bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheological studies of uncured epoxy–organoclay nanocomposite coatings
Authors: Zaarei Davood , Sarabi Ali Asghar , Sharif Farhad , Kassiriha Seyed Mahmoud , Gudarzi Mohsen Moazzami
Published: August 2014

We investigated the influence of loading two different types of organoclay on the linear viscoelastic properties of an uncured epoxy nanocomposite coating. Meanwhile, the effect of sonication in the dispersion process on the characteristics of nanocomposite has been studied. To achieve fully dispersed structures of clay-epoxy, we applied high shear mixing and high-intensity ultrasound during the synthesis of clay-epoxy nanocomposites.The flow properties of the compositions with clay loadings more than 4 wt% of low CEC quaternary ammonium modified clay, as analyzed by rheomechanical spectroscopy (RMS), showed a solid-like behavior. While the neat resin system exhibited Newtonian flow, some nanodispersed coatings exhibited pseudo plastic flow behavior, typical of polymeric fluids such as gels and pastes. With varying the type of the clay the resultant coatings exhibited a storage modulus ranging from 0.01 to over 400 Pa and a loss modulus ranging from 4 to over 200 Pa. Moreover, the complex viscosity was ranging from 12 to 1100 Pas as the clay loading increased from 0 to 8wt %. The strong increase in modulus of one type of the clays was due to the mainly intercalated and dispersed silicate platelets. The increase rate in storage modulus of these compositions decreased at higher organoclay loadings and was not linear. These results can lead to the prediction of film formation properties and application conditions of these nanocomposite coatings
Assessment of protective effect of polycation on plasmid DNA attached on the metal surface by SPR
Authors: Bao Junbo , Song Cunxian
Published: August 2014

Surface modification of the metal is a critical procedure for gene therapy on the metal implants, such as stent and artificial joint. Polycations can condense with DNA by self-assembly, form polyplexes spontaneously as a result of electrostatic interactions and protect DNA from degradation by DNase. The ability of chitosan, polyethyleneimine (PEI), and poly(amidoamine) (PAMAM) dendrimers to condense plasmid DNA(pDNA) was determined by electrophoresis, X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance (SPR). Polycation’s attachment of pDNA to the metal surface was confirmed by XPS which showed no phosphorus peaks on the interface showing the protective effect on pDNA from DNase degradation. Polycations with higher molecular weight or hyperbranched or dendrimer structures can fulfill many of the requirements for effective gene protection from DNase degradation. Chitosan with higher molecular weight (>= 200 kDa) has superior efficiency to protect pDNA against DNase degradation on the surface of the gold chip. Hyperbranched PEIs and PAMAM dendrimers, even with lower molecular weight (for example, 20kDa for PEI, 50kDa for G5) can protect pDNA against DNase degradation. The results of this study present a platform for further optimization studies of polycation-based gene delivery systems.
Thermomechanical behavior of nanoclay filled TPU/PP blends
Authors: Kannan M. , Bhagawan S.S. , Joseph Kuruvilla , Thomas Sabu
Published: August 2014

Both ester- and ether- based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt blending, using 3 wt % Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement. The nanocomposites were subsequently melt-blended with polypropylene (PP) using maleic anhydride grafted polypropylene (MA-g-PP) as a compatibilizer (in the ratio of 70/30- TPU nano/PP, 70/25/5-TPU nano/PP/MA-g-PP). Besides giving substantial increase in modulus, tensile strength and other properties organoclay reinforcement functions as a surface modifier for TPU hard segment. X-ray diffraction studies revealed that compatibilization is further improved by introducing functionalized PP (MA-g-PP) in the organoclay containing blends. The blend system was evaluated by DSC, DMA, SEM, mechanical properties and Xray diffraction. The results indicate that the ester- TPU exhibited greater miscibility than ether-TPU. Abrasion resistance and water absorption were also better for compatibilised ester- TPU blends as compared to the ether-TPU materials.
Improving the biocompatibility of poly(ε-caprolactone) by surface Immobilization of chitosan and heparin
Authors: Zhong Wei , Liu Zongjun , Tomasik Piotr , Jin Huigen , Lv Nianjian , Meng Sheng , Guo Zhang , Wu Lingxiang
Published: August 2014

Oppositely charged natural polyelectrolyte Heparin (HS) and chitosan (CS) were immobilized on the surface of poly(ε-caprolactone) (PCL) by a layer-bylayer (LBL) self-assembly procedure. Positively charged poly(allylamine hydrochloride) (PAH) was used as the first layer onto the surface of PCL. Then negatively charged HS and positively charged CS were deposited in a LBL assembly manner. The effect of this surface modification method was evaluated by ATR-FTIR spectroscopy and static contact angle measurements. The anticoagulant activity of modified PCL was evaluated using full human blood. The modified PCL samples showed prolonged activated partial thromboplastin time (APTT), prothrombin time (PT) and thromboplastin time (TT) compared with neat PCL. Scanning electron microscopy (SEM) indicated that adhered platelets retained their natural, round morphology on the modified PCL surface. The cytocompatibility of the HS/CS surface modified PCL sample was evaluated with pig iliac arteries endothelial cells (PIECs). The proliferation of the cells cultured on modified PCL films was better than those on neat PCL films.
Use of 4-vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture grafted poly(ethylene terephthalate) fibers for removal of congo red from aqueous solution
Authors: Arslan Metin , Yiğitoğlu Mustafa
Published: August 2014

In this study, a novel fibrous adsorbent made by grafting 4-vinyl pyridine (4-VP) and 2-hydroxyethylmethacrylate (HEMA) monomer mixture onto poly(ethylene terephthalate) (PET) fibers was used for removal of Congo red (CR) in aqueous solutions by a batch equilibration technique. The influence of treatment time, pH of solution, dyes concentration, and reaction temperature on adsorbed amount was investigated. Adsorption time of 60 min. was found sufficient to reach adsorption equilibrium for CR. It was found that the adsorption isotherm of CR fits to Langmuir type isotherms. The highest adsorption capacity was found to be 11.87 mg CR per gram adsorbent. The adsorption rate of CR is much higher on the comonomers grafted PET fibers than on the ungrafted PET fibers. CR was removed 97 % when the initial dye concentration was 5 mg L-1 and 38% at 150 mg L-1 by monomers mixture grafted PET fibers. The adsorption of the dye was endothermic in nature (ΔH°=45.3 KJmol-1). It was found that the reactive fibers are stable and regenerate by acid without losing its activity.
Effect of internal electron donor on copolymerization of ethylene and 1-hexene catalyzed by supported Ziegler- Natta catalysts
Authors: Fan Zhiqiang , Zhang Letian , Fu Zhisheng
Published: August 2014

The four kinds of TiCl4/MgCl2 type supported Ziegler-Natta catalysts, Cat-1, Cat-2, Cat-3 and Cat-4, were prepared by reaction of MgCl2-ethanol adduct with TiCl4. Cat-1 contains no internal electron donor (ID), Cat-2 contains diethyl phthalate (DEP) as ID, Cat-3 contains anisole as ID, and Cat-4 contains both DEP and anisole as ID. Ethylene copolymerizations with 1-hexene by these catalysts were compared. Influences of the internal electron donor on catalyst activity, copolymer composition, composition distribution, molecular weight and molecular weight distribution were investigated. Cat-3 showed the largest ability of incorporating 1-hexene into copolymer chains among the four catalysts. Each copolymer sample was fractionated into two fractions: fraction soluble in boiling nheptane (HS) and fraction insoluble in boiling n-heptane (HI). 1-Hexene content of the HS fraction is 6~10 times of that in the HI fractions. Amount of the HS fraction of copolymer by Cat-2 and Cat-4 was much lower than that of Cat-1 and Cat-3. Introduction of internal donor to the catalysts, especially diethyl phthalate (DEP), increased the blockiness of HI fractions. The molecular weight of both fractions increased when there is ID in the catalyst. Addition of anisole reduced the difference in molecular weight between HS fraction and HI fraction, but addition of PA enlarged the difference. The results are discussed based on a mechanistic model of MgCl2-supported Ziegler-Natta catalysts.
Novel conductive polymer composites based on poly(butylene terephtalate) filled with carbon fibers
Authors: Bardash Liubov , Boiteux Gisèle , Seytre Gérard , Hakme Chady , Dargère Nicolas , Rybak Andrzej , Melis Flavien
Published: August 2014

Poly(butylene terephthalate) (cPBT) synthesized from cyclic Butylene Terephthalate oligomers (CBT) was used as a matrix for carbon fibre (CF) conducting polymer composites (CPC). DSC, rheological studies and measurements of torque of CBT/CF were performed in order to optimise the processing conditions of CPC. DC and AC measurements were carried out for these composites and have shown a low percolation threshold for cPBT/CF.
Synthesis of new polyimides with 1,2,3-triazole units
Authors: Gaina Constantin , Gaina Viorica
Published: August 2014

New polyimides with 1,2,3-triazole units were prepared by click reaction of α,α’-bis(azidosuccinimide)s with bispropargyl monomers or AB-monomers containing azide and propargyl groups. The α,α’-bis(azidosuccinimide)s were obtained by the addition of hydrazoic acid to bismaleimide monomers. The structure of monomers and polymers was confirmed by FTIR and 1H-NMR spectroscopy and all synthesized compounds were characterized through thermal methods.
Stabilization effect of polypyrrole in ϒ-irradiated low density polyethylene
Authors: Zaharescu Traian , Jipa Silviu
Published: August 2014

Under the degradative action of γ-rays, low density polyethylene (LDPE) blended with 5% polypyrrole (PPy) was oxidized extra slow than the neat polymer. FTIR and UV-Viz spectroscopy’s were used for the assessment of the accumulation of oxygen-containing products. The transmittance recorded for LDPE at characteristic bands was higher than similar features obtained for LDPE/PPy samples. The protective action of PPy against oxidative ageing of polymer substrate is due to the movable proton belonging to pyrrole ring. A protection mechanism scheme is proposed for antioxidant activity of polypyrrole
Residual stresses determination in injection molded virgin and recycled HDPE blends: mechanical properties and morphology
Authors: Altan Mirigul , Yurci Mehmet Emin , Nugay Nihan
Published: August 2014

An experimental study of residual thermal stresses has been carried out in injection molded virgin and recycled high density polyethylene (HDPE) blends. Effects of blend concentrations on residual stresses were investigated under different injection conditions such as melt temperature, mold temperature and cooling time. Layer removal technique was used for measuring residual stresses. In order to determine the relation between the residual stresses and material characteristic of HDPE blends, mechanical and morphological properties of the blends were also investigated. Elastic modulus and impact strength were important key factors for determining the blend characteristics. As a result, it was found that HDPE blends gave higher residual stresses but lower impact strength with higher elastic modulus when recycled concentration was increased. Furthermore, it was seen that shape and size of the crystallites were also effective on residual stresses. Small and spherulitic crystallite structured blends such as 30 % recycled HDPE induced reduction in residual stresses due to easier relaxation with lower elastic modulus and higher impact strength while lamellar crystallite structured blends such as 50 % recycled HDPE gave higher elastic modulus but lower impact strength with higher residual stresses.
Synthesis and characterization of triphenylamine and Bbis(indolyl)methane center-functionalized polymer via reversible addition-fragmentation chain transfer polymerization
Authors: Xu Jie , Shang Wei , Zhu Jian , Cheng Zhenping , Zhou Nianchen , Zhu Xiulin
Published: August 2014

A novel bis-functional reversible addition-fragmentation chain transfer (RAFT) agent bearing triphenylamine (TPA) and bis(indolyl)methane (BIM) groups, {4-[bis(1-carbodithioic acid benzyl ester-indol-3-yl)methyl]phenyl}diphenylamine (BCIMPDPA), was synthesized and successfully used as the RAFT agent to mediate the polymerization of styrene (St). The polymerization results showed that reversible addition-fragmentation chain transfer (RAFT) polymerization of St could be well controlled. The kinetic plot showed it was of first order and the numberaverage molecular weight (Mn(GPC)) of the polymer measured by GPC increased linearly with monomer conversion, simultaneously, the molecular weight distribution of the polymer was also relatively narrow. In addition, the existence of the TPA and BIM groups in the middle of polymer chain was confirmed by chain extension reaction and 1H NMR spectrum. The optical properties of the functionalized polystyrene (PS) in chloroform solution were also investigated. Furthermore, the redox process of the RAFT agent and the functionalized PS were studied by cyclic voltammetry method.
Synthesis and RGD peptide modification of poly{(lactic acid)-co-[(glycolic acid )-alt-(L-lysine)]}
Authors: Yan Qiongjiao , Li Juan , Li Shipu , Yin Yixia , Zhang Ping
Published: August 2014

A new polymer poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (poly[LA-co-(Glc-alt-Lys)]) was synthesized and modified with a cell adhesion peptide, Gly-Arg-Gly-Asp-Tyr (GRGDY, abbreviated as RGD). The process for preparing poly[LA-co-(Glc-alt-Lys)]/RGD involved four steps: Firstly, (3S)-3-[4- (benzyloxycarbonylamino)butyl]morpholine-2,5-dione (BMD) was synthesized by bromoacetyl bromide and Nε-(benzyloxycarbonyl)-L-lysine [L-Lys(Z)]. Secondly, poly{(lactic acid)-co-[(glycolic acid)-alt-(Nεn-benzyloxycarbonyl-L-lysine)]} (poly{LAco-[ Glc-alt-Lys(z)]}) was obtained by copolymerization of D,L-lactide and BMD. Then, poly[LA-co-(Glc-alt-Lys)] was synthesized by catalytic hydrogenation of poly{LA-co-[Glc-alt-Lys(z)]}. Finally, poly[LA-co-(Glc-alt-Lys)] was modified with RGD peptide in the presence of 1,1́-carbonyldiimidazole (CDI). The structures of poly[LA-co-(Glc-alt-Lys)]/RGD and its precursors were characterized by FT-IR, 1H NMR, 13C NMR, MS, gel permeation chromatography (GPC), amino acid analysis(AAA). RSC96 cells were used to evaluate the cell affinity of the poly[LAco-( Glc-alt-Lys)]/RGD films and poly(D,L-lactide) (PDLLA ) films. The results of cell culture showed that poly[LA-co-(Glc-alt-Lys)]/RGD was more beneficial to cell adherence and growth than PDLLA.
Stability of inverse microemulsions of acrylamide-based anionic flocculants: evidence about the need of unsaturated surfactants
Authors: Ochoa G José R. , Muñoz H. Marta , Reinoso Diego , Sasia Pedro M. , Escudero Francisco J. , Río Francisca , Nieto Mestre Javier , Torrecilla Jesús
Published: August 2014

Influence of surfactant structural characteristics on stability of inverse microemulsions of acrylamide-based anionic flocculants (40% (w/w) sodium acrylate and 60% (w/w) acrylamide, based on total amount of comonomers) has been studied by using 17 surfactant blends consisting of two non ionic surfactants with different length of hydrophobic chains, different number of hydrophobic chains per molecule, and with and without double bonds on their hydrophobic chains. Experimental evidence shows that unsaturated emulsifiers are needed for obtaining stable inverse microemulsions of acrylamide-based anionic flocculants and that presence of double bonds on the hydrophobic tails of a surfactant is its major structural characteristic to stabilize this kind of polymeric inverse microemulsions (PIM).
Electrical conductivity of poly(N-vinylcarbazole)-based polysodium-2,9,16,23-tetramethylamine tetracyclohexane tetrazaporphyrin composites
Authors: Zamora Fernando , González Carmen , Carballo Tamara , Zamora Nuria , Lezama Luis
Published: August 2014

Efforts to improve dc-conductivity in poly(N-vinylcarbazole) (PVK) are addressed through composites. Such systems included phthalocyanine-based additives with both electronic and ionic character. We present a polysodium- 2,9,16,23-tetramethylamine tetracyclohexanetetrazaporphyrine, acting as the conductive additive in a PVK-binder. A paramagnetic behaviour appears in the additive when heated in the range 70-100°C, which induced further conductivity in the sample. Dc-electrical conductivity was studied for different PVK-additive compositions, in isothermal conditions, using a sandwich Pt/sample/Pt cell. By applying the Poole-Frenkel theory a trapping state was evidenced showing temperature and electric field dependence. An electric field of 9x104V/m establishes a frontier from which the conductivity mechanism is changed. Mobility of charge carriers was calculated according to the Mott-Gurney´s equation
The effect of temperature on tacticity for bulk thermal polymerization of styrene
Authors: Ziaee Farshid , Nekoomanesh Mehdi , Mobarakeh Hamid Salehi , Arabi Hassan
Published: August 2014

Three types of polystyrenes were prepared at different temperatures of 50, 150 and 250°C by bulk thermal polymerization of styrene below 20 percent of conversion. The assignment of all stereosequences at pentad level of quaternary aromatic carbon and hexad level of methylene carbon of the polystyrenes were done using 13C Liquid NMR in deuterated chloroform at similar conditions. Bernoullian and first-order Markov statistics were calculated and the results were compared with experimental NMR results. It is shown that first-order Markov statistics fit slightly better than Bernoullian statistics for the assigned carbons. The results indicated that by increasing polymerization temperature the probability of meso addition (Pm) in polystyrene chains was enhanced. Pm was calculated for polystyrenes prepared at 50, 150 and 250°C and corresponding values were 0.378, 0.398 and 0.402 respectively. It was shown that by increasing temperature the polymerization is directed toward the Bernoullian propagation. By increasing the NMR acquisition temperature from 20 to 65°C higher resolution especially in quaternary aromatic carbon was achieved and the related peak was splitted to 16 peaks corresponding to a heptad level compared to 10 peaks in 20°C.
Novel polymeric surfactants and their applications in miniemulsions
Authors: Cismaru Lucretiu , Hamaide Thierry , Popa Marcel
Published: August 2014

N-Vinyl-2-pyrrolidone (NVP) and maleic anhydride (MA) copolymers were synthesized via radical polymerization. The synthesized copolymers were grafted with methoxypolyethylene glycol (MPEG) chains of different average molecular weights (350, 550, 750 Da). The grafted copolymers were used as surfactants in the synthesis of poly(ε-caprolactone) (PCL) nanoparticles in water by solvent evaporation technique. In order to further test the synthesized surfactants, the miniemulsion polymerization of vinyl acetate was performed. Two methods of obtaining miniemulsion were employed: a sonicator and a static mixer. The synthesized surfactants performed well in both type of experiments while in the case of static mixer nanoparticles with a lower polydispersity were obtained. Droplets with a mean diameter of 250 nm were obtained when using the sonicator while the static mixer led to formation of droplets with a mean diameter of 600 nm.
Studies on thermal stability and UV-resistant performance of poly(MMA-co-M12-co-BPMA)/TiO2 composite particles
Authors: Zou Jiangpeng , Yang MingJiao , Jiang Long , Dan Yi
Published: August 2014

In this paper, the thermal stability and UV-resistant performance of the poly(methyl methacrylate-co-sodium sulfopropyl lauryl maleate-co-2-hydroxy-4-(3- methacryloxy-2-hydroxylpropoxy) benzophenone) /TiO2 (i.e. poly(MMA-co-M12-co- BPMA)/TiO2) composite particles were studied by means of laser diffraction particle size analyzer (LDPSA), thermogravimetric analysis (TGA), ultraviolet-visible absorption spectroscopy (UV-vis), ultraviolet-visible diffuse reflectance spectroscopy (DRS), differential scanning calorimeter (DSC) and weight loss measurements. The results indicate that the dispersion of composite particles is better than that of TiO2 particles and the thermal stability of composite particles is better than that of poly(MMA-co-M12-co-BPMA). The poly(MMA-co-M12-co- BPMA)/TiO2 composite particles could absorb more than 90% of UV light in the 210-400 nm wavelength, which was useful to enhance the UV-resistant performance of polymers (e.g. PMMA) . The Tg of polymer grafted from the surface of TiO2 did not change after UV irradiation for 500 h but that of PMMA changed a lot, the weight loss of composite particles was much lower than that of PMMA after UV irradiation, showing that the UV-resistant performance of PMMA has been enhanced by introducing the organic UV-stabilizer BPMA and the inorganic UVstabilizer titanium dioxide into the polymer chains by covalent bonding.
Synthesis and Characterization of Poly(methyl acrylate) + SiO2 Hybrids
Authors: Brostow Witold , Datashvili Tea , Hackenberg Ken P.
Published: August 2014

Poly(methyl acrylate) (PMA) + SiO2 composites were synthesized via a sol-gel reaction. The base acrylic copolymers with a content of alkoxysilane groups were prepared by co-polymerization of methylacrylate (MA) with 3-(trimethoxysilyl) propylmethacrylate (3MPS) or vinyltrimethoxysilane (VTMS); the products were cocondensed with tetraethylorthosilicate (TEOS). The PMA + SiO2 hybrids were characterized. Thermal stability of PMA is enhanced by copolymerization with 3-MPS or VTMS and the presence of SiO2; significant weight loss occurs only above 400°C. Decomposition temperatures are higher by 20 - 25 K as compared to the initial PMA. During the sol-gel process the trimethoxysilyl groups in PMA/3MPS are transformed into a strong silica network. Two different methods of creation of hybrids were used; ESEM shows that only one of them leads to uniform distribution of silica in polymeric matrices.
Sulphonation of Expanded Polystyrene Waste Under Microwave Irradiation
Authors: Sułkowski Wiesław W. , Wolińska Agnieszka , Sułkowska Anna , Nowak Krzysztof , Bogdal Dariusz
Published: August 2014

Chemical modification of polymeric materials is one way of polymer waste management. In our study, expanded polystyrene waste (EPS), used as the reference material, was converted into polymeric flocculants by the sulphonation reaction. Thus, poly(styrenesulphonate) acids (EPSS) were obtained from EPS during the sulphonation process with sulphuric acid as the sulphonation agent and Ag2SO4 as the catalyst under both conventional heating and microwave conditions. At the termination of the process the products were precipitated in the form of sodium salts (NaEPSS) in the reaction with Na2CO3 and their characteristics were given. The influence of temperature and time of reaction on the properties of EPSS and NaEPSS was studied and compared with conventional and microwave conditions. The results showed that the sulphonation process performed under microwave irradiation allowed us to receive products with properties similar to the ones obtained under conventional conditions but the reaction time was substantially reduced from 1 and ½ hour to 15 min.
Preparation of high-yield polyaniline nanofibers via an unstirred polymerization
Authors: Lü Qiufeng , Cheng Xiansu
Published: August 2014

Polyaniline nanofibers with high yield (93%) have been synthesized by an unstirred polymerization of aniline in aqueous acid media with ammonium persulfate as an oxidant in the absence of any template, dopant or surfactant. The morphology, structure and electrical conductivity of the nanostructural polyaniline prepared under different conditions were characterized by means of scanning electron microscopy, FTIR, UV-vis and four-probe techniques. It was found that branched network-like polyaniline nanofibers were prepared without any mechanical stirring, whereas irregular and rodlike structural polyaniline samples were obtained with mechanical stirring under the same reaction conditions. Flowerlike polyaniline microspheres of ca. 3.5 μm in outer diameter, which were constructed with nanostructural polyaniline lamellar by self-assembly process, were synthesized during the polymerization at 0 °C for 72 h. The as-synthesized HCldoped polyaniline nanofibers have good room-temperature electrical conductivity of 5.0 S/cm.
Supercritical carbon dioxide-assisted solid-phase free radical grafting of butyl acrylate onto PP
Authors: Jian Wang , Deng-Fei Wang , Wei Du , En-Guang Zou , Qun Dong
Published: August 2014

Free radical grafting copolymerization of butyl acrylate (BA) onto polypropylene (PP) matrix was investigated using supercritical CO2 as a swelling agent and carrier solvent. The monomer BA and initiator AIBN were first dissolved in supercritical CO2, and then these small molecules were diffused into the grafting zones of PP matrix. As grafting reaction temperature (about 80 °C) was far below the melting point, PP was modified in the solid phase. The effects of different experimental conditions such as soaking time and temperature, supercritical CO2 pressure; monomer and initiator concentration; PP particle diameter; solid phase grafting reaction time and temperature on grafting percentage were studied. Fourier transform infrared spectroscopy (FTIR) results and gel content experiment prove that the monomers were indeed grafted onto PP chains. Scanning electron microscope (SEM) analysis of the grafted sample indicates that the grafting branches PBA were homogeneously distributed onto the surfaces and micropores of PP particles. Thermal gravimetric analysis (TGA) results show that the grafted samples had a higher onset thermal degradation temperature and a lower weight loss at a particular temperature than pure PP. The water contact angle of PP-g-BA decreased from 98° to 72°, indicating the polarity and hydrophilicity of PP were improved effectively. The melt flow rate (MFR) and mechanical analysis results show that the grafting sample remained its versatile physical properties though introducing the grafting BA branch chain. This is prominent when it was compared with normal solid grafting product.
A biodegradable copolymer from coupling poly(pdioxanone) with poly(ethylene succinate) via toluene-2,4- diisocyanate
Authors: Wang Xiu-Li , Chen Si-Chong , Zhang Yu-Hua , Yang Ke-Ke , Wang Yu-Zhong
Published: August 2014

Poly(p-dioxanone) (PPDO) and poly(ethylene succinate) (PES) prepolymers were reacted together using toluene-2,4-diisocyanate (TDI) as a chain extender to produce high molecular weight of chain-extended products of PPDO and PES (PPDOES) in a suitable reaction condition. The novel biodegradable polymers were characterized by 1H-NMR, DSC, POM and WAXD. DSC measurement shows that PPDOES has only one Tg, which means that PPDO has good compatibility with PES. Beside this, the glass transition temperatures and the melting temperatures of PPDOES increased with the increase of PES content. The crystallization rate of PPDOES was slower than that of PPDO as confirmed by DSC and POM. The diffraction peaks of PPDOES appear at the same 2θ angles as that of homopolymers, suggesting that PPDO and PES segment of the chainextended products reserve their own crystallization form. The results of thermal oxidative degradation show that chain-extended products have better thermal stability than PPDO.
Poly(N-isopropylacrylamide) gel beads prepared by waterin- oil suspension polymerization for the adsorption of fluorescently tagged hepcidin
Authors: Abbate Vincenzo , Jaiash Dareen , Bansal Sukhi
Published: August 2014

Poly(N-isopropylacrylamide) (PNIPAm) gel beads were prepared by water in oil (w/o) suspension polymerization using aqueous acetonitrile to dissolve the monomer phase, toluene or cyclohexane as the continuous phase and ethyl cellulose (EC) as the stabilizer. The beads were analyzed by FT-IR and their morphology was investigated by optical and electron microscopy. The advantages of this novel synthetic method for PNIPAm preparation include efficient polymerization and mild experimental conditions, as well as the formation of spherical and relatively uniformly sized particles. The microgels were then evaluated for their efficiency to absorb fluorescently labelled hepcidin. The beads were found to rapidly capture the target peptide from neutral aqueous solutions. Notably, bovine serum albumin (BSA) did not bind to the polymer beads at the cross-linking ratio used; therefore, size-exclusion properties may be controlled by finely tuning monomer to cross-linker ratio and/or monomer concentration during polymer design. The route could potentially be useful for diagnostic, drug delivery or peptide immobilization, as well as for the molecular imprinting of peptides and proteins.
Study of rheological behaviours of electrostatic thermoset powder coatings
Authors: Ehsani Morteza , Yousefi Ali Akbar , Yeganeh Saeed Samiei
Published: August 2014

The use of dynamic viscosity/time (temperature) cure curves is seen as a powerful technique to quantify formulation and resin design parameters. The behaviour of different thermoset powder coating systems, epoxy/polyester (50/50, 40/60 and 30/70) as well as the impact of the filler, the curing temperature and the frequency upon gel-time have been examined based upon the rheological measurements and compared with PE/TGIC systems. Two disparate methodologies have been utilized to determine gel-time. The behaviour of dissimilar systems bearing different formulations has been compared by means of the non-isothermal DSC test. The effects of resin percentage and the formulation on physical and mechanical properties of coating have been studied.
Release behavior of 2,4-dichlorophenoxyacetic acid herbicide using novel porous polyacrylamide hydrogels
Authors: Mahdavinia Gholam Reza , Mousavi Seyyed Bahman , Karimi Farrokh , Marandi Gholam Bagheri , Shahabivand Saleh , Harati Mohammad
Published: August 2014

Porous polyacrylamide (PAAm) was synthesized using calcium carbonate (CCb) micro-powder and subsequent leaching process. Polymerization was carried out in a solution environment system containing methylenebis acrylamide (MBA) and acrylamide (AAm) as crosslinker and monomer, respectively. CCb micro-powders were introduced to the polymerization solution before adding initiator. Ammonium persulfate/sodium metabisulfite (APS/SMBS) were used as a redox initiator system. HCl solution was used to remove CCb powders. The effect of MBA concentration and CCB amount on the swelling of hydrogels were studied. The porous structure of hydrogels was investigated and verified using scanning electron microscopy (SEM). 2,4-Dichlorophenoxyacetic acid (2,4-D) was loaded into the hydrogels and release of this herbicide was investigated. The effect of MBA concentration and addition of CCb on the content of released herbicide was studied. Also, the study of herbicide release in a solution under various pH revealed the pH-dependency release of 2,4-D herbicide.
A feasible synthetic strategy for three-armed star poly(ester amine) via Michael addition polymerization
Authors: Yang Wei , Pan Cai-Yuan
Published: August 2014

Three-armed star-shaped poly(ester amine) was synthesized by Michael addition polymerizations of equal molar ratio of ethylene glycol diacrylate (EGDA) and piperazine (PZ) in the presence of a small amount of multifunctional monomer, 1,3,5-triacryloylhexa-hydro-1,3,5-triazine (TT) in CHCl3. When the polymerization proceeded almost completely, the molecular weight of the polymers formed were determined by the feed molar ratio of difunctional monomer to multifunctional monomer, and the molecular weight distribution (Mw/Mn) approached the theoretical value (Mw/Mn =1+1/f). The mechanism of the polymerization was investigated by 1H NMR and Gel permeation chromatography (GPC). The monomer concentration and the molar ratio of difunctional monomers/multifunctional monomer played an important role in the polymerization.
Optimization of melting conditions for the analysis of crystallization kinetics of poly(3-hydroxybutyrate)
Authors: Di Lorenzo Maria Laura , Sajkiewicz Pawel , Gradys Arkadiusz , La Pietra Paola
Published: August 2014

Studies of kinetics of polymer crystallization are generally performed by heating the material above the melting point, in order to erase previous thermal and mechanical history, followed by rapid cooling to the desired crystallization temperature or by cooling at a constant rate. For poly(3-hydroxybutyrate) this procedure implies some degradation of the polymer chain, which starts below the onset of melting. In this article the effects of melting conditions on the subsequent crystallization kinetics are discussed. It is shown that in order to sufficiently cancel memories of previous crystalline order of the analyzed PHB, it is necessary to bring the material at a temperature higher than 192 °C. Thermal treatments conducted at lower temperatures are not sufficient to destroy all solid aggregates, and crystallization of PHB has an anticipated onset of crystallization due to nucleation occurring via self-seeding. The chain degradation attained upon exposure at high temperatures has much lesser influence on crystallization kinetics than incomplete melting, with some effects detectable on the spherulitic morphology and on the final degree of crystallinity.
(Quaternized/betainized) amino-based amphiphilic block copolymers: quantitative composition characterization via FTIR and thermogravimetry
Authors: Bomfim João A. S. , Mincheva Rosica , Beigbeder Alexandre , Persenaire Olivier , Dubois Philippe
Published: August 2014

The objective of the present study is the introduction of well known and readily accessible analytical methods as FTIR, thermogravimetric (TGA) and evolved gas analysis (EGA) for quantitative determination of the degree of polymerization (DP) and degree of quaternization (DQ)/betainization (DB) of amino-based amphiphilic block copolymers. For this purpose a series of amphiphilic poly(dimethylsiloxane)-b-poly[2-{dimethylamino)ethyl methacrylate] (PDMS-b-DMAEMA) diblock copolymers with DP of the PDMAEMA-block ranging from 22 to 162 was synthesized by atom transfer radical polymerization and analyzed by 1H NMR, ATR-FTIR and TGA-co-EGA. The determined composition results have shown linear correlation between the FTIR or TGA and the 1H NMR data and equations allowing the quantitative calculation of PDMAEMA-block DP were found. The errors estimated by ATR-FTIR were less than 1.5%. Further, the PDMAEMA-block was quaternized (or betainized) with DQ (or DB) from 25 % to 100 % and analyzed by TGA-co-EGA. Again, a linear correlation between the quaternized (betainized) PDMAEMA-block mass fraction and the DQ (DB) degrees was obtained by 1H NMR.
Morphology and orientation of thin poly(3-hexylthiophene) (P3HT) films on differently silanized silicon oxide
Authors: Scavia Guido , Porzio William , Destri Silvia , Schieroni Alberto Giacometti , Bertini Fabio
Published: August 2014

The morphology and structure of the overlying poly(3-hexylthiophene) (P3HT) layer onto differently silanized silicon oxide has been studied by Atomic Force Microscopy (AFM) and X-Ray Diffraction (XRD) techniques. By increasing the silanizer alkyl chain length, the layer morphology evolves from a filament like to globular needle like as a consequence of the different SAM organization, while the P3HT conformation remains edge-on. For each case the effect of the annealing temperature has been studied. For all the cases a particular attention has been paid to the first thin layers close to the interface P3HT/SiOx. The effect of a polar substituent and presence of aromatic ring has been also studied.
Determination of thermorheological phase diagram of poly(propylene)/poly(ethylene-b-ethylene oxide) blends
Authors: Özen İlhan , Rustal Claude , Dirnberger Klaus , Fritz Hans-Gerhard , Eisenbach Claus Dieter
Published: August 2014

The phase diagram of the polypropylene (PP)/poly(ethylene-blockethylene oxide) (P(E-b-EO) blends exhibiting upper critical solution temperature (UCST) was experimentally established by using small amplitude oscillatory shear rheology, in which the binodal line was obtained by dynamic temperature ramps and the spinodal temperatures were quantitatively estimated on the basis of the theory developed by Ajji et al. The measurements were carried out in the linear viscoelastic regime in which the material functions are sensitive to phase separation.
Photosensitive poly(ether sulfone)s for thiol/ene UV curable coatings: synthesis, characterization and crosslinking
Authors: Zeng Zhi , Guan Shaowei , Zhang Haibo , Zhang Linlin , Liu Baijun , Jiang Zhenhua
Published: August 2014

Novel photocrosslinkable poly(ether sulfone)s copolymers with allyl pendants (AS-PES) have been synthesized from 3,3’-diallyl-4,4’-dihydroxydiphenyl sulfone (DA-DHDPS), 4,4’-dihydroxydiphenyl sulfone (DHDPS) and 4,4’- dichlorophenylsulfone (DCDPS). The resulting polymers could be photocrosslinked in the presence of thiol at room temperature. The crosslinking process was monitored by “Real Time Fourier Transform Infrared Spectroscopy” (RTIR). It proves that a small amount (1.0 wt%) of the thiol crosslinker addition is sufficient to form a chemical network under UV irradiation. After UV curing, AS-PES-20 coating showed high Tg, good thermal stability and excellent resistance to the acid, salt, and alkali. Accordingly, this method could successfully provide a new approach to make rapidly photocrosslinking poly(ether sulfone) coatings without losing their good thermal properties.
Preparation of vinyl polymer/polyurethane hybrid latex particles and their application in nano-sized vinyl polymer particle/thermoplastic polyurethane blends
Authors: Wei Yanyan , Zong Chengzhong , Wang Fufang
Published: August 2014

Vinyl polymer/polyurethane hybrid latex particles with various compositions were successfully prepared via emulsion polymerization of vinyl monomer in the presence of self-emulsified polyurethane dispersion without using any surfactant. Studies were carried out on polymerization kinetics, characterization of the hybrid particles and the physical properties of nano-sized vinyl polymer particle/thermoplastic polyurethane blends. It was found that the maximum content of vinyl polymer in polyurethane hybrid particles was up to 80 percent and all of the vinyl polymer/polyurethane hybrid particles were less than 120 nm. Infrared spectroscopy, thermal gravimetric analysis and differential scanning calorimetry analysis indicated the influence of vinyl polymer on the polyurethane hybrid particles. With the polyurethane shells outside and, therefore, good compatibility with polyurethane matrix, the hybrid particles can be easily blended into polyurethane matrix. Some unusual changes of dynamic mechanical properties in the low temperature region were found in the blends of hybrid particles and thermoplastic polyurethane. With the addition of only 3%, the mechanical properties of these blends did not show a significant change. This study provided a new method to prepare hybrid particles in the absence of surfactant and made an attempt on application of vinyl polymer/polyurethane hybrid particles in the blending modification
Preparation of core-shell polymeric nanocapsules containing liquid cores via redox interfacial-initiated microemulsion polymerization
Authors: Weijun Liu
Published: August 2014

In this work, polystyrene (PSt) nanocapsules were successfully prepared by one-stage redox Interfacial-initiated inversed micro-emulsion polymerization of styrene (St), the cumene hydroperoxide (CHPO) and tetraethylenepentamine (TEPA) as the redox initiation pairs. The water-soluble TEPA acted as the reducing component and the oil-soluble CHPO as the oxidant component of the redox initiation system. The primary radicals were produced mainly at the oil/water interface to initiate the polymerization of styrene (St). Core-shell polymeric PSt nanocapsules were obtained by one-stage polymerization via this method, which was supported by the techniques of transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The particle size and polydispersity index (PDI) of nanocapsules were determined by dynamic light scattering (DLS). The results demonstrated that interfacial-initiated inversed microemulsion polymerization to form core-shell nanocapsules containing liquid cores by one-stage is successful.
Preparation of the crosslinked polymer electrolyte membranes based on a hyperbranched poly(amidoamine) and their proton conductivity
Authors: Zhang Yongwen , Huang Wei , Zhou Yongfeng , Yan Deyue
Published: August 2014

A series of novel crosslinked polymer electrolyte membranes were successfully prepared based on the modification of a hyperbranched poly(amidoamine) with terminal vinyl groups. The membranes possessed the different contents of proton-generating sites (i.e., protonated tertiary amine groups) and triflate (Tf2N-) in the crosslinked network. They showed good mechanical and thermal stability. The water uptakes of them were ca. 8.4-24.5%. Their proton conductivity was of the order of ca. 10-5-10-2 S/cm in the range of 30-80 °C, and the proton conductivity increased with improving the protonation ratio. AFM results disclosed the micro-phase separation of the hydrophilic proton-generating sites and the hydrophobic domains of Tf2N- ions. The resulting locally continuous hydrophilic clusters could provide proton transport channels to produce the high proton conductivity. This kind of polymer electrolyte membranes may have potential applications in PEFCs and other electrochemical fields.
Enhanced impact strength and deviated thermal decomposition of PP and PS toughened with graft-modified rubbers
Authors: Liu Hongtao , Zuo Danying , Liu Heng , Li Linzhou , Li Jianlin , Xu Weilin
Published: August 2014

Graft-modified rubbers including maleic anhydride grafted ethylene propylene diene monomer (MAH-g-EPDM) and 49% methyl methacrylate grafted natural rubber (MMA-g-NR, i.e. MG49 rubber) were employed to toughen polypropylene (PP) and polystyrene (PS). The results showed that Charpy impact strength of the notched PP specimens and unnotched PS specimens at room temperature was improved markedly by addition of the graft-modified rubbers. Moreover, Charpy impact strength of the plastics increased with increasing graftmodified rubbers content and the incorporation of MAH-g-EPDM enhanced impact strength of the plastics more markedly than MG49. The result of thermogravimetric analysis (TGA) indicated that the addition of MAH-g-EPDM improved the thermal stability of PP, while the incorporation of MG49 reduced it. Good compatibility between the plastics and MAH-g-EPDM and saturation of EPDM could be responsible for these mechanical and thermal features. This preliminary work may also provide some information for oil-resistant modification of plastics due to the polar groups grafted onto the backbone of rubbers.
Improvement of thermal properties of polyhydroxybutyrate by grafted chemicals
Authors: Hong Shinn-Gwo , Lin Chia-Hau
Published: August 2014

The crystallization and thermal degradation behaviors of polyhydroxybutyrate (PHB) grafted with maleic acid (MAc) and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride (ETA) are analyzed with differential scanning calorimetry (DSC), dynamic thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). It is obtained that the PHB grafted with MAc or ETA has a faster crystallization rate, larger crystallinity, and better thermal stability than the as-received PHB. The thermal stability of specimens are in the order of the as-received PHB < PHB grafted with ETA < PHB grafted with MAc. The grafting ratio of MAc is larger than that of ETA. The thermal stability of PHB can be greatly improved by grafting a small amount of MAc. The activation energy of the PHB degradation reaction are little affected by the grafted chemicals, nonetheless, the reaction order and frequency factor are significantly affected by the grafted MAc.
Studies on the properties and the thermal decomposition kinetics of natural rubber prepared with calcium chloride
Authors: Li Cheng-peng , Zhong Jie-ping , Yang Lei , Li Si-dong , Kong Ling-xue , Hou Ting-ting
Published: August 2014

To evaluate calcium chloride coagulation technology, two kinds of raw natural rubber samples were produced by calcium chloride and acetic acid respectively. Plasticity retention index (PRI), thermal degradation process, thermal degradation kinetics and differential thermal analysis of two samples were studied. Furthermore, thermal degradation activation energy, pre-exponential factor and rate constant were calculated. The results show that natural rubber produced by calcium chloride possesses good mechanical property and poor thermo-stability in comparison to natural rubber produced by acetic acid.
The preparation of phosphorylcholine-containing poly(Llactide) nanoparticles with solvent evaporation method
Authors: Cao Jun , Chen Yuanwei , Chen Niancao , Luo Xianglin
Published: August 2014

Phosphorylcholine-containing poly(L-lactide) (PLLA-PC) is a kind of amphiphilic copolymer synthesized with L-lactide (LLA) as monomer and glycerophosphorylcholine as ring-opening reagent. In this paper, self-assembly nanoparticles of PLLA-PC were prepared with solvent evaporation method. The factors that affected the properties and stability of nanoparticles were investigated. Transmission electron microscope (TEM) indicated that PLLA-PC nanoparticles presented typical core/shell structure. The critical micelle concentration (CMC) was determined with fluorescent probe method. The results showed that the CMCs were quite low (< 1×10-3 g/l) and were dependent on LLA units in the copolymer. The size of the nanoparticles was detected by dynamic light scattering (DLS). The results indicated that the size could be affected by LLA units, the amount of solvent and water in the preparation process. On the other hand, the obtained nanoparticles were stable while being stored at 4 °C, and hardly changed over the dilution with water, which was of great importance in venous injection. The solubility of clofazimine was better in aqueous solution of PLLA-PC nanoparticles than in pure water. This preliminary study suggested that PLLA-PC nanoparticles had a great potential as delivery system for hydrophobic drug.
Property of poly(hydroxybutyrate) complexed polymer with soy protein isolate using glycerol as a medium
Authors: Ma, Xiaolu , Cheng Guoxiang
Published: August 2014

A kind of poly(hydroxybutyrate) complexed polymer with soy protein isolate (PcSg) was prepared using glycerol as a medium. Effect of content of SPI on thermal, mechanical properties and water absorption of the PcSg polymer was investigated. The results indicated that SPI not only is miscible with PHB, but also may improve tenacity. The PcSg polymer displayed single glass transition ranges on their differential scanning calorimetry (DSC) curves. The fracture stress and Yang’s modulus of the PcSg increased with PHB concentration, but fracture elongation declined. Water absorption of the PcSg was estimated by water absorption rate of the polymers. By the ratio of hydrophobic PHB and hydrophilic SPI, water absorption of the PcSg was efficaciously modified. It was proposed that the effect on the PcSg mainly was because of intermolecular interactions between PHB and SPI.