bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of annealing on microstructure & molecular orientation, thermal behaviour, mechanical properties and their correlations of uniaxially drawn iPP thin film
Authors: Saengsuwan Sayant 
Published: August 2014

AbstractThe influence of annealing on the microstructure and molecular orientation, thermal behaviour and mechanical properties of uniaxially drawn iPP thin film was studied by wide-angle X-ray diffraction, differential scanning calorimetry and tensile testing, respectively. The correlations of mechanical and microstructural properties of annealed films were also examined. The transformation of smectic phase of iPP to the α-form was more pronounced with increasing annealing time and temperature. The true and apparent crystallinities and crystal thickness were strongly enhanced with annealing time and temperature. The relative molecular orientation tended to increase with annealing time. These results caused the significant improvement of modulus and tensile strength of the annealed films in both machine (MD) and transverse (TD) directions. The increases in MD-Young’s modulus and MD-tensile strength were well correlated with the increase in true crystallinity obtained in equatorial scans. Some relationship between the increase in crystal thickness and the increase in Young’s modulus in both MD and TD directions was also found.
Mechanical properties and morphology of low density polyethylene/polydimethylsiloxane immiscible blends: modeling and influence of curing agent
Authors: Razavi-Nouri Mohammad , Morshedian Jalil , Ehsani Morteza , Faghihi Farhad 
Published: August 2014

AbstractThe tensile behavior of low density polyethylene/polydimethylsiloxane immiscible blends was investigated with respect to morphological variation of the blends. Experimental data of elastic modulus was compared with theoretical predictions of parallel model (mixing rule), as the upper bound of modulus, Halpin- Tsai model, and a two-parameter equivalent mechanical model proposed by Kolarik, which takes into account the continuity of minor phase. As the predictions of these models were not in good quantitative agreement with experiment, some modifications were made to the Kolarik model. Furthermore, a new approach for determining equivalent mechanical model parameters was proposed based on the calculation of phase continuity parameters as a function of composition. Using this approach, the values predicted for elastic modulus were found to be in good agreement with the experimental data. Moreover, the influence of a peroxide curing agent on the tensile properties of the blends was studied. The improvement of the tensile properties of the blends could have resulted from two contributions: the effect of curing reaction on the tensile properties of constituents and the better interfacial adhesion, because of possible interfacial reaction, as indicated by morphological observation.
Novel cross-linkable polyphosphazene with o-acetyl phenoxide as the pendant group
Authors: Huang Yawen , Tang Xiaozhen , Pan Yang , Fu Jianwei , Huang Xiaobin 
Published: August 2014

AbstractA new polyphosphazene which bears o-acetylphenoxide group [NP(o- C6H4-COCH3)]n, PAOP was synthesized. PAOP can be efficiently thermally crosslinked at mild condition using p-phthalaldehyde as cross-linker and sodium hydroxide as catalyst both in solution and solid reaction. It was found that solid reaction gives more products with carbon-carbon double bond. The suggested process of cross-linking reaction was described based on the progress of small molecular reaction. Influence factors of cross-linking reaction including water and temperature were also discussed and it was concluded that water prevents crosslinking and higher temperature causes higher percent conversion. The photochemical reaction of cross-linked PAOP was simply studied using UV and it was demonstrated that carbon-carbon double bond decayed under UV irradiation and more complicated products were obtained.
Effect of glycidyl methacrylate (GMA) on the stability of acrylic latex
Authors: Wu Guangfeng , Tao Yue , Kang Hong , Zhang Huixuan 
Published: August 2014

AbstractThe stability of core-shell particles (CSPs) with butyl acrylate (BA) as the core and methyl methacrylate (MMA)/glycidyl methacrylate (GMA) mixture in various compositions as the shell was investigated by turbidity measurements. The experiments demonstrate that lower amount addition of GMA could not improve the latex stability. When the amount of GMA exceeded 2% of the total reactants, it began to improve the stability of the latex. With the increasing content of GMA, the latex became more and more stable. On the other hand, experimental data also show that the stability was improved by increasing the concentration of sodium dodecyl sulfate (SDS).
Morphology and properties of halloysite nanotubes reinforced polypropylene nanocomposites
Authors: Du Mingliang , Guo Baochun , Cai Xiaojia , Jia Zhixin , Liu Mingxian , Jia Demin 
Published: August 2014

AbstractHalloysite nanotubes (HNTs) were utilized to prepare polypropylene (PP) nanocomposites by simple melt-compounding approach. Compared with other silicates such as montmorillonite and kaolinite, HNTs show much better dispersion property. The PP nanocomposites with HNTs exhibit concurrence increase in tensile and flexural strength, flexural modulus and impact toughness. Surface modification of HNTs lends the PP nanocomposites higher strength, modulus and lower toughness. The increase in mechanical properties is correlated with the well dispersion of the high aspect ratio HNTs and the orientation of HNTs in PP matrix. Morphology studies show that HNTs can be dispersed in PP uniformly at lower HNTs loading and excessive loading of HNTs causes a little aggregation. Surface modification of HNTs can alleviate the aggregation effectively. The storage modulus of the nanocomposites increases consistently with the HNTs concentration. The surface modification is beneficial to the further improvement in storage modulus. Similar to other silicates, HNTs facilitate the crystallization of PP due to the heterogeneous nucleation
Synthesis of antimicrobial polymer composition and in vitro drugs release study
Authors: Nita Tudorachi 
Published: August 2014

AbstractThe study presents a procedure to acquire a colloidal silver-based antimicrobial polymer composition. Carboxymethylstarch (CMS) as polymer matrix, and colloidal silver particles (Ag0) obtained by in situ synthesis with silver nitrate and sodium citrate as reducing agent, were used. In solution, the presence of COOH and OH groups in carboxymethylstarch directs to silver complexation and acquirement of a stable suspension of silver particles. Due to the presence of colloidal silver particles, the composition presents bacteriostatic activity and in association with some drugs (acetylsalicylic acid or diclofenac sodium) pharmaceutical compositions can be obtained, which are useful in the prevention and treatment of some infections or diseases. The compositions were characterized by FTIR spectroscopy, UV-vis spectrophotometry, particle size analysis and zeta potential measurements. Drug release tests were done in vitro in phosphate buffer solution (pH=7.4, at 37°C).
Synthesis and properties of a spinnable phase change material CDA-IPDI-MPEG
Authors: Cheng Shiliang , Chen Yanmo , Yu Hao , Zhu Meifang 
Published: August 2014

AbstractA comb like phase change material (PCM) CDA-IPDI-MPEG, based on cellulose diacetate (CDA) as a backbone, with methoxy polyethylene glycol (MPEG) grafted onto it, was synthesized by a two-step reaction in the presence of dibutyltin dilaurate (DBTDL) catalyst system, using acetone as solvent and isophorone diisocyanate (IPDI) as crosslinking reagent. Size exclusion chromatography (SEC) was used to characterize the molecular weight distribution of each step reaction products. Back titration was utilized for determination of free isocyanate. The molecular structures were confirmed qualitatively using FTIR and H1-NMR measurements. Phase change properties were characterized by differential scanning calorimetry (DSC).
Synthesis of acrylated styrene-isoprene-styrene copolymer
Authors: Klinpituksa Pairote , Chaisuriyathepkul Anont , Phinyocheep Pranee , Nakason Charoen , Kittipoom Sumet 
Published: August 2014

AbstractVulcanization of polymer by ultraviolet irradiation has been playing an important role in the industrial sector especially for coating, ink and printing applications. Polymers used in this area are sensitive to ultraviolet (UV) radiation. Their final products have properties required for particular specifications. One of the methods to synthesize ultraviolet-sensitive polymers is the grafting of ultraviolet-sensitive units onto other polymer backbones. In this work, styreneisoprene- styrene copolymer (SIS) was selected as a polymer backbone whilst acrylic acid served as an ultraviolet sensitiser. The grafting reaction was carried out in a solution state of toluene through the ring-opening addition reaction of epoxidized SIS molecules. The results indicated that acrylic acid can be successfully grafted onto a previously epoxidized SIS backbone at a reaction temperature of 100°C. Furthermore, the acrylation yield increased with the increase of reaction time.
Alkoxymethylcyclosiloxanes - new efficient precursors of crystalline (CH3SiO3/2)8 silsesquioxane and polymethyl silsesquioxanes
Authors: Kowalewska Anna , Rózga-Wijas Krystyna , Handke Mirosław 
Published: August 2014

AbstractA new, highly efficient and very simple method for the synthesis of pure octahedral methylsilsesquioxanes (CH3SiO3/2)8, from cyclic 2,4,6,8-tetraalkoxy- 2,4,6,8-tetramethylsiloxane, was developed. We have found that T8Me can be synthesized from a mixture of alkoxymethylcyclosiloxane isomers in the hydrolytic condensation process, utilizing an ionic catalyst - tetrabutylammonium fluoride (TBAF). The reaction was carried out under very mild conditions, at room temperature, in a variety of solvents of different polarity. A substantial solvent effect was observed. THF helped in the formation of pure T8Me, whereas in other solvents mixtures of T8Me and poly(methylsilsesquioxanes) (PMQS) of substantial degree of regularity, were obtained.
Effect of temperature on structure, morphology and crystallinity of PVDF nanofibers via electrospinning
Authors: Huang Fenglin , Wei Qufu , Wang Jiaxi , Cai Yibing , Huang Yubo 
Published: August 2014

Abstract Influence of temperature on morphology, structure and crystallinity of Poly (vinylidene fluoride) (PVDF) nanofibers was investigated in this study. The Wehilmy technique and viscosity testing apparatus were used to evaluate the surface tension and viscosity of electrospun solutions at various ambient temperatures. Surface morphologies and diameters of nanofibers were examined by Field-emission Scanning Electron Microscopy (FE-SEM) and atomic force microscopy (AFM). It was found that the surface morphologies were obviously affected by ambient temperature. This dependence was attributed to the change of the properties of Poly (vinylidence fluoride) solutions with temperature. The thermal properties and crystal structures of the PVDF nanofibers electrospun at different temperatures were also studied by differential scanning calorimetry (DSC), and Xray diffraction (XRD). The results revealed that the crystallinity and thermal properties were improved by increasing the ambient temperature during electrospinning
Controlled release of indomethacin from crosslinked alginate beads
Authors: Inal Murat , Yiğitoğlu Mustafa , Işiklan Nuran 
Published: August 2014

AbstractBeads of the sodium alginate (NaAlg) were prepared by dropping aqueous sodium alginate (NaAlg) into glutaraldehyde (GA) as a crosslinker and HCl as a catalyst mixture solution. Beads prepared were used to deliver a model non-steroid, anti-inflammatory drug, indomethacin (IM). The beads were characterized with Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Chemical stability of the IM after encapsulation into beads was confirmed by FTIR. SEM photograph indicated that alginate bead has spherical shape and rough surface. Preparation conditions of the beads were optimized by considering the percentage of entrapment efficiency, swelling capacity of the beads, particle size and their release data. In vitro release studies were performed in simulated gastric fluid (pH 1.2) for the initial 2 h, followed by simulated intestinal fluid (pH 7.4) for 4 h. Effects of variables such as, GA concentration, exposure time to GA, drug/polymer (d/p) ratio and percentage of HCl on the release of the IM were investigated. It was observed that, IM release from the beads decreased with increasing GA concentration, exposure time to GA, d/p ratio and percentage of HCl. The highest cumulative IM release obtained at the end of 6 h was 68% for alginate beads which were prepared with 0.5% HCl. On the other hand the least cumulative IM release obtained was to be 20 % for alginate beads which were prepared with 30 min exposure time to GA. In order to understand the crosslinking of the polymeric matrix, the molar mass between crosslinks were calculated using the swelling parameters. It was also found from the swelling experiments that swelling degree of the beads increases with increase in the temperature. The release data have been fitted to an empirical equation to estimate the kinetic parameters. The diffusion coefficient was also calculated for the transport of the drug through the polymeric beads. Values of these parameters were found to be consistent with the release data.
PAAm and PEDOT/PSS hydrogel as potential electroactive devices: evaluation of surface and hydrophilic properties
Authors: Aouada Fauze A. , de Moura Márcia R. , Radovanovic Eduardo , Girotto Emerson M. , Rubira Adley F. , Muniz Edvani C. 
Published: August 2014

AbstractThe aim of this work was to analyze the hydrophilic and surface properties of semi-IPN hydrogels with good electroactive properties based on poly (acrylamide) (PAAm) and conductive polymer poly(3,4-ethylene dioxythiophene)/ poly(styrenesulfonate) (PEDOT/PSS). The hydrogels properties were analyzed by degree of swelling (DS), drop water contact angle (DWCA) and atomic force microscopy (AFM). In addition, the state of water in the hydrogels was estimated by differential scanning calorimetry (DSC) analysis. Results revealed that the presence of PEDOT/PSS reduce the hydrophilicity of the network, mainly those prepared with lower cross-linking density, demonstrating that PEDOT/PSS chains (or their segments) are displayed in surface hydrogels. The possibility of producing PAAm-PEDOT/PSS hydrogels with controlled properties in a desired range of values is of key importance to optimize its use in several applications, mainly in optical devices, capacitors, artificial muscles, and rechargeable lithium batteries
In air synthesis of GA-cl-poly(MAA) hydrogel and study of its salt- resistant swelling behavior in different salts
Authors: Kaith B. S. , Ranjta Shabnam , Kumar Kiran 
Published: August 2014

AbstractA novel hydrogel has been synthesized by grafting methacrylic acid (MAA) onto Gum arabic (GA) through free radical graft co-polymerization in the presence of potassium persulphate (KPS) as an initiator and hexamethylene tetramine (HMTA) as a cross-linker. Various reaction parameters like reaction temperature, reaction time, concentration of initiator, amount of solvent, pH, concentration of monomer and concentration of cross-linker were optimized. GAcl-poly(MAA) was characterized by FTIR spectroscopy, SEM and TGA-DTA techniques. Optimized polymer was studied for its salt-resistant swelling behavior in different solutions: NaCl, MgCl2, CaCl2, FeCl3, ZnCl2 and BaCl2 as a function of salt concentration, temperature and pH. It was observed that GA-cl-poly(MAA) exhibits following salt-resistant swelling trend in different salts: NaCl > ZnCl2 > MgCl2 > CaCl2 > BaCl2 > FeCl3
Synthesis, characterization and evaluation of poly [glucose acrylate-methacrylic acid] hydrogels for colon-specific drug delivery
Authors: Mahkam Mehrdad 
Published: August 2014

AbstractNew biodegradable polymeric hydrogels based on biocompatible materials, glucose acrylate (GA) and methacrylic acid (MAA) were designed and synthesized. In the first time, the glucose-6-acrylate-1,2,3,4-tetraacetate (GATA) monomer was prepared under mild conditions. The removal of protecting acetate groups from GATA will be carried out before the polymerization and then, the corresponding water soluble glycomonomer (GA) was obtained. This deprotected glycomonomer can be polymerized in aqueous media, which points to a way to obtain polymers with applications in biomedical and biochemical fields. Hydrogel synthesis was carried out by free-radical polymerization of the co-monomers using persulfate as an initiator and N,N′-methylenebisacrylamide as crosslinker. The hydrogels was characterized by FT-IR. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). The swelling behaviour of the copolymers was dependent on the content of MAA groups and caused a decrease in gel swelling in pH 1 or an increase in gel swelling in pH 7.4. Model drug, 5-aminosalicylic acid (5-ASA) was entrapped into these hydrogels and the in vitro release profile of this drug was established separately in both enzyme-free SGF and SIF. Based on the great difference in swelling ratio at pH 1 and 7.4 for these hydrogels, it appears to be good candidates for colon-specific drug delivery.
Preparation and characterization of thermoplastic elastomers (TPEs) based on waste polypropylene and waste ground rubber tire powder
Authors: Zhang Shu Ling , Zhang Zhen Xiu , Kang Dong jin , Bang Dae Suk , Kim Jin Kuk 
Published: August 2014

AbstractIn this article, the possibility of obtaining the recycled material based on waste polypropylene (WPP) and waste ground rubber tire powder (WGRT) has been studied. It has been proved that partially replacing WPP with PP-g-MA increased the elongation at break of WPP/WGRT blends, whereas decreased the thermal stability. The presence of compatibilizer increased the elongation at break and thermal stability of WPP/WGRT blends, whereas decreased the processing flowability, as revealed by using universal testing machine (UTM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and capillary rheometer. Moreover, the tendency of the change became more obvious with the content of PP-g-MA and compatibilizer or with the combination of PP-g-MA and compatibilizer. In addition, the improvement of the nonpolar compatibilizer (SEBS) in properties of WPP/WGRT blends was better than that of the polar compatibilizer (SEBS-g-MA).
Microstructure and properties of PET/EPDM, EPDM-g- MA/organoclay ternary hybrid nanocomposites: effect of blending sequence
Authors: Khatibi Morad Ali , Arefazar Ahmad , Esfandeh Masoud 
Published: August 2014

AbstractPoly(ethylene terphthalate) (PET)/organomontmorilonite (OMMT)/maleic anhydride ethylene-propylene-diene rubber (EPDM-g-MA) nanocomposites were prepared via melt blending of the ingredients in a Haake Rheocord mixer. To make the hybrid composites, four different blending routes were examined: 1) preparing EPDM/EPDM-g-MA (EPMA)/organoclay nanocomposite and then blending it with PET, (S1), 2) dispersion of organoclay in PET and then blending it with EPMA, (S2), 3) blending PET with EPMA and then mixing it with organoclay, (S3), 4) blending PET, EPMA and organoclay in a single process, (S4). The microstructure of the PET/(EPMA)/organoclay ternary hybrids were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The result showed that the blending sequence greatly affects the dispersion of organoclay in the polymer matrix as well as the microstructure of the blends. Mechanical behavior of the blends including tensile and impact properties were also studied. Results revealed that PET/ (EPMA)/organoclay nanocomposites made by mixing sequence, S1, has the maximum tensile and impact strength among the others. This was attributed to its fine “Sea-Island” morphology and good dispersion of the organoclay in the continuous PET matrix.
Investigation of Ethylene Polymerization Kinetics over Ziegler-Natta Catalysts: Employing Moment Equation Modeling to Study the Effect of Different Active Centers on Homopolymerization Kinetics
Authors: Salami-Kalajahi Mehdi , Haddadi-Asl Vahid , Najafi Mohammad , Ghafelebashi Zarand Sayyed Mehdi 
Published: August 2014

AbstractIn the present work, ethylene polymerization kinetics was modeled using moment equations. According to the results obtained, the molecular weight distribution of each active center follows a Schultz-Flory distribution. However, the molecular weight distribution of polymer produced is much broader than a Schultz- Flory distribution. Besides, the order of polymerization with regard to monomer concentration is higher than unity. Moreover, the catalyst active centers deteriorate in the presence of hydrogen and consequently catalyst yield drops; nevertheless, polymerization kinetics is not mainly affected by hydrogen. Hydrogen also reduces polymer molecular weight since it is a strong transfer agent in olefin polymerizations. Notwithstanding, it does not affect polydispersity index. Last of all, although increasing cocatalyst concentration does not influence the activity of active centers, it lessens the molecular weight as a transfer agent
Novel poly(aryl ether ketone)s with anthracene in the backbone
Authors: Ying Na , Haibo Zhang , Yunhe Zhang , Yaming Niu , Sibo Jiang , Zhenhua Jiang 
Published: August 2014

AbstractTwo novel poly (aryl ether ketone)s with anthracene moieties in the backbone were synthesized through the conventional nucleophilic aromatic substitution polycondensation for the first time, by using a new bisfluoro monomer, 9,10-bis(4-fluorobenzoyl) anthracene (AnBF). The structures of obtained polymers were confirmed by NMR, IR and UV characterizations. The polymers have high molecular weight and show good solubility in common organic solvents. Differential Scanning Calorimetry (DSC) indicates that they are vitrified polymers with high glass transition temperatures above 188° Thermogravimetric analysis (TGA) shows that these polymers have good thermal stability in nitrogen atmosphere with a 5% weight loss (TGA-5%) above 465°.
Effect of Melting Conditions on Crystallization Behavior of Poly(trimethylene terephthalate)
Authors: Xu Yong , Jia Hong-bing , Ye Sheng-rong , Huang Jian 
Published: August 2014

AbstractThe effect of melting conditions on the crystallization kinetics of poly(trimethylene terephthalate)(PTT) was presented by means of depolarized light intensity (DLI) technique. The kinetics of PTT crystallization from melt depends on melting conditions and primarily upon the temperature of the melt. Higher melt temperature or longer time of melting may cause a reduction of crystallization rates at the melt temperature range from 506 to 531 K. Crystallization mechanism of PTT crystallizing from various melting conditions has been discussed according to Avrami kinetics parameters and morphology study. The reduction of the rate may result from two reasons: 1) the decrease of regularity such as residual nuclei in the PTT melt which lead to a reduction in the number of heterogeneous nuclei in the crystallization process; 2) the decreased spherulitic growth rate of PTT with higher melt temperature or longer residence time for melting