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ABSTRACT In this study, a novel reactive toughener for the epoxy resin was developed and compared with traditional hydroxyl-terminated polybutadiene (HTPB). For this purpose, the highly reactive aliphatic amine-terminated polybutadiene (ATPB) was synthesized at ambient conditions by nucleophilic substitution amination. The characterizations of the product were provided by Fourier transform infrared and 1H NMR spectroscopy. According to the mechanical test results, incorporation of ATPB into epoxy networks can significantly toughen the epoxy matrix. The addition of 10 phr ATPB increased the critical stress intensity factor ( KIC) and critical strain energy release rate ( GIC) of the epoxy from 0.85 to 2.16 MPa m1/2 and from 0.38 to 3.02 kJ m−2, respectively. Furthermore, unlike HTPB, the presence of the ATPB did not deteriorate the tensile strength of the matrix. The toughening and failure mechanisms were discussed based on the epoxy network morphological characteristics. The reduction in cross-linking density and glass transition temperature of the epoxy system upon modification with liquid rubbers was confirmed by dynamic mechanical analysis. This article opens up the possibility of utilizing reactive flexible diamines with polybutadiene backbone as effective toughening agents for thermoset polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44061. [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]

In this study, biocompatible magnetic FeO/polyurethane elastomer nanocomposites were synthesized using in situ polymerization method. Pure FeO nanoparticles were synthesized by coprecipitation method and characterized by X-ray diffraction, Fourier transform infrared (FTIR), vibrating sample magnetometer and transmission electron microscopy. The chemical structure, thermal properties, and mechanical properties of the FeO/PU nanocomposites, as well as the evaluation of effect of nanoparticles content on thermal and mechanical properties, were studied by FTIR, thermogravimetric analyzer (TGA), dynamic mechanical thermal analysis (DMTA), and tensile analysis. The dispersion and morphology of the nanoparticles in the nanocomposites were studied by scanning electron microscopy (SEM) technique. SEM results confirmed that nanoparticles tend to be more agglomerated in polyurethane matrices with increasing of nanoparticles content. TGA analysis also showed a decrease in the thermal stability of FeO/polyurethane nanocomposites compared to pure polyurethane, which was attributed to disruption of hydrogen bonds between polyurethane chains by FeO nanoparticles. DMTA results also showed an increase in glass transition temperature of FeO/PU nanocomposites compared to pure polyurethane. Biocompatibility studies demonstrated that fabricated nanocomposites can be good candidates for biomedical application. [ABSTRACT FROM AUTHOR]

The novel soluble alginate-based polyurethanes in organic solvents were synthesized by the reaction of NCO-terminated prepolymers and tributylammonium alginate (TBA-Alg) for the first time. The chemical structures of synthesized polyurethanes were characterized using FTIR,1H NMR and TGA. The reaction completion was confirmed by disappearing of NCO band in FTIR spectra. Furthermore, a peak at 4.71ppm and some small peaks at a range of 4.12–4.37ppm in the1H NMR of alginate-based polyurethanes were assigned to the backbone of alginate. The results of both FTIR and1H NMR were remarkably confirmed by TGA data. The ionic nature of polyurethane backbone not only affects on thermal properties of samples, but it also changes the chemically-bonded alginate morphology. Both polyether and polyester based non-ionic polyurethanes extended by TBA-Alg illustrated the distinct alginate, whereas those ionomers extended by alginate were appeared as the continuous systems at nanoscale. [ABSTRACT FROM AUTHOR]

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]

The article presents the conducted study to analyze the chemical structures of the biodegradable polyurethane (PU) elastomers that were synthesized through the reaction of poly(&#x03B5-caprolactone) (PCL) and isophorone diisocyanate (IPDI), which are extended with various mass ratio of chitosan and 1,4-butane diol (BDO). The methods used in the study include the Fourier transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The properties that were examined include crystallinity.

In present research, polypropylene (PP) was selected as a model nonpolar substrate for chemical modification using plasma. In the first step, the PP samples were treated using oxygen and argon atmospheres, individually. The prepared samples were analyzed using both FTIR and AFM techniques. The output of these techniques revealed that the carbonyl, carboxylic acid and its derivatives have been formed on the surface of PP. Afterward, a series of aqueous polyurethane-urea dispersions were synthesized as the novel polar coating for modified nonpolar polymers and characterized by different techniques including FTIR, DSC, TGA, mechanical properties and contact angle. Finally, the plasma treated samples were coated by prepared polyurethane ionomer. The results of pull-off analysis confirmed the significant role of the polyurethane as an extremely polar coating to create hydrogen bonding with functional groups on the surface of treated PP. The adhesion strength of polypropylenes increased from 0.04 MPa to 0.61 MPa for neat and oxygen-based plasma treated samples, respectively. [ABSTRACT FROM AUTHOR]

In this study, a new type of flexible polyurethane foam containing p-tert-butyl thiacalix[4]arene (TC4A) macrocycle was synthesized. TC4A macrocycle was incorporated into polyurethane foam as a part of crosslinking agent as well as glycerol. Structural, morphological, thermal and mechanical properties of this prepared foam were studied and compared with a polyurethane foam based on only glycerol as crosslinking agent, by Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), Thermal gravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The effect of introduction of TC4A crosslinker on cream time, rise time, apparent density, and water absorbency of the PU foams was evaluated. Moreover, it was shown that new TC4A-based polyurethane foam (TC-PUF) can be a high performance adsorbent for removal of malachite green from aqueous media using batch adsorption technique. The adsorption results indicated that TC-PUF has a high adsorption capacity of 58.82 mg/g for malachite green due to the presence of TC4A macrocycles in the structure of polyurethane foam. The kinetics of adsorption of malachite green was also investigated using the pseudo-first-order and pseudo-second-order kinetic models. The results of kinetic studies showed that the adsorption of malachite green onto TC-PUF followed pseudo-second-order kinetic model. [ABSTRACT FROM AUTHOR]

Abstract: This work presents the structural properties of gas permeation of a group of polyurethane membranes. All polymers were synthesized using a 1:3:2 molar ratio of polyol:diisocyanate:chain extender. The obtained results from Fourier transform infrared spectrometer (FT-IR) of polymers indicate that by changing the diisocyanate from aromatic to linear aliphatic, the microphase separation of hard and soft segments increases. Study of the differential scanning calorimetery (DSC) and X-ray diffraction (WAXD) patterns confirmed that PTMG and PCL polyols can be arranged in small crystalline structures. Furthermore, a hard ordered segment in crystal phase could be obtained, owing to the high phase separation of the polymer based on HDI. Permeation measurements of polymers revealed that the permeability of gases increases with microphase separation in polymer and selectivity of gases drops down. Polymers based on PPG showed the highest phase separation and permeability. The obtained results revealed more phase mixing of the polymer based on DMPA chain extender in comparison to BDO, which lead to lower permeability and higher selectivity. The solubility and diffusivity of gases indicate solubility domination of gas transport in these membranes. The observed solubility domination increases by phase separation. The results of permeability tests indicate high permeability, up to 186Barrer (1Barrer=1×10−10 [cm3 (STP) cm/cm2 scmHg]), and high selectivity for carbon dioxide with respect to nitrogen (CO2/N2: 45). Our data sheds light on gas permeation properties of polyurethane membranes. [Copyright &y& Elsevier]

Abstract: The effect of urethane and urea contents on gas separation properties of the groups of polyurethane–urea membranes is studied. The membranes used in this study were prepared by polytetramethylene-glycol (PTMG) and isophorone diisocyanate (IPDI) prepolymers. The prepolymers were converted to final polymer using the designed proportion of 1,4-butane diol (BDO) and 1,4-butane diamine (BDA) as a chain extender. Five different BDO/BDA ratios were chosen in order to synthesize poly(urethane-urea)s with different urethane/urea linkage content. The prepared polymers were characterized and the permeability of gases through them was investigated. Results obtained by Fourier transform infrared spectrometer (FT-IR) and differential scanning calorimetery (DSC) indicate that by increasing the urea linkage in the polymers, the microphase separation of hard and soft segments increase. Study of the X-ray diffraction (WAXD) patterns confirmed that polyols may be arranged in small crystalline structures. Permeation measurements of polymers revealed that the permeability of gases decreases with increasing urethane content in the polymers and selectivity of gases decreases with increasing urea content. The solubility and diffusivity of gases indicate solubility domination of gas transport in these membranes. The results of permeability also show high amounts up to 128Barrer (1Barrer=1×10−10 [cm3 (STP) cm/cm2 scmHg]), and high selectivity for carbon dioxide with respect to nitrogen (CO2/N2: 27). [Copyright &y& Elsevier]