bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparing iPP/HDPE/CB functionally gradient materials: influence factors of components and processing
Authors: Gao Yong‐Juan , Liu Zheng‐Ying , Yin Chao‐Lu , Huang Shi‐Lin , Yang Ming‐Bo 
Published: April 2011

AbstractIn this work, gradient materials with low electrical resistivity were prepared by compounding isotactic polypropylene (iPP)/high density polyethylene (HDPE) blends with carbon black (CB) through extruding and injection molding. Contact angle measurements and morphology measurements showed that the CB particles were selectively located in HDPE phase and the final composites had a gradient structure that the HDPE/CB phase exhibited different morphologies in the skin layer and core layer of the composites under different processing procedures. The main factors influencing the formation of the functional gradient materials (FGM), including screw speed during extruding, iPP types and CB contents were discussed. They affect the phase morphology by shear stress, the restoration of HDPE phase, and the viscosity ratio of polymer blends, respectively. In conclusion, iPP/HDPE/CB FGM could be formed easily in the composites blending with the iPP type with narrow molecular weight distribution (MWD) and higher CB content extruded at higher screw speed. The electrical properties of iPP/HDPE/CB composites were studied and the results showed that screw speed in extrusion significantly influenced the percolation curve and electrical property of the final composites. Copyright © 2011 John Wiley & Sons, Ltd.
Copolymer of star poly(epsilon‐caprolactone) and polyglycidols as potential carriers for hydrophobic drugs
Authors: Mou Liang , Chen Niancao , Zhu Kun , Chen Yuanwei , Luo Xianglin 
Published: April 2011

AbstractAmphiphilic star shape poly(ε‐caprolactone)‐b‐hyperbranched polyglycidol (sPCL‐HPG) were synthesized and used to investigate micell formation and to encapsulate hydrophobic drugs. The synthesis of sPCL‐HPG copolymers was carried out by using sPCL as macroinitiator for the ensuing of hypergrafting reaction with glycidols. 1H‐NMR and FTIR were used to characterize sPCL‐b‐HPG structures. The self‐assembled structure of the sPCL‐HPG was characterized by scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The size and size dispersities of micelles were measured by dynamic light scattering DLS. Critical micelle concentration (CMC) was determined using pyrene as fluorescent probe. Hydrophobic methyl red was encapsulated in sPCL‐HPG micelles to illustrate hydrophobic drug loading. The copolymer micelles were used to enhance paclitaxel solubility. The results showed that hydrophobic drugs could be encapsulated in the sPCL‐HPG micelles. The paclitaxel solubility in the micelles of 5 wt% of sPCL23‐HPG170 got to 168 µg/ml. sPCL‐HPG, which have biodegrability and hydrophobicity at PCL part and smaller size of HPG fragments while maintaining the total repeating units of glycidols, provide an alternative choice of carriers for poorly soluble drugs. Copyright © 2011 John Wiley & Sons, Ltd.
Film formation of poly (methyl methacrylate) latex with pyrene functional poly (divinylbenzene) microspheres prepared by click chemistry
Authors: Uğur Şaziye , Yargı Önder , Durmaz Yasemin Yüksel , Karagöz Bünyamin , Bıçak Niyazi , Yağcı Yusuf , Pekcan Önder 
Published: April 2011

AbstractThis work reports on the application of steady state fluorescence (SSF) technique for studying film formation from poly(methyl methacrylate) (PMMA) latex and poly(divinylbenzene) (PDVB) microsphere composites. Pyrene (P) functionalized PDVB cross‐linked spherical microspheres with diameters of 2.5 μm were synthesized by using precipitation polymerization technique followed by click coupling reaction. The diameter of the PMMA particles prepared by emulsion polymerization were in the range of 0.5–0.7 μm. PMMA/PDVB composite films were then prepared by physically blending of PMMA latex with PDVB microspheres at various composition (0, 1, 3, 5, 10, 20, 40, and 60 wt%). After drying, films were annealed at elevated temperatures above Tg of PMMA ranging from 100 to 270°C for 10 min time intervals. Evolution of transparency of the composite films was monitored by using photon transmission intensity, Itr. Monomer (IP) and excimer (IE) fluorescence intensities from P were measured after each annealing step. The possibility of using the excimer‐to‐monomer intensity ratio (IE/IP) from PDVB microparticles as a measure of PMMA latex coalescence was demonstrated. Diffusion of the PMMA chains across the particle–particle interfaces dilutes the dyes, increasing their separation. The film formation stages of PMMA latexes were modeled by monitoring the IE/IP ratios and related activation energies were determined. There was no observable change in activation energies confirming that film formation behavior is not affected by varying the PDVB composition in the studied range. SEM images of PMMA/PDVB composites confirmed that the PMMA particles undergo complete coalescence forming a continuous phase in where PDVB microspheres are dispersed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Experimental study of flexible injection to manufacture parts of strong curvature
Authors: Causse Philippe , Ruiz Edu , Trochu François 
Published: April 2011

AbstractFlexible injection (FI) is a new process for the manufacture of high performance composites, which consists of injecting a thermosetting resin through a fibrous reinforcement contained in the lower chamber of a double cavity mold. Resin is injected in the lower cavity, which is sealed by a membrane, and then a compaction fluid is injected in the upper chamber to compress the reinforcement. This new composite manufacturing technique, which allows a limited and controlled deformation of the flexible membrane during processing, was shown to be very effective in reducing filling times in the case of planar or slightly curved geometries. In the present study, flexible injection is applied to strongly curved parts, namely here a composite rectangular panel with two 90° corners. After setting up an experimental procedure to produce the stair‐shaped components out of fiberglass and vinylester resin, longitudinal cross‐sections of the parts are analyzed to assess the quality of the final product in both the flat and curved zones. This characterization method allows detecting manufacturing defects such as thickness gradients or resin‐rich zones. Such defects are likely to induce geometrical deformations of the component and may decrease its mechanical performance. Therefore they ought to be minimized to improve the overall quality of the part. Modifications of the manufacturing procedure are proposed in this article to decrease the importance of process‐induced defaults and improve the performance of the flexible injection. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Elastic buckling of circular annular plate reinforced with carbon nanotubes
Authors: Jam J. E. , Kia S. M. , Pour A. G. , Emdadi M. 
Published: April 2011

AbstractThe buckling analysis of circular annular plate reinforced by carbon nanotubes (CNTs) subjected to compressive and torsional loads with various axially symmetric boundary conditions are studied in this paper. The developed model is based on the classical laminated plate theory (CLPT). The Mori‐Tanaka method is employed to calculate the effective elastic modulus of composites having aligned oriented straight CNTs. The eigenvalues of the problem are obtained by means of an analytical approach based on the optimized Rayleigh‐Ritz method. The effects of CNTs orientation angles, edge conditions, geometric ratio of plate and agglomeration of the randomly oriented straight CNTs are investigated on the critical buckling loads. Extensive studies validity of the results based on available data have been carried out prior to the presentation of salient results of this analysis. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Modeling the effective properties and thermomechanical behavior of SMA‐SMP multifunctional composite laminates
Authors: Jarali Chetan S. , Raja S. , Kiefer Björn 
Published: April 2011

AbstractThe research work presents the modeling of effective properties and thermo‐mechanical behavior of shape memory fiber (SMF) and shape memory polymer (SMP) composite laminates using micromechanical approaches based on the method of mixtures (MOM) and method of cells (MOC). The fiber is made of a nickel‐titanium (Ni‐Ti) shape memory alloy (SMA), while the matrix consists of a shape memory thermoset epoxy polymer (SMP). The use of an SMP matrix provides large strain compatibility with the SMA fiber, while being active at high temperatures without losing its elastic properties. Additionally, the SMP matrix is also able to produce similar pseudoelastic and shape memory effects, which are noticed in SMAs. In the analysis, a two step homogenization scheme is followed. In the first step the effective properties of each layer are determined via a micromechanics approach with iso‐strain conditions. In the second step the effective properties of the SMF‐SMP composite are computed making a thin plate theory assumption, which takes into account the transverse shear deformations. The possible elastic couplings for SMF‐SMP laminates are discussed, and the laminate force and moment resultants are computed for various laminate configurations. The analysis takes into account the effects of phase transformations and the resulting change in the fiber–matrix modulus. The results have been compared by considering different fiber volume fractions, temperatures, fiber orientations, and lamina stacking sequences. The results show that adaptive SMA‐SMP composites laminates can be developed that provide shape controllability via tunable laminate stiffnesses leading to optimal response. Furthermore, the work presents the necessary framework for a reliable and efficient analysis of SMA‐SMP laminates for practical applications. The theory can be directly used in established plate and shell formulations of finite element analysis. Finally, the variations in force and moment resultants with respect to fiber orientations and stacking sequences are presented, which are useful to study the bending and buckling characteristics of active composites for shape control of adaptive structures. The work concludes that efficient adaptive laminate development for high performance composite applications, exhibiting large shape adaptivity, high stresses, and increased stiffness, are feasible as compared to SMA composites without active matrix. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Studies on drying and swelling of PAAm‐NIPA composites in various compositions
Authors: Akın Evingür Gülşen , Pekcan Önder 
Published: April 2011

AbstractThe steady‐state fluorescence technique was introduced for studying the drying and swelling of disc‐shaped PAAm‐NIPA composites. Disc‐shaped gels were formed with various acrylamides (AAm) and N‐isopropylacrylamides (NIPA) by free radical crosslinking copolymerization in water. Composites were prepared with pyranine (Py) doped as a fluorescence probe. Scattered light, Isc, and fluorescence intensities, I, were monitored during drying of these gels. The fluorescence intensity of pyranine increased and decreased as drying and swelling time increased respectively for all samples. The Stern‐Volmer equation combined with moving boundary and Li‐Tanaka models were used to explain the behavior of I during drying and swelling, respectively. It was found that the desorption coefficient, D, increased as NIPA contents were increased for a given temperature during drying. However, the cooperative diffusion coefficient, D0, increased as NIPA contents were decreased during swelling at a given temperature. Supporting gravimetrical and volumetric experiments were also carried out during drying and swelling of PAAm‐NIPA composites. It was observed that NIPA contents affect the drying and swelling process. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Classification and identification of damage mechanisms in polyethylene self‐reinforced laminates by acoustic emission technique
Authors: Wang Xu , Zhang Hui‐Ping , Yan Xiong 
Published: April 2011

AbstractThe objective of present study is to classify and identify damage mechanisms in polyethylene(PE) self‐reinforced composites by acoustic emission (AE) technique. Model specimens including LDPE resin, [90°]laminate, single fiber composite, fiber bundle composite, and [±45°] laminates are fabricated to obtain expected damage mechanisms during tensile testing. First, mechanical behaviors and corresponding AE response of model specimens are studied to validate damage mechanisms in UHMWPE/LDPE laminates. Second, relationship among AE descriptors is investigated by hierarchical cluster analysis, and AE signals are classified by k‐means cluster analysis. Correlations between damage mechanisms and AE are established in terms of amplitude, duration, and peak frequency of AE signals. Finally, an artificial neural network is created and trained by various optimal algorithms to identify damage mechanisms. The results reveal that typical damage mechanisms in PE self‐reinforced composite can be classified in terms of the similarity between AE signals and identified by trained artificial neural network. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Exposure to CYP3A4‐inducing and CYP3A4‐non‐inducing antiepileptic agents and the risk of fractures
Authors: Schelleman Hedi , Pollard John R. , Newcomb Craig , Markowitz Clyde E. , Bilker Warren B. , Leonard Mary B. , Hennessy Sean 
Published: April 2011

ABSTRACTPurposeTo evaluate whether exposure to Cytochrome P450, family 3, subfamily A, polypeptide 4 (CYP3A4)‐inducing antiepileptics increases fracture risk compared to CYP3A4‐non‐inducing antiepileptics.MethodsWe performed a retrospective cohort study of initiators of antiepileptic agents using a UK medical record database (The Health Improvement Network) from 1995 to 2007. We considered an antiepileptic user an initiator if he or she had not received a prescription for an antiepileptic agent within the first year after entry in the database. Proportional hazards regression was used to calculate hazard ratios for fracture during long‐term (≥6 months) exposure to CYP3A4 inducing versus CYP3A4 non‐inducing antiepileptics.ResultsWe identified 4077 initiators of CYP3A4‐inducing antiepileptics and 6433 initiators of CYP3A4‐non‐inducing antiepileptics with at least 6 months of antiepileptic exposure. During 6006 person‐years exposed to CYP3A4‐inducing antiepileptics, 118 fractures were identified for an incidence rate of 1.96 (95% confidence interval (CI): 1.63–2.35) fractures per 100 person‐years. During 7184 person‐years exposed to CYP3A4‐non‐inducing antiepileptics, 127 fractures were identified, for an incidence rate of 1.77 (95% CI: 1.47–2.10) fractures per 100 person‐years. The adjusted hazard ratio for CYP3A4‐inducing antiepileptic versus CYP3A4‐non‐inducing antiepileptic was 1.21 (95% CI: 0.93–1.56). No duration–response relationship was evident.ConclusionsOur results do not support the hypothesis that CYP3A4 induction by antiepileptic agents increases the fracture risk. Further research will be needed to evaluate whether mechanisms other than CYP3A4 induction might explain some of the elevated risk of fractures associated with long‐term use of antiepileptic agents. Copyright © 2011 John Wiley & Sons, Ltd.
Variation in initiating secondary prevention after myocardial infarction by hospitals and physicians, 1997 through 2004
Authors: Margulis Andrea V. , Choudhry Niteesh K. , Dormuth Colin R. , Schneeweiss Sebastian 
Published: April 2011

ABSTRACTPurposeMyocardial infarction (MI) survivors benefit from receiving secondary prevention, including beta‐blockers, angiotensin‐blocking agents, and statins, as recommended by guidelines. Compliance with these guidelines is suboptimal. We sought to describe the initiation of secondary prevention in MI survivors, and to describe the variation in initiation by discharging the hospital, the physician, and the physician “responsible” for secondary prevention prescribing decisions in British Columbia in 1997–2004.MethodsWe assembled a cohort of 28 613 patients discharged alive from the hospital after their first MI and were not readmitted within 30 days. Physicians responsible for prescribing post‐MI secondary prevention medications were identified as the physicians prescribing the greatest number of cardiac medications (post‐discharge cardiac prescribers). We used multilevel logistic regression to assess the variation in drug initiation at discharging hospital, discharging physician, and post‐discharge cardiac prescriber levels, which were adjusted for patient and provider characteristics during the study period.ResultsBeta‐blockers initiation increased from 56 to 71% over the 8‐year study period; angiotensin‐converting enzyme/angiotensin II receptor blocker initiation increased from 37 to 70%, and statin initiation increased from 22 to 66% (0–28% for high‐potency statins). The probability for initiating an average patient with the study drugs varied widely in age–sex‐adjusted models at the hospital and physician levels. Further adjustment did not meaningfully change findings. The variation was largest for statins. The maximum between‐provider variance was found for high‐potency statins in 2003–2004 at the post‐discharge cardiac prescriber level.ConclusionsStudy‐drug initiation is increasing among MI survivors, but the variation in initiation is wide between discharging hospitals and physicians. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis of amphiphilic ABC triblock copolymers by single electron transfer nitroxide radical coupling reaction in tetrahydrofuran
Authors: Lin Wencheng , Jing Rongkuan , Wang Guowei , Huang Junlian 
Published: April 2011

AbstractA series of ABC triblock copolymers, that is, polyisoprene‐block‐polystyrene‐block‐poly(ethylene oxide) (PI‐PS‐PEO), PI‐block‐poly(tert‐butyl acrylate)‐block‐PEO (PI‐PtBA‐PEO), and PI‐block‐poly(acrylic acide)‐block‐PEO (PI‐PAA‐PEO) were obtained by combination of anionic technique, atom transfer radical polymerization (ATRP), and single electron transfer nitroxide coupling (SETNRC) reaction. Anionic polymerization of isoprene followed by end capping with ethylene oxide yielded hydroxyl‐terminated PI. After esterification, PI with Br end group was used as a macroinitiator to initiate the polymerization of styrene and tBA by ATRP that was then trapped by 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) group in PEO by SETNRC reaction rapidly with high efficiency in tetrahydrofuran at room temperature. The effect of reaction time and polymer chain length on SETNRC reaction was discussed in detail. In the presence of Cu0/tris[2‐(dimethylamino)ethyl]amine, SETNRC between PI‐PS‐Br and PEO‐TEMPO was carried out with the efficiency of up to 91.6% in 2 h. With the increase in polymer chain length, the efficiency decreased fleetly. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of H‐shaped A3BA3 copolymer by methyl‐2‐nitrosopropane induced single electron transfer nitroxide radical coupling
Authors: Zhang Zhongning , Wang Guowei , Huang Junlian 
Published: April 2011

AbstractAmphiphilic H‐shaped [poly(ethylene oxide)]3‐polystyrene‐[poly(ethylene oxide)]3(PEO3‐PS‐PEO3) copolymer was synthesized by 2‐methyl‐2‐nitrosopropane (MNP) induced single electron transfer nitroxide radical coupling (SETNRC) using PEO3‐(PS‐Br) as a single precursor. First, the A3B star‐shaped precursor PEO3‐(PS‐Br) was synthesized by atom transfer radical polymerization (ATRP) using three‐arm star‐shaped PEO3‐Br as macro‐initiator. Then, in the presence of Cu(I)Br/Me6TREN, the bromide group at PS end was sequentially transferred into carbon‐centered radical by single electron transfer and then nitroxide radical by reacting with MNP in mixed solvents of dimethyl sulfoxide (DMSO)/tetrahydrofuran (THF), and in situ generated nitroxide radical could again capture another carbon‐centered radical by fast SETNRC to form target PEO3‐PS‐PEO3 copolymer. The MNP induced SETNRC could reach to a high efficiency of 90% within 60 min. After the product PEO3‐PS‐PEO3 was cleaved by ascorbic acid, the SEC results showed that there was about 30% fraction of product formed by single electron transfer radical coupling (SETRC) between carbon‐centered radicals. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Various brush polymers through ring opening metathesis polymerization and nitroxide radical coupling reaction
Authors: Cerit Nese , Cakir Nese , Dag Aydan , Sirkecioglu Okan , Durmaz Hakan , Hizal Gurkan , Tunca Umit 
Published: April 2011

AbstractA 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO)‐terminated poly(ethylene glycol) (PEG) or ‐poly(ε‐caprolactone) (PCL) (PEG11‐TEMPO or PCL23‐TEMPO) is grafted as a side chain onto a ROMP‐generated polyoxanorbornene (PONB) main backbone with bromide pendant groups (PONB20‐Br) using the NRC click reaction to yield related the brush copolymers, PONB20‐g‐PEG11 or PONB20‐g‐PCL23 catalyzed by Cu(I), Cu(0), and N,N,N′,N″,N″‐pentamethyldiethylenetriamine in N,N‐dimethylformamide at room temperature. Additionally, a ROMP‐generated brush copolymer PONB9‐g‐poly(methyl methacrylate)24 (PMMA)24‐Cl was reacted with a PEG11‐TEMPO or a PCL23‐TEMPO precursor via the NRC click reaction to yield a corresponding brush terpolymer, PONB9‐g‐(PMMA24‐b‐PEG11) or PONB9‐g‐(PMMA24‐b‐PCL23) under a similar reaction condition described above. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Segmented polyurethanes derived from novel siloxane–carbonate soft segments for biomedical applications
Authors: Choi Taeyi , Masser Kevin A. , Moore Erica , Weksler Jadwiga , Padsalgikar Ajay , Runt James 
Published: April 2011

AbstractA novel macrodiol based on mixed silicone and carbonate chemistries was synthesized and used as a soft segment precursor in the synthesis of two series of segmented polyurethane (PU) copolymers varying in hard segment content and soft segment molecular weight. The hard segments in these copolymers were derived from 4,4‐methylene diphenyl diisocyanate and 1,4‐butane diol. The phase transitions, microphase separation behavior, and mechanical properties of the copolymers were investigated using a variety of experimental methods. When compared with segmented PU copolymers having predominately poly(dimethyl siloxane) soft segments, these siloxane–carbonate soft segment copolymers exhibit enhanced intersegment mixing, and consequently relatively low mechanical modulus. With relatively low modulus and siloxane units in the soft phase, the siloxane–carbonate PUs have potential for use in cardiac and orthopedic biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
A new FcεRI receptor‐mimetic peptide (PepE) that blocks IgE binding to its high affinity receptor and prevents mediator release from RBL 2H3 cells
Authors: Sandomenico Annamaria , Monti Simona M. , Palumbo Rosanna , Ruvo Menotti 
Published: April 2011

AbstractWe have recently reported on a class of IgE‐binding peptides designed based on the crystallographic structure of the high affinity FcεRI. Peptides contain receptor key residues located within the two distinct binding sites for IgE and selectively bind IgE with an affinity ranging between 6 and 60 µM. We have here designed and characterized a new molecule containing the receptor loops C′–E and B–C and an optimized linker for joining them made of a Lys side chain and a β‐Ala. This new peptide shows an increased affinity (around 30 times) compared to the parent loop C′–E + B–C previously described, while retaining the same two‐site mechanism of binding and the same selectivity. It also blocks the binding of IgE to the cell‐anchored receptor and efficiently prevents histamine release from mast cells. These properties make the peptide a useful scaffold for the development of new anti‐allergic drugs. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.