bluuebunny/crossref_metadata_2025_split huggingface dataset:
High thermal conductive epoxy molding compound with thermal conductive pathway
Authors: Zeng Jun , Fu Renli , Shen Yuan , He Hong , Song Xiufeng 
Published: April 2009

AbstractThe epoxy molding compound (EMC) with thermal conductive pathways was developed by structure designing. Three kinds of EMCs with different thermal conductivities were used in this investigation, specifically epoxy filled with Si3N4, filled with hybrid Si3N4/SiO2, and filled with SiO2. Improved thermal conductivity was achieved by constructing thermal conductive pathways using high thermal conductivity EMC (Si3N4) in low thermal conductivity EMC (SiO2). The morphology and microstructure of the top of EMC indicate that continuous network is formed by the filler which anticipates heat conductivity. The highest thermal conductivity of the EMC was 2.5 W/m K, reached when the volume fraction of EMC (Si3N4) is 80% (to compare with hybrid Si3N4/SiO2 filled‐EMC, the content of total fillers in the EMC was kept at 60 vol %). For a given volume fraction of EMC (Si3N4) in the EMC system, thermal conductivity values increase according to the order EMC (Si3N4) particles filled‐EMC, hybrid Si3N4/SiO2 filled‐EMC, and EMC(SiO2) particles filled‐EMC. The coefficient of thermal expansion (CTE) decreases with increasing Si3N4 content in the whole filler. The values of CTE ranged between 23 × 10−6 and 30 × 10−6 K−1. The investigated EMC samples have a flexural strength of about 36–39 MPa. The dielectric constant increases with Si3N4 content but generally remains at a low level (<6, at 1 MHz). The average electrical volume resistivity of the EMC samples are higher than 1.4 × 1010 Ω m, the average electrical surface resistivity of the EMC samples are higher than 6.7 × 1014 Ω. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of poly(vinyl alcohol) nanocomposites made from cellulose nanofibers
Authors: Qua E. H. , Hornsby P. R. , Sharma H. S. S , Lyons G. , McCall R. D. 
Published: April 2009

AbstractA method using a combination of ball milling, acid hydrolysis, and ultrasound was developed to obtain a high yield of cellulose nanofibers from flax fibers and microcrystalline cellulose (MCC). Poly(vinyl alcohol) (PVA) nanocomposites were prepared with these additives by a solution‐casting technique. The cellulose nanofibers and nanocomposite films that were produced were characterized with Fourier transform infrared spectrometry, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Nanofibers derived from MCC were on average approximately 8 nm in diameter and 111 nm in length. The diameter of the cellulose nanofibers produced from flax fibers was approximately 9 nm, and the length was 141 nm. A significant enhancement of the thermal and mechanical properties was achieved with a small addition of cellulose nanofibers to the polymer matrix. Interestingly, the flax nanofibers had the same reinforcing effects as MCC nanofibers in the matrix. Dynamic mechanical analysis results indicated that the use of cellulose nanofibers (acid hydrolysis) induced a mechanical percolation phenomenon leading to outstanding and unusual mechanical properties through the formation of a rigid filler network in the PVA matrix. X‐ray diffraction showed that there was no significant change in the crystallinity of the PVA matrix with the incorporation of cellulose nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Crack‐healing behavior of epoxy–amine thermosets
Authors: Rahmathullah M. Aflal M. , Palmese Giuseppe R. 
Published: April 2009

AbstractThis work offers detailed experimental evidence for crack healing in fully formed epoxy–amine polymer networks. Compact tension specimens of diglycidyl ether of bisphenol A (EPON‐828) and 4,4′‐methylene biscyclohexanamine were synthesized at stoichiometry and with an excess or paucity of an amine curing agent. Healing efficiencies were measured on the basis of the regain in the fracture load after a healing protocol was applied. For all systems investigated, the average healing efficiency for first fracture was greater than 50% when healing was conducted at 185°C for 1 h. The crack‐healing behavior was highly repeatable at all stoichiometries, and healing was found to occur for repeated fracture–heal cycles of the same specimen. On the basis of results from size exclusion chromatography for the extractable phase, infrared spectroscopy, and scanning electron microscopy, it is postulated that healing is primarily due to mechanical interlocking of the nodular topology of a fractured crack interface that occurs in the rubbery state and is set in place by vitrification upon cooling. A ½ power dependence of the healing efficiency on the healing time was observed, and this suggests that the interlocking of topographical features is governed by diffusive processes. For networks cured with a large excess of epoxide groups, the recovered fracture load was higher than that of virgin specimens. In this case, polyetherification or homopolymerization of previously unreacted epoxy groups increased the healing efficiency significantly, and this suggests that low degrees of covalent bonding can significantly enhance healing behavior in these systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and properties of aromatic polyimide, poly(benzoxazole imide), and poly(benzoxazole amide imide)
Authors: Wu Sheng‐Yen , Yuen Siu‐Ming , Ma Chen‐Chi M. , Huang Yuan‐Li 
Published: April 2009

AbstractTwo series of heterocyclic aromatic polymers were synthesized from 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthaltic anhydride) and 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride by two‐step method. The inherent viscosities were in the range of 24–45 cm3/g. The effects of the rigid benzoxazole group in the backbone of copolymer on the thermal, mechanical, and physical properties were investigated. These polymers exhibit good thermal stability. The temperatures of 5% weight loss (T5) of these polymers are in the range of 403–530°C in air and 425–539°C in nitrogen. The chard yields of these polymers are in the range of 15–24% in air and 54–61% in nitrogen. These polymers also have high glass‐transition temperatures and a low coefficient of thermal expansion and good mechanical properties. The poly(benzoxazol imide) has a higher tensile strength and modulus than those of neat polyimide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Incorporation of lead phthalocyanine into periodic nanolayered assemblies for advanced optical systems
Authors: Armstrong Shannon , Zhou Zheng , Hiltner Anne , Baer Eric 
Published: April 2009

AbstractPeriodically structured polymeric materials can lead to the next generation of electro‐optic and nonlinear optical devices for applications in information technology. Layer‐multiplying melt coextrusion is an attractive method for fabricating periodic structures with thousands of alternating polymer microlayers or nanolayers. Many advanced applications for periodic polymeric structures would be enabled by locating a photoactive dye in one or both layers. However, it is anticipated that due to the thinness of the individual layers and the relatively low molecular weight of many dyes, a substantial fraction of the dye will diffuse from the doped layers into the undoped layers during melt coextrusion. In the present study, we demonstrate two methods for confining the activity of a photoactive dye, lead phthalocyanine, to the doped layers. Polycarbonate containing lead phthalocyanine was coextruded with undoped polyester as an assembly of 128 alternating 86 nm‐thick layers. Using the absorption spectra, we demonstrated that a high concentration of the monomer form persisted in the polycarbonate layers, whereas the lead form was converted to the less active lead‐free form in the polyester layers. Thus, the active monomer form of PbPc(β‐CP)4 was maintained selectively in the polycarbonate layers. In the second approach, the coextrusion process was altered so that the alternating polycarbonate and polyester layers were separated by a thin layer of a barrier polymer. The barrier layer prevented diffusion of the dye during melt coextrusion and the dye remained selectively in the polycarbonate layers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polysiloxane‐lignin composites
Authors: Stiubianu George , Cazacu Maria , Cristea Mariana , Vlad Angelica 
Published: April 2009

AbstractA series of composites based on polydimethylsiloxane‐α,ω‐diol (PDMS) as polymeric matrix, silica aerogel as reinforcing filler, and the lignin powder—a biomass derivative, as bulking filler, have been prepared. Different weight ratios between components were used. The composites were investigated by scanning electron microscopy, dynamic mechanical analysis, tensile strength tests, X‐ray diffraction analysis, thermogravimetric analysis, and differential scanning calorimetry. The results were compared with those obtained on a reference sample prepared by using a classical material—diatomite and a pure crosslinked PDMS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study of activation process and active site of co‐based catalyst for 1, 3‐butadiene polymerization using X‐ray absorption spectroscopy and DFT calculations
Authors: Kwag Gwanghoon , Bae Chulbeom , Kim Sunghyun 
Published: April 2009

AbstractActivation process and active site of Co‐based Ziegler‐Natta catalysts were studied by using synchrotron X‐ray absorption spectroscopic technique and an optimum model of the cobalt active site was proposed with density functional theory (DFT) calculations. In the X‐ray absorption near edge structure (XANES) spectrum of Co(2‐ethylhexanoate)2, the preedge peak, 1s → 3d transition at 7707.8 eV and the K‐edge peak, 1s → 4p transition at 7719.2 eV were observed. Both the intense K‐edge and the weak preedge peaks indicate that Co(2‐ethylhexanoate)2 possesses high Oh symmetry and the cobalt exists in a divalent state. Upon addition of methylaluminoxane (MAO), some changes in peak positions and intensities were observed. The preedge peak was a little shifted to 7708.2 eV with increased intensity, and the K‐edge peak was shifted to a lower energy, 7717.2 eV with decreased intensity. This indicates that the oxidation state of cobalt still mainly remained +2 and the coordination geometry was altered from Oh to Td resulting from Co 3d and 4p orbital mixing with a loss of Oh symmetry. In the XANES spectrum of a mixture of Co(2‐ethylhexanoate)2, MAO and t‐BuCl, the K‐edge peak at 7715.7 eV was observed. The orbital mixing of 4p cobalt and 2p chlorine orbitals results in a low energy transition. In 1,3‐butadiene polymerization, this is attributable to the coordination of chlorine to cobalt, which is believed to facilitate cis‐configuration and increasing reactivity. B(C6F5)3 was employed as Lewis acid, but no significant interaction with cobalt was found in the XANES spectrum of a mixture of Co(2‐ethylhexanoate)2, Al(iBu) and B(C6F5)3, which is similar to the XANES of a mixture of Co(2‐ethylhexanoate)2 and Al(iBu)3. B(C6F5)3 as Lewis acid does not greatly disturb the coordination symmetry of cobalt nor influence the oxidation state. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
m/p‐Cresol–based t‐BOC protected alternating “high ortho” copolymer as a possible e‐beam resist: Characterization using multidimensional NMR spectroscopy
Authors: Sharma Maneesh , Hopson Russell , Raghunathan P. , Eswaran S. V. 
Published: April 2009

AbstractSynthesis of a m/p‐cresol–based novolac resin and its subsequent esterification using di‐tert‐butyl dicarbonate (t‐BOC) is described. The product has been characterized using techniques of FTIR spectroscopy, one dimensional 1H NMR, 13C NMR, and DEPT‐135 spectra. Two dimensional NMR experiments like, COSY, HSQC, and HMBC have been used for exhaustive probing of the microstructural details of the derivatized copolymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Solution blow spinning: A new method to produce micro‐ and nanofibers from polymer solutions
Authors: Medeiros Eliton S. , Glenn Gregory M. , Klamczynski Artur P. , Orts William J. , Mattoso Luiz H. C. 
Published: April 2009

AbstractA solution blow spinning technique was developed using elements of both electrospinning and melt blowing technologies as an alternative method for making non‐woven webs of micro‐ and nanofibers with diameters comparable with those made by the electrospinning process with the advantage of having a fiber production rate (measured by the polymer injection rate) several times higher. The diameters of fibers produced ranged from 40 nm for poly(lactic acid) to several micrometers for poly(methyl methacrylate). This solution blow spinning method uses a syringe pump to deliver a polymer solution to an apparatus consisting of concentric nozzles whereby the polymer solution is pumped through the inner nozzle while a constant, high velocity gas flow is sustained through the outer nozzle. Analysis of the process showed that pressure difference and shearing at the gas/solution interface jettisoned multiple strands of polymer solution towards a collector. During flight, the solvent component of the strands rapidly evaporates forming a web of micro and nanofibers. The effect of injection rate, gas flow pressure, polymer concentration, working distance, and protrusion distance of the inner nozzle was investigated. Polymer type and concentration had a greater effect on fiber diameter than the other parameters tested. Injection rate, gas flow pressure, and working distance affected fiber production rate and/or fiber morphology. Fibers were easily formed into yarns of micro‐ and nanofibers or non‐woven films that could be applied directly onto biological tissue or collected in sheets on a rotating drum. Indeed, virtually any type of target could be used for fiber collection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Phase behavior of a sodium dodecanol allyl sulfosuccinic diester/n‐pentanol/methyl acrylate/butyl acrylate/water microemulsion system and preparation of acrylate latexes by microemulsion polymerization
Authors: Hu Aixi , Yao Zhigang , Yu Xi 
Published: April 2009

AbstractPseudoternary phase diagrams of quaternary microemulsion systems composed of the reactive surfactant sodium dodecanol allyl sulfosuccinic diester, n‐pentanol, methyl acrylate/butyl acrylate, and water were made. The influence of the mass ratio of sodium dodecanol allyl sulfosuccinic diester to the cosurfactant (n‐pentanol) in the system and the influence of electrolyte sodium chloride on the microemulsion area were examined. The microstructure of the microemulsion was determined with a conductance technique. The results suggested that there were three structures in the microemulsion system: water in oil, oil in water, and a bicontinuous phase. Microemulsion polymerizations were carried with some point in the microemulsion region being chosen as the formulation. The structure and configuration of the polymer latexes were determined and analyzed with Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. The results suggested that the reactive surfactant could participate in the polymerization with the monomers to some extent; the glass‐transition temperature of the latex was −31.4°C. The polymer latex was transformed gradually from an open porous structure to a closed porous structure when its pregnant microemulsion was varied from a bicontinuous structure to an oil‐in‐water structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Graft copolymerization of 4‐vinyl pyridine onto konjac glucomannan initiated by ammonium persulfate
Authors: Liu Changhua , Dai Xun , Chen Jianguang , Chen Yanqing , Guo Xiaoli , Huang Yuming 
Published: April 2009

AbstractThe grafting of 4‐vinyl pyridine (4‐VP) onto konjac glucomannan (KGM) by ammonium persulfate (APS) as the initiator was studied in an acid aqueous solution under an inert atmosphere. The grafting ratio (G%) and grafting efficiency (E%) were evaluated comparatively. The dependence of these parameters on the initiator concentration, sulfuric acid concentration, ratio of monomer to KGM, temperature, and reaction time was also investigated. Under conditions of [KGM] = 1.00 g/L, [APS] = 1.00 × 10−2 mol/L, [4‐VP] = 9.32 × 10−2 mol/L, [H+] = 5.00 × 10−2 mol/L, temperature = 35°C, and time = 120 min, the optimum G% and E% were 307.27 and 52.75%, respectively. The proof of grafting was obtained from thermogravimetric analysis and infrared spectra. Preliminary research of the graft's adsorption capacity for heavy‐metal ions [Cr(VI), Cu(II), Pb(II), and Cd(II)] was done. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Potential for desalination using lower critical solution temperature polymers: Concentration of salt solutions by pluronic PE6200
Authors: Maurdev George , Millington Keith R. 
Published: April 2009

AbstractA commercially available lower critical solution temperature (LCST) polymer was demonstrated to preferentially adsorb water containing a reduced ion concentration, from CrCl3 salt solutions and release some of this scavenged water at higher temperatures. The scavenging ability of the polymer was demonstrated to be dependent on the bulk salt concentration. The volume of water scavenged and the concentration of the remaining CrCl3 solution increased linearly with the amount of LCST polymer (Pluronic PE 6200) used. Both the volume of water removed and the amount by which the remaining CrCl3 solution was concentrated decreased with increasing CrCl3 concentration. Implications for research into a novel method for sea water desalination are addressed. We also show water extraction from dilute sodium chloride and sea water, and that these results are consistent with the CrCl3 model system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study of crosslinking of polyphosphazene with allyl pendant groups initiated by benzoyl peroxide
Authors: Huang Yawen , Pan Yang , Fu Jianwei , Huang Xiaobin , Tang Xiaozhen 
Published: April 2009

AbstractA selected polyorganophosphazene containing three substituents: phenoxy group, 2‐allylphenoxy group, and ethoxy group, had been thermally cross‐linked. The polymer can be crosslinked at 85°C which was lower than the general reported operation temperature. The transformation of chemical structure was analyzed by FTIR technique. It was found that oxidization caused the formation of peroxides, ether and ester during crosslinking. The effect of different conditions including time, temperature, and initiator on properties of crosslinked polymer had been studied. The change of properties was well consistent with the change of chemical structure including vinyl and peroxide. Detailed cross‐linking mechanisms were proposed based on FTIR spectra by monitoring the possible association sites. It was suggested that the initiation reaction preferentially occurred at methylene but not vinyl, and major linkages between polymer chains were ether and peroxide bonds. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and biocidal efficacy of self‐spreading polydimethylsiloxane oligomers possessing oxyethylene‐functionalized quaternary ammoniums
Authors: Pant Ramesh R. , Fulmer Preston A. , Harney Matthew B. , Buckley Joseph P. , Wynne James H. 
Published: April 2009

AbstractIn an effort to develop a more versatile creeping biocide that is capable of self‐spreading and self‐decontaminating of pathogenic bacteria, we report the development of two new homologous series of hybrid PDMS molecules. These oligomers were synthesized with terminal quaternary ammonium functionalities bearing variable length oxyethylene moieties. It is shown that the ionic interaction of the ammonium groups with the surface onto which it spreads can be tempered by the oxyethylene segments through close association of the polar chains with the cationic centers within the hydrophobic PDMS environment, thereby promoting self‐spreading of the molecule. Once the compounds spread to a humid environment, the oxyethylene chains “blossom” and subsequently expose the biocidal centers, at which point, function as broad spectrum versatile antimicrobials. While biological evaluation showed antimicrobial activity against both Gram‐positive and Gram‐negative bacteria for all samples, one series was found to be much more effective due to lower steric hindrance surrounding the biocidal cationic termini. However, this increased exposure of the cationic center also altered the physical properties of the compounds except those isolated as a waxy solid. Self‐spreading abilities with increasing oxyethylene chain length correlating to a decreasing spread rate. The decontaminating ability of the two most active compounds was demonstrated by allowing samples to spread to pools of water contaminated with S. aureus, yielding log reductions as high as 5.7 in less than two hours without external influences. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mechanical properties of the flexible‐type epoxy/clay nanocomposites prepared by slurry method
Authors: Harada Miyuki , Ueda Ayumu , Miyazaki Hironori , Ochi Mitsukazu 
Published: April 2009

AbstractThe bisphenol‐F type flexible epoxy resin, having a good flexibility, was combined with an organo‐ and slurry‐clay. The clay dispersions in the obtained epoxy/clay systems are significantly different depending on the type of clay. Particularly, the epoxy/slurry‐clay system showed a high clay dispersibility into the epoxy matrix and was transparent in spite of the addition of 10 wt % clay. This result means that the swelling of the clay with formamide is effective for the expansion of the basal spacing of the clay. The slurry‐clay nanocomposite (clay content: 5 wt %) showed a 4 times higher fracture energy than the neat epoxy system in the tensile test, though the organo‐clay system (clay content: 5 wt %) was 1.5 times higher. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The microstructure of polyacrylonitrile‐stabilized fibers
Authors: Ge Heyi , Liu Huashi , Chen Juan , Wang Chengguo 
Published: April 2009

AbstractThe microstructure of the polyacrylonitrile (PAN)‐stabilized fibers was investigated by X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and high‐resolution transmission electron microscope (HRTEM). XRD analysis indicated that the chemical reactions sped up notably when temperature was above 250°C. The crosssection SEM image of the stabilized fibers presented concentric multilayer morphology. TEM images showed that the lamellar‐like skin was compact and the core was disorderly and loose. The vermiculate‐like crystallites in the precursor fibers were transferred to spheres during stabilization process. HRTEM images showed that many spheres existed in the stabilized fibers. The exterior of spheres which had annular structure was amorphous phase. The inner of spheres which was not completely stabilized had some crystallite areas. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009