bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modification of porous PVC particles with polyacrylate elastomers using a surfactant-free aqueous dispersion polymerization technique
Authors: Hammer Shir , Tzur Aliza , Cohen Yachin , Narkis Moshe 
Published: August 2014

AbstractThe modification of porous suspension-type polyvinyl chloride (PVC) particles by an in-situ stabilizer-free polymerization/crosslinking of a monomer solution absorbed within the PVC particles is presented. The modifying polymers are polybutyl acrylate (PBA) and polyethylhexyl acrylate (PEHA) crosslinked with ethylene glycol dimethacrylate (EGDMA). The effect of the unique blending procedure on the physical and mechanical properties of PVC has been investigated. The modified PVC characterizations includes polymerization yield, transparency, fracture surface morphology, thermal stability, dynamic mechanical properties, tensile properties, impact resistance and melt rheology. The polymer chains formed are dispersed as a separate phase as observed by scanning electron microscopy (SEM), and two separate glass transitions are observed by dynamic mechanical thermal analysis (DMTA) system, typical of immiscible polymer blends. Mechanical properties of PVC/PEHA blends reveal a substantial increase in impact strength particularly when the blend is crosslinked; however, there is a decrease in the yield stress and elastic modulus. A shift from brittle failure to ductility has been observed in blends of PVC on incorporation of PEHA. SEM studies have been carried out to support these observations.
Non-isothermal degradation kinetics for polycarbonate/ polymethylphenylsilsesquioxane composites
Authors: Wang Jiangbo , Xin Zhong 
Published: August 2014

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process
Microstructures of fiber suspensions in complex geometry
Authors: Ruan Chunlei , Ouyang Jie 
Published: August 2014

AbstractEvolutions of molecular conformation and fiber orientation in fiber suspensions are investigated by collocated finite volume method on unstructured triangular meshes. FENE-P (Finite Extensible Nonlinear Elastic Dumbbell model with Peterlin’s approximation) model which is microstructure-based is chosen to describe the polymeric matrix and TIF (transversely isotropic fluid) model is used to calculate the fiber contribution in order to realize the coupling of flow and fiber orientation. Microstructures of molecule and fiber are obtained by analyzing the information of molecular conformation tensor and second-order fiber orientation tensor respectively. Two numerical examples are considered, namely, a planar contraction flow and a planar flow past a confined cylinder. Present results are hoping to give more insight into the microscopic details of complex flows and thus be more helpful for industrial application.
Surface and electrical properties of high density polyethylene + carbon black composites near the percolation threshold
Authors: Vigueras-Santiago Enrique , Hernández-López Susana , Brostow Witold , Olea-Mejia Oscar , Lara-Sanjuan Omar 
Published: August 2014

AbstractWe have studied friction, scratch resistance and electrical resistivity in high density polyethylene (HDPE) + carbon black (CB) composites in relation to electric resistivity percolation threshold. Below the threshold, CB addition lowers dynamic friction by providing a smaller surface area of contact of the composites with the pin surface; the effect is stronger at higher loads. Above the percolation concentration, an increase in friction is seen due to formation of CB agglomerates and thus an increase in the area of contact. The recovery depth in scratch testing behaves similarly as dynamic friction and for the same reasons, particularly so at high loads, with a minimum at the percolation threshold. Thus, at the threshold we have simultaneously superior scratch resistance, low dynamic friction and low electric resistivity.
Influence of silica content in sulfonated polysulfone/ phosphotungstic acid hybrid membranes on properties for fuel cell application
Authors: Zhang Jian , Fei Guoping , Liang Yile , Zhang Youwei , Zhao Jiongxin 
Published: August 2014

AbstractThe sulfonated polysulfone (SPSU)/phosphotungstic acid (PWA)/silica (SiO2) hybrid membranes were researched for proton exchange membranes. The influence of silica content on the properties of composite membranes was studied in detail. The study displays that inorganic silica particles have a great influence on membrane properties, such as membrane durability, PWA extraction, proton and methanol transport behavior, thermal stability and water uptake. Interestingly, the hybrid membrane with 2 wt.% silica content showed the best results: low PWA extraction, long membrane life time under oxidative condition, high proton conductivity, and low methanol permeability. However, excessive silica content caused a large aggregation of SiO2 particles, leading to the deterioration of membrane properties.
Synthesis and characterization of organogel from poly(acrylic acid) with cellulose acetate
Authors: Rivas-Orta Valeria , Antonio-Cruz Rocío , Rivera-Armenta José Luis , Mendoza-Martínez Ana , Ramírez-Mesa Roberto 
Published: August 2014

AbstractIn the last decade, the interest in physical organogels has grown rapidly with the discovery and synthesis of a very large number of diverse molecules, which used organic solvents at low concentrations. New organogels based on poly (acrylic acid) (PAA) and cellulose acetate (CA) were prepared as thin films to study properties and swelling behavior. In organogels synthesis different crosslinking agent and initiator concentrations were studied. The swelling for PAA/CA organogels was carried out with acetone at 3 different temperatures (30°, 40° and 50 °C) and pH of 6.5 (pHacetone= 6.5). The higher swelling for PAA/CA organogels was 770% for 25PAA/75CA composition ratio with 3%wt N,N´-methylene-bis acrylamide (MBA) and 1%wt potassium persulphate (KPS) at 30 °C. The films were analyzed by FTIR and the presence of functional groups of each polymer was confirmed without secondary reactions. The DSC analysis indicated two glass transition temperatures (Tg); at 106 °C corresponding to PAA and 86 °C, corresponding to CA, respectively, indicative of phase separation, characteristic of gels. Surface morphology was analyzed by Scanning electron microscopy (SEM) showing smooth surface and small crystal forms.
Preparation and mechanical properties of PCL-based polyurethanes as potential biomaterials for short-term applications
Authors: Sobczak Marcin , Dębek Cezary , Goś Piotr 
Published: August 2014

AbstractA series of polyurethanes (PURs) were prepared by metal-free method, containing polycaprolactone (PCL) as the soft segment with molecular weights of 1600, 2400 and 2600. PCL was obtained by the ring-opening polymerization of ε- caprolactone in the presence L-alanine and L-phenyloalanine. The structure of synthesized oligoesters and PURs were spectroscopically confirmed. The molecular weights, mechanical and thermal properties of the obtained materials were reported.
Nucleation loci in the ring-opening polymerization of octamethyl- cyclo-tetrasiloxane in Winsor I system with dodecylbenzene sulfonic acid sodium salt and sulfuric acid
Authors: Suzuki Kiyoshi , Andoh Daisuke , Hyodoh Akira , Satoh Shuzaemon , Nomura Mamoru 
Published: August 2014

AbstractThe ring-opening polymerization of octamethylcyclotetrasiloxane (OTS) was carried out in an Winsor I system with dodecylbenzene sulfonic acid, sodium salt (DBSNa) as emulsifier and sulfuric acid as initiator, to clarify the mechanism of the polymerization, especially focusing on the nucleation loci, the rate of generation of nonvolatile molecules and the average diameter of generated polymer droplets. In the system where DBSNa concentration is higher than the critical micellar concentration (CMC), nonvolatile molecules were generated in the aqueous phase and their generation rate became higher with an increase in DBSNa concentration, while nonvolatile molecules were not generated at emulsifier concentrations lower than the CMC. These experimental results support that nucleation did not take place in the true aqueous phase, but originated from the micelles.
Study of polyamide-6 hollow fiber membranes prepared via a thermally induced phase-separation method
Authors: Jiang Zhao-Hui , Xiao Chang-Fa , Hu Xiao-Yu 
Published: August 2014

AbstractHollow fiber membranes of polyamide-6(PA6) with porous structure were prepared by a thermally induced phase-separation method. N-Ethyl-o/p-toluene sulfonamide was chosen as diluent. On the basis of scanning electron microscopy (SEM) images, porosity, bubble point pore diameter and pure water flux, the influential factors including polymer concentration, coagulation bath temperature, post-stretching were investigated. The results indicate that with the increasing of PA6 concentration ‘slit-shaped’ pores in inner surfaces and cellular structure in cross-sections disappear, correspondingly, the properties of membranes such as porosity and pure water flux become poor. As the coagulation bath temperature varied from 20 °C to 50°C, the pure water flux of membranes is improved from 136 to 244 L·m-2·h-1. Post-stretching make the ‘interfacial micro-pores’ expand due to ‘stress concentration’ phenomenon, thus changing the structure and improving the properties of membranes. PA6 hollow fiber membranes with rational structure and high performance could be obtained by altering polymer concentration, coagulation bath temperature and post-stretching.
Hydrodegradation of starch incorporated polylactic acid with acrylic acid as interfacial linker
Authors: Xiao Yinghong , Che Jianfei , Bergeret Anne , Mao Chun , Shen Jian 
Published: August 2014

AbstractGraft modification of polylactic acid (PLA) with acrylic acid (AA) using double initiators was studied. The composition of the graft copolymer (PLA-AA) was characterized with Fourier transform infrared (FTIR) spectroscopy and introduction of AA was demonstrated. Differential scanning calorimetry (DSC) analysis indicated that due to the increasing graft efficacy the modified PLA had better interfacial adhesion with starch compared to neat PLA. Fracture surfaces of starch/PLA and starch/PLA-AA were observed using scanning electron microscope (SEM) and the results also demonstrated the better interfacial adhesion of the latter composite. Graft modification of PLA matrix and introduction of starch played important roles in enhancing the mechanical properties (strength and modulus) while remaining good degradability of the composite.
Synthesis of conductive nanocomposites based on polyaniline/poly(styrene-alt-maleic anhydride)/polystyrene
Authors: Najafi Moghadam P , Nazarzadeh Zareh E 
Published: August 2014

AbstractConducting polyaniline (PANI) nano particles doped with HCl was synthesized by a sonochemical method. Polyaniline/poly(styrene-alt-maleic acid)/polystyrene composites with different polyaniline content were developed by solution-dispersion blending method. The influence of poly(styrene-alt-maleic acid) concentration in composite structure was also investigated. The composite dispersed solution in tetrahydrofuran (THF) was cast to fabricate conductive films with evaporation of the solvent. With only a mixing procedure and without any dispersant added, the PANI nanoparticles were well dispersed in the matrix polymer as indicated by scanning electron microscopy (SEM) images. The conductivity of obtained composites was measured with four probe technique. All of obtained composites have conductivity and between them, the maximum electrical conductivity was 2.4 S/cm. The obtained composites were characterized by FT-IR and UV-Vis spectroscopy.
Characterization of chitin and chitosan extracted from shrimp shells by two methods
Authors: Gartner Carmiña , Peláez Carlos Alberto , López Betty Lucy 
Published: August 2014

AbstractShrimp shells from Penaeus Vannamei species were hydrolyzed for chitin extraction by a chemical and a papain enzymatic method. Composition of shells was analyzed and their microstructure was characterized before and after hydrolysis by microscopy. Chitin fibers arrangement in the tissue was preserved after chemical extraction, but after papain hydrolysis the tissue presented structural disarrangement indicating that papain reacts indistinctly with peptidic and N-acetyl linkages. Although chemical purification is very effective, by-products are not recoverable. Conversely, papain hydrolysis yields partially purified chitosan but permits aminoacids isolation, which is important in food industry. This method has other advantages such as low cost and easy accessibility of papain. Chitin and chitosan were characterized by thermogravimetric analysis, infrared spectrophotometry and capillary electrophoresis. Degree of N-acetylation (DA) was determined by cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS 13CNMR) or potentiometry and crystallinity was measured by X ray diffraction.
Coalescence during annealing of quiescent immiscible polymer blends
Authors: Dimzoski Bojan , Fortelný Ivan , Šlouf Miroslav , Nevoralová Martina , Michálková Danuše , Mikešová Jana 
Published: August 2014

AbstractCoalescence during annealing of quiescent immiscible polymer blends, containing polypropylene (PP) matrix and different amount of ethylene-propylene copolymer (EPR) as dispersed phase, was studied. Comparison of experimental results with available coalescence theories revealed that changes in the phase structure after 20 min annealing can be precisely estimated using the approximate theory of coalescence induced by van der Waals forces and considering drainage of the matrix film between spherical droplets. All results evidenced growth of the EPR droplet size with the annealing time and temperature; increase in the content of dispersed phase contributed to higher growth rate of the dispersed phase, more pronounced at the coalescence origin. Anisometry of the EPR droplets and droplet shape relaxation were perceived, both interfering the course of coalescence. Enhanced elasticity of examined blends at low frequencies and positive deviation of the complex viscosity from the linear mixing rules was observed.
Electrospinning technique in the nano-photocatalyst research
Authors: Li Cong-Ju , Xu Guo-Rong 
Published: August 2014

AbstractPhotocatalysts have attracted much scientific interest stemming from their high catalytic efficiency and environmental friendly properties. However, due to the development of nanosicence and nanotechnology, nano-photocatalysts have attracted more and more attention. Generally speaking, nano-photocatalyst indicates photocatalytic materials in nano size, including nanoparticles, nanofibers, nanowires, and so on. Electrospinning, used as a simple method to fabricate nanomaterials, is playing a very important role on nano-photocatalyst research, both on the production of novel nano-photocatalysts and on the study of innovative fabrication methods. The applications of electrospinning on nano-photocatalyst research are reviewed with an emphasis on fabrication of nano-photocatalysts and on the strategies that have been tried to improve nano-photocatalysts performance.
Phase transition behavior of silicone based liquid crystalline polymers
Authors: Jana R. N. , Bhunia H. , Im C. 
Published: August 2014

AbstractPhase transition behavior of silicone based liquid crystalline (LC) polymers with variable isotropic transition temperatures (Ti), synthesized from poly(methyl hydrosiloxane), 10-undecenoic acid based crosslinking agent and cholesterol based side chain mesogen, was studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. The chemical structure of the mesogenic monomer and the LC polymers were confirmed by Fourier transform infra-red (FT-IR) spectroscopy and 1HNMR spectroscopy. DSC studies showed that the glass transition temperatures (Tg) and Ti of the LC polymers decreased with increasing proportion of mesogenic crosslinking agent at its low proportion and at its higher proportion Ti disappeared completely indicating that the polymeric chains had less chance to orient in the network structure. The results were consistent with the XRD and POM studies.
Quaternary ammonium salt substituted polyhedral oligosilsesquioxanes (POSSes) as structure directing agents in the generation of porous silica materials
Authors: Rózga-Wijas Krystyna , Fortuniak Witold , Chojnowski Julian 
Published: August 2014

AbstractThe sol-gel base catalysed hydrolytic polycondensations of tetramethoxysilane (TMOS) were studied in the presence of quaternary ammonium chloride substituted polyhedral oligosilsesquioxanes (POSSes): octa{3-[(2- hydroxyethyl)dimethylammonio]propyl chloride}octasilsesquioxane or octa[3-(noctyldimethylammonio) propyl chloride]octasilsesquioxane. Small amounts of these POSSes added to the sol-gel system markedly affected the morphology of the silica gel polycondensation products. The morphology was highly dependent on the POSS concentration. Amorphous mesoporous silica gels were obtained showing a high porosity and the surface area up to 615 m2g-1. Most of gels had a fairly large average pore diameters, 4-11 nm and pore volume 0.4-1.3 cm3g-1. TMOS having inserted hexamethyltrisiloxane chain, 1,1,1,7-tetramethoxyhexamethyltetra siloxane, (TMOSD3) in the mixture with TMOS was also used as the monomer in the sol-gel polycondensation; but obtained gels showed a low porosity.
Suzuki polycondensation: a simple way for synthesis of new polyazines containing thiophene and fluorene moieties
Authors: Mihai Iulia , Ivanoiu Maria , Vacareanu (Stafie) Loredana , Grigoras Mircea 
Published: August 2014

AbstractTwo novel polyazines were successfully synthesized via palladiumcatalyzed Suzuki coupling method of N,N'-bis(5-bromothiophene)-2-aldehyd azine with 2,5-thiophenediboronic acid and 9,9-dioctylfluorene-2,7-diboronic acid, respectively. The polymers were characterized by 1H-NMR, FT-IR and UV-VIS spectroscopy. The thermal properties of the polymers were investigated by TGA analysis. The semi-crystalline structure of these compounds was demonstrated by X-ray diffraction study.
Thermal characterization of novel aliphatic polyesters with ether and thioether linkages
Authors: Soccio M. , Lotti N. , Finelli L. , Munari A. 
Published: August 2014

AbstractSeveral novel ether or thioether linkage containing aliphatic polyesters and poly(alkylene dicarboxylate)s for comparison were synthesized and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the ether or thioether linkage-containing polyesters. The decrement of the thermal stability appears to be more relevant in the case of presence of sulphur atoms. At room temperature the samples appeared semicrystalline, except PTTDG and PDEDG, which were viscous oils; the effect of the introduction of ether or thioether group was an increment of the Tg value, a decrement of the melting temperature and a significant decrease of the crystallization rate. The entity of the variations was found to be affected by the kind of group introduced, and the trend observed can be explained on the basis of atom electronegativity and dimensions.
Study on the coagulation process of cellulose nascent fibers with ionic liquid AMIMCl as a solvent during dry-wet spinning
Authors: Song Jun , Cheng Bowen , Jie Xiuji , Liang Yi , Lu Fei , Zhang Feining 
Published: August 2014

AbstractThe coagulation process of nascent fiber of cellulose with ionic liquid 1- allyl-3-methylimidazolium chloride (AMIMCI) as the solvent was studied during drywet spinning. The diffusion rate and the crystallization situation of nascent fiber were tested, its fracture morphology was observed, and the diffusion coefficient D of solvent and the crystallization degree of nascent fiber were calculated according to relevant equations. The diffusion rate and diffusion coefficient of ionic liquid decrease with cellulose concentration increasing in spinning solution and then remain almost the same when the cellulose mass fraction reaches 7%. With the increase of coagulation bath concentration, the diffusion rate and diffusion coefficient of the solvents increase first and then decrease. When the coagulation bath concentration reaches 5%, the diffusion rate and diffusion coefficient of the solvents are at their maximum. With the increase of coagulation bath temperature and the length of air gap, the diffusion rate and diffusion coefficient of ionic liquid increase slightly. The cellulose solution concentration and the spinning air gap have an influence on the crystallization degree of nascent fiber. With the increase of cellulose solution concentration and the spinning air gap, the crystallization degree of the produced nascent fiber increases slightly, but the coagulation bath temperature basically have no influence on the nascent fiber formation.
On the mechanism of conductivity enhancement in PEDOT/PSS film doped with sorbitol
Authors: Li Jiao , Liu Juncheng , Gao Congjie 
Published: August 2014

AbstractThe mechanism of conductivity enhancement in PEDOT/PSS film doped with sorbitol is investigated by X-ray diffraction (XRD), Fourier transform Raman spectroscopy (FT-RM), Atomic force microscopy (AFM), Scanning electron microscopy (SEM). The XRD show that the amorphous state of sorbitol-doped films is not changed and the FT-RM indicate that the main characteristic absorption peak of PEDOT shifts to red. These observations indicate that the increase in conductivity is not attributed to the crystallization behavior of PEDOT, but to the change of the resonant structure of PEDOT chain from a ‘benzoid’ to a ‘quinoid’ structure, which increase the rigidity of PEDOT chain. In addition, there is a conformational conversion of the PEDOT chains from the coil structure to expanded-coil or linear structure. These chains changes are helpful to charge transport through the PEDOT chains and conductivity enhancement of composite films. The increased inter-molecule interactions were investigated by the morphological changes of films as observed in AFM and SEM images, which further confirmed the change of the resonant structure of PEDOT chain.