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A unique blowing-assisted electro-spinning process has been demonstrated recently to fabricate hyaluronic acid (HA) nanofibers. In this article, effects of various experimental parameters, such as air-blowing rate, HA concentration, feeding rate of HA solution, applied electric field, and type of collector on the performance of blowing-assisted electro-spinning of HA solution were investigated. With...
While waterborne two-component polyurethanes (WB 2K-PURs) offer an attractive approach toward the reduction of volatile organic compounds (VOC), a number of fundamental processes related to the colloidal stability and solution morphology of WB 2K-PUR reactive dispersions are not understood. These studies focus on mechanisms of inter-particle reactant aggregation in heterogeneous aqueous dispersions...
Resorcinol-based phthalonitrile, 1,3-bis(3,4-dicyanophenoxy)benzene, has been synthesized in high yield by a simple nucleophilic displacement of a nitro-substituent from 4-nitrophthalonitrile in a dipolar aprotic solvent. The monomer can be thermally polymerized to a network polymer in the presence of an amine curing additive. The resin is readily processed in a controlled manner as a function of...
The synthesis and characterization of bisester-oligoamides segments with varying segment length that can be used in segmented block copolymers were studied. The bisester-oligoamides segments were made form diamines and terephthalate or isophthalate esters. The diamines used were p-xylylene diamine, m-xylylene diamine and hexamethylene diamine. The esters used are dimethyl terephthalate, diphenyl terephthalate,...
A family of amphiphilic poly(acrylic acid-g-styrene), P(AA-g-S), graft copolymers has been prepared by quantitative hydrolysis from poly(tert-butyl acrylate-g-styrene), P(tBA-g-S), precursors and evaluated by 1 H NMR and FTIR. The thermal characterization of these copolymers as a function of the number of grafted repeat units has been performed by thermogravimetric analysis, TGA, differential...
Poly(ethylene terephthalate-co-ethylene naphthalate) (PETN) nanocomposites containing two different organoclays, Cloisite 20A and 30B, were prepared by melt intercalation using an extruder. The organoclays was treated with epoxy monomer to further improve the polar interactions with PETN matrix. The morphological, thermal-mechanical, mechanical and gas barrier characteristics of the nanocomposites...
We present experiments on the melt and crystal morphology of a asymmetric semi-crystalline poly(ethylene/butylene-b-ethyleneoxide) diblock copolymer (PB h -b-PEO) in bulk as well as in thin films. Simultaneous small- and wide-angle X-ray scattering combined with AFM and TEM images reveal in the melt a bulk morphology of hexagonally packed cylinders of PEO in a PB h matrix, that transforms...
Polypropylene nanocomposites containing organophilic layered silicate were prepared by melt mixing. In order to increase polypropylene polarity, Cl and SO 2 Cl groups were introduced by reaction with sulfuryl chloride under UV irradiation. Chlorosulfonated polypropylene was subsequently melt-compounded with organophilized montmorillonite clay to produce a masterbatch. The masterbatch was then...
A new post functional strategy was developed to prepare polyphosphazenes with a high density of the indole based chromophore (nitro-indole or sulfonyl-indole chromophores) and carbazolyl side groups. Thus polyphosphazene (P1) with carbazolyl and indole groups was first prepared by direct nucleophilic substitution reaction with poly(dichlorophosphazene). Then, polyphosphazenes (P2–P4) containing charge-transporting...
Reactive macromers, consisting of hydrophilic poly(oxyethylene) and hydrophobic poly(oxypropylene) blocks and alternating chloro-triazine linking groups, were prepared from the tri-functional cyanuric chloride and poly(oxyalkylene)-diamines (POA-amines) in a selective manner. Macromers with multiple reactive chlorides could be structurally tailored by varying the ratios of amine/cyanuric chloride,...
In this paper, the results of using a mass spectrometer technique to measure mixed-gas diffusion through polymer films are presented. Mixtures of oxygen, carbon dioxide and nitrogen are diffused through films of polyethylene with different degrees and type of chain branching. It is shown that in the case of pure gases Henry's law applies; the gas concentration is proportional to the partial pressure...
A precise data set describing the kinetics of the free radical copolymerization of acrylamide/acrylic acid (AM/AA) in the range of low total monomer concentration as a function of the pH, total monomer concentration, initiator concentration, and comonomer ratio is presented. Strong impact on the reactivity ratios has been identified for the pH and total monomer concentration. Specifically, at constant...
In injection molded specimens consisting of isotactic polypropylene (iPP)/poly(ethylene-co-octene) (EOR) blends with different viscosity ratio of η(EOR)/η(iPP), the coefficient of linear thermal expansion (CLTE) was investigated by thermal mechanical analysis (TMA). It was found that the blend with a smaller viscosity ratio showed the larger anisotropy of CLTE depending upon the directions. TEM observations...
The influence of platelet-type clay nanoparticle (nanoplatelet) on the structural evolution in injection-molded nylon 6)/carbon composites was investigated. In the absence of nanoplatelets, the nylon 6/CB systems were found to exhibit unoriented structure with nylon 6 crystalline regions exhibiting exclusively α crystal form throughout the thickness of the samples. However, inclusion of nanoplatelets...
A continuous, industrially scalable process called solid-state shear pulverization (SSSP) leads to compatibilization of polystyrene (PS)/high-density polyethylene (HDPE) blends by addition of a commercially available styrene/ethylene–butylene/styrene (SEBS) triblock copolymer. Partial or full compatibilization is characterized by a reduction or elimination of coarsening of the dispersed-phase domains...
The viscoelastic solid model proposed in this work can predict the rheological responses of gelatin gels for finite deformations. This rheological model considers a degree of physical cross-links at a given maturation time, which is partially attained from those links totally available when a pure elastic network is achieved. Thus, both an elastic network formed by permanent links on the average and...
Phase separations in conjugated polymer (MEH-PPV) and non-conjugated polymer (PMMA) blended films are studied by photoluminescent (PL) near-field scanning optical microscope and spectrometer. The morphologies of blended films changed from stripe patterns to isolated islands as PMMA concentrations increased. The PL spectra in isolated micron dots are the same as MEH-PPV. Nevertheless, we found new...
Conducting polymers (CP) obtained by oxidative polymerization using iron(III) salts shrink when Fe(II) and the excess counter ions are washed out after polymerization. This phenomenon can be used to incorporate active molecules into the CP matrix via their addition to the wash liquid. In the present work we demonstrate this principle on three different CP's: polypyrrole (PPy), poly-terthiophene (PTTh)...
Numerous acrylate monomers have been synthesized and evaluated extensively as a means to explore the relationship between molecular polarity and monomer reactivity. Various monomers, characterized by high values of dipole moment, were polymerized in bulk, and no correlation of dipole moment to monomer reactivity was established. Solution polymerization studies were performed on phenyl carbamate ethyl...
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