bluuebunny/crossref_metadata_2025_split huggingface dataset:
The synergistic effect of dope concentration and jetdrawing on structure development of wet-spun poly(acrylonitrile)
Authors: Arbab Shahram , Mohammadi Naser , Noorpanah Parviz 
Published: August 2014

AbstractAcrylic fibers are the major precursor of carbon fibers. In this work, the synergistic effect of polymer concentration and jet stretching on porosity, morphology and mechanical properties of wet-spun poly(acrylonitrile) fibers were studied and then the role of void size was elucidated. The results showed that the effect of jet stretching on fiber porosity is negligible below a threshold polymer concentration. Increasing polymer concentration up to 20 vol. % reduced the total porosity significantly but increased the nanometric void population slightly. On the other hand increasing polymer concentration and jet stretching simultaneously, improved mechanical properties as a result of a remarkable reduction in porosity. In addition, stretching shifted nanovoids distribution strongly toward smaller sizes. This was attributed to the effect of stretching and increasing polymer concentration on reducing the diffusion coefficient. Young's modulus of fibers also increased with decreasing overall porosity. Finally, strength-diameter correlation showed a good agreement with the Griffith's theory.
Synthesis, characterization and thermal crosslinking behavior of new poly(aryl ether sulfone)s based on naphthalene isomers
Authors: Ying Zhang , Yunhe Zhang , Yaming Niu , Ying Na , Zhenhua Jiang 
Published: August 2014

AbstractFour new poly(aryl ether sulfone)s containing naphthalene rings were synthesized from 1,5- and 2,7-bis-(4-fluorosulfonyl)naphthalene isomers with different diphenols. These polymers exhibited high glass transition temperatures and good thermal stability. The glass transition temperatures ranged from 220 to 236°C and the 5% weight-loss temperatures were above 423°C. As the four polymers were treated at 300°C, the glass transition temperatures of polymer series a obviously increased and the polymers became insoluble in common organic solvents including NMP, DMAc, and chloroform, etc., but the series b did not, which indicate that a thermal crosslinking reaction via free radicals happened leading to crosslinked polymers
In-situ polymerization of EDOT in water/methanol with different DBSA contents
Authors: Chen Chia-Fu , Dai Chi-an , Chiu Wen-Yen 
Published: August 2014

AbstractIn this work, poly(3-ethylenedioxythiophene) (PEDOT) was synthesized on glass by spin coating for 10 seconds at 500 rpm and polymerization was carried out in an oven at 110°C for 10 min. Methanol and water mixture were used as the solvent and dodecylbenzene sulfonic acid (DBSA) as the surfactant. The conductivities of films were measured and their relationship with different solvent or various surfactant contents were discussed. The morphology of films was observed by SEM, and PEDOT synthesized in methanol-rich solvents or with less DBSA content had more smooth surfaces, showed lower degradation temperature (by TGA). Also, PEDOT synthesized in methanol-rich solvents or with less DBSA were doped better, as observed by UV-Vis spectra.
Polymerization of n-butyl methylacrylate using bis(β- ketoamino)nickel(II)/MAO catalytic systems
Authors: He Xiaohui , Chen Yiwang , Liu Yongming , Chen Muqing , Yu Shuxian , Hong Sanguo , Wu Qing 
Published: August 2014

AbstractThe polymerizations of n-butyl methylacrylate (nBMA) were carried out using bis(β-ketoamino)nickel(II) complexes (Ni[CH3C(O)CHC(NR)CH3]2: R = phenyl, 1; R = naphthyl, 2) in combination with methylaluminoxane (MAO) in toluene. The effect of parameters such as polymerization temperature, Al/Ni molar ratios, polymerization time, and monomer concentration, on catalytic polymerization activity and polymer molecular weights, were examined in detail. Both of the nickel(II) catalytic systems exhibited moderate activity, and produced P(nBMA) with high molecular weight and relatively broad molecular weight distribution (Mw/Mn=2.0~3.0. The obtained polymer has been characterized by means of FTIR, 1H NMR, 13C NMR, DSC, and WAXD technique and was confirmed to be syndio-rich stereospecific P(nBMA).
Water dispersible carbon black prepared through ultrasonically assisted radical polymerization
Authors: Huang Jianfeng , Li Qiuying , Bao Yubin , Wu Chifei 
Published: August 2014

AbstractTo improve the dispersion stability of carbon black (CB) in aqueous media, an anion vinyl monomer, namely potassium 4-vinylbenzoate (K-4VBA) was polymerized and coated on to the CB particles through ultrasonically assisted radical polymerization. FT-IR was used to detect the presence of poly(K-4VBA) on the CB surface. The TGA results indicated that the polyelectrolyte contents of the CB particles could reach 77.5% in weight. The TEM studies revealed that the surface morphologies for the coated polyelectrolyte. Combined aqueous electrophoresis and DLS studies confirmed that these polyelectrolyte modified CB particles had pH-dependent colloid stabilities, as expected. The modified particles were colloidal stable at high or neutral pH, but became aggregated at low pH.
Quantum-mechanical simulation of the structure and stability of starch – metal cation complexes
Authors: Ciesielski Wojciech 
Published: August 2014

AbstractMolecular mechanics computations and simulations involving the Mopac assisted SCF LCAO MO ZINDO1 method were performed for complexes of ɑ-Dglucose with Co(II), Cu(II), Fe(III), Mn(II) and Ni(II) acetates, chlorides and nitrates. The computations resulted in the following findings: Usually the saccharide ligand completely repulsed water molecules from the inner coordination sphere of the central metal atoms. The complexes with Fe(III) acetate and chloride and nitrates of Co(II) and Cu(II) constituted random exceptions having some water molecules in that sphere. The oxygen atom of the 3-hydroxyl group in ɑ-D-glucose (the O3 atom) was the preferred coordination site. The stability of complexes declined as the primary saccharide chain composed of one ɑ-D-glucose was extended by subsequently 1→4 bound ɑ-D-glucose mers. Also such chains coordinated to the central atoms through the O3 oxygen atom. Analysis of the increment of increase in the heat formation with each subsequent ɑ-D-glucose mer in the saccharide chain might suggest that such chain forms chelates with the central metal atom. With CuCl2 first and third ɑ-D-glucose mers were involved in the chelate formation, whereas in case of CoCl2 the first and fourth D-glucose mers were involved.
Synthesis and characterization of novel optically active poly(ester-imide-imine)s
Authors: Hajipour Abdol Reza , Roosta Parniyan , Zahmatkesh Saeed , Ruoho Arnold E. 
Published: August 2014

Abstract N,N´-(3,3´,4,4´-Benzophenonetetracarboxylic)-3,3´,4,4´-diimido-di-Lamino acids (1a-1d) and N,N´-pyromelliticdiimido-di-L-amino acids (2a-2d) are prepared from the reaction of 3,3´,4,4´-benzenetetracarboxylic-3,3´,4,4´- dianhydride or pyromellitic dianhydride with the corresponding L-amino acids in a solution of glacial acetic acid/pyridine (3:2) at refluxing temperature. 4-(4-((4- Hydroxyphenylimino)methyl)benzylidene amino) phenol (3) is prepared from 4- amino phenol and terephthaldialdehyde in refluxing ethanol. Interfacial polycondensation method was used to prepare the corresponding polymers (PEII1-8) in two immiscible solvents (water/dichloromethane). The resulting poly(esterimide- imine)s (PEIIs) having good inherent viscosities (0.13-1.25 dl g-1), optical activity and thermal stabilities is obtained in high yields.
Synthesis of monodisperse poly(styrene-co-divinyl benzene) microspheres by precipitation polymerization in acetonitrile and n-butanol mixture
Authors: Hongyan Jiang , Hou Chen , Ying Liang , Yuhong Xuan , Mingliang Wang 
Published: August 2014

AbstractNarrow disperse poly(styrene-co-divinylbenzene) microspheres were prepared by precipitation polymerization using acetonitrile/n-butanol mixture as the reaction medium and 2,2’-azobis(2-methylpropionitrile) (AIBN) as initiator. The resulting particles have smooth surfaces due to the absence of any additional stabilizer. Effects of the reaction parameters such as n-butanol fraction in the reaction medium, monomer and initiator concentration, and divinylbenzene content were investigated. It was found that the particle size increased with an increasing concentration of monomer and initiator, while the uniformity was kept constant. The number-average particle diameter ranged from 2.36 to 1.63 μm and decreased with an increasing divinylbenzene concentration. In addition, the uniformity was enhanced as the concentration of divinylbenzene increased. On the basis of the DSC and TGA data, the microspheres prepared by the precipitation polymerization possessed a highly crosslinked structure and the thermal stability improved with the DVB concentration.
Physical and mechanical properties of sulfonated aromatic copolyimide membranes
Authors: Rabiee Ahmad , Mehdipour-Ataei Shahram 
Published: August 2014

AbstractPhysical and mechanical properties of four series of chemically and thermally stable sulfonated copolyimides as ion-conducting ionomers for application in fuel cell membrane, depending on chemical structure of diamine monomers were studied. The physical and mechanical properties of solid polymer membranes including thermal stability, mechanical strength, water uptake, stability in water, crystallinity and morphology were evaluated. All the polymers were thermally stable. The XRD analysis and SEM micrograph revealed that the polymers were almost amorphous and hydrophobic-hydrophilic phase separation in polyimide did not occur. Use of flexible monomers such as 4,4'-oxydianiline (ODA) and 4,4'-(4-aminophenoxy) diphenylsulfone (APDS) in the hydrophobic sequences increased the plastic behavior compared to rigid polymers prepared from 4,4'-(5- amino-1-naphthoxy) diphenylsulfone (ANDS) and m-phenylenediamine (m-PDA). It was concluded that the properties of polymeric films were strictly dependent on chemical composition of monomers and molecular weight of copolymers.
Dissolution of microcrystalline cellulose and its graft copolymer in ionic liquid of 1-allyl-3-ethylimidazolium chloride
Authors: Guo Liying , Shi Tiejun , Li Zhong 
Published: August 2014

AbstractThe ionic liquid of 1-allyl-3-ethylimidazolium chloride ([AEIM]Cl) was synthesized and its chemical structure was confirmed. Dissolution of microcrystalline cellulose (MCC) in [AEIM]Cl by microwave heating method was researched. Acrylamide (AM) was grafted onto the dissolved MCC with initiator in [AEIM]Cl and aqueous medium respectively. The effect of temperature, initiator and its dosages on monomer conversion and grafting efficiency was studied. The results showed that [AEIM]Cl was a good solvent for MCC and dissolution rate was the highest (28.8%) when the MCC pretreated with 15% NaOH under the high pressure. Graft copolymer prepared by AM and MCC in [AEIM]Cl had higher monomer conversion and grafting efficiency than in aqueous medium. The best condition for preparing graft copolymer was that potassium persulfate was used as initiator with the dosage of 1g/L under the temperature of 45 °C-50 °C. Spectra of FT-IR had proved that AM was grafted onto MCC. The thermal stability of MCC improved after grafting, and the crystal form was destroyed thoroughly.
Controllable fabrication of poly(vinyl pyrrolidone) (PVP) nanofibers by wheel-spinning technique
Authors: Chang Guo-Qing , Chen Zhen 
Published: August 2014

AbstractA simple and facile approach to fabricate PVP fibers by wheel-spinning technique was investigated. Poly(vinyl pyrrolidone) sol (PVP, Mw =1,300,000, 6-14 w% in ethanol) was used as the candidate polymeric material. It was demonstrated by a rotating wheel with the speeds of 18.84, 15.70 and 12.56 m/s, respectively, PVP fibers can be drawn with diameters ranging from under 200 to over 2 μm and controlled by changing the rotating speed and sol concentration. The morphologies of the wheel-spinning fibers were observed by electronic scanning microscopy (SEM). The nanofibers obtained by this technique are long, straight and smooth, and the fabricated apparatus is simple.
An investigation on modelling and measurements of transient elongational rheology of polymer melts by SER testing platform
Authors: Rajabian Mahmoud , Naderi Ghassem , Piroozfar Hamid , Beheshty Mohammad H. , Samadfam Mohammad 
Published: August 2014

AbstractTransient elongational rheology of PP is investigated experimentally. A specifically designed fixture consisting of two drums mounted on a TA Instruments ARES rotational rheometer was used to measure the transient uniaxial extensional viscosity of two commercial grades polypropylene in the molten state. The Hencky strain was varied from 0.003 to 2 s-1 and the temperature was fixed at 180 oC. The measurements show that the steady state elongational viscosity was reached at the measured Hencky strains for polypropylene. Eslami and Grmela have recently introduced a reptation diffusion term arising from the intermolecular chain forces into the rigid FENE-P dumbbells model. The same approach has been used in this study to interpret the transient rheological data in both shear-free and simple shear flows.
Preparation and characterization of poly(styrenemethacrylic acid)/MCM-41 core/shell nanocomposite microspheres
Authors: Zhao Yansheng , Ma Xingji , Liu Yongmei , Yuan Guangwei , Guo Meijuan , Chen Kai , Shen Yinghua 
Published: August 2014

AbstractIn acidic media, poly(styrene-methacrylic acid)/MCM-41 [P(St- MAA)/MCM-41] core/shell microspheres were synthesized using monodisperse P(St-MAA) particles contained in soap-free emulsion and cetyltrimethylammonium bromide as co-templates by adsorption self-assembly method. The effects of P(St- MAA) composition on shell structure of the core/shell microspheres were investigated. The morphology and composition of P(St-MAA)/MCM-41 microspheres were characterized by TEM, XRD and FTIR. The results show that the ordering degree of MCM-41 shells increased as the molar ratio of MAA to St increased. When n(MAA)/n(St) is 0.2, the average diameter and the shell thickness of nanocomposite microspheres are about 170 nm and 20 nm, respectively.
Materials for intraocular lenses (IOLs): Review of developments to achieve biocompatibility
Authors: Tripti D. , Haldar R.S. , Geetha S. , Niyogi U.K. , Khandal R.K. 
Published: August 2014

AbstractIt is true that the developments in material sciences along with the improvements in various aspects of technology involved in transforming materials into products, over the years, have been responsible for making many of the impossible-looking devices possible. It is also a fact that the demand for a new, improved and better material has never ended; in fact it has been increasing to a greater degree and with bigger dimensions than ever before, especially in recent times. As a matter of fact, for certain advanced applications, the need for efforts to have new materials can never be over emphasized; for example, in the area of biomedical devices such as intraocular lens (IOL). The advances in the field of bio-medical applications require the materials of high quality meeting stringent norms of performance. For implants such as the ones like IOL used for correction of vision of the eyes, besides the quality and performance of materials, biocompatibility is an issue of major concern. The material scientists have been working on the development of materials for IOLs targeting the needs arising out of the developing countries. The challenges include not only to bring down the cost of the materials used for IOLs but also to increase the biocompatibility of IOLs. For making the development process easy and bringing the state-of-the- art of knowledge to those looking for new materials, it is thought necessary to review various facets of IOLs in the present paper. Not only the aspects related to the recent developments in biomedical devices of eye care but also related to the properties of available materials vis a vis the deficiencies in properties of existing materials have been covered in this review. The aim has been to bring out the gap areas at various levels of process of product chain starting from the monomer to polymer, blank to IOL, insertion of IOL into eyes to life cycle of IOLs, mainly to provide certain possible and feasible leads to meet the challenges of making new and more biocompatible materials.
Effect of different amine modified clays on the compatibility and clay dispersion of polypropylene nanocomposites
Authors: Sánchez-Valdes S. , Méndez-Nonell J. , Ramos de Valle L. F. , Lozano-Ramírez T. , Ramírez-Vargas E. , López-Quintanilla M. L. , Gutiérrez-Rodríguez J. M. 
Published: August 2014

AbstractThe compatibilization effects provided by different amines in the synthesis of polypropylene/amine modified montmorillonite clay nanocomposites (PP/ A-MMT) were studied. Nanocomposites were prepared by melt processing using a twin-screw extruder, by compounding maleic anhydride grafted polypropylene (PPgMA) with MMT modified with three different amines: ethanolamine (EA), hexamethylenediamine (DA6) and 1,12-diaminododecane (DA12) to form amine modified montmorillonite "A-MMT". FTIR characterization confirmed the formation of characteristic amide linkages and X-ray confirmed the intercalation of PPgMA between the silicate layers. X-ray, scanning electron microscopy with transmission modulus (STEM), thermogravimetric analysis (TGA), rheological properties plus mechanical properties were used to characterize those nanocomposites. X-ray diffraction patterns of the composites using A-MMT showed 001 basal spacing enlargement with good clay exfoliation-intercalation compared with the natural MMT (Na-MMT). The DA12 modified MMT showed the greatest increase in basal spacing. TGA revealed that the decomposition of the composite took place at a slightly higher temperature than that of neat PP. Nanocomposites using EA or DA6 modified MMT showed a decrease in viscosity whereas those using DA12 showed an increase in viscosity. Nanocomposites using the DA12 modified MMT showed the most substantial improvement in terms of both mechanical properties and clay exfoliation. It appears that the longer the amine chain the higher the separation of the clay platelets and the higher the interactions between the clay and the polymer matrix.
Gate location optimization scheme for plastic injection molding
Authors: Zhai Ming , Lam Yeecheong , Au Chikit 
Published: August 2014

AbstractGate location of injection molding is vital to achieve high quality plastic part. The determination of gate location is an important issue in mold design. A computationally efficient scheme based on flow path is proposed to locate the optimum gate for achieving balanced flow. The range of filling time is employed as objective function. Comparisons were made between the flow path search scheme and the existing adjacent node evaluation scheme, and between the objective function of the range of filling time and the existing standard deviation of filling time. The two examples investigated indicated that the search routine based on the concept of flow path is more efficient computationally and the range of filling time is a better objective function to reflect the uniformity of fill.
A new salt-resistant superabsorbent hydrogel based on kappa-carrageenan
Authors: Hosseinzadeh Hossein 
Published: August 2014

AbstractIn this work, a novel biopolymer-based superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of 2-hydroxyethyl acrylate (HEA) onto kappa-carrageenan, using potassium persulfate (KPS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The chemical structure of the hydrogels was confirmed by FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The certain variables of the graft copolymerization (i.e. the monomer, the initiator, the polysaccharide, and the crosslinker concentration) were systematically optimized to achieve a hydrogel with maximum swelling capacity. The swelling ratio in various salt solutions was also investigated in detail. Since this hydrogel exhibited a very high absorptivity in saline, it may be referred to as low salt sensitive superabsorbent. The swelling of superabsorbing hydrogels was also measured in solutions with pH ranging from 1 to 13.
Synthesis and characterization of a solvent-based acrylate pressure adhesive for transdermal drug delivery
Authors: Sun Fang , Zhu Guoqiang. , Li Shunlai , Du Hongguang 
Published: August 2014

AbstractThe present investigation was directed towards the synthesis of a copolymer of vinyl acetate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid and acrylamide to be exploited as a pressure sensitive adhesive (PSA) in transdermal drug delivery systems. The experimental methodology involved the optimization of reaction conditions for the polymer synthesis. The optimal synthesis conditions of PSA were determined as that polymerization reaction of PSA in ethyl acetate with BPO of 0.5% w/w of reactants at 75 oC throughout the whole process with polymerization reaction time of eight hours. The copolymer was then characterized by FTIR, 1H-NMR, 13C-NMR and DSC. The PSA was also evaluated for residual monomer content, viscosity, tack, peel adhesion and drug release behavior. The synthesized PSA’s tack is 21#; peel adhesion is 1.39 N/mm. And the residual monomers content in the copolymer after polymerizing for eight hours are VAc 2.98%, BA 0.004%. The PSA also exhibited excellent drug release behavior. Membranes containing oxybutynin were capable of releasing in zero order fashion. It was found that the release velocity depended on the concentration of modified monomer. Drug release from those membranes could be easily tailored by changing the content of the modified monomers. It was found suitable for use in transdermals and could be further exploited either as an adhesive or as a system component in the area of transdermal drug delivery.
Prediction of the polarity parameter π for the radical derived from monomer
Authors: Yu Xinliang , Yu Wenhao , Yi Bing , Wang Xueye 
Published: August 2014

AbstractAn artificial neural network (ANN) model was successfully developed for the modelling and prediction of the polarity parameter π used in the revised patterns scheme for the prediction of monomers reactivity ratios in radical polymerizations. Four quantum chemical descriptors based on density functional theory (DFT) calculations were used to develop the ANN model. The optimal condition of the neural network was obtained by adjusting various parameters by trial-and-error. Simulated with the final optimum BP neural network 4-4-1, the results show that the predicted parameter π values are in good agreement with the experimental ones, with the root mean square (rms) errors being 0.053 (R=0.960) for the training set and 0.070 (R=0.942) for the test set. The ANN model has better statistic quality than the MLR model, which indicates there are nonlinear relationships between these quantum chemical descriptors and the parameter π.