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In order to provide more insight into the effect of core functionality on hyperbranched polymer characteristics, two series of hyperbranched polyesters ( HBPEs) were synthesized by reacting 2,2-bis(methylol)propionic acid (bis- MPA) as AB2 monomer with both dipentaerythritol ( DPE) and pentaerythritol as six ( B6)- and four ( B4)-functional core molecules. The molar mass, composition and structure of HBPEs were determined with respect to the negative substitution logic and monomer self-condensation effect. The molar masses and structures of HBPEs containing DPE core were less influenced by the negative effect of a reacted hydroxyl group on the reactivity of other hydroxyl groups in the same monomer unit. Thus, the use of DPE core in copolymerization with bis- MPA monomer could help slightly to increase the molar mass of HBPEs. Conversely, the effect of self-condensation of bis- MPA on the molar mass reduction was more pronounced in the case of DPE hyperbranched polymers due to the A-B negative substitution effect. These two effects become more significant with increasing pseudo-generation numbers of the HBPEs. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A series of polyurethane elastomers ( PUEs) derived from three thiacalix[4]arene derivatives ( TC4As), namely p-tert-butylthiacalix[4]arene, tetrasodium thiacalix[4]arenetetrasulfonate and thiacalix[4]arenetetrasulfonic acid, as a portion of chain extender in a mixture with glycerol were synthesized. The effects of the chemical structure of TC4As used as chain extenders on the various properties of the prepared PUEs were investigated and compared with PUE extended with only glycerol as chain extender using Fourier transform infrared ( FTIR) spectroscopy, differential scanning calorimetry ( DSC), thermogravimetric analysis ( TGA), X-ray diffraction ( XRD), scanning electron microscopy and a universal tensile tester. Moreover, the effect of the introduction of TC4As as a portion of chain extender on the hydrophobicity of the PUEs was also evaluated. DSC, FTIR spectroscopy and XRD revealed that the degree of phase separation and crystallinity in TC4A-based PUEs was much higher than that of the glycerol-based ones. Thus, it was concluded that the presence of TC4As in TC4A-based PUEs seems to favour the formation of a more ordered structure due to an increase in the degree of phase separation. The TGA results also showed that, with incorporation of TC4As into the polyurethane backbone, the thermal stability of PUEs was improved. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: In this study, superparamagnetic thiodiglycol coated Fe3O4 nanoparticles (TDG-Fe3O4) were synthesized using in situ coprecipitation method in alkali media and were characterized by XRD, FTIR, TGA, VSM, TEM, and SEM. TGA and FTIR results confirmed the binding of thiodiglycol onto the surface of Fe3O4 nanoparticles. XRD pattern showed the presence of peaks corresponding to the inverse spinel structure of Fe3O4 nanoparticles. In addition, the magnetic properties of nanoparticles determined by VSM exhibited TDG-Fe3O4 nanoparticles that have superparamagnetic property with high enough saturation magnetization of 44.55emu/g. TEM and SEM results showed that TDG-Fe3O4 nanoparticles have good dispersion and are smaller and less agglomerated than pure Fe3O4 nanoparticles due to reduction in attractive forces between the nanoparticles by thiodiglycol. Additionally, the result of DTG analysis of TDG-Fe3O4 nanoparticles suggested that thiodiglycol molecules were bonded to the surface of the Fe3O4 nanoparticles with different binding modes. [Copyright &y& Elsevier]

The effect of structural chemistry of different soft segments on various structural properties of polyurethane-urea (PUU) elastomers was evaluated in this study. A series of PUU elastomers were prepared by the reaction of 4,4'-diisocyanato dicylohexylmethane (H12MDI) with polycaprolactone (PCL), Polytetramethylene glycol (PTMG), Polyethylene glycol (PEG), Polybutylene adipate (PBA) and amine chain extender 4,4'-methylenebis(2,6-diethylaniline) (MBDEA). Fourier transform infrared (FTIR) spectroscopy was used to study the synthesis of final PUU elastomers. Thermal behaviour of PUU elastomers was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The surface properties and hardness of elastomers were characterized by measuring contact angle and hardness in shore A scale. The results showed highest thermal stability and hydrophobicity of PUPCL i.e., Polycaprolactone polyol based PUU elastomer. The proposed synthesis of PUU elastomers was confirmed by the appearance of -NH peak at 3305-3315 cm-1 and disappearance of -NCO peak at 2270 cm-1 in FTIR spectra. [ABSTRACT FROM AUTHOR]

Phase morphology and rheological behavior of polyamide 6 (PA6)/acrylonitrile butadiene styrene (ABS) polymers blends was studied using scanning electron microscopy and rheometry. The results showed that the phase morphology and rheological properties depends on blend composition. We evaluated the effect of addition of ABS as dispersed phase and EnBACO-MAH (ethylene n-butyl acrylate carbon monoxide maleic anhydride) as a compatibilizer on the morphological and rheological behaviors of PA6/ABS blends. It was concluded that there is a good agreement between the results obtained from rheological and morphological studies. As a consequence, addition of the ABS and compatibilizer weight percent led to a significant change in morphological structure and a great mounting in the viscosity as well as the elasticity. The rheological properties results demonstrate that adding compatibilizer to polymer blends led to increasing the crossover point, which shows a transition from a high viscous to a considerably more elastic behavior. Also, the slow transition of relaxation time peak from the peak of the PA6 to the peak of the ABS implies increasing the miscibility of the PA6/ABS blend components by increasing compatibilizer content. In addition, the Carreau-Yasuda model was used to extract information on rheological properties (zero shear viscosity and relaxation time) for PA6/ABS/EnBACO-MAH blends by fitting the experimental data with this model. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

In this study, segmented polyurethane/clay nanocomposites were prepared via in situ intercalative polymerization of polyether polyol mixed nanoclay with toluene diisocyanate, followed by chain extending with 1,4-butanediol. The reactive prepolymer tended to gel by increasing the clay content from 0.4 to 1.5 wt.%. This unusual phenomenon was found to be caused by a catalytic effect of quaternary ammonium intercalant on the organoclay. The procedure used for intercalated nanocomposites, is confirmed by wide angle X-ray diffraction studies. Thermogravimetric analysis results demonstrated a very good increase in onset degradation temperature by adding only 0.8 wt.% of organoclay. [ABSTRACT FROM AUTHOR]