Poly(2,3-dimethylaniline)/nano-Al2O3 composite (PAC) was synthesized by emulsion polymerization using dodecyl benzene sulfonic acid as emulsifier and dopant. The structure of PAC was characterized by Fourier fransformation infrared spectroscopy, UV–visible adsorption spectroscopy, and field emission scanning electron microscopy. The thermal stability was studied by thermogravimetric analysis, and the electrochemical performances were studied by cyclic voltammetry measurements. Epoxy coatings containing PAC and poly(2,3-dimethylaniline) (P(2,3-DMA)), respectively, were painted on steel, and accelerated immersion tests were performed to evaluate the anticorrosion property of the coatings in 3.5% NaCl solution. The results showed that the addition of PAC and P(2,3-DMA) could improve the anticorrosion performance of epoxy coating significantly and the PAC coating had higher corrosion resistance than that of P(2,3-DMA). Copyright © 2013 John Wiley & Sons, Ltd.
]]>In this work, cross-linked poly(1-vinylimidazole) (PVIm) and poly(1-vinylimidazole-co-acrylic acid) [poly(VIm-co-AA)] polyampholytes microgel were synthesized by precipitation polymerization in supercritical carbon dioxide at 14 and 20 MPa. The obtained products were characterized by Fourier transform infrared spectroscopy and Energy-dispersive X-ray spectroscopy. The results indicate that the functional monomers including 1-VIm and AA were cross-linked in polymers successfully. Aggregate particles with diameters of approximately 200 nm were observed by scanning electron microscopy and particle size distribution. Surface area analysis showed that the surface area of microgel prepared at a pressure of 14 MPa are 40.28 m2/g. The swelling behavior of polyampholytes microgel was studied. The cross-linking degrees of PVIm and copolymers can reach 92.6% and 98.1%. The effect of pH values of solution, contact time, adsorbent dosage, initial Cr(VI) concentration on adsorption capacity were also investigated. The results revealed that cross-linked polymer has a high adsorption capacity of 306.0 mg/g for Cr(VI) in 130 mg/l solution at pH 2 and cross-linker ratio of 27.3%. Copyright © 2013 John Wiley & Sons, Ltd.
]]>PVA based hydrogel was synthesised using, as crosslinking agent, trisodium trimetaphosphate (STMP) and its morphology was modified inducing a microporous structure to obtain potential substitutes for cartilage tissue. The hydrogel was characterised by Infrared Spectroscopy combined with Time of flight mass spectrometry (ToF-SIMS) that confirmed the successful occurrence of crosslinking reaction, the hyphotised crosslinking arm and its homogeneous distribution.
The mechanical spectra of the fully hydrated samples confirmed covalently crosslinked systems with a rheological behaviour similar to that of tibial cartilage. Further analysis in terms of water content measurements, thermal stability and cytotoxicity confirmed the applicability of such a hydrogel as cartilage substitute. Copyright © 2013 John Wiley & Sons, Ltd.
This paper proposes a novel evaluation method for three types of velocities of the bending processes of polymer actuators. These velocities are the initial, bending, and backtracking velocities, and the method considers three processes of the bending motion. By calculating the time–width differentiation of the displacement of each process, the initial, bending, and backtracking velocities can be evaluated. Δt of 0.1, 1.0, and 10.0 s were considered to be the differentiations of bending displacement, and the initial, bending, and backtracking velocities were calculated to be 2.15, 0.46, and 0.002 mm/s, respectively. By using the method proposed here, we found that the initial velocity at 75%RH is 2.5 times faster than it was at 45%RH by increasing the adsorption of water. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Nickel ion-imprinted polymer (IIP) was synthesized from dimethylglyoxime and 4-vinyl pyridine monomers. These functional monomers were self assembled with the Ni2+ template and then copolymerized with divinylbenzene and ethylene glycol dimethacrylate crosslinkers in toluene porogen via suspension polymerization. Imprinting was achieved by removing the template ion from the copolymers by extensive washing. The IIP particles produced were 300–700 µm in diameter and were spherical. The chemical and physical structures were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analysis. The adsorption capacity and kinetics, and separation selectivity were investigated using atomic adsorption spectroscopy in batch adsorption operation mode. The Ni2+-imprinted polymers showed excellent adsorption ability and selective separation property. The adsorption capacity for Ni2+ was 320 µmol/g, and the selectivity factors (α) for Cu2+, Zn2+, Fe2+, and Cd2+ were 6, 11, 12, and 27, respectively. The adsorption capacity and separation selectivity were affected by the environmental pH, as the protonation easily took place in acidic condition. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Polymers containing silatrane units were prepared by the free radical polymerization of methacryloylsilatrane (MPS), and their conductivities were evaluated. We confirmed that MPS can be polymerized without excessive decomposition of the silatrane units by the radical polymerization initiated by azobisisobutyronitrile. The chemical structure of the polymerized MPS (pMPS) was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. The pMPS formed a homogeneous complex with lithium trifluoromethyl sulfonate (LiOTf), although the obtained pMPS/LiOTf complex did not show conductivity. The negligible conductivity was caused by the high glass transition temperature (Tg) of the pMPS matrix, which exceeded 70°C. The pMPS was subsequently utilized as a salt-dissociation enhancer for the poly(ethylene oxide)-based polymer electrolyte. MPS was copolymerized with poly[methacryloyl oligo(ethylene oxide)] (pMEO) by free radical polymerization. When the pMEO incorporated a small amount of MPS units (i.e. lower than 15 mol%), the elevation in Tg was not observed, and the conductivity markedly improved. Among the series of copolymers and when compared with pristine pMEO, the copolymer containing 6.3% of MPS units had the maximum conductivity (3.1 × 10−4 S cm−1 at 80°C). The Vogel–Fulcher–Tammann fitting parameters showed that the conductivity was improved by the increase in the number of carrier ions. The enhancement in salt dissociation was presumably due to the homogeneous incorporation of polar MPS units. However, when the MPS unit content exceeded 15 mol%, the conductivity was lowered because of the increase in Tg. Copyright © 2013 John Wiley & Sons, Ltd.
]]>The bio-based shape memory polymers have generated immense interest as advanced smart materials. Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU)/Fe3O4 nanocomposites were prepared by the in-situ polymerization technique. The transmission electron microscopy confirmed the homogeneous distribution of the Fe3O4 nanoparticles in polymer matrix, whereas Fourier transform infrared spectroscopic study revealed the presence of strong interfacial interactions between them. The incorporation of Fe3O4 (0 to 10 wt%) into the HBPU resulted in an increase in tensile strength (5.5–15 MPa) and scratch resistance (3–6 kg). The thermo-gravimetric analysis indicated the improvement of thermal stability (240–270°C) of the nanocomposites. The nanocomposites exhibited full shape fixity, as well as almost full shape recovery under the microwave stimulus. The shape recovery speed increased with the increase of Fe3O4 nanoparticles content in the nanocomposites. Thus, the studied nanocomposites might be used as advanced shape memory materials in different potential fields. Copyright © 2013 John Wiley & Sons, Ltd.
]]>In this study, we introduced photolabile 4-(4-(1-hydroxyethyl)-2-methoxy-5-nitrophenoxy)butyric acid (HMNB) to prepare photoresponsive nanogels. Hyaluronate (HA) grafted with 4-(4-(1-hydroxyethyl)-2-methoxy-5-nitrophenoxy)butyric acid (HA-g-HMNB) was self organized in aqueous solution. Interestingly, HA-g-HMNB nanogels exhibited caging and photo-uncaging properties for an encapsulated antitumor drug. Photoactivation allowed accelerated antitumor drug release from uncaged nanogels. We found a significant improvement in KB tumor-cell-killing efficacy when this system was associated with local light irradiation. Copyright © 2013 John Wiley & Sons, Ltd.
]]>The present study deals with preparing stimuli-responsive poly N-isopropyl acryl amide/chitosan (PNCS) nano hydrogel and looks into their effects as a surface modifying system of cotton fabric. The semi-batch surfactant-free emulsion polymerization method was proposed to reduce the size of particle and synthesis of PNCS nano particles. Fourier transform infrared, nuclear magnetic resonance, differential scanning calorimetry, scanning electron microscopy and dynamic light scattering methods confirmed the nano size of synthesized PNCS particles and sensitivity of these nano particles to the different temperature and pH, respectively. The water retention capacity (WRC) and carboxyl content of modified cotton with PNCS nano particles were assessed through the central composite design. The bounded PNCS nano particles to the surface of cotton fabrics made them responsive to these dual stimuli. The results demonstrated the dual effect of BTCA amount on WRC. Increase of the amount of BTCA itself led to the decrease of the WRC of modified cotton, but in the presence of PNCS, WRC was significantly increased. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Novel biobased crosslinked polymer networks were prepared from vegetable oil with 2,5-furan diacrylate as a difunctional stiffener through UV photopolymerization, and the mechanical properties of the resulting films were evaluated. The vegetable oil raw materials used were acrylated epoxidized soybean oil (AESO), acrylated castor oil (ACO), and acrylated 7,10-dihydroxy-8(E)-octadecenoic acid (ADOD). 2,5-Furan dicarboxylic acid (FDCA), which can be synthesized through the oxidative dehydration of C6 sugars, was identified by the US Department of Energy as one of 12 priority chemicals for establishing the green chemistry industry of the future. 2,5-Furan dimethanol (bis-hydroxymethylfuran), which can be derived from FDCA, was used as a starting material to synthesize 2,5-furan diacrylate, which was used as a biobased comonomer along with AESO, ACO, or ADOD to form photo-crosslinked polymer networks. The synthesis of acrylate derivatives was confirmed using FT-IR and 1H-NMR spectroscopic techniques. The composition of the reaction mixture was changed to obtain crosslinked polymer networks with various mechanical properties. The addition of 2,5-furan diacrylate increased the tensile strengths of the polymer films by up to 1.4–4.2 times relative to those obtained without the addition. These fully biobased polymers derived from vegetable oil and sugar can be used as environmentally friendly renewable materials for various applications to replace the existing petroleum-based polymers currently used. Copyright © 2013 John Wiley & Sons, Ltd.
]]>A series of novel optically active poly(ester-imide)s (ter-PEIs) with high glass transition temperature (Tg), good thermal stability, and solubility were successfully designed and synthesized by direct polycondensation reactions, using p-hydroxybenzoic acid (PHB), 4,4’-dihydroxybenzophenone, and a chiral diacid, N,N'-(pyromellitoyl)-bis-L-phenylalanine diacid as monomers. The resulting terpolymers were characterized by1H-NMR, FTIR, element analysis, thermogravimetric analysis, different scanning calorimeter and wide-angle x-ray diffraction, etc. The ter-PEIs are amorphous polymers with good heat resistance and high Tgs. They are soluble in many common polar organic solvents and show optically rotation property. The specific rotation values of the ter-PEIs increase with the molar ratio of the chiral diacid, and the rigid PHB monomer is beneficial to increase the Tgs of the polymers. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Considering the application potentials of organic materials possessing both conducting and ferromagnetic functions in various electronic devices, an attempt was made to prepare conducting polyaniline (PANI) layered magnetic nano composite polymer particles. Two routes were used to modify magnetic Fe3O4 core particles. In one route, seeded emulsion polymerization of methyl methacrylate (MMA) was carried out in presence of nano-sized Fe3O4 core particles. In another route, cross-linker ethyleneglycol dimethacrylate (EGDM) was used in addition to MMA. The modified composite particles were named as Fe3O4/PMMA and Fe3O4/P(MMA-EGDM), respectively. Finally, seeded chemical oxidative polymerization of aniline was carried out in the presence of Fe3O4/PMMA and Fe3O4/P(MMA-EGDM) composite seed particles to obtain Fe3O4/PMMA/PANI and Fe3O4/P(MMA-EGDM)/PANI composite polymer particles. The modification of Fe3O4 core particles was confirmed by electron micrographs, FTIR, UV–visible spectra, X-ray photoelectron spectra, X-ray diffraction pattern and thermogravimetric analyses. A comparative study showed that crosslinking of intermediate shell improved the magnetic susceptibility and electrical conductivity of PANI layered magnetic nano composite particles. Copyright © 2013 John Wiley & Sons, Ltd.
]]>New forms of hybrid multiaxial nanocomposites with enhanced mechanical and stab resisting properties are presented. This study is motivated by the lack of knowledge in the study of the multiaxial fabric nanocomposites with two modified thermoplastic matrices for antiballistic protection. Introduction of 5 wt.% silica nanoparticles in the composite of polyurethane/p-aramid/poly (vinyl butyral) leads to significant improvement in mechanical properties, and the addition of silane as a coupling agents and glutaraldehyde as a crosslinking agents yielded maximal values of storage modulus, tensile modulus and anti-stabbing properties for hybrid nanocomposites. Ballistic resistance testing and penetration depth of the hybrid nanocomposites were visualized using image analysis. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Nowadays, there is a growing availability of biodegradable industrial materials intended to food contact applications whose service life behavior needs to be further investigated. This article is focused on the degradation of two materials based on polylactic acid. The correlation between the rate of degradation and the amount of trapped degradation products was investigated applying three characterization techniques in parallel, namely rheology, high-performance liquid chromatography (HPLC), and matrix-assisted laser desorption/ionization (MALDI). The rate of degradation was studied through the evaluation of their rheological properties and calculation of the number of average molecular weights, and weight-average molecular weights. Water-soluble oligomers and lactic acid were quantified by HPLC-ultraviolet. Changes in cyclic and linear oligomers were monitored by MALDI-time-of-flight mass spectrometry. Specimens of 4-mm thickness of each biopolymer were subjected to hydrolysis in deionized water up to 6 months at two temperatures, simulating service conditions of food packaging. The diminution in viscosity and consequently in molecular weight distribution (20–60%) showed the degradation of the molecular structure of both polylactic acids. The chain scission was followed through the increasing values of lactic acid and hydrolyzed oligomers (twofold to eightfold), and the predominant signal of the linear oligomers over the cyclic ones with aging. Rheology, HPLC, and MALDI showed to be complementary tools to better understand the changes in the molecular structure. The obtained results showed the necessity of adding suitable stabilizers for each particular food packaging application. Copyright © 2013 John Wiley & Sons, Ltd.
]]>This paper discusses results of the pulse width modulation (PWM) control of the bending displacement and force generation of ionomer-based polymer actuators. The idea of PWM control for polymer actuators is based on the frequency dependence on relaxation processes of the bending motion of the actuator. The actuators were fabricated by electroless plating of platinum on a perfluorinated sulfonated polymer (i.e. Nafion). It was noted that the duty cycles of PWM can smoothly control both the displacement and force generated by the actuator. The performance of the actuator was evaluated under 40%RH and 90%RH conditions because of the moisture sensitivity of the actuators. Copyright © 2013 John Wiley & Sons, Ltd.
]]>The synergistic effect of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) immobilized silica (SiO2-DOPO) nanoparticles with an intumescent flame retardant (IFR) on the flame retardancy of polypropylene (PP) was investigated by UL 94 vertical tests and limiting oxygen index (LOI) measurements. It was found that the PP/IFR composites (25 wt%) achieved the UL94 V0 grade and LOI increased to 32.1 with an incorporation of 1.0 wt% SiO2-DOPO nanoparticles. Based on thermogravimetric analysis, scanning electronic microscopy and rheological analysis, it is speculated that three factors are mainly contributed to the improvement of the flame retardancy. First, the thermal stability of PP/IFR composites was improved by incorporating SiO2-DOPO nanoparticles. Second, the presence of SiO2-DOPO nanoparticles could induce the formation of a continuous char skin layer during combustion. The compact char layer could effectively impede the transport of bubbles and heat. Third, rheological analysis indicated that SiO2-DOPO nanoparticles could increase viscosity of the PP/IFR composites, which was also benefited to increase flame retardancy. Copyright © 2013 John Wiley & Sons, Ltd.
]]>In this study, the mechanical properties and non-isothermal degradation kinetics of polypropylene (PP), high-density polyethylene (HDPE) with dilauroyl peroxide and their blends in different mixture ratios were investigated. The effects of adding dilauroyl peroxide (0–0.20 wt%) on the mechanical and thermal properties of PP + HDPE blends have been studied. On the other hand, the kinetics of the thermal degradation and thermal oxidative degradation of PP + HDPE (80/20 wt%) blends were studied in different atmospheres, to analyze their thermal stability. The kinetic and thermodynamic parameters such as the activation energy, Ea, the pre-exponential factor, A, the reaction order, n, the entropy change, the enthalpy change, and the free energies of activated complex related to PP, HDPE, and blend systems were calculated by means of the several methods on the basis of the single heating rate. A computer program was developed for automatically processing the data to estimate the reaction parameters by using different models. Most appropriate method was determined for each decomposition step according to the least-squares linear regression. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Polypropylene (PP) can hardly be reinforced by the layered silicate montmorillonite (MMT), but the material fatigue appears somewhat reduced. The probable reason is amplified competitive nucleation of the PP by MMT component. Utilizing small-angle X-ray scattering (SAXS) from synchrotron, we investigate the nanostructure evolution of the PP in straining experiments from neat PP and compatibilized composite materials. The compatibilizer is a styrene–ethylene/butylene–styrene copolymer (SEBS). Oriented injection-molded test bars are studied.
The discrete SAXS probes variations of sizes and distances among those crystalline domains that are not placed at random. Crystallite dimensions and distances are documented for modeling purposes. The nanoscopic strain is computed from the distance variation and compared with the macroscopic strain. Differences between macroscopic and nanoscopic strain are observed. They require postulating regions with statistical placement of crystallites (poorly arranged region, PAR) in addition to the SAXS-probed well-arranged semi-crystalline entities (WAE). The extensibility of WAEs must be different from that of the PARs. In neat PP, the observed WAEs are well developed and stronger than the PARs. In the composites, the WAEs are made from thin and less extended crystalline domains. They are weaker than the PARs that appear reinforced. Thus, enclosing each MMT layer a PAR is formed, and the WAEs generated farther away remain imperfect. Consequently, in the composites, the narrow crystalline domains from the WAEs do not break into even smaller pieces, and the fatigue of the composites is lower than that of the neat PP. Copyright © 2013 John Wiley & Sons, Ltd.
Conducting nanofibers coated with polypyrrole (PPy) and poly(3-hexylthiophene) (P3HT) exhibiting core-sheath structures were prepared by vapor-phase polymerization of the conducting polymers on electrospun polyurethane nanofibers. The synthesis of the conducting polymers was confirmed by Fourier transform infrared spectroscopy and energy-disperse X-ray spectroscopy. The surfaces of the PPy-coated nanofibers were slightly rough, while very smooth and regular surfaces were observed in the case of the P3HT-coated nanofibers. The initial polymerization rate of PPy was higher than that of P3HT. In addition, the electrical conductivities of the core-sheath structured nanofiber webs of both types increased with polymerization time. The maximum sheet conductivity of the PPy and P3HT-coated nanofiber webs was 5 × 10−3 S/cm and 1 × 10−2 S/cm, respectively. The webs of the conducting core-sheath structured nanofibers were effective in generating sufficient electrical heating necessary for harnessing these materials for electroactive shape-memory-based applications. Copyright © 2013 John Wiley & Sons, Ltd.
]]>The swelling with supercritical carbon dioxide (sc-CO2) of thin films of polyimides having various structures was investigated. It was shown that the degree of swelling is significantly influenced by the solvent which was used for the synthesis of those polyimides, by the solvent which was used for the preparation of thin films and by the conformational rigidity of the polymers. The presence of hexafluoroisopropylidene groups in the main chain of a polymer prevents its swelling with sc-CO2. The best results were obtained for polyimide film ULTEM, based on m-phenylene-diamine and isopropylidene-diphenoxy-bis(phthalic anhydride), synthesized in benzoic acid, whose free volume increased twice and its dielectric constant decreased from 3.15 to 2.45 by swelling with sc-CO2. Copyright © 2013 John Wiley & Sons, Ltd.
]]>A shape memory thermoset comprising of a co-reacted system of epoxy resin (diglycidylether of bisphenol A), cyanate ester (bisphenol A dicyanate ester) and phenol telechelic poly(tetramethylene oxide) (PTOH) was investigated for its morphology, viscoelasticity and shape memory characteristics at the transition temperature regime. The system exhibited a switching temperature (Tswitch) centered at about 105°C. Atomic force microscopy analyses at different temperatures provided evidences for the existence of a discrete phase at Tswitch regime. Polarized light microscope images gave evidence for the birefringence and tubular crystal formation due to PTOH segments in the shape memory thermoset. It is concluded that the Tswitch has its origin from melting transition of PTOH and Tg of the thermoset matrix, the latter being lowered through plasticization by PTMO segments. Reversibility of Tswitch, and stress relaxation behavior of the blend were investigated by dynamic mechanical analysis (DMA). The reversibility of transition temperature was ascertained by cyclic DMA. Temperature dependency of shape memory properties implied fast recovery of original shape above the Tswitch. The cured system manifests shape memory properties even below Tswitch though it is a slow process. The extent of shape recovery increased with temperature and became faster in league with the trend in temperature dependency of stress relaxation of the polymer. Copyright © 2013 John Wiley & Sons, Ltd.
]]>We present here the effect of degradation on electronic properties of polymer solar cells. Investigations were performed on two types of solar cells based on the bulk-heterojunction network of poly(3-hexylthiophene) and phenyl [6,6] C61 butyric acid methyl ester, one with slow degradation whereas other with faster degradation. Samples were prepared in identical conditions with controlled atmosphere, but for faster degradation, one of the samples was exposed to ambient air (rich in O2 and H2O molecules) before deposition of top metal electrode. The sample with slow degradation showed linear degradation in short circuit current density (Jsc), whereas the sample with faster degradation exhibited exponential degradation in Jsc. Linear degradation happens due to degradation in the active layer only whereas the exponential degradation is because of through degradation of the solar cell. The effect of degradation is investigated on different diode parameters. Because of different degradation processes in the two samples, the variations in diode parameters with time are different. Copyright © 2013 John Wiley & Sons, Ltd.
]]>To reduce both the cost and the environmental impact of copper-based thermal solar absorbers, we have investigated their possible substitution by bio-based conductive polymer nanocomposite (CPC) elements. Our results show that carbon nanotubes (CNT) have no significant influence on polymers’ calorimetric properties such as Tm and Tg but lead to a strong increase in crystallinity of poly(lactic acid) (PLA) and to a lesser extent of poly(amide 12) poly(amide 12) (PA12) for 2 and 3 CNT wt % respectively. Percolation thresholds as low as 0.5 and 0.58 were obtained for PA12 and PLA, respectively, and visco-elastic properties such as η*, G’ and G” were found to increase exponentially with CNT content confirming the formation of a CNT network within the matrix. All CPC are absorbing more energy in the visible and infrared than in the ultraviolet wavelength ranges. Finally, the thermal conductivity k of PLA–CNT and PA12–CNT were increased, respectively, of 85% and 24%, to reach 0.28 W.m−1.K−1 and 0.26 W.m−1.K−1, for only 5 wt% CNT. The figure of merit suggests that PA12 is the polymer which satisfies at best all criteria, particularly combining a lower viscosity at almost equivalent thermal conductivity and absorptivity. Copyright © 2013 John Wiley & Sons, Ltd.
]]>α-zirconium phosphate (ZrP) (prepared by both reflux and hydrothermal methods) is silylated with chlorotrimethylsilane and characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Polystyrene/silylated-ZrP composites show higher thermal stability as the ZrP content increases. Cone calorimetry suggests that the reduction of the peak heat release rate of polystyrene (PS)/ZrP composites does not increase as the ZrP loading increases; the aspect ratio of ZrP has little effect in fire performance of PS/ZrP composites. Copyright © 2013 John Wiley & Sons, Ltd.
]]>A novel organophosphorus containing spiro and caged bicyclic phosphate, 3,9-Bis-(1-oxo-2,6,7-trioxa-1-phospha-bicyclo[2.2.2]oct-4-ylmethoxy)-2,4,8,10-tetraoxa-3,9-diphospha-spiro[5.5]undecane 3, 9-dioxide (SBCPO), was synthesized and characterized by Fourier transform infrared (FTIR), hydrogen-1 nuclear magnetic resonance (NMR) and phosphorus-31 NMR. The flame retardancy of polypropylene (PP) containing the novel intumescent flame retardant (IFR) based on the combination between SBCPO and melamine (MA) was studied by limiting oxygen index (LOI), UL-94 test and cone calorimeter test. Results indicated that this combination showed the excellent flame retardancy for PP at appropriate proportions (with the total loading of 30 wt. % and SBCPO: MA = 4:1). The value of LOI was as high as 31.6, and the rating in UL94 reached to V-0. Moreover, the HRR and THR of IFR/PP decreased significantly in comparison with that of neat PP. The scanning electron microscopy results indicated that the incorporation of SBCPO could induce the formation of intumescent char layer, which retarded the degradation and combustion process of PP. The thermal oxidative degradation of the PP samples at different temperature was analyzed by FTIR. The thermal stabilities of the composites were further investigated by thermogravimetric analysis. It was found that the amount of residues was increased greatly with the addition of SBCPO that remained in the form of polyaromatic stacks and phosphoric or polyphosphoric acid at the residual chars. Copyright © 2013 John Wiley & Sons, Ltd.
]]>In the present work, a new porous low density lipoprotein (LDL) adsorbent membrane is prepared by 60Co γ-ray irradiation-induced grafting copolymerization of polypropylene (PP) non-woven fabric with acrylic acid, followed by immobilizing heparin covalently. The amount of carboxyl group and heparin on the resultant PP non-woven fabric is determined by titration and colorimetry, respectively. The new adsorbent membrane is characterized by attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscope, and contact angle microscopy. Static adsorption and hemoperfusion tests indicate this new adsorbent can efficiently and selectively remove LDL from human plasma. Meanwhile, good adsorption of triglyceride (TG) is also obtained. The best result is achieved by the adsorbent membrane P0.45-A15-H, where 33.3 ± 2.9 µg of LDL-C, 14.7 ± 1.9 µg of high density lipoprotein cholesterol (HDL-C), 64.9 ± 4.3 µg of total cholesterol (TC), and 202.4 ± 5.7 µg of TG are removed from human plasma per square centimeter. Hemocompability and toxicity tests show this new adsorbent membrane has good blood compatibility and low toxicity. Considering the adsorbent performance, safety, low cost, and simple preparation, this new adsorbent membrane has potential clinical application for removal of LDL. Copyright © 2013 John Wiley & Sons, Ltd.
]]>Composites of nanostructured polyaniline (PANI) conducting polymer in a polyester acrylate (PEA) formulation were made to provide conductive organic coatings. The effect of the presence and amount of PANI on the photocuring performance of the ultraviolet (UV)-curable acrylate system has been investigated employing real-time Fourier transform infrared spectroscopy as the main technique. Longer initial retardation of the radical polymerization and lower rates of cross-linking reactions were observed for dispersions containing PANI of higher than 3wt.%. The PEA/PANI samples were more affected than the neat PEA resin by the changes in UV light intensity and oxygen accessibility during UV curing. Samples with higher PANI content, of up to 10wt.%, were tested and could be partially cured even at UV light intensities as low as 2 mW cm−2 when the oxygen replenishment into the system was inhibited. Thermal analysis revealed that the presence of PANI did not induce any significant change in Tg of the cured system, meaning that early decrease in mobility and vitrification is not the reason for lower ultimate conversion of the dispersions with higher PANI content compared with the neat PEA resin. Curing under strong UV lamps, of 1.5 W cm−2 intensity, made it possible to reach high degrees of conversion on films with similar mechanical properties independent of the PANI content. Copyright © 2013 John Wiley & Sons, Ltd.
]]>The analysis on the recovery performance and characteristics in shape memory effects is helpful for the optimal design and engineering applications of shape memory polymers and their composites. To investigate the relationships among recovery performance, material parameters, and loading conditions, by taking aliphatic polyether urethane as an example, the researchers simulate the shape memory behaviors numerically using a three-dimensional viscoelastic model. The material parameters for this model are taken from stress relaxation tests, rather than dynamic mechanical analysis tests. Both the unconstrained and the constrained recovery behaviors during strain-controlled shape memory processes are analyzed. The results reveal that the unconstrained recovery occurs at the same temperature regardless of the applied strain values. Another interesting result is that the shape recovery temperature in unconstrained recovery situations increases and the maximum recovery stress under constrained recovery conditions decreases with the increase of heating rates. Copyright © 2013 John Wiley & Sons, Ltd.
]]>The polyzwitterionic brushes comprised of poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC) segments, which are used for surface modification of polymers and biocompatible coatings, were investigated. In this work, reverse surface-initiated atom transfer radical polymerization (RATRP) of zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) is employed to tailor the functionality of graphene oxide (GeneO) in a well-controlled manner and produce a series of well-defined hemocompatible hybrids (termed as GeneO-g-pMPC). The complexes were characterized by FT-IR, XRD, and Raman. Results show that MPC has been coordinated on the graphene oxide sheet. Thermal stability of the nanocomposites in comparison with the neat copolymer is revealed by thermogravimetric analysis and differential thermal analysis. Scanning electron microscopy and transmission electron microscope images of the nanoconposite displays pMPC chains were capable of existing on GeneO sheet by RATRP. The biocompatibility properties were measured by plasma recalcification profile tests, hemolysis test, and MTT assays, respectively. The results confirm that the pMPC grafting can substantially enhance the hemocompatibility of the GeneO particles, and the GeneO-g-pMPC hybrids can be used as biomaterials without causing any hemolysis. With the versatility of RATRP and the excellent hemocompatibility of zwitterionic polymer chains, the GeneO-g-pMPC nanoparticles with desirable blood properties can be readily tailored to cater to various biomedical applications. Copyright © 2013 John Wiley & Sons, Ltd.
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