of calendering, i.e. cold rolling and folding. Combinations of NiTi and Ti inclusions were used in polypropylene, polycarbonate, and high density polyethylene. Fundamental aspects to the process of calendering/rolling dissimilar materials are the deformatio...

The compressive creep and recovery of foam earplugs was studied at various applied stresses leading to different fi nal creep strains. Deformation was determined from digital videos of the earplugs via image processing software. Creep could not be modeled by a single exponential in time; creep approximated a power law in time. Nonlinear viscoelasti...

In a nonmixed environment, bacterial population growth can be influenced significantly by cell motility properties as well as by growth kinetic properties. Therefore, in a situation of competition between two bacterial populations for a single chemical nutrient in a nonmixed environment, the outcome may depend upon the respective cell motility prop...