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This work reports the synthesis of silver nanoparticles from the precursors, silver nitrate and sodium bromide, and the in situ synthesis of polysulfone (PSf)‐poly(ethylene‐glycol) (PEG) block copolymer (BCP) in the presence of developed Ag. The PSf‐PEG BCP nanocomposite containing 3 wt.% of the nanoparticles, when electrospun, is observed to be helpful in separating the oil‐in‐water emulsion. Mechanical properties such as dynamic mechanical strength and tensile strength measurements and high thermal degradation temperature (~6°C) illustrate the reinforcing effect of the Ag nanoparticles. The presence of Ag influences the glass transition temperature (Tg) of the BCP and its elasticity due to its well distribution in the BCP during the in situ synthesis of nanocomposite. Electrospun fiber mat of the in situ synthesized PSf‐PEG/Ag nanocomposite shows improved wettability as evident from the respective aqueous contact angle values of 80.66° ± 1.3, 85.70° ± 2.0, and 101.50° ± 1.0 for PSf‐PEG/Ag, PSf‐PEG, and neat PSf. The combination of PEG to PSf has increased the overall polymer reinforcement effect, and this property along with the antimicrobial activity (inhibited growth of Staphylococcus aureus) of Ag nanoparticles are applied in developing bio‐fouling resistant BCP nanocomposite fibers for oil/water emulsion separation. [ABSTRACT FROM AUTHOR]

Incorporation of pre-reacted monofunctional polyhedral oligomeric silsesquioxane (POSS)-epoxy adducts dramatically improves dispersion of POSS in epoxy-amine networks. The relationship between reaction kinetics and mechanism for formation of POSS-epoxy adducts versus reaction temperature was investigated. Reactivities of epoxy-monoamine functional POSS molecules were determined using in situ reaction monitoring by dynamic dielectric sensing and 29Si NMR spectroscopy. The amine-functional POSS-epoxy isothermal reaction showed reduced reactivity due to reduced molecular mobility, that is, diffusion limitations. Kinetic parameters were determined by fitting 29Si NMR data to the model of Kamal that was extended to include diffusion. Fitting of this model to experimental data showed very good agreement over the entire conversion range for pre-reaction between amine-functionalized POSS and epoxy. An autocatalytic mechanism, the same as that for the neat epoxy-amine systems, was indicated. Gel permeation chromatography, scanning electron microscopy and transmission electron microscopy were used to investigate molecular weight evolution and morphology of final networks cured by 4,40 diaminodiphenyl sulfone using pre-reacted POSS-epoxy adducts. POSS aggregate size decreased with increased pre-reaction temperature, more homogenous POSS dispersion was observed with higher pre-reaction temperature. Dynamic mechanical analysis demonstrated that Tg of composites decreased slightly compared to that of the neat matrix and there appeared to be little change in microstructural heterogeneity. [ABSTRACT FROM AUTHOR]

ABSTRACT Meltblown fibers are typically produced using a die technology based on the slot concept, an extension of the sheet die technology with a series of holes substituting the center rectangular slot of the sheet die. While this prevalent technology has met with considerable success, an economical, facile design would be desirable. In this study a new parallel plate die concept to fabricate micro-meltblown fibers that offers simplicity, ease of use, and low cost was examined. The new die concept had parallel plates forming channels for polymer melt to flow through with a set of air holes surrounding them. This die design produced meltblown fibrous media with fibers in the range of 3-10 μm with pore size between 20 and 60 microns. The underlying mechanisms leading to such large fiber size formation and its implication in air filtration performance has been discussed. While conventional meltblown die generates fibers of smaller diameter and webs with higher filtration efficiency than the parallel plate geometry, design modifications could enhance the parallel plate meltblown die performance and make it a viable alternative. These die adaptations that include reducing air flow resistance, increasing the number of air nozzles around the polymer nozzles, recessing the polymer spinnerets above the die face, and having inclined air channels to increase the drag force on the fibers has been discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42998. [ABSTRACT FROM AUTHOR]

ABSTRACT Polymer-fullerene nanocomposites consisting of linear polyurethane (PU) chains crosslinked via increasing loadings of polyhydroxylated fullerenes (C60 and Sc3N@C80, a metallic nitride fullerene) were prepared and characterized for their mechanical and dielectric properties using dynamic mechanical analysis (DMA) and broadband dielectric spectroscopy (BDS). Fullerene-polymer networks [C60-PU and Sc3N@C80-PU] having high gel fractions, good mechanical properties and thermal stabilities were produced. Polyhydroxylated fullerenes C60(OH)29 and Sc3N@C80(OH)18 were synthesized in high yield through a high-speed vibration milling method and characterized using FTIR, matrix-assisted laser desorption/ionization mass spectroscopy, and thermal gravimetric analysis. DMA of fullerene-PU networks indicates Tg ∼ −50°C, with a sub- Tg relaxation due to local chain motions. BDS analyses of the fullerenes, before and after hydroxylation and before incorporation into the networks, revealed one relaxation and large real permittivity (ε′) values for C60(OH)29 relative to C60. Analogous samples for Sc3N@C80 exhibit two relaxations, where the extra relaxation is attributed to motions of the cage-encapsulated Sc3N clusters. ε′ values for Sc3N@C80-PU at a given frequency are higher than corresponding values for C60-PU, likely because of the rotationally mobile Sc3N encapsulates. Surface and bulk resistivities of fullerene-PU networks were found to have a modest dependence on relative humidity. Capacitance versus voltage characteristics of the fullerene-PUs were also studied in the range of the applied dc bias voltage of −30 to +30 v. It is generally concluded, based on all the evidence that this class of materials can be rendered quite polarizable and could be used as high dielectric permittivity materials in capacitance applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40577. [ABSTRACT FROM AUTHOR]

Photoluminescent cellulose fibers were prepared by impregnation of bleached bagasse pulp with the different cadmium and zinc sulfides nanostructures, namely, CdS, ZnS, CdS/ZnS, ZnS/CdS (Core/shell nanostructures), CdS/ZnS/CdS and ZnS/CdS/ZnS multilayered nanostructures. The prepared cellulosic nanocomposites were characterized regarding strength properties (tensile strength, tensile energy absorption, and burst resistance), optical properties (fluorescence emission), thermal stability, and dielectric properties. The strength properties of paper sheets nanocomposites impregnated with different nanoparticles solutions were noticeably decreased in spite of the very low loading of the fibers with the semiconductor nanoparticles. The decrease in tensile index, tensile energy absorption, and burst index of paper sheets nanocomposites are found to be ranged from 12-27, 13-36, and 11-38 %, respectively. The different paper sheets nanocomposites showed fluorescence emission different from the as prepared polyethyleneimine-stabilized nanoparticles. Thermogravimetric analysis results showed that: the semiconductor nanoparticles did not affect the onset degradation temperature of cellulosic fibers but it caused faster termination of the main degradation step. The dielectric loss and the dc-conductivity of cellulosic fibers increased as a result of impregnating the fibers. The nature of the nanoparticles and the properties of the interphases strongly influenced the dielectric properties of the cellulosic/semiconductors nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

The article presents a study which synthesized and characterized degradable thermoplastic polyurethane (TPU) elastomers incorporating poly(D,L-lactide-co-glycolide) (PLGA). The contents of the soft and hard segments are described. All of the PLGA-containing TPUs suggested enhanced degradation compared to those with only BPA as the soft segment. Molecular weights of TPUs with degradable polyols were found to be lower than those derived from PBA polyol.