bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study on functionalizing SEBS through ozone treatment and the mechanical properties of its blend with polyamide 6
Authors: Liu Pengbo , Qiu Jian , Fan Ping , Zou Huawei , Xu Wen 
Published: January 2008

AbstractTwo types of styrene‐b‐(ethylene‐co‐1‐butene)‐b‐styrene triblock copolymer (SEBS) were functionalized through ozone treatment. The structure and properties of ozonized SEBS and the mechanical properties of their blend with Polyamide 6 (PA6) were studied by FTIR spectroscopy, gel permeation chromatography, gel content measurement, contact angle measurement, SEM, and mechanical properties measurement. The experimental results show that through ozone treatment, some oxygen‐containing groups (mainly carbonyl groups) are introduced onto the molecular chains of SEBS. The polarity of SEBS is thus improved. Compared with star‐shaped SEBS602, SEBS503 of linear shape is more susceptible to ozone oxidation. The polarity of ozonized SEBS503 is higher than that of ozonized SEBS602. The improvement of mechanical properties of PA6/ozonized SEBS blend is attributed to the improvement of the dispersion of ozonized SEBS in PA6 matrix and the interfacial adhesion between PA6 and ozonized SEBS. Compared with that of PA6/ozonized SEBS602 blend, the size of dispersed phase in PA6/ozonized SEBS503 blend is smaller, and the interfacial adhesion is stronger. The notched Izod impact strength of PA6/ozonized SEBS503 (90 min) (90/10) blend is 49.6 kJ/m2, is higher than that of PA6/ozonized SEBS602 (90 min) (90/10) blend, which is only 21.3 kJ/m2. The impact strength of PA6/ozonized SEBS503 (90 min) (80/20) blend is 68.7 kJ/m2, is still higher than that of PA6/ozonized SEBS602 (90 min) (80/20) blend, which is 60.2 kJ/m2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of the hydrophobic diblock copolymers of poly(dimethylsiloxane)‐block‐poly(ethyl methyl acrylate) through atom transfer radical polymerization
Authors: Luo Zheng‐Hong , Yu Hai‐Jiang , He Teng‐Yun 
Published: January 2008

AbstractThe poly(dimethylsiloxane)‐block‐poly(ethyl methylacrylate) diblock copolymers (PDMS‐b‐PEMA) were synthesized by atom transfer radical polymerization (ATRP). The chemical structure of the copolymers was characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Thermal behaviors were observed via differential scanning calorimetry (DSC). In the DSC curve, the resulting copolymers appear two glass transition temperatures (Tg's), one at −123°C corresponding to the PDMS block and the other at 65°C ascribed to the PEMA segment. Moreover, the copolymer microstructure was investigated by transmission electron microscopy (TEM). The results show that the diblock copolymers are microphase separated if the bulk contains enough PEMA segment. The surface properties of the PDMS‐b‐PEMA diblock copolymers were searched by contact angle. The PDMS‐b‐PEMA diblock copolymers are of low surface energy. The polymerization kinetics was also investigated, and the results show that the reaction proceeds in a living manner. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of the epoxy resin chemistry on the viscoelasticity of its cured product
Authors: Nakka J. S. , Jansen K. M. B. , Ernst L. J. , Jager W. F. 
Published: January 2008

AbstractA detailed study investigating the relation between the initial resin composition and mixing ratio on the viscoelastic behavior was performed. The resin system, containing a difunctional aromatic epoxy (DER 332), was mixed with three aliphatic amines containing functionalities of 2, 3, and 4 in different stoichiometric mixing ratios and was cured. For each of the cured mixtures, the viscoelastic master curve and corresponding shift factors were determined. Depending on the crosslink density, the viscoelastic curves shifted by about 12 decades with respect to the frequency scale. This shift in the viscoelastic curve was predicted by the combination of the Miller–Macosko theory for crosslink density with a parameterized Havriliak–Negami model for the master curve. A single set of 9 parameters turned out to be sufficient to describe all viscoelastic data. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Polymer–protein interaction, water retention, and biocompatibility of a stimuli‐sensitive superporous hydrogel containing interpenetrating polymer networks
Authors: Yin Lichen , Zhao Ziming , Hu Yizhe , Ding Jieying , Cui Fuying , Tang Cui , Yin Chunhua 
Published: January 2008

AbstractThe swelling of a superporous hydrogel containing poly(acrylic acid‐co‐acrylamide)/O‐carboxymethyl chitosan interpenetrating polymer networks (SPH‐IPN) was sensitive toward the pH, ionic strength, and temperature stimuli. With insulin as a model drug, polymer–protein interaction was detected, and it was physical rather than covalent. Freezing water was the majority of the imbibed water in the swollen SPH‐IPNs, and the water‐retention ability of the polymer against compression and time of exposure at 37°C was improved as the amount of the O‐carboxymethyl chitosan network increased. A 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay on AD293 and RBL‐2H3 cells and an in situ lactate dehydrogenase assay and morphological study on rat intestine confirmed that the SPH‐IPNs had satisfactory biocompatibility. These pronounced properties suggested that the SPH‐IPNs could be developed as an attractive peroral delivery vehicle for peptide and protein drugs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Crystallization of polypropylene in the presence of a rigid and flexible additive
Authors: Prakashan K. , Gupta A. K. , Maiti S. N. 
Published: January 2008

AbstractThe effect of a rigid additive (nano‐SiO2 filler) and a flexible additive [poly(dimethylsiloxane) elastomer] on the crystallization of polypropylene was studied under nonisothermal conditions with differential scanning calorimetry. Crystallization parameters were evaluated with standard equations, and the results were interpreted on the basis of the rate of nucleation, crystallization, and activation energy of crystallization. The observed effect of polydimethylsiloxane of increasing the crystallization rate and lowering the activation energy of crystallization was attributed to the effect of polydimethylsiloxane chain mobility at the interface, which facilitated the molecular mobility of polypropylene. Nano‐SiO2, on the other hand, acted as a nucleating agent, and the nucleation effect was dependent on the cooling rate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Cationic curing of diglycidyl ether of bisphenol A and 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane and degradation of the thermosets obtained
Authors: González Lidia , Ramis Xavier , Salla Josep Maria , Mantecón Ana , Serra Angels 
Published: January 2008

AbstractYtterbium and lanthanum triflates were used as cationic initiators to cure mixtures of diglycidyl ether of bisphenol A and 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane in several proportions. The evolution of the epoxy and lactone during curing and the linear ester groups in the final materials were evaluated with Fourier transform infrared in the attenuated total reflection mode. The shrinkage after curing and the thermal degradability of the materials with variations in the comonomer ratios and initiator used were evaluated and related to the chemical structure of the final network. The expandable character of 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane was confirmed. The obtained materials were more degradable than conventional epoxy resins because of the tertiary ester groups incorporated into the network by copolymerization. The kinetic parameters of the curing and degradation processes were calculated with differential scanning calorimetry and thermogravimetric analysis, respectively, with isoconversional procedures applied in both cases. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Comparative study of three lignin fractions isolated from mild ball‐milled Tamarix austromogoliac and Caragana sepium
Authors: Xu Feng , Sun Run‐Cang , Zhai Mei‐Zhi , Sun Jin‐Xia , Jiang Jian‐Xin , Zhao Guang‐Jie 
Published: January 2008

AbstractSix lignin fractions from mild ball‐milled Tamarix austromogoliac (TA) and Caragana sepium (CS) were sequentially isolated with 80% dioxane containing 0.05M HCl at 75°C for 4 h, 50% aqueous ethanol containing 1M triethylamine at 70°C for 4 h, and 8% aqueous NaOH at 45°C for 3 h. The results showed that the successive treatments made it possible to isolate lignin from wood with a high yield and purity, in which 89.4 and 90.6% of the original lignin from TA and CS were released, respectively. The lignin fractions isolated with the three‐step method were analyzed with Fourier transform infrared, 1H‐ and 13C‐NMR, alkaline nitrobenzene oxidation, and gel permeation chromatography. It was found that the three lignin fractions isolated from TA were rich in syringyl units, and the molar ratio of the relatively total moles of vanillin, vanillic acid, and acetovanillin to the relatively total moles of syringaldehyde, syringic acid, and acetosyringone decreased from 1: 2.6 to 1 : 3.2 to 1: 3.6 in the lignin preparations, whereas this ratio in the corresponding lignin fractions isolated from CS was found to be 1.4 : 1, 1.1 : 1, and 1 : 1.4, respectively. More importantly, the results revealed that the sequential extractions of the mild ball‐milled TA and CS with 80% acidic dioxane, 50% alkaline ethanol, and 8% aqueous NaOH under the conditions used did not significantly cleave the β–O‐4 and α–O‐4 linkages in lignin macromolecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of biopolymer‐based electrical conducting graft copolymers
Authors: Tiwari Ashutosh , Singh S. P. 
Published: January 2008

AbstractThe naturally occurring Guar gum (GG) was chemically modified with polyaniline (PANI) using ammonium persulfate (APS) as oxidant/initiator in acidic condition. The representative graft copolymer was characterized using UV–vis, FTIR, H1 NMR, XRD, TGA, and SEM taking GG and PANI as reference. The affinity of the upper limit for the graft copolymerization has been extensively studied by varying different chemical and physical parameters. All the findings have been discussed, and proposed a plausible mechanism for the graft copolymerization. The grafted GG exhibited hybrid properties of biopolymer as well as PANI, and has electrical conductivity in the range of 1.6 × 10−2 S/cm at room temperature. The electrical conductivity of the grafted biomaterial was quite sensitive with pH, and it could be interesting to combine a biopolymer, isolated from the natural resources with synthetic polymer from petrochemical origin, and yielded an eco‐friendly material of high performance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Crystallization‐induced shrinkage, crystalline, and thermomechanical properties of in situ polymerized cyclic butylene terephthalate
Authors: Harsch M. , Karger‐Kocsis J. , Apostolov A. A. 
Published: January 2008

AbstractThe polymerization and crystallization of cyclic butylene terephthalate oligomers (CBT) were followed by fiber Bragg grating (FBG) and normal force measurements under isothermal conditions at T = 170 and 190°C, respectively. It was found that the FBG and normal force sense only the crystallization‐induced shrinkage. The course of the FBG signal and the normal force as a function of time suggested that crystallization of the polymerized CBT (pCBT) occurs in two steps. The primary crystallization‐induced shrinkage is several hundreds by contrast to the secondary one showing several tens in ppm/min unit according to the FBG results. The two‐step crystallization was confirmed by normal force measurements. The crystallinity and crystalline structure of the pCBTs were studied by differential scanning calorimetry and wide‐angle X‐ray scattering. It was found that the crystallinity and the crystalline parameters slightly differ for the pCBTs formed at T = 170 and 190°C, respectively. The pCBT produced at T = 190°C had slightly higher crystallinity and more perfect crystals than the pCBT formed at T = 170°C. The reliability of the FBG sensing was checked by thermomechanical analysis (TMA). A fair agreement was established between the thermal contraction and thermal expansion measured by FBG and TMA, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Effect of diluents on the crystallization behavior of poly(4‐methyl‐1‐pentene) and membrane morphology via thermally induced phase separation
Authors: Tao Haijun , Zhang Jun , Wang Xiaolin 
Published: January 2008

AbstractThe effect of diluents on polymer crystallization and membrane morphology via thermally induced phase separation(TIPS) were studied by changing the composition of the mixed‐diluents systematically, in the system of poly(4‐methyl‐1‐pentene) (TPX)/dibutyl‐phthalate (DBP)/di‐n‐octyl‐phthalate (D‐n‐OP) with TPX concentration of 30 wt %. The TPX crystallization was observed with differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD). The membranes were characterized with scanning electron microscopy (SEM), porosity, and pore size measurement. As the content of D‐n‐OP increased in mixed‐diluents, the solubility with TPX increased, inducing the phase separation changing from liquid–liquid phase separation into solid–liquid phase separation, which changed the membrane morphology and structure. When the ratios of DBP to D‐n‐OP were 10 : 0, 7 : 3; 5 : 5, and 3 : 7, membranes were formed with cellular structure and well connected pores, while the ratio was 0 : 10, discernable spherulities were found with not well‐formed pore structure. The effect of composition of the mixed‐diluents on membrane morphology was more remarkable in TPX/dioctyl‐sebacate (DOS)/dimethyl‐phthalate (DMP) system, since good cellular structure was formed when the ratios of DOS to DMP were 10 : 0, 7 : 3, while spherulites were observed when 5 : 5. Dual endotherm peaks behavior on DSC melting curves emerged for all the samples in this study, which was attributed to the special polymer crystallization behavior, primary crystallization, and secondary crystallization occurred when quenching the samples. As the content of D‐n‐OP increased, the secondary crystallization enhanced which induced the first endotherm peak on DSC melting curves moving to a lower temperature and the broadening of the overall melting peak, as well as the increasing of the overall crystallinity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The influence of the different modifying agents on the synthesis of poly(methylmethacrylate)‐calcium carbonate nanocomposites via soapless emulsion polymerization
Authors: Ma Xiaokun , Liu Yanhua , Yu Yang , Lei Hong , Lv Xiaotang , Zhao Lina , Ren Suxia , Wang Zichen 
Published: January 2008

AbstractThe synthesis of poly(methylmethacrylate)‐calcium carbonate nanocomposites via the soapless emulsion polymerization was investigated after the CaCO3 nanoparticles were modified with different modifying agents. Such three kinds of modifying agents as sodium stearate (SS), oleic acid (OA), and PMMA were used to improve the surface property of CaCO3 nanoparticles. What was the most important factor to improve the amount of nanoparticles in the composites is one of the general goals. As determined by Field‐emission scanning electron microscopy (FESEM), the nanocomposites size of the diluted polymer emulsion was over 250 nm, while the sample without CaCO3 had a diameter of about 150 nm. It was worth pointing out that the surface morphology of polymer changed from slick to scraggy, when the nano‐CaCO3 particles participated in the polymerization process. The increase of the droplet size and the change of the polymer morphology indicated that the CaCO3 nanoparticles were present in the emulsion droplets. The X‐ray diffraction results of the nanocomposites showed the existence of typical calcite peaks. The results of the TGA, FTIR, and the contact angles indicated that the hydrophobic surface of CaCO3 nanoparticles was crucial to improve the compatibility between the CaCO3 and MMA monomer in emulsion system. The results of the TGA, FTIR, and the contact angles indicated that the hydrophobic surface of CaCO3 nanoparticles was crucial to improve the compatibility between the CaCO3 and MMA monomer in emulsion system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Poly(ϵ‐caprolactone) grafted dextran biodegradable electrospun matrix: A novel scaffold for tissue engineering
Authors: Bajgai Madhab Prasad , Aryal Santosh , Bhattarai Shanta Raj , Bahadur K. C. Remant , Kim Kawn‐Woo , Kim Hak Yong 
Published: January 2008

AbstractThe main objective of the present work was to fabricate poly(ϵ‐caprolactone) grafted dextran (PGD) electrospun matrix (matrix) and to investigate the scaffold potential in tissue engineering application. In this work, at first we synthesized PGD polymer via ring opening polymerization (ROP), and with predetermined electrospinning conditions, nanofibrous matrix with high molecular weight PGD (PGD‐50, Mw = 45,500) has been successfully fabricated for the first time. Mouse osteoblast like cells, MC3T3 was used to test biocompatibility, assays of cell adhesion, survival, and effects on cell morphology of the matrix. The data demonstrate that PGD‐50 matrix represent a suitable substrate for supporting cell proliferation, process outgrowth and migration and as such would be a good material for artificial extra cellular matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Synthesis and characterization of processable polyaniline doped with novel dopant NaSIPA
Authors: Saini Parveen , Jalan Rajesh , Dhawan S. K. 
Published: January 2008

AbstractAniline has been polymerized in the presence of a novel dopant sodio‐5‐sulfo‐isophthallic acid (NaSIPA), via the chemical oxidative polymerization route. The thermal stability and processability of polyaniline prepared by indirect method (PD1) have been improved significantly (290°C) as compared to polyaniline doped with conventional inorganic dopants like HCl or H2SO4, without much loss of electronic conductivity (5.07 S/cm in PD1). This suggests its use for melt blending with engineering thermoplastics. However, polyaniline prepared by direct method (PD2) can be melt‐blended only with conventional thermoplastics like polyethylene, polypropylene, polystyrene, etc. Low‐temperature studies reveal the 1‐D variable range hopping as a conduction mechanism for direct polymer (PD2), with parameters To and σo as 4112 K and 15.1 S/cm, respectively. However, for indirectly doped polymer (PD1) Arrhenius‐type model, having parameters |(EF − EC)| and σC as 0.04 eV and 28.4 S/cm, respectively, it suited well. The coherence length as found from XRD data was around 28.8 nm for PD1 and 25.2 nm for PD2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Synthesis, characterization, and properties of novel fluorine containing aromatic polyamides
Authors: Maji Samarendra , Banerjee Susanta 
Published: January 2008

AbstractA series of novel fluorine containing aromatic polyamides were synthesized by the direct polycondensation of various fluorine containing aromatic diamines and commercially available 5‐t‐butyl isophthalic acid. These polyamides have good solubility in several organic solvents such as dimethylformamide, N,N‐dimethylacetamide, 1‐Methyl‐2‐pyrrolidone, dimethyl sulfoxide, and tetrahydrofuran. The synthesized polymers exhibited inherent viscosities up to 0.93 dL/g and Mw up to 1,52,000 with PDI of 2.49. The polyamides exhibited good thermal stability up to 489°C for 10% weight loss in nitrogen and high glass transition temperature up to 273°C. Dynamic mechanical analysis showed a very good retention of storage modulus up to the glass transition temperature. The tan δ peak value at 1 Hz was used to calculate the Tg and these values are in good agreement with differential scanning calorimetry data. The polyamide films were flexible with tensile strength up to 72 MPa, elongations at break up to 14%, and modulus of elasticity up to 1.39 GPa depending on the exact repeating unit structure. X‐ray diffraction measurements indicate that these polyamides are semicrystalline. Rheology study showed same trend of melt viscosity behavior with different shear rate for all polymers. Water absorption study indicates the hydrophobic nature of the polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and Anticandidal Activity of Azole‐Containing Sulfonamides
Authors: Qandil Amjad M. , Hassan Mohammad A. , Al‐Shar'i Nizar A. 
Published: January 2008

AbstractTwenty five benzenesulfonamides containing one imidazole or triazole ring, or two imidazole or triazole rings have been synthesized and evaluated as anticandidal agents. The most active compounds were 5c, 6b, 6c, 6e, and 17b, which exhibited MIC values of 4.55–24.39 mM depending on the clinical isolate. Comparing imidazole to triazole derivatives did not show a clear effect on activity. Compounds containing a N‐benzyl group also showed no clear evidence on activity given the fact that they have an extra aromatic ring. Secondary sulfonamides, 5l, 5m, and 5n showed activities that were proportional to their lipophilicity. The activities of N‐aryl‐substituted derivatives 5j, 5k, 5l, 5m, 5n, and 6j were also proportional to their lipophilicity. Halogenation enhanced the activity as a result of improvement of lipophilicity. The presence of two imidazole or triazole rings in the same compound did not show a clear enhancement of activity.
Peptides derived from HIV‐1 Rev inhibit HIV‐1 integrase in a shiftide mechanism
Authors: Hayouka Zvi , Rosenbluh Joseph , Levin Aviad , Maes Michal , Loyter Abraham , Friedler Assaf 
Published: January 2008

AbstractThe HIV‐1 Integrase protein (IN) mediates the integration of the viral cDNA into the host genome. IN is an emerging target for anti‐HIV drug design, and the first IN‐inhibitor was recently approved by the FDA. We have developed a new approach for inhibiting IN by “shiftides”: peptides derived from its cellular binding protein LEDGF/p75 that inhibit IN by shifting its oligomerization equilibrium from the active dimer to an inactive tetramer. In addition, we described two peptides derived from the HIV‐1 Rev protein that interact with IN and inhibit its activity in vitro and in cells. In the current study, we show that the Rev‐derived peptides also act as shiftides. Analytical gel filtration and cross‐linking experiments showed that IN was dimeric when bound to the viral DNA, but tetrameric in the presence of the Rev‐derived peptides. Fluorescence anisotropy studies revealed that the Rev‐derived peptides inhibited the DNA binding of IN. The Rev‐derived peptides inhibited IN catalytic activity in vitro in a concentration‐dependent manner. Inhibition was much more significant when the peptides were added to free IN before it bound the viral DNA than when the peptides were added to a preformed IN‐DNA complex. This confirms that the inhibition is due to the ability of the peptides to shift the oligomerization equilibrium of the free IN toward a tetramer that binds much weaker to the viral DNA. We conclude that protein–protein interactions of IN may serve as a general valuable source for shiftide design. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 481–487, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com