bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonisothermal crystallization of poly(ethylene terephthalate) and its blends in the injection‐molding process
Authors: Okamoto Masami , Shinoda Yoshihiro , Kinami Nobuyuki , Okuyama Tomoko 
Published: April 2003

AbstractWe investigated the nonisothermal crystallization during the cooling process of injection molding of poly(ethylene terephthalate) (PET), PET/talc, and PET/Surlyn blends. We applied the isothermal crystallization parameters obtained by the Hoffman–Lauritzen theory to the kinetics of nonisothermal crystallization and then calculated the relative crystallinity χ/χc as a function of the mold temperature. χ/χc were nicely interpreted by calculation without effect of the pressure history on crystallization in PET and PET/talc (1 wt %) blends. In contrast, in the PET/Surlyn (3 wt %) blend, crystallization occurred at a lower mold temperature than predicted by our calculation. The transmission electron micrograph near the surface of the injection‐molded PET/Surlyn blend showed deformation and stretching of dispersed Surlyn particles, suggesting that orientation of the PET matrix proceeds with the flow in processing. The orientation of the PET matrix resulted in acceleration of the crystallization in the injection molding. © 1995 John Wiley & Sons, Inc.
Use of factorial experimental design in static and dynamic light scattering characterization of water‐soluble polymers
Authors: Hester R. D. , Flesher L. M. 
Published: April 2003

AbstractWhen characterizing solutions of random coil polymers by static light scattering (SLS) or dynamic light scattering (DLS), linear regression is used to fit experimental data to theoretical relationships. These relationships are expressed as polynomial equations, which contain two independent variables—sample concentration and scattering angle—and a response or dependent variable that is related to radiation intensities (SLS) or intensity fluctuations (DLS). The coefficients of the terms in the polynomial are used to estimate parameters such as molecular weight and polymer coil radius of gyration. One major problem during data analysis involves deciding which polynomial model is appropriate for use with the data that inherently contains a high level of random noise that is produced by the presence of dust in the solutions. Dust is an especially troublesome problem when dealing with large polymers in aqueous solutions. Polynomial models having more terms than justified are unacceptable because the coefficients of these models are excessively corrupted by the noise. Thus, conclusions from unjustified models can be erroneous. This article discusses use of a factorial experimental design technique that obtains an acceptable model for fitting light scattering data containing high levels of random noise. © 1995 John Wiley & Sons, Inc.
Transfer of copper and zinc in polymeric materials oxidized in contact with brass
Authors: Lin D. G. , Eliseeva I. M. 
Published: April 2003

AbstractTransfer particularities were investigated for zinc and copper in polymeric films oxidized in contact with brass. Inversion in selectivity of alloy component transfer proved to be the fact for a wide range of polymers. The results obtained are explained by an irregular development of oxidative transformations within the polymer layer, thus leading to a two‐stage mode of transfer in the case of catalytically active metals. The influence of various factors (e.g., oxidation temperature, polymer film thickness, polymer origin) on the level of ultimate concentrations of copper and zinc accumulated in polymers was considered. © 1995 John Wiley & Sons, Inc.
Poly(vinyl alcohol)–poly(sodium acrylate) composite hydrogels. I. Kinetics of swelling and dehydration
Authors: Graiver Daniel , Hyon Suong‐Hyu , Ikada Yoshito 
Published: April 2003

AbstractIncorporation of sodium polyacrylate (NaPAA) in poly(vinyl alcohol) (PVA) gels as small, uniformly distributed precipitates greatly accelerates their volume expansion during swelling in water to form hydrogels. In addition to the usual water absorption, the swelling process includes dissolution of the precipitates that leads to a locally high osmotic pressure that in turn causes a further increase in water penetration and volume expansion. During swelling, soluble NaPAA is released into the water phase with a high initial release rate that then decreases continuously. The release can be described by an exponential decay function with a power dependent rate coefficient. Because the diffusion of NaPAA through the PVa walls is too slow to account for this release rate, a morphology of a closed cell foamlike structure with interconnecting channels is proposed. An aqueous solution of NaPAA seems to diffuse out of the hydrogel through these channels. © 1995 John Wiley & Sons, Inc.
Copper (II) transfer through carboxylic ion‐exchange membranes prepared by paste method
Authors: Alexandrova I. , Iordanov G. 
Published: April 2003

AbstractInterpolymer carboxylic membranes were prepared by the paste method. Transport of copper through the membrane was investigated by using a system containing HCl (receiver solution) and CuCl2 (feed solution). The transfer rate was found to be greatly affected by the membrane composition and HCl concentration in the receiver solution. A membrane based on poly(vinyl chloride)/poly(methyl methacrylate‐co‐divinylbenzene) with 5 wt % divinylbenzene showed the highest transfer rate. © 1995 John Wiley & Sons, Inc.
Mechanism and kinetics of adiabatic anionic polymerization of ϵ‐caprolactam in the presence of various activators
Authors: Kim Kap Jin , Kim Yun Young , Yoon Byung Sook , Yoon Kee Jong 
Published: April 2003

AbstractNylon 6 was prepared by adiabatic anionic polymerization of ϵ‐caprolactam using hexamethylene dicarbamoyl dicaprolactam (HDC), cyclohexyl carbamoyl caprolactam (CCC), or phenyl carbamoyl caprolactam (PCC) as activators and sodium caprolactamate (NaCL) as a catalyst at various initial reaction temperatures ranging from 130 to 160°C. Adiabatic temperature rise was recorded as a function of polymerization time to investigate polymerization kinetics. Kinetic parameters for polymerization, which are more accurate than data reported to date, could be obtained by fitting the temperature rise data with a new polymerization kinetic equation involving crystallization exotherm and thermal conduction. The polymerization rate highly depended on the chemical structure of the activator used, which indicates that the initiating step where the activator is attacked nucleophilically by NaCL is a very important reaction step, affecting the overall polymerization rate. CCC showed the fastest polymerization rate, whereas HDC and PCC showed the medium and the slowest rate, respectively. The contributions of crystallization exotherm and thermal conduction to the resultant temperature rise during polymerization were significant, when the initial reaction temperature was lower than 140°C. In all cases, the molecular weight obtained from intrinsic viscosity measurement was greater than the expected molecular weight. This may be attributed to the branching and/or crosslinking reaction through Claisen‐type condensation reactions. © 1995 John Wiley & Sons, Inc.
A study on the preparation and properties of the heterogeneous cation‐exchange membranes of sulfonated polystyrene/divinyl benzene on an acetal base
Authors: Lam‐Leung Suei Y. , Li Huan R. 
Published: April 2003

AbstractThe heterogeneous acetal‐based membranes containing 50, 60, 70, 80, and 90% (w/w) of the sulfonated polystyrene crosslinked with 7% divinyl benzene were fabricated and studied. In addition, the heterogeneous acetal‐based membranes of 85% (w/w) sulfonated polystyrene crosslinked with 1, 4, and 7% divinyl benzene were also prepared and studied. The gel water content, dimensional stability, ion‐exchange capacity, area and specific ohmic resistance, permselectivity, and rate of ion exchange of the acetal‐based membranes were determined. The sulfonated polystyrene crosslinked with 7% divinyl benzene resin was found to be the better material for preparing the acetal‐based membrane with comparable good characteristics. A commercially available heterogeneous membrane (Shanghai Chemicals, 3361) of dry‐molding sulfonated polystyrene–divinyl benzene resin was used as the reference membrane for the present investigation. © 1995 John Wiley & Sons, Inc.
Poly(ethylene‐2,6‐naphthalenedicarboxylate) fiber for industrial applications
Authors: Jager J. , Juijn J. A. , van den Heuvel C. J. M. , Huijts R. A. 
Published: April 2003

AbstractPoly(ethylene‐2,6‐naphthalenedicarboxylate) (PEN) has been prepared from commercial dimethyl‐2,6‐naphthalenedicarboxylate (DM‐2,6‐NDC) and ethylene glycol (EG) according to the well‐known transesterification/polycondensation route. PEN fibers, intended for industrial yarn applications, were obtained by melt spinning and drawing high molecular weight PEN. The properties of these yarns were measured in detail and compared with those of PET industrial yarns. The development of molecular orientation in the spinline is more pronounced for PEN than for PET. Because the yield stress is lower, PEN yarns can more easily be drawn. Breaking tenacities of PEN yarns are comparable with those of PET yarns, but the modulus is much higher and the thermal shrinkage is lower. Therefore, PEN yarns have a better dimensional stability than PET yarns. In addition, it was demonstrated that the thermal resistance of PEN yarns is better. © 1995 John Wiley & Sons, Inc.
Measurement of diffusivities of sulfur mustard (SM) and its analog oxygen mustard (OM) in cured butyl, nitrile, and natural‐rubber sheets by weight gain and FTIR–ATR methods
Authors: Banerjee Susanta , Semwal Rajendra P. , Agarwal Seema 
Published: April 2003

AbstractThe breakthrough time of butyl, nitrile, and natural‐rubber sheets (cured) of different compositions against a potent chemical warfare (CW) agent have been determined using the spot disc test (SDT) method. It was observed that butyl rubber is the best material in comparison to nitrile and natural rubber for protection against sulfur mustard (SM). One of the butyl formulations provides more than 100 h protection against SM. The diffusion coefficient of oxygen mustard (SM analog) for the same formulation (F8) and one nonblack butyl formulation (F5) was determined by weight gain as well as by FTIR–ATR methods. Both methods provide consistent results and the diffusion coefficient of oxygen mustard (OM for butyl rubber is in the order of 10−9cm2/s. The diffusion coefficient of SM for the form lation F8 and F5 was also determined from the SDT retardation time. © 1995 John Wiley & Sons, Inc.
Statistical design in isothermal aging of polyimide resins
Authors: Sutter James K. , Jobe J. Marcus , Crane Elizabeth A. 
Published: April 2003

AbstractRecent developments in research on polyimides for high temperature applications have led to the synthesis of many new polymers. Among the criteria that determines their thermal oxidative stability, isothermal aging is one of the most important. Isothermal aging studies require that many experimental factors are controlled to provide accurate results. In this article we describe a statistical plan that compares the isothermal stability of several polyimide resins, while minimizing the variations inherent in high‐temperature aging studies. © 1995 John Wiley & Sons, Inc.
Measurement of cure in optical fiber coatings by infrared microspectroscopy
Authors: Louden J. D. 
Published: April 2003

AbstractA method suitable for measuring the state of cure in acrylate optical fiber coating is described. Both the outermost (secondary) and the innermost (primary) coatings cure states can be determined. The method is reproducible and suitable for manufacturing process control and quality control in produced fiber. © 1995 John Wiley & Sons, Inc.
New measures of polydispersity from rheological data on polymer melts
Authors: Shroff R. , Mavridis H. 
Published: April 2003

AbstractThe rheological properties of polymer melts depend strongly on the underlying molecular structure: molecular weight distribution, and long chain branching. It is of considerable importance, both fundamental and practical, to relate the molecular architecture to polymer melt rheology. The focus of the present work is in extracting a measure of polydispersity from rheological data. Various polydispersity measures that have been proposed in the literature are critically examined and their limitations are pointed out. New measures of polydispersity are proposed that overcome these limitations. The evaluation of the various polydispersity measures is performed by reference to rheology fundamentals, with model calculations and examples drawn from industrial practice. The issues of eliminating molecular weight and temperature effects in characterizing polydispersity are comprehensively addressed. The presence of small levels of long chain branching in an otherwise linear polymer alters most of these measures of polydispersity dramatically, while no detectable change appears in the molecular weight distribution obtained using a gel permeation chromatograph. It is demonstrated that the polydispersity measures proposed in the present work, and which are extracted from frequency response data in the linear viscoelastic region, can be used reliably to characterize polydispersity in polymer melts. © 1995 John Wiley & Sons, Inc.
Physical principles of using polyelectrolyte hydrogels for purifying and enrichment technologies
Authors: Budtova T. , Suleimenov I. 
Published: April 2003

AbstractThe main physical regularities which allow one to use a strongly charged hydrogel in purifying and/or enrichment technologies are analyzed. The proposed cyclic method is based on the two known phenomena—the salt concentration redistribution in the presence of the polyelectrolyte hydrogel and the reversible gel contraction under electric current. It is shown that in order to obtain high degrees of purification and/or concentration the salt concentration must be lower than that of the polymer. Under these conditions, there is no dependence on the nature of the salt and the cycle may be repeated several times without regeneration of the gel. © 1995 John Wiley & Sons, Inc.
Ring‐opening polymerization of ethylene oxide by anion initiation using sulfadiazine as parents compound
Authors: Huang Junlian , Wang Haiyuan , Zhou Cunling 
Published: April 2003

AbstractA new kind of anion initiator using sulfadiazine as the parent compound was prepared by the reaction of sulfadiazine with epoxy ethylene, and then the metal potassium. The structure of the intermediate was characterized in detail by NMR, MS, UV, IR, and DSC. Ring‐opening polymerization of epoxy ethylene could be carried out by this initiation system. The molecular weight of the polymerized product, polyethylene oxide with a sulfadiazine end group (PEOsf), is in the range of 3000–4000. © 1995 John Wiley & Sons, Inc.
Terpene–anhydride resins as coating materials
Authors: Trumbo D. L. , Giddings C. L. , Wilson L. R. A. 
Published: April 2003

AbstractLow to moderate molecular weight terpene–anhydride resins were synthesized and evaluated in coatings applications. The terpenes used were terepinolene, β‐pinene, and alloocimene. The comononmers used were maleic or itaconic anhydride. The terpene–anhydride resins were used to formulate solvent‐borne coatings with an epoxy or diol as a coreactant. The coatings were evaluated as films over aluminum or steel panels. When a diol was used as a coreactant, the film properties were relatively poor. When epoxy was used as a coreactant, the properties of the films were much improved in terms of resistance to solvent and hardness. © 1995 John Wiley & Sons, Inc.
Empirical models for melt blowing
Authors: Milligan M. W. , Haynes B. D. 
Published: April 2003

AbstractA large data set obtained for melt blowing using a single hole die has been used to develop empirical models which express final average fiber diameter as a function of dimensionless independent variables. The resulting empirical models or equations have been compared to multihole melt‐blowing die data. The conclusion of this investigation is that appropriate first‐order variables have been identified and the dependence of average final fiber diameter on the independent variables has been established. The resulting model should prove very useful for use in melt‐blowing process control and in the design of melt‐blowing equipment for polypropylene with an MFR between 500 and 900. © 1995 John Wiley & Sons, Inc.
Chemical stability of polyimide membranes at temperatures near Tg
Authors: Rezac Mary E. , Koros William J. , Miller Stephen J. 
Published: April 2003

AbstractThe success of polymeric membranes for use in high temperature gas separation applications relies, in part, on the chemical stability of these materials in separation environment. This paper details experimental evaluation of the stability of the membranes prepared using a polyimide as the selective separating layer when exposed to butane/butene/hydrogen mixtures at temperatures near the glass transition temperature of the polymer, 310°C. Further, the effects of small concentrations of sulfur and ammonia compounds in the feed mixture were investigated, as was the influence of a simulated air leak. The gas transport rates and selectivities were unchanged when testing in the hydrocarbon/hydrogen environment for over 30 days. Further, no changes in transport properties were observed when hydrogen sulfide or ammonia was added to the feed mixture. However, degradation due to oxygen exposure was observed. The chemical stability of the polyimide layer appears to be sufficient to be utilized for the separation of high temperature petrochemical streams. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of model associative polymers
Authors: Jenkins Richard D. , Bassett David R. , Silebi Cesar A. , El‐Aasser Mohamed S. 
Published: April 2003

AbstractModel linear associative polymers with number average molecular weights in the range of 16,600 to 100,400 were prepared by connecting blocks of commercially available poly(oxyethylene) with isophorone diisocyanate, followed by capping with either hydroxyl, dodecyl, or hexadecyl linear alkyl end groups. The molecular weight distributions measured by gel permeation chromatography are somewhat broad, as expected from the synthetic method. In a 40/60 by weight solvent mixture of diethylene glycol monobutyl ether (Butyl Carbitol) and water, the relative viscosities of model associative polymers and poly(oxyethylene) standards collapsed to a single master curve; viscosity average molecular weights obtained from the intrinsic viscosities measured in this solvent mixture compare favorably to those obtained by size exclusion chromatography. In water, the model polymers with alkyl end groups interact at extremely dilute concentrations to produce a pronounced increase in reduced viscosity that increases as concentration and alkyl end group length increase. The Huggins parameters for solutions of model associative polymers with the hexadecyl and dodecyl end groups vary between 1 and 16, and decrease as molecular weight increases, as hydrophobe length decreases, and as temperature increases. The concentration at which the viscosity data deviate from the Huggins equation is less than the polymer coil overlap concentration, which is on the order of 1–3 g/dL, as estimated from the reciprocal of the intrinsic viscosity data. This suggests that we can define a critical network concentration c*h as the concentration at which the associative polymers hydrophobic end groups first interact to form a rheologically significant network. However, the transition occurs over a concentration range, rather than at a particular critical micellar concentration, as is the case of ordinary surfactants or hydrophobically modified hydroxyethylcellulose. The dimensions of the associative polymer coils in solution, and the signs and relative magnitudes of heat and entropy of dilution as estimated from classical molecular theories, are similar to those obtained by other authors for poly(oxyethylene) homopolymers. A physical model based on equilibrium kinetics for the association process correctly mimics the dependence of viscosity on molecular weight and concentration, and indicates that the free energy of association must become larger as the length of the alkyl end groups becomes larger relative to the hydrophilic backbone. © 1995 John Wiley & Sons, Inc.
Kinetics of adsorption and desorption of water‐soluble associative polymers on planar titanium dioxide surfaces by ellipsometry
Authors: Filippov Leonid K. , Silebi Cesar A. , El‐Aasser Mohamed S. 
Published: April 2003

AbstractThe adsorption and desorption kinetics of water‐soluble associative polymers with different molecular weights on crystals of titanium dioxide [TiO2(001)] have been studied by ellipsometry. The model water‐soluble associative polymers used in the kinetic study are nonionic polyurethanes based on polyethylene glycol, and have average molecular weights of 17,000, 51,000, and 100,000 with a C16H33 linear alkyl group on each end of the molecule. It is shown that the adsorption and desorption kinetics over a wide range of polymer concentrations is governed by: (1) the kinetics of adsorption and desorption of polymer chains at the interface, (2) the kinetics of adsorption and desorption at the interfaces as well as simultaneous diffusion in the adsorbed layer, and/or (3) diffusion in the adsorbed layer. The existence of regimes (1), (2), and (3) of the adsorption and desorption kinetics are justified by using the experimental data for the adsorption and desorption of water‐soluble associative polymers with different molecular weights. It is shown that the adsorption is an irreversible process for the strongly convex adsorption isotherms. Equations were derived to calculate: (a) the rate constant for polymer adsorption and desorption processes, (b) the coefficient of diffusion, (c) the activation energy of diffusion in the adsorbed layer, and (d) the time needed to attain the equilibrium states for the adsorption and desorption processes by using adsorption and desorption kinetics data with associative polymers of different molecular weights at different polymer concentrations. © 1995 John Wiley & Sons, Inc.
Orientational ordering of grafted nonmobile rod polymers
Authors: Vugmeister B. E. , Hong Daniel C. 
Published: April 2003

AbstractWe studied the orientational ordering of grafted rod polymers on the surface. The rod polymers were nonmobile and allowed to have two configurations: either lying down on the surface or standing up. The only interaction between the rods were hard core interaction. We computed the orientational order parameter using the recently developed random local field theory. We found that the order parameter increased monotonically as a function of the concentration of the rods and, thus, there existed no pancake‐brush transition. © 1995 John Wiley & Sons, Inc.