Encapsulation of insulin-producing cells in alginate beads could improve the treatment of type 1 diabetes by reducing or eliminating the need for immunosuppression. We have recently adapted an emulsion and internal gelation process to β-cell encapsulation. This process has the advantages of being well suited for m(3)/h production rates and allowing the use of increased alginate concentrations. Compared with 1.5% alginate beads generated by a standard extrusion process, 5% alginate emulsion-generated beads demonstrated greater in vitro stability and greater volumetric exclusion of antibody-sized pullulan. When βTC3 cells were transplanted into streptozotocin-induced allogeneic diabetic mice, a significant decrease in the blood glucose levels was seen within 2 days with the 5% emulsion-generated beads but not until >16 days with the 1.5% extrusion-generated beads. This was correlated with higher cell survival and lower graft-specific plasma immunoglobulin levels. These results suggest that higher-concentration alginate beads generated by emulsion and internal gelation have improved graft immunoprotection. The emulsion process is a promising and scalable technology for cellular therapies requiring immune isolation.

Summary: Biodegradable polymer/clay nanocomposites and/or composites based on poly(ε‐polycaprolactone) (PCL) were prepared by conventional melt mixing. Three kinds of clays, organomodified Cloisite 15A and Cloisite 10A with different ammonium cations located in the silicate gallery and unmodified Cloisite with Na cations were used for composites preparation. The degree of dispersion of silicate layers in the matrix was determined by X‐ray diffraction and transmission electron microscopy. Oscillatory rheological measurements were used for characterization of the physical network formed by the filler. The presence of intercalated and exfoliated structures were observed for the composites PCL/Cloisite 15A and PCL/Cloisite 10A, indicating that nanocomposite structure was formed. Changes of viscoelastic properties to more solid‐like behavior, especially in the low frequency range were explained by formation of silicate network structure, which can be detected by modified Cole‐Cole plots.

High‐density polyethylene (HDPE)/graphite nanocomposites containing up to 30 vol% of graphite powder filler were prepared by melt mixing in a Brabender Plasticorder at 180°C for 15 min. The nanocomposites were characterized for their rheological, dynamic mechanical, crystallographic, and electrical properties as a function of graphite loading. The results indicated that graphite loading affects storage modulus, loss modulus, complex viscosity, and conductivity of HDPE matrix. The storage modulus increases while the graphite loading increases in the studied concentration range (up to 30%). When the graphite loading was increased to 30%, storage modulus at room temperature was about 300% higher than that of pure HDPE. Also, the composites containing 20 and 30% graphite shows more conductivity than the others. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Rubber magnetic composites were prepared by incorporation of strontium ferrite into rubber compounds based on acrylonitrile butadiene rubber and ethylene propylene diene monomer rubber. The sulfur, peroxide, and mixed sulfur/peroxide curing systems were introduced as cross-linking agents for rubber matrices. The aim was to investigate the influence of curing system composition on curing process and cross-link density of composite materials. Then, static and dynamic mechanical properties and thermal and magnetic characteristics were investigated in relation to the cross-link density of rubber magnetic composites and structure of the formed cross-links. The changes of dynamical and physicomechanical properties were in close correlation with the change of cross-link density, whereas the tensile strength of magnetic composites showed increasing trend with increasing amount of peroxide in mixed curing systems. On the other hand, thermal conductivity and magnetic characteristics were found not to be dependent on the curing system composition. Incorporation of magnetic crystalline ferrites into various rubber matrices leads to the preparation of magnets, known as ferrite rubber magnets. [5][6][7][8] Rubber magnetic composites are materials that consisted of at least 2 phases, magnetic powder as filler and continuous rubbermatrix. An advantage of these materials is the fact that they are possible to be prepared and processed by the technologies typically used for polymer composites processing. Rubber magnetic composites show excellent flexibility and easy workability, and moreover, they are characterized by good magnetic characteristics. They can be bent, coiled, and shaped without the loss of their magnetic characteristics. Additionally, they are very resistant to corrosion; therefore, no surface treatment is necessary.A lot of vulcanization systems have already been investigated as cross-linking agents for rubber formulations, among which sulfur and peroxide curing systems are still the most frequently used.Sulfur vulcanization is the oldest method used for cross-linking of unsaturated elastomers. It is a complex process that leads to the forming of different types of sulfide cross-links between macromolecules of rubber, namely, monosulfide C-S-C, disulfide C-S 2 -C, and polysulfide cross-links C-S x -C (x = 3-6). In general, sulfur-cured vulcanizates exhibit good tensile properties, high tensile and tear strength, and good elastic behavior, but weak high-temperature stability and poor resistance to aging. 9-13The application of peroxide curing system in cross-linking of elastomers leads to the forming of covalent carbon-carbon crosslinks between elastomer chain segments. C-C bonds have higher dissociation energy in comparison with sulfidic cross-links; therefore, peroxide-vulcanized elastomers exhibit higher thermal stability and good resistance to thermo-oxidative aging. Good electrical properties, low compression set, and no discoloration of the final products are next cognitive features of peroxide cured vulcaniz...