bluuebunny/crossref_metadata_2025_split huggingface dataset:
A variationally consistent αFEM (VCαFEM) for solution bounds and nearly exact solution to solid mechanics problems using quadrilateral elements
Authors: Liu G. R. , Nguyen‐Xuan H. , Nguyen‐Thoi T. 
Published: July 2010

AbstractA variationally consistent alpha finite element method (VC αFEM) for quadrilateral isoparametric elements is presented by constructing an assumed strain field in which the gradient of the compatible strain field is scaled with a free parameter α. The assumed strain field satisfies the orthogonal condition and the Hellinger–Reissner variational principle is used to establish the discretized system of equations. It is shown that the strain energy is a second‐order continuous function of α, and the VC αFEM can produce both lower and upper bounds to the exact solution in the strain energy for all elasticity problems by choosing a proper α∈[0, αupper]. Based on this bound property, an exact‐α approach has been devised to give an ultra‐accurate solution that is very close to the exact one in the strain energy. Furthermore, the exact‐α approach also works well for volumetric locking problems, by simply replacing the strain gradient matrix by a stabilization matrix. In addition, a regularization‐α approach has also been suggested to overcome possible hourglass instability. Intensive numerical studies have been conducted to confirm the properties of the present VC αFEM, and a very good performance has been found in comparing to a large number of existing FEM models. Copyright © 2010 John Wiley & Sons, Ltd.
Optimization of a variable mouth acoustic horn
Authors: Udawalpola Rajitha , Wadbro Eddie , Berggren Martin 
Published: July 2010

AbstractBy using boundary shape optimization on the end part of a semi‐infinite waveguide for acoustic waves, we design transmission‐efficient interfacial devices without imposing an upper bound on the mouth diameter. The boundary element method solves the Helmholtz equation modeling the exterior wave propagation problem. A gradient‐based optimization algorithm solves the resulting least‐squares problem and the adjoint method provides the necessary gradients. The results demonstrate that there appears to be a natural limit on the optimal mouth diameter. Copyright © 2010 John Wiley & Sons, Ltd.
Superabsorbent composite XXII: Effects of modified sepiolite on water absorbency and swelling behavior of chitosan‐g‐poly(acrylic acid)/sepiolite superabsorbent composite
Authors: Xie Yuntao , Wang Aiqin , Liu Gang 
Published: July 2010

AbstractIn this work, a series of chitosan‐g‐poly(acrylic acid)/sepiolite (CTS‐g‐PAA/ST) superabsorbent composites containing raw sepiolite, acid‐activated sepiolite, and cation‐exchanged sepiolite were synthesized by free‐radical graft polymerization in aqueous solution, using N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of raw sepiolite, acid‐activated sepiolite, and cation‐exchanged sepoilite on equilibrium water absorbency, swelling rate, and swelling behavior in different pH value solution of superabsorbent composites were systematically investigated. The results from FTIR spectra showed that chitosan and sepiolite participated in graft polymerization reaction with acrylic acid. The introduction of acid‐activated and cation‐exchanged sepiolite into chitosan‐g‐poly(acrylic acid) polymeric network could improve water absorbency and swelling rate compared with that of the raw sepiolite. All prepared samples have similar swelling behavior in different pH solutions and the equilibrium water absorbencies of samples keep roughly constant in the pH range from 4 to 12. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Influence of composition and phase morphology on rheological properties of polypropylene/poly(ethylene‐co‐octene) blends
Authors: Zhu Lin , Xu Xinhua , Ye Ning , Song Na , Sheng Jing 
Published: July 2010

AbstractIn this article, the phase morphology and rheological properties of polypropylene (PP)/poly(ethylene‐co‐octene) (POE) blends with a droplet‐matrix microstructure were studied by scanning electron microscopy and rheological experiments. The data were analyzed to yield the variations of rheological behavior with blend composition and insight into the microstructure of PP/POE blends. The Palierne's emulsion type model was used to extract information on rheological properties, and the interfacial tensions between the PP and POE were determined by fitting the experimental data with this model. The results indicated that the interfacial tensions were shown to depend on blend composition and temperature. Rheological properties of PP/POE blends were investigated in a systemic way with varying shear histories. The results showed that shear history had an important effect on the rheological properties of the blends due to the dispersed phase (POE) domains refined with increasing preshear rate and preshear time. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Water absorption behavior of different types of organophilic montmorillonite‐filled polyamide 6/polypropylene nanocomposites
Authors: Kusmono  , Mohd Ishak Z.A. , Chow W.S. , Takeichi T. , Rochmadi  
Published: July 2010

AbstractThe water absorption behavior of different types of organophilic montmorillonite (OMMT)‐filled polyamide 6/polypropylene nanocomposites with and without compatibilizers (maleated PP or PP‐g‐MA and maleated styrene‐ethylene/butylene‐styrene or SEBS‐g‐MA) was evaluated. Four different types of OMMT, i.e., dodecylamine‐modified MMT (D‐MMT), 12 aminolauric acid‐modified MMT (A‐MMT), stearylamine‐modified MMT (S‐MMT), and commercial organo‐MMT (C‐MMT) were used as reinforcement. The water absorption response of the nanocomposites was studied and analyzed by tensile test and morphology assessment by scanning electron microscopy (SEM). The kinetics of water absorption of the nanocomposites conforms to Fick's law. The Mm and D are dependent on the types of OMMT and compatibilizers. The equilibrium water content and diffusivity of PA6/PP blend were increased by the addition of OMMT but decreased in the presence of compatibilizers. On water absorption, both strength and stiffness of the nanocomposites were drastically decreased, but the ductility was remarkably increased. Both PP‐g‐MA and SEBS‐g‐MA played an effective role as compatibilizers for the nanocomposites. This was manifested by their higher retention ability in strength and stiffness (in the wet and re‐dried states), reduced the equilibrium water content, and diffusivity of the nanocomposites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
The impact of silane chemistry conditions on the properties of wood plastic composites with low density polyethylene and high wood content
Authors: Geng Yu , Laborie Marie‐Pierre G. 
Published: July 2010

AbstractSilane chemistry was implemented on various formulations of wood/thermoplastic polymer composites (WPCs) with low density polyethylene (LDPE) and high wood content (60 wt%). Taguchi analysis was used to evaluate the impact of vinyltrimethoxysilane content (VTMS), dicumyl peroxide content (DCP), and processing temperature on the rheological, morphological, and dynamic mechanic properties of WPCs. The torque power was measured by a Haake torque rheometer and indicated that the VTMS content and temperature most significantly impacted the rheological properties related to silane reactions. Differential scanning calorimetry also showed a larger depression in LDPE melting point and crystallinity index when a high VTMS content (35 phr), high DCP content (0.5 phr), and a high compounding temperature (200°C) were used. With dynamic mechanical analysis (DMA), it was shown that the compounded formulations had a higher storage modulus over a wide range of temperature whereas the β transition temperature increased with higher content in silane reactants. Interestingly, the high humidity/temperature conditioning step aimed at crosslinking resulted in a drop of dynamic moduli compared to the freshly compounded formulations. This was explained by the fact that during compounding of LDPE with high wood content and silane reactants, significant amounts of matrix and interfacial silane crosslinking already occurred. Subsequent conditioning in a high humidity and temperature environment was proposed to hydrolyze the interfacial siloxane bonds resulting in a degradation of mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Liquid Crystal Polymers. IV. Liquid Crystalline Aromatic Polyesters
Authors: Jackson W. Jerome 
Published: July 2010

AbstractMelt‐spun and injection‐moulded liquid crystalline polyesters have very high strength and stiffness and a very low coefficient of linear thermal expansion. The exceptional properties that characterise these polyesters are due to the presence of stiff, rod‐like polymeric chains, which become highly oriented during melt‐spinning or injection‐moulding, and long relaxation times, which permit the chains to retain their orientation while the polymer is cooling. The introduction of either flexible aliphatic groups or kinks in the rod‐like polymer chains reduces the polyester melting points and thereby permits easier melt processing but also adversely affects the strength and stiffness properties which are obtained. The effects of composition on the melting point and properties of plastics and fibres of liquid crystalline aromatic polyesters is discussed.
Observations on the Melt Rheology of Thermotropic Aromatic Polyesters
Authors: Wissbrun Kurt F. 
Published: July 2010

AbstractRheological measurements were made on a variety of substantially aromatic copolyesters. All of them differ from flexible chain polymers in having unusually long relaxation times, estimated from shear rate dependence of viscosity and from melt elasticity. This behaviour is not accounted for by an unusual molecular weight distribution (MWD); limited measurements indicate that the MWD is somewhat narrower than that of conventional condensation polymers.Numerous anomalous flow phenomena have been observed, though not necessarily with all samples. These include the occurrence of a yield stress, large secondary shear stress maximum after start‐up of steady shear, transient negative normal stress, and shear‐thickening of melt viscosity. Although the melts are highly elastic, they do not exhibit swelling after extrusion from a capillary.The melt rheology is often very sensitive to temperature and dependent upon thermal history. In one material this dependence has been linked to the destruction and/or growth of crystallites formed from blocks of one comonomer.
MassSieve: Panning MS/MS peptide data for proteins
Authors: Slotta Douglas J. , McFarland Melinda A. , Markey Sanford P. 
Published: July 2010

AbstractWe present MassSieve, a Java‐based platform for visualization and parsimony analysis of single and comparative LC‐MS/MS database search engine results. The success of mass spectrometric peptide sequence assignment algorithms has led to the need for a tool to merge and evaluate the increasing data set sizes that result from LC‐MS/MS‐based shotgun proteomic experiments. MassSieve supports reports from multiple search engines with differing search characteristics, which can increase peptide sequence coverage and/or identify conflicting or ambiguous spectral assignments.
Synthesis and properties of novel benzimidazole‐containing sulfonated polyethersulfones for fuel cell applications
Authors: Qi Yinghua , Gao Yan , Tian Shuanghong , Hlil Antisar R. , Gaudet Julie , Guay Daniel , Hay Allan S. 
Published: July 2010

AbstractA novel series of benzimidazole‐containing sulfonated poly(arylene sulfones)s with controllable amount of basic 2,6‐bis(benzimidazol‐2‐yl)pyridine (BIP) and sulfonic acid groups have been prepared by the copolycondensation of a new BIP‐containing arylene difluoride monomer (DFSBIP) with a sulfonated arylene difluoride (DSDFS) and 4,4′‐biphenol (BP). All the resulting polymers have high molecular weights, good thermal stability, and can form uniform and tough membranes by simple solution casting. Because of the strong acid–base interaction between BIP and sulfonic acid groups, ionic crosslinking networks forms that resulted in polymer membranes with good dimensional stability in water even at high temperature (e.g., 100 °C). The ion exchange capacity (IEC) of the polymer membranes was investigated through a new simple pH‐determination method. A comparison between the experimental IEC values with the calculated ones based on the polymer structures indicated that each BIP unit interacted with one sulfonic acid group. Thus, by controlling the relative content of BIP units and sulfonate groups in the polymers, the intra‐ and intermolecular acid–base interactions could be readily optimized so as to achieve polymers with high IEC values, high proton conductivities as well as low swelling ratios, demonstrating good potential for proton exchange membrane applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1920–1929, 2009
Single‐step process to produce functionalized multiresponsive polymeric particles
Authors: Bousquet Antoine , Ibarboure Emmanuel , HÉRoguez ValÉRie , Papon Eric , Labrugere Christine , Rodríguez‐Hernández Juan 
Published: July 2010

AbstractMonodisperse functional multiresponsive particles were prepared by encapsulation of an amphiphilic diblock copolymer during the precipitation polymerization of polystyrene and divinylbenzene in one single step. The amphiphilic diblock copolymer employed throughout this study, polystyrene‐b‐poly (dimethylaminoethyl methacrylate) (PS‐b‐PDMAEMA) has been synthesized by ATRP in two consecutive polymerization steps. After encapsulation of the block copolymer within the microsphere, the surface modification of the particle occurs spontaneously upon exposure to water by surface segregation of the hydrophilic PDMAEMA block, thus without any additional post‐polymerization and/or chemical modification steps. The response of the functionalized particles both to pH and temperature was analyzed by potential zeta and DSC measurements. Upon dispersion of the particles in acidic media, the PDMAEMA block in its charged state is soluble and does not exhibit any change by heating. At higher pH values and temperatures above 35 °C (Low Critical Solubility Temperature of the PDMAEMA block) the hydrophilic segment collapses as detected by differential scanning calorimetry. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3523–3533, 2010
Complex, degradable polyester materials via ketoxime ether‐based functionalization: Amphiphilic, multifunctional graft copolymers and their resulting solution‐state aggregates
Authors: Iha Rhiannon K. , van Horn Brooke A. , Wooley Karen L. 
Published: July 2010

AbstractDegradable, amphiphilic graft copolymers of poly(ε‐caprolactone)‐graft‐poly(ethylene oxide), PCL‐g‐PEO, were synthesized via a grafting onto strategy taking advantage of the ketones presented along the backbone of the statistical copolymer poly(ε‐caprolactone)‐co‐(2‐oxepane‐1,5‐dione), (PCL‐co‐OPD). Through the formation of stable ketoxime ether linkages, 3 kDa PEO grafts and p‐methoxybenzyl side chains were incorporated onto the polyester backbone with a high degree of fidelity and efficiency, as verified by NMR spectroscopies and GPC analysis (90% grafting efficiency in some cases). The resulting block graft copolymers displayed significant thermal differences, specifically a depression in the observed melting transition temperature, Tm, in comparison with the parent PCL and PEO polymers. These amphiphilic block graft copolymers undergo self‐assembly in aqueous solution with the P(CL‐co‐OPD‐co‐(OPD‐g‐PEO)) polymer forming spherical micelles and a P(CL‐co‐OPD‐co‐(OPD‐g‐PEO)‐co‐(OPD‐g‐pMeOBn)) forming cylindrical or rod‐like micelles, as observed by transmission electron microscopy and atomic force microscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3553–3563, 2010
Preparation of thermoresponsive polymers bearing amino acid diamide derivatives via RAFT polymerization
Authors: Liu Zhilei , Hu Jiwen , Sun Jianping , He Guping , Li Yinghui , Zhang Ganwei 
Published: July 2010

AbstractWe report here the synthesis of well‐defined homopolymer bearing amino acid diamide, poly(N‐acryloyl‐L‐valine N′‐methylamide), via reversible addition fragmentation chain transfer (RAFT) polymerization using alkynyl‐functionalized 2‐dodecylsulfanylthiocarbonylsulfanyl‐2‐methyl‐propionic acid propargyl alcohol ester as chain transfer agent (CTA) and 2,2′‐azobis(isobutyronitrile) as initiator. The effects of a variety of parameters, such as temperature and solvent, on RAFT polymerization were examined to determine the optimal control of the polymerization. The controlled nature of RAFT polymerization was evidenced by the controllable molecular weight and low‐molecular‐weight polydispersity index (Mw/Mn) of resulting homopolymers and further demonstrated to have retained end‐group functionality by the fact of the successful formation of block copolymers from further RAFT polymerization by using the resultant polymer as macro‐CTA, as well as from “click” chemistry. Thermoresponsive property of the prepared polymer was evaluated in terms of the lower critical solution temperature in aqueous solution by measuring the transmittance variation at 500 nm from UV/vis spectroscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3573–3586, 2010
Synthesis of highly luminescent organoboron polymers connected by bifunctional 8‐aminoquinolate linkers
Authors: Tokoro Yuichiro , Nagai Atsushi , Chujo Yoshiki 
Published: July 2010

AbstractNew organoboron aminoquinolate‐based polymers linked by π‐conjugated bridge were prepared by Sonogashira–Hagihara coupling of organoboron aminoquinolate‐based bisiodo monomers bearing biphenyl or bithiophene moiety with 1,4‐diethynylbenzene derivatives. Tetracoordination states of boron atoms in the obtained polymers were confirmed by 11B NMR spectroscopy, and they were also characterized by 1H NMR and IR spectroscopies and size‐exclusion chromatography. Their optical properties were studied by UV–vis absorption and photoluminescence spectroscopies. In the region above 400 nm, the polymers prepared from 1,4‐diethynyl‐2,5‐dioctyloxybenzene showed bathochromic shifts when compared with those prepared from 1.4‐diethynyl‐2‐perfluorooctyl‐5‐trifluoromethylbenzene. The polymers with biphenyl moiety showed higher absolute fluorescence quantum yields (ϕF = 0.28 and 0.65), whereas those with bithiophene moiety led to decreasing of the low quantum yields (ϕF = 0.19 and 0.00). The density‐functional theory (DFT) and time‐dependent–DFT calculations of model compounds corresponding to the polymers were in good agreement with the results from UV–vis properties. The calculations revealed that the electronic structure of the polymer with bithiophene moiety is different from that with biphenyl moiety, and predicted the electron transfer from the bithiophene moiety to the π‐extended quinoline moiety in transition state. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3693–3701, 2010
Theoretical implications of the elastic modulus discontinuity in rubber networks
Authors: Hanson David E. , Roland C. M. 
Published: July 2010

AbstractThe existence of a discontinuity in the modulus of rubber as the strain transitions from compression to extension is strongly suggested by multiple experiments. Classical rubber elasticity theories, however, do not admit such behavior. Here, we investigate a modification of the assumptions of classical elasticity theory to reconcile this discrepancy. We present an analysis of the consequences of assuming that chain forces are nonzero only for chain extension relative to the unstrained state, in contrast to the classical elasticity theory, which assumes that the chain force is directly proportional to the chain end‐to‐end distance (an entropic spring). Assuming an affine transformation of the network node coordinates, we derive two modulus discontinuity factors between compression and extension:D1, based on the differing number of network chains being extended andD2, based on the average differential chain extension. The discontinuities arise due to geometric effects, inherent in the affine transformation between compressive and extensive strains. We find thatD1, the ratio of the numbers of participating chains (compressive/extensive = 1.37), suffices to account for the experimentally observed modulus discontinuity in natural rubber of 1.34. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1795–1798, 2010
Cancer as the cause of changes in work situation (a NOCWO study)
Authors: Lindbohm M.‐L. , Kuosma E. , Taskila T. , Hietanen P. , Carlsen K. , Gudbergsson S. , Gunnarsdottir H. 
Published: July 2010

AbstractObjective: To investigate the frequency of changes in work situation due to cancer and to analyze the association of physically demanding work, social support from supervisors, colleagues or occupational health services, and disease‐related factors, with changing employers due to cancer.Methods: Working‐aged patients with breast, testicular or prostate cancer, or lymphoma with a good prognosis between 1997 and 2002 were identified from a hospital or cancer registry in four Nordic countries. The registers provided data on the disease‐related factors. Information on changes in work situation, received support, and other work‐related factors was collected using a questionnaire (response rate 72%). The frequency of changes in work situation was evaluated among a total of 2030 survivors. Further analyses were carried out among 688 survivors using a multivariable logistic regression model, to investigate factors affecting the risk of changing employers due to cancer.Results: Altogether, 5–10% of cancer survivors had changed employers, occupations or work tasks, 5% had been unemployed, and 9% had retired due to cancer. The physical demands of previous work were the most important reason behind changing employers after cancer. Among women, weak support from supervisors and occupational health personnel increased the risk of changing employers because of cancer.Conclusions: A minority of cancer survivors changed employers, occupations, or work tasks because of cancer. Supervisors' support in the form of lightening physically demanding jobs and taking illness into consideration when planning work tasks, and health‐care workers' advice on coping at work may help survivors to maintain their jobs. Copyright © 2010 John Wiley & Sons, Ltd.