bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of surface energy of boron nitride on polymer processability
Authors: Rathod Nimish , Hatzikiriakos Savvas G. 
Published: August 2004

AbstractFlow instabilities manifest themselves as distortions on the extrudate surface (melt fracture). They are usually observed at high production rates in many polymer processing operations. Certain fluoropolymers/fluoroelastomers have long been used as processing aids for surface melt fracture elimination. Recent developments have shown that a small amount of boron nitride (BN) powder may successfully eliminate surface melt fracture and also delay the onset of gross melt fracture to higher rates. It has also been reported that a combination of BN and fluoropolymer/fluoroelastomer enhances the effectiveness of the polymer processing even further. The main objective of the present work was to measure the surface properties of a number BN powders, mainly surface energy, in order to gain a better understanding of its performance as a processing aid. Based on this study, it can be concluded that surface energy plays an important role in deciding the possible interactions between the processing aid, polymer melt and the extruding surface. It is observed that the lubricious nature of BN along with an optimum balance of its polar (non‐dispersive) and non‐polar (dispersive) components of surface energy renders BN a successful processing aid in eliminating both sharkskin and gross melt fracture phenomena. Polym. Eng. Sci. 44:1543–1550, 2004. © 2004 Society of Plastics Engineers.
Relationship between cell morphology and impact strength of microcellular foamed high‐density polyethylene/polypropylene blends
Authors: Rachtanapun Pornchai , Selke Susan E. M. , Matuana Laurent M. 
Published: August 2004

AbstractPolymer blends, such as those resulting from recycling postconsumer plastics, often have poor mechanical properties. Microcellular foams have been shown to have the potential to improve properties, and permit higher‐value uses of mixed polymer streams. In this study, the effects of microcellular batch processing conditions (foaming time and temperature) and HDPE/PP blend compositions on the cell morphology (the average cell size and cell‐population density) and impact strength were studied. Optical microscopy was used to investigate the miscibility and crystalline morphology of the HDPE/PP blends. Pure HDPE and PP did not foam well at any processing conditions. Blending facilitated the formation of microcellular structures in polyolefins because of the poorly bonded interfaces of immiscible HDPE/PP blends, which favored cell nucleation. The experimental results indicated that well‐developed microcellular structures are produced in HDPE/PP blends at ratios of 50:50 and 30:70. The cell morphology had a strong relationship with the impact strength of foamed samples. Improvement in impact strength was associated with well‐developed microcellular morphology. Polym. Eng. Sci. 44:1551–1560, 2004. © 2004 Society of Plastics Engineers.
Deformation and morphology development of poly(ethylene terephthalate)/polyethylene and polycarbonate/polyethylene blends with high interfacial contact during elongation
Authors: Li Zhong‐Ming , Fu Xiao‐Rong , Yang Shuying , Yang Ming‐Bo , Yang Wei , Huang Rui 
Published: August 2004

AbstractImmiscible blends of poly(ethylene terephthalate) (PET)/polyethylene (PE) and polycarbonate (PC)/PE were examined to study the influence of the high interfacial contact (pseudo‐adhesion) on the mechanical properties and the morphology developed during elongation. The high interfacial contact resulted from the contraction difference of the two polymers during cooling from the processing temperature to room temperature. As a result of the pseudo‐adhesion, the tensile strength and modulus of the PET/PE and PC/PE blends increased steadily with the increase of PET and PC concentration. In PC/PE blends, numerous PC microfibers were formed in‐situ, while in PET/PE blends, slippage took place between the PET particles and the matrix. Moreover, the macroscopic morphology development of both blends upon elongation was quite different. For PET/PE blend, necking was initiated at one point close to the non‐gate end of the specimen, and then propagated uniformly from this point. For the PC/PE blend, necking‐initating sites and propagation were irregular, and consequently the whole tested zone was deformed. The recoil of partially elongated specimens indicated that the recoverability of the PC/PE blend is higher than that of the PET/PE blend. Polym. Eng. Sci. 44:1561–1570, 2004. © 2004 Society of Plastics Engineers.
Capacitive transducer for in‐mold monitoring of injection molding
Authors: Chen Xi , Chen Guohua , Gao Furong 
Published: August 2004

AbstractA capacitive transducer is developed for online monitoring of the in‐mold material status for injection molding, particularly for measurements of melt‐front position and flow‐rate. This paper will show, in addition to fulfilling its design purposes, that such a sensor can also be effectively used for the detection of the start and end of mold filling, the time of gate freezing, and over‐packing. Polym. Eng. Sci. 44:1571–1578, 2004. © 2004 Society of Plastics Engineers.
Recycled poly(ethylene terephthalate) chain extension by a reactive extrusion process
Authors: Awaja Firas , Daver Fugen , Kosior Edward 
Published: August 2004

AbstractA commercial‐scale reactive extrusion processing system for recycled poly(ethylene terephthalate) (PET) flakes with an added chain extender, pyromellitic dianhydride (PMDA), was investigated. The PMDA concentration was varied with the intention of reaching a higher recycled PET intrinsic viscosity ([η]). The effect of changing the extruder residence time on the system's stability and the recycled PET [η] was also investigated. Reactive extruded PET with a PMDA concentration up to 0.3 wt% was found to have a higher [η] and lower carboxyl content than recycled PET processed in a normal extrusion system. A shift in [η] of about 0.18 dl/g was obtained with a 0.3 wt% PMDA concentration. A PMDA concentration above 0.3 wt% produced chemical, thermal and hydrodynamic instability in the system, causing crosslinking reactions and gel formation. The reactive extrusion system was stable at low residence time (45 s) and moderate (0.15 wt%) PMDA concentration; however, using 0.2 wt% PMDA produced higher reactive extruded recycled PET [η] with lower carboxyl content than other PMDA concentration levels examined. Residence times higher than 45 s produced higher reactive extruded recycled PET [η]. Reactive extruded recycled PET was also tested for mechanical properties. Polym. Eng. Sci. 44:1579–1587, 2004. © 2004 Society of Plastics Engineers.
Biodegradable polymers with variable architectures via ring‐expansion polymerization
Authors: Kricheldorf Hans R. 
Published: August 2004

AbstractKinetically controlled ring‐expansion polymerizations (REPs) are defined syntheses generating cyclic oligomers and polymers without linear intermediates and without equilibration reactions. This review reports syntheses of cyclic metal alkoxides and their use as initiators for REPs of lactones, cyclic diesters, and cyclocarbonates. In addition to homopolyesters, telechelic oligoesters or polyesters, random copolyesters, and A–B–A triblock copolymers can be prepared by these REPs. The in situ combination of REPs with condensation (mostly acylation) reactions allows a broad variation of end groups. The in situ combination of REPs with polycondensation enables various chain‐extension reactions, including the syntheses of multiblock copolymers. With spirocyclic initiators, four‐armed stars with functional end groups may be prepared. The in situ combination of REPs with condensation reactions of trifunctional or multifunctional reagents makes a broad variety of networks accessible. The average segment lengths may be controlled via the monomer/initiator ratios of the REP. All materials produced via the aforementioned REP processes are biodegradable and nontoxic, and this allows for biomedical and pharmaceutical applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4723–4742, 2004
Charge transfer interactions in polyesters with a donor‐(σ‐bridge)‐acceptor moiety in the repeating unit
Authors: Oosterbaan Wibren D. , Kaats‐Richters Veronica E. M. , Jenneskens Leonardus W. , Van Walree Cornelis A. 
Published: August 2004

AbstractTwo high molecular weight linear polyesters were investigated to gain insight in how the photophysics of electron donor‐(σ‐spacer)‐electron acceptor (DσA) compounds are affected by incorporation into a polymer. They were prepared by condensation of either adipoyl or sebacoyl chloride with a diol that was functionalized with an N,N‐dialkylaniline donor, a cyclohexyl type σ‐spacer, and a 1,1‐dicyanovinyl acceptor. The solubility, which is very low, and the thermal properties of the polyesters are dictated by physical crosslinking as a consequence of interchain donor‐acceptor interactions. Charge transfer (CT) absorption and emission are observed, which involve CT between DσA moieties of different chains rather than CT processes within a single DσA unit. As a result, the photophysics of the DσA units in the polyesters differs strongly from that of similar DσA compounds in solution. Upon swelling the polymers with THF, the CT fluorescence disappears partly. Analogous polymers containing only an N,N‐dialkylaniline donor display dual fluorescence; one band reflects local emission, while the other is attributed to excimer emission. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4775–4784, 2004
Poly[2,7‐(9,9‐dihexylfluorene)‐alt‐pyridine] with donor‐acceptor architectures: A new series of blue‐light‐emitting alternating copolymers
Authors: Liu Shou‐Ping , Chan Hardy S. O. , Ng Siu‐Choon 
Published: August 2004

AbstractA novel series of well‐defined alternating poly[2,7‐(9,9‐dihexylfluorenyl)‐alt‐pyridinyl] (PDHFP) with donor‐acceptor repeat units were synthesized using palladium (0)‐catalyzed Suzuki cross‐coupling reactions in good to high yields. In this series of alternating polymers, 2, 7‐(9,9‐dihexylfluorenyl) was used as the light emitting unit, and the electron deficient pyridinyl unit was employed to provide improved electron transportation. These polymers were characterized by 1H‐NMR and 13C‐NMR, gel permeation chromatography (GPC), thermal analyses, and UV‐vis and fluorescence spectroscopy. The glass transition temperature of copolymers in nitrogen ranged from 110 to 148 °C, and the copolymers showed high thermal stabilities with high decomposition temperatures in the range of 350 to 390 °C in air. The difference in linkage position of pyridinyl unit in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film phases. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable to polymer for pure blue emission and prevention of aggregation of polymer chain than para‐linkage (2,5‐linkage) of the pyridinyl units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4792–4801, 2004
Conformational changes and phase transformation mechanisms in PVDF solution‐cast films
Authors: Salimi A. , Yousefi A. A. 
Published: August 2004

AbstractThe supramolecular crystal structure in poly(vinylidene fluoride) (PVDF) solution‐cast films is studied through changing crystallization conditions in two solvents of different structures and polarities. The crystalline‐state chain conformations of isothermally solution‐crystallized PVDF in N, N‐dimethylacetamide (DMAc), and cyclohexanone are studied through the specific FTIR absorption bands of α, β, and γ phase crystals. There are no changes in the FTIR spectra of cyclohexanone solution‐crystallized films in the temperature range of 50–120 °C. In the case of DMAc solution‐crystallized films, low temperature crystallization mainly results in formation of trans states (β and γ phases), whereas at higher temperatures gauche states become more populated (α phase). This is due to the variations in solvent polarity and ability to induce a specific conformation in PVDF chains, through the changes in chain coil dimensions. This indicates that in spite of cyclohexanone solutions, the intermolecular interactions between PVDF and DMAc are temperature‐sensitive and more important in stabilizing conformations of PVDF in crystalline phase than temperature dependence of PVDF chain end‐to‐end distance <r2>. The high‐resolution 19F NMR spectroscopy also showed little displacement in PVDF characteristic chemical shifts probably due to changes in PVDF chain conformation resulting from temperature variations. Upon uniaxial stretching of the prepared films under certain conditions, contribution of trans state becomes more prominent, especially for the originally higher α phase‐containing films. Due to formation of some kink bands during film stretching and phase transformation, α phase absorption bands are still present in infrared spectra. Besides, uniaxial stretching greatly enhances piezoelectric properties of the films, maybe due to formation of oriented β phase crystals, which are of more uniform distribution of dipole moments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3487–3495, 2004
Control of self‐organized low‐dimensional morphology in poly(styrene‐b‐4vinylpyridine)/polystyrene blend thin films
Authors: Zhao Junchai , Jiang Shichun , Ji Xiangling , An Lijia , Jiang Bingzheng 
Published: August 2004

AbstractThe surface morphologies of poly(styrene‐b‐4vinylpyridine) (PS‐b‐P4VP) diblock copolymer and homopolystyrene (hPS) binary blend thin films were investigated by atomic force microscopy as a function of total volume fraction of PS (ϕPS) in the mixture. It was found that when hPS was added into symmetric PS‐b‐P4VP diblock copolymers, the surface morphology of this diblock copolymer was changed to a certain degree. With ϕPS increasing at first, hPS was solubilized into the corresponding domains of block copolymer and formed cylinders. Moreover, the more solubilized the hPS, the more cylinders exist. However, when the limit was reached, excessive hPS tended to separate from the domains independently instead of solubilizing into the corresponding domains any longer, that is, a macrophase separation occurred. A model describing transitions of these morphologies with an increase in ϕPS is proposed. The effect of composition on the phase morphology of blend films when graphite is used as a substrate is also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3496–3504, 2004
The ‘Business’ of Quality Assurance
Authors: Grunbaum Len 
Published: August 2004

AbstractThis article will address how a quality assurance function (QA) can and should be a value to the business. QA represents a Management control; it is, or should be, the business instrument by which management is advised as to the status of regulatory compliance. And regulatory compliance is a business issue – make no mistake about it. But QA does not always discharge its responsibilities or perform its activities in a manner that truly serves the business purposes. The article examines some of the common scenarios in the industry, which are ‘sin‐dromes’ because they can result in increased business expenses and reduced profitability, and thus they are business ‘sins’. Copyright © 2004 John Wiley & Sons, Ltd.
Standard operating procedures for clinical research personnel ‐ Part 21
Authors: Bohaychuk Wendy , C.D. Graham Ball 
Published: August 2004

AbstractThis is the 21st in a series of articles containing proposals for wording and content of standard operating procedures (SOPs) for clinical research activities conducted by sponsors and Contract Research Organisations (CROs). The procedures include those required by the International Conference on Harmonisation (ICH), the Food and Drug Administration (FDA), many other guidelines and regulations, and ‘best practice’ observed by the authors. The model forms require modification for actual use. In this article, SOPs are presented for management of safety events: recording and reporting serious adverse events (SOP 603); and reporting safety information externally (SOP 604). (The full text of all 101 SOPs is available from the authors.) Copyright © 2004 John Wiley & Sons, Ltd.
cGMP violations may be the basis for QUI TAM lawsuits in the United States
Authors: Nolan Kenneth J. 
Published: August 2004

AbstractPharmaceutical manufacturers continue to battle with the Food and Drug Administration (FDA) over compliance with current Good Manufacturing Practice regulations (cGMP), which outline the requirements that drug manufacturers must follow for the manufacture, processing, packing, and holding of a drug. Pharmaceutical manufacturers have already been the target of successful Federal False Claims Act (FCA) prosecutions, mostly due to pricing and kickback issues raised in qui tam lawsuits. Qui tam lawsuits are brought under the FCA by private citizens who sue on behalf of the United States (US). In exchange for their efforts, the US law provides that the private citizen is entitled, generally, to 15 to 30 % of the recovery generated by the qui tam lawsuit.Kenneth J. Nolan, a top qui tam attorney says that in the last several years, total payouts by manufacturers to settle qui tam lawsuits have amounted to over USD 2.0 billion. Copyright © 2004 John Wiley & Sons, Ltd.
Data quality of the clinical trial process – costly regulatory compliance at the expense of scientific proficiency
Authors: Lörstad Mats 
Published: August 2004

AbstractThe reasons for the belief in the need for perfection of clinical data are carefully nursed myths. The logical shortcomings in Good Clinical Practice are nothing but embarrassing to its scientifically trained promoters. Modern quality management methods, which increasingly degrade the importance of inspections, are described and their application in clinical research recommended. The documentation of procedures to attain acceptable quality levels of trial data is suggested to be standardized into a Quality Declaration. Copyright © 2004 John Wiley & Sons, Ltd.
Efficient evaluation of the molecular auxiliary function Bn by downward recursion
Authors: Harris Frank E. 
Published: August 2004

AbstractIt is known that the molecular auxiliary function Bn(q) can be generated stably by downward recurrence for the range n > |q|, but doing so requires a starting value of BN, where N is the largest n value needed. The question of the choice of upward vs. downward recursion is revisited. Then, it is shown that by writing BN(q) in terms of incomplete gamma functions and introducing an asymptotic expansion for the latter the necessary starting values can be obtained far more rapidly than heretofore for a significant range of |q| and N. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Relative energies, stereoelectronic interactions, and conformational interconversion in silacycloalkanes
Authors: Freeman Fillmore , Fang Christine , Shainyan Bagrat A. 
Published: August 2004

AbstractStereoelectronic hyperconjugative interactions, geometrical parameters, and relative energies of conformations and isomers of silacycloalkanes have been calculated at the B3LYP/6‐311+G(d,p) level of theory. The chair conformer of silacyclohexane was calculated to be 3.89, 4.82, and 5.18 kcal/mol more stable than the respective 1,4‐twist conformer, 2,5‐twist conformer, and 2,5‐boat transition state. Intrinsic reaction path (IRC) calculations connected the half‐chair transition state to the chair and 2,5‐twist conformers of silacyclohexane. The energy difference (ΔE) between the chair conformer and the half‐chair transition state that connects the chair conformer and 2,5‐twist conformer of silacyclohexane is 5.47 kcal/mol. The chair conformer of equatorial 1‐methyl‐1‐silacyclohexane is 0.45 kcal/mol more stable than the chair conformer of axial 1‐methyl‐1‐silacyclohexane. Axial 1‐methyl‐1‐silacyclohexane is 3.53 and 4.67 kcal/mol more than its 1,4‐twist and 2,5‐twist conformers, and equatorial 1‐methyl‐1‐silacyclohexane is 3.97 and 4.82 kcal/mol more stable than its 1,4‐twist and 2,5‐twist conformers. 1‐Silabicyclo[2.2.1]heptane is 4.58 and 10.8 kcal/mol, respectively more stable than 2‐silabicyclo[2.2.1]heptane and 7‐silabicyclo[2.2.1]heptane. The influences of selectively replacing a CH2group in a cycloalkane with a SiH2group on the geometrical parameters, conformational properties, ring strain, and stereoelectronic hyperconjugative interactions are discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Analysis of stock management gaming experiments and alternative ordering formulations
Authors: Barlas Yaman , Özevin Mehmet Günhan 
Published: August 2004

AbstractThis paper investigates two different yet related research questions about stock management in feedback environments. The first purpose is to analyse the effects of selected experimental factors on the performances of subjects (players) in a stock management simulation game. In light of these results, our second objective is to evaluate the adequacy of standard decision rules typically used in dynamic stock management models and to seek improvement formulations. To carry out the research, the generic stock management problem is chosen as the interactive gaming platform. In the first part, gaming experiments are designed to test the effects of three factors on decision‐making behaviour: different patterns of customer demand, minimum possible order decision (‘review’) interval and, finally, the type of receiving delay. ANOVA results of these three‐factor, two‐level experiments show which factors have significant effects on 10 different measures of behaviour (such as max–min range of orders, inventory amplitudes, periods of oscillations and backlog durations). In the second phase of research, the performances of subjects are compared against some selected ordering heuristics (formulations). First, the patterns of ordering behaviour of subjects are classified into three basic types. Comparing these three pattern types with simulation results using different decision rules, we observe that the common linear ‘anchoring and adjustment rule’ can represent the smooth and gradually damping type of behaviour, but cannot generate the non‐linear and/or discrete ordering dynamics. Thus, several alternative non‐linear rules are formulated and tested against subjects' behaviour patterns. Some standard discrete inventory control rules (such as (s, S)) common in the inventory management literature are also formulated and tested. These non‐linear and/or discrete rules, compared with the linear stock adjustment rule, are found to be more representative of the subjects' ordering behaviour in many cases, in the sense that these rules can generate non‐linear and/or discrete ordering behaviours. Another major finding is the fact that the well‐documented oscillatory dynamic behaviour of the inventory is a quite general result, not just an artifact of the linear anchor and adjust rule. When the supply line is ignored or underestimated, large inventory oscillations result also with the non‐linear rules, as well as the standard inventory management rules. Furthermore, depending on parameter values, non‐linear ordering rules are more prone to yield unstable oscillations—even if the supply line is taken into account. Further methodological and experimental research questions are suggested. Copyright © 2004 John Wiley & Sons, Ltd.