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Di- and triblock copolymers of poly(ethylene oxide) (PEO) and poly(dl-valine-co-dl-leucine) were synthesized by ring-opening polymerization of N-carboxyanhydride (NCA)s of dl-valine and dl-leucine initiated by amine-terminated PEOs. The resulting block copolymers were characterized by 1HNMR, FT-IR, DSC, and wide-angle X-ray diffraction (WAXD). Differential scanning calorimeter revealed that the melting...
A mixed biopolymer gel, consisting of a protein (gelatin) and polysaccharide (maltodextrin) mixture has been investigated. By controlling the composition it was possible to construct an ‘emulsion-like’ structure, with included spherical particles of one phase (maltodextrin) within a continuous matrix of the second (gelatin). Large strain deformation and failure behaviour of this system has been examined...
Some kinds of sugar and amino acid are used to interact with polyaniline emeraldine base in neutral aqueous solution. PANI complexed with these molecules shows interesting induced circular dichirom (ICD) spectra, which indicates that excess one-handed helical structure is induced on PANI. Furthermore, opposite ICD spectra are observed for PANI while it is interacted with l- and d-amino acid, respectively...
The effect of cooling rate on crystallization and subsequent aging of high stereoregular poly(lactide) (PLA) blended with poly(ethylene glycol) (PEG) was studied by thermal analysis and by direct observation of the solid state structure with atomic force microscopy (AFM). Blending with PEG accelerated crystallization of PLA. When a PLA/PEG 70/30 (wt/wt) blend was slowly cooled from the melt, PLA crystallized...
Polyurethane (PU) resins having different degree of cross-linking were prepared by the reaction of 4,4′-methylenebis(phenyl isocyanate) (MDI) with various molar ratio of two kind of pentaerythritol ethoxylates (PEE15, ratio of ethyleneoxy (EO) unit/hydroxyl (OH) unit=15/4; PEE3, EO/OH=3/4) in the presence of cobalt(II) chloride at 100 °C for 48 h. Metallization behavior of the CoCl 2 -containing...
We report experimental observations on the drastically enhanced toughness in the high-strength and high-modulus ultrahigh molecular weight polyethylene (UHMWPE) films due to the addition of 1wt% multiwalled carbon nanotubes (MWCNTs). A combination of tensile and Raman spectroscopic measurements showed that the presence of MWCNTs in the composites can lead to a ∼150% increase in strain energy density...
Small-angle X-ray scattering and wide-angle X-ray scattering studies were carried out for perfluorinated sulfocationic membranes MF-4SK (membranes of a Nafion type) in the normal ‘as-manufactured’ state and soaked in ethylene glycol at 110 °C and subsequently washed with water. It was shown that such a treatment of MF-4SK membranes resulted in alterations of their nanostructure and these alterations...
The effects of clay dispersion and the interactions between clays and polymer chains on the viscoelastic properties of polymer/clay nanocomposites are investigated using oscillatory shear rheology, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Four different montmorillonite silicates of natural clays, plasma-treated clays, and organically...
The long-range order of some bioerodable polyesteramides based on a desaminotyrosyl [Thermochim Acta 396 (2003) 141; Polym Adv Technol 13 (2002) 926; J Am Chem Soc 119 (1997) 4553] diol monomer has been investigated. The order is mesogenic, best described as a ‘condis crystal’ or smectic-like. In all cases where long-range order is present, ordered H bonds between amide groups are observed. The order...
A novel electrically conducting polymer consisting of selenophene moiety, poly(biselenophene) (PBSE) was generated by chemical and electrochemical polymerization. This polymer gave lower bandgap energy (1.9eV) than pristine polyselenophene (2.0eV). The electrochemical and optical properties of PBSE was investigated by UV–Vis near infrared spectroscopy and electrochemistry. In situ electrochemical...
We have studied the effect of shear rate on the very early stages of poly(ε-caprolactone) crystallization with in situ rheology and ex situ optical microscopy. The effect of shear rate is mainly to increase the nucleation density and to speed-up the crystallization process. Thermally-induced crystallization is separated from strain-induced crystallization allowing the construction of a ‘master curve’...
The catalytic reaction of the melt transesterification of diphenyl carbonate (DPC) and bisphenol-A (BPA) is investigated theoretically. A reaction mechanism based on the nucleophilic substitution on the carbonyl group of reactants is proposed for the description of the kinetic behavior of the reaction under consideration. Previous models are extended so that the kinetic model derived is not only more...
Silica nanoparticle-filled poly(ethylene 2,6-naphthalate) (PEN) composites were melt-blended to improve the mechanical and rheological properties of PEN. The melt viscosity and total torque values of the composites were reduced by the silica content. The crystallization exothermic peak shifted to a higher temperature, and the overall crystallization time was reduced by increasing the silica content...
Epoxy composites based on aligned CVD-grown multi-wall carbon nanotubes with weight fractions ranging from as low as 0.001 up to 1wt% were produced. The resulting electrical properties were analysed by AC impedance spectroscopy. The composite conductivity σ follows a percolation scaling law of the form σ∝(p−p c ) t with the critical mean concentration p c to form a conductive...
In this study, an addition–fragmentation chain transfer agent bearing dithioester group is synthesized and applied to conventional dispersion photopolymerization of styrene in ethanol medium in the presence of poly(N-vinylpyrrolidone) stabilizer with varying amounts of the RAFT agent and optionally with conventional initiator, azobisisobutyronitril (AIBN) at various temperatures. Monomer conversion,...
The photophysics of the hydrogen-bonded (HB) state and the protonated (PR) state of a photosensitizer, 2,6-bis(4′-diethylaminobenzylidene)cyclopentanone (DBC) in a polymer matrix containing carboxyl groups was investigated by fluorescence spectroscopy and decay curve analysis. The fluorescence spectrum of the excited DBC HB with the carboxyl unit was composed of emission from two species peaking at...
We investigate the simultaneous effect of pressure P and shear flow on the crystallization process of polypropylene using a modified pressure–volume–temperature measurement system that has been developed in our laboratory. We focus on the inverse of half-conversion time 1/t 1/2 that is defined by the inverse of the time when the relative crystallinity of system reaches to one half. It is found...
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