Stability of Silk and Collagen Protein Materials in Space

Collagen and silk materials, in neat forms and as silica composites, were flown for 18 months on the International Space Station [Materials International Space Station Experiment (MISSE)-6] to assess the impact of space radiation on structure and function. As natural biomaterials, the impact of the space environment on films of these proteins was investigated to understand fundamental changes in structure and function related to the future utility in materials and medicine in space environments. About 15% of the film surfaces were etched by heavy ionizing particles such as atomic oxygen, the major component of the low-Earth orbit space environment. Unexpectedly, more than 80% of the silk and collagen materials were chemically crosslinked by space radiation. These findings are critical for designing next-generation biocompatible materials for contact with living systems in space environments, where the effects of heavy ionizing particles and other cosmic radiation need to be considered

Studies of Electrical and Thermal Conductivities of Sheared Multi-Walled Carbon Nanotube with Isotactic Polypropylene Polymer Composites

Polymer nanocomposite materials of higher thermal and electrical transport properties are important to nanotechnology applications such as thermal management, packaging, labelling and the textile industry. In this work, thermal and electrical conductivities in nanocomposites of multiwalled carbon nanotubes (MWCNT) and isotactic polypropylene (iPP) are investigated in terms of MWCNT loading, temperature dependence, and anisotropy caused by melt shearing. IPP/MWCNT nanocomposites show a significant increase in thermal and electrical conductivity with increasing MWCNT loading, reaching 17.5 W/m K and 10−6 S/m, respectively, at a MWCNT 5.0 weight percentage at 40°C. The increase in MWCNT/iPP is more than would be expected based on the additivity rule, and suggests a reduction of the interfacial thermal electrical resistance at nanotube-nanotube junctions and the nanotube-matrix interface. The anisotropy in both conductivities was observed to be larger at low temperature and to disappear at higher temperature due to isotropic electrical and thermal contact in both directions. Oriented MWCNT/iPP nanocomposites exhibit higher electrical and thermal conductivities, attributed primarily by orientation of nanotubes due to the shearing fabrication process

On the electrospinning of PVDF: influence of the experimental conditions on the nanofiber properties

none4simixedErika Simona Cozza;Orietta Monticelli;Enrico Marsano;Peggy CebeCozza, ERIKA SIMONA; Monticelli, Orietta; Marsano, Enrico; Peggy, Ceb

Nanostructured nanofibers based on PBT and POSS: Effect of POSS on the alignment and macromolecular orientation of the nanofibers

reserved4simixedErika Simona Cozza;Qian Ma;Orietta Monticelli;Peggy CebeCozza, ERIKA SIMONA; Qian, Ma; Monticelli, Orietta; Peggy, Ceb

Impact of synthetic talc on PLLA electrospun fibers

Poly(L-lactic acid) (PLLA) is an important biomaterial with application as surgical meshes, sutures, and in artificial tissue. Here we prepared novel fibers by electrospinning solutions containing PLLA and a specially synthesized talc (ts), characterized by the presence of aliphatic chains in the structure and completely soluble in the electrospinning solutions. Even a small amount of ts (2 wt.-%) in the toluene/chloroform solvent increases the solution viscosity, most likely because of specific interactions between talc and PLLA. Morphological characterization demonstrated that homogenous fibers, of neat PLLA and PLLA/ts, are obtained by proper choice of electrospinning conditions. Among the parameters studied, relative humidity (Rh) was found significantly to affect fiber morphology. Morphological homogeneity increases by increasing Rh. In contrast to fibers containing a commercial talc, which is insoluble in the electrospinning mixture, and whose aggregates render the fiber irregular, in the case of PLLA/ts fibers the dispersion of the synthetic talc is achieved at the nanometric length scale. Electrospun mats based on PLLA/ts showed a much higher water contact angle than the neat PLLA mats, the contact angle increasing from 92° to ca. 140°, thus highlighting that a superhydrophobic PLLA surface is obtained by dispersing synthetic talc into PLLA fibers, widening the potential for biomedical applications of this material. Fiber properties of superhydrophobic PLLA were studied by means of differential scanning calorimetry (DSC), static and real-time wide angle X- ray diffraction (WAXD), and water contact angle measurements. Talc was found to promote the development of a small amount of crystallinity during the electrospinning process, and to favor the development of the α crystallographic form during annealin