bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Cementation on the Mechanical Properties of Sandstones
Authors: Al-Tahini A. M. , Sondergeld C. H. , Rai C. S.
Published: August 2006

The variability in mechanical properties measured on sands from the Jauf and Unayzah formations of Saudi Arabia is observed to be dependent upon cementation. Understanding the role of cementation in controlling the mechanical properties can improve the design of hydraulic-fracture treatments and, hence, improve reservoir performance.

Strength measurements from triaxial-testing data and examination of core in thin sections were used to relate the detailed microstructure and cementation to the variation of mechanical properties. Strength and elastic moduli were determined for 65 samples cored from five different wells. Forty-seven samples were analyzed in thin sections and point counted to determine and quantify cementation. Cements in these two formations have variable composition and habits; both affect the mechanical properties and strength. It is not sufficient to know that cements exist; it is also necessary to know where the cement occurs.

Pure quartz overgrowths play a major role in increasing strength, while clay coatings play a minor role. Simple linear correlations were found relating cement concentrations to strength.
A Hybrid Numerical/Analytical Model of a Finite-Conductivity Vertical Fracture Intercepted by a Horizontal Well
Authors: Al-Kobaisi M. , Ozkan E. , Kazemi H.
Published: August 2006

This paper presents a hybrid numerical/analytical model for the pressure-transient response of a finite-conductivity fracture intercepted by a horizontal well. The model dynamically couples a numerical fracture model with an analytical reservoir model. This approach allows us to include finer details of the fracture characteristics while keeping the computational work manageable. For example, the fracture may have irregular shape, nonuniform width, and variable conductivity, and the well may not intersect the fracture at its geometric center.

In this paper, we use the hybrid model to investigate the effects of fracture properties on the pressure-transient characteristics of a single, finite-conductivity horizontal-well fracture. The single horizontal-well-fracture model can be extended easily to multiply fractured horizontal wells by superposition. The model also can be used to compute the pseudoskin caused by the effects of nonideal fracture geometry, variable conductivity, and flow choking around the wellbore and to investigate the influence of fracture properties on the performance of horizontal wells.
A Reliable Correlation To Predict the Change in Minimum Miscibility Pressure When CO2 Is Diluted With Other Gases
Authors: Emera Mohammed K. , Sarma Hemanta K.
Published: August 2006

A new genetic algorithm (GA)-based correlation has been developed to estimate the change in MMP when CO2 is diluted with other gases, termed "impure CO2" in the context of this paper. The advantage of this correlation over others is that it can be used for gas mixtures with higher N2 concentrations (tested up to 20 mol%) and with non-CO2 component concentrations up to 78 mol% (e.g., H2S, N2, SOx, O2, and C1−C4) with a higher accuracy. Equally important, it could be a useful screening tool when experimental data are not available and when developing an optimal and economical laboratory program to estimate the MMP.

In developing this correlation, the GA software developed in our earlier work (Emera and Sarma 2005a) has been modified to account for various components in the injected-gas stream. The correlation estimates the change in MMP as a function of injected-gas solvency in the oil. The solvency, in turn, is related to critical properties of the injected gas (critical temperature and pressure). In addition, pure CO2/oil MMP is used as an input in this correlation. The correlation has been validated successfully against published experimental data and several correlations in the literature. It yielded a better match with an average error of 4.7% and a standard deviation of 6.3%, followed by the Sebastian et al. (1985) correlation with a 13.1% average error and a 22.0% standard deviation and the Alston et al. (1985) correlation with a 14.1% average error and a 43.2% standard deviation.
Optimal Coarsening of 3D Reservoir Models for Flow Simulation
Authors: King Michael J. , Burn Karam S. , Wang Pengju , Muralidharan Venkataramanan , Alvarado Freddy , Ma Xianlin , Datta-Gupta Akhil
Published: August 2006

We have developed a new constrained optimization approach to the coarsening of 3D reservoir models for flow simulation. The optimization maximally preserves a statistical measure of the heterogeneity of a fine-scale model. Constraints arise from the reservoir fluids, well locations, pay/nonpay juxtaposition, and large-scale reservoir structure and stratigraphy. The approach has been validated for a number of oil and gas projects, where flow simulation through the coarsened model is shown to provide an excellent approximation to high-resolution calculations performed in the original model.

The optimal layer coarsening is related to the analyses of Li and Beckner (2000), Li et al. (1995), and Testerman (1962). It differs by using a more accurate measure of reservoir heterogeneity and by being based on recursive sequential coarsening instead of sequential refinement. Recursive coarsening is shown to be significantly faster than refinement: the cost of the calculation scales as (NX·NY·NZ) instead of (NX·NY·NZ)2. The more accurate measure of reservoir heterogeneity is very important; it provides a more conservative estimate of the optimal number of layers than the analysis of Li et al. The latter is shown to be too aggressive and does not preserve important aspects of the reservoir heterogeneity. Our approach also differs from the global methods of Stern and Dawson (1999) and Durlofsky et al. (1996). It does not require the calculation of a global pressure solution, nor does it require the imposition of large-scale flow fields, which may bias the analysis (Fincham et al. 2004). Instead, global flow calculations are retained only to validate the reservoir coarsening.

Our approach can also be used to generate highly unstructured, variable-resolution computational grids. The layering scheme for these grids follows from the statistical analysis of the reservoir heterogeneity. Locally variable resolution follows from the constraints (reservoir structure, faults, well locations, fluids, pay/ nonpay juxtaposition). Our reservoir simulator has been modified to allow a fine-scale model to be initialized and further coarsened at run time. This has many advantages in that it provides both simplified and powerful workflows, which allow engineers and geoscientists to work with identical shared models.
Tidal Pressure Response and Surveillance of Water Encroachment
Authors: Langaas K. , Nilsen K. I. , Skjaeveland S. M.
Published: August 2006

A review of the tidal response in petroleum reservoirs is given. Tidal response is caused by periodic changes in overburden stress induced by the ocean tide; the "tidal efficiency factor" is derived by two different approaches and is in line with a recent well test in the Ormen Lange gas field.

For small geomechanical pertubations like the tidal effect, we show that a simplified coupling of geomechanics and fluid flow is possible. The coupling is easy to implement in a standard reservoir simulator by introducing a porosity varying in phase with the tide. Simulations show very good agreement with the theory.

The observation of the tidal response in petroleum reservoirs is an independent information provider [i.e., it provides information in addition to the (average) pressure and its derivative from a well test]. The implementation of the tidal effect in a normal reservoir simulator gives us the opportunity to study complex multiphase situations and to evaluate the potential of the tidal response as a reservoir-surveillance method. The case studies presented here focus on the possibility of observing water in the near-well region of a gas well.
Influence of Initial Water Saturation on Recovery by Spontaneous Imbibition in Gas/Water/Rock Systems and the Calculation of Relative Permeability
Authors: Li Kewen , Chow Kevin , Horne Roland N.
Published: August 2006

It has been a challenge to understand why recovery by spontaneous imbibition could both increase and decrease with initial water saturation. To this end, mathematical models were developed with porosity, permeability, viscosity, relative permeability, capillary pressure, and initial water saturation included. These equations foresee that recovery and imbibition rate can increase, remain unchanged, or decrease with an increase in initial water saturation, depending on rock properties, the quantity of residual gas saturation, the range of initial water saturation, and the units used in the definitions of gas recovery and imbibition rate. The theoretical predictions were verified experimentally by conducting spontaneous water imbibition at five different initial water saturations, ranging from 0 to approximately 50%. The effects of initial water saturation on residual saturation, relative permeability, capillary pressure, imbibition rate, and recovery in gas/water/rock systems by cocurrent spontaneous imbibition were investigated both theoretically and experimentally. Water-phase relative permeabilities and capillary pressures were calculated with the experimental data of spontaneous imbibition. Experimental results in different rocks were compared.
The Genetic Counseling Video Project (GCVP): Models of practice
Authors: Roter D. , Ellington L. , Erby L. Hamby , Larson S. , Dudley W.
Published: August 2006

Genetic counseling is conceptualized as having both “teaching” and “counseling” functions; however, little is known about how these functions are articulated in routine practice. This study addresses the question by documenting, on videotape, the practices of a national sample of prenatal and cancer genetic counselors (GCs) providing routine pre‐test counseling to simulated clients (SCs). One hundred and seventy‐seven GCs recruited at two annual conferences of the National Society of Genetic Counselors (NSGC) were randomly assigned to counsel one of six female SCs of varying ethnicity, with or without a spouse, in their specialty. One hundred and fifty‐two videotapes were coded with the Roter Interaction Analysis System (RIAS) and both GCs and SCs completed evaluative questionnaires. Two teaching and two counseling patterns of practice emerged from cluster analysis. The teaching patterns included: (1) clinical teaching (31%) characterized by low psychosocial, emotional and facilitative talk, high levels of clinical exchange, and high verbal dominance; and (2) psycho‐educational teaching (27%) characterized by high levels of both clinical and psychosocial exchange, low levels of emotional and facilitative talk, and higher verbal dominance. The counseling patterns included: (1) supportive counseling (33%) characterized by low psychosocial and clinical exchange, high levels of emotional and facilitative talk, and low verbal dominance; and (2) psychosocial counseling (9%) with high emotional and facilitative talk, low clinical and high psychosocial exchange, and the lowest verbal dominance. SCs ratings of satisfaction with communication, the counselor's affective demeanor, and the counselor's use of non‐verbal skills were highest for the counseling model sessions. Both the teaching and counseling models seem to be represented in routine practice and predict variation in client satisfaction, affective demeanor, and nonverbal effectiveness. © 2006 Wiley‐Liss, Inc.
Secondary centers of ossification of the human toes: Exceptional polymorphism and evolutionary perspectives
Authors: Billmann Franck , Le Minor Jean‐Marie
Published: August 2006

As great morphological variability characterizes the phalanges of the human toes in adults, we hypothesized for a possible variability in the presence or absence of their secondary (= epiphyseal) centers of ossification linked to the unique morphology of the human foot within primates. The aim of this study was thus to provide original and detailed data on the occurrence of these centers. Classically, the big toe or hallux (I) presents two secondary centers and the lateral toes (II–V) three centers, and consequently the five toes present a total of 14 secondary centers. The material studied consisted of 261 foot radiographs from 261 young individuals of European origin (202 males and 59 females; 6–16 years). The presence (or absence) of the secondary centers of the phalanges of the toes was assessed for each foot. Feet presenting a biphalangeal variant in one or more lateral toes were studied separately. The theoretical possibilities of association of the three secondary centers in a given lateral toe (II–V) are eight in number; these eight patterns were studied and coded in the present study by types A–H. An exceptional variability in the occurrence of the secondary centers in lateral toes (II–V) was observed, and the classic pattern of phalangeal ossification was never observed. The absence of one or more secondary centers seems to be observed only in the human species, and we suggest that this could be a derived pattern specific to the human species, i.e., autapomorphic pattern. These results are of interest in the characterization and understanding of the reduction in size of the lateral toes which characterizes the specific evolution of the human foot. Am J Phys Anthropol, 2006. © 2006 Wiley‐Liss, Inc.
Phenotypic, maximum genetic, and special environmental variability in prehistoric human populations
Authors: Varela Héctor Hugo , Cocilovo José Alberto
Published: August 2006

The phenotypic variance (VP) may be divided into the genetic variance (VG), the general environmental variance (VEg), and the special environmental variance (VEs). The latter is estimated through repeatability calculation (b). This value is considered the upper limit of heritability and represents maximum genetic variance proportion (VGm = VG + VEg) in relation to VP (b = (VG + VEg)/VP). This process allows an improved determination of biological relationships among groups from estimators maximizing the genetic information of quantitative characters. Two hundred and thirty‐seven individuals inhabiting the northern coast of Chile for 4,000 years were taken as a sample. Measurement was made of six metric characters at both sides of the cranium. Special environmental values (es) were obtained by regression. The difference between these values and the phenotypic values (p) consists in the genetic values plus the general environmental values (g + eg). A mean b value of 0.83 indicated that VEs represents 17% of VP. The results showed: 1) high stability of the maximum genetic variance in time and space, 2) high correlation between the biological relationships model, the phenotypic model, and the maximum genetic model, and 3) random distribution of the nongenetic variation, as expected from the quantitative genetics theory. These results support the use of phenotypic data for the interpretation of the evolution history of prehistoric populations. Am J Phys Anthropol, 2006. © 2006 Wiley‐Liss, Inc.
Codierte Mikropartikel für Hochdurchsatz‐Mehrfachanalysen
Authors: Wilson Robert , Cossins Andrew R. , Spiller David G.
Published: August 2006

Nach der Entschlüsselung des Genoms wächst nun der Wunsch, mehr molekulare Information aus immer kleineren Proben zu gewinnen. Derzeit vertraut man auf planare Testanordnungen, doch die Qualität der Ergebnisse variiert von Versuchssystem zu Versuchssystem. Suspensionen codierter Mikrokügelchen ergeben höherwertige Daten, allerdings ist die auf diese Weise erhältliche molekulare Information durch die Zahl unterscheidbarer Codes in einer Probe beschränkt. Neue Synthesemethoden für codierte Partikel könnten hier Abhilfe schaffen, aber bei der wachsenden Vielfalt an neuen Technologien fällt die Auswahl nicht leicht. Dieser Aufsatz wägt kritisch ab, ob die neuartigen codierten Partikel gut in Mehrfachanalysen abschneiden werden.
Very high modulus high‐density polyethylene and high‐modulus polypropylene obtained by solid‐state roll drawing
Authors: Ajji A. , Dumoulin M. M.
Published: August 2006

This article describes results obtained with a process developed for rolling and drawing simultaneously polymer profiles in the solid state. Solid‐state roll drawing has the advantage of being continuous, which allows relatively high production rates and the generation of high deformation ratios with some degree of biaxial orientation. The roll‐drawing process allows the extent of biaxial orientation to be controlled by the adjustment of the tension and compression loads applied to the polymers, in particular semicrystalline thermoplastics. Some experimental results obtained with a four‐station roll‐drawing apparatus are presented, particularly on high‐density polyethylene (HDPE) and polypropylene. The effect of process parameters, such as the gap between the rolls and tension, are discussed. Aspects discussed also include relaxation; structure development in terms of orientation and crystallinity as a function of draw ratio (λ); λ as a function of process parameters; and finally, mechanical and thermal properties as a function of λ. Moduli as high as 25 GPa in the longitudinal direction and about 4 GPa in the transverse direction were obtained with successively rolled, initially thick, HDPE profiles. © 2006 Government of Canada. Exclusive worldwide publication right in the article have been transferred to Wiley Periodicals, Inc. J Appl Polym Sci 102: 3391–3399, 2006
Some insight into hydrolytic scission mechanisms in bioerodible polyesters
Authors: Alexis Frank , Venkatraman Subbu , Kumar Rath Santosh , Gan Leong‐Huat
Published: August 2006

PLLA, PDLLA, and PLGA copolymers have been studied to understand the details of their degradation behavior. All polymers exhibited a homogeneous mode of degradation, with uniform rates of degradation throughout the film. Crystallinity inhibited water absorption and hence retarded degradation. The degradation rate was increased by the presence of glycolic acid units in the PLGA copolymer; this effect overwhelms any decrease in degradation rate because of increased crystallinity due to the additional GA units. This effect is demonstrated quantitatively in this study. In PLGA polymers, there is evidence of unusual recrystallization behavior as degradation proceeds, due mainly to the higher rate of hydrolytic scission of the glycolide linkage compared with the lactide, as verified quantitatively with the use of 1H NMR studies. Application of a Monte Carlo model to the degradation results, however, appears to show a random scission process. The details of the mechanistic study of different factors influencing the process of degradation, as reported here, may have important implications in terms of selecting the right material for specific biomedical applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3111–3117, 2006
Effect of crosslinking concentration on mechanical and thermodynamic properties in acrylic acid–co–methyl methacrylate hydrogels
Authors: Katime Issa , de Apodaca E. Díaz , Rodríguez E.
Published: August 2006

The mechanical and thermodynamic properties of poly(acrylic acid‐co‐methyl methacrylate) hydrogels with varying crosslinker N,N′‐methylenebisacrylamide (NMBA) content are reported. A higher NMBA content generally led to a stronger and harder gel with lower water content. Swelling capacity decreased as the NMBA concentration increased between 0.5% and 2%, remaining constant beyond this range. The temperature changes of the partial molar Gibbs free energy of dilution and enthalpic and entropic contributions were examined. The thermodynamic parameters showed that swelling was an unfavorable and endothermic process. The freezing and nonfreezing water in the hydrogel was determined by differential scanning calorimetry (DSC). Freezing water content decreased with increasing crosslinker (NMBA) content, whereas the ratio of nonfreezing water to total water content increased with NMBA content because of the promoting of hydrophobic interactions in the hydrogels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4016–4022, 2006
Bismaleimide modified bis propargyl ether bisphenol A resin: Synthesis, cure, and thermal properties
Authors: Liu Feng , Li Wanwan , Wei Liuhe , Zhao Tong
Published: August 2006

Bis propargyl ether bisphenol A (PBPA) was synthesized and blended with 4,4′‐bismaleimide diphenyl methane (BDM) at different molar ratios. The cure behavior of the blend resins was measured by DSC and FTIR spectra. The results indicated that the onset cure temperatures of the blend resins were about 20–30°C lower than that of pure PBPA, and the cure exothermic enthalpy of the resins also significantly reduced from 1320 (PBPA) to 493 J/g (PBPA–BDM (1.0:2.0)). The thermal stabilities and dynamic mechanical properties of the cured resins were characterized by TGA and DMA, respectively. The thermal stability of the resins improved markedly with the increase in BDM content, and the glass transition temperature increased from 306°C for PBPA–BDM (1.0:0.5) to 358°C for PBPA–BDM (1.0:2.0). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3610–3615, 2006
Synthesis and characterization of a macromolecular surface modifier for polypropylene
Authors: Chen Hanjia , Zhu Yafei , Zhang Yi , Xu Jiarui
Published: August 2006

A novel macromolecular surface modifier, a polypropylene‐graft‐poly(butyl methylacrylate) copolymer, was synthesized through the coupling of polypropylene containing maleic anhydride with monohydroxyl‐terminated poly(butyl methylacrylate). The effects of the raw ratio, reaction temperature, and molecular weight of the branches on the graft reaction were studied. The graft copolymers were characterized with IR, 1H‐NMR, thermogravimetry, and differential scanning calorimetry. The results of attenuated total reflection/Fourier transform infrared and contact‐angle measurements indicated that polypropylene‐graft‐poly(butyl methylacrylate) could diffuse preferably onto the surface and be used as a surface modifier for polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3413–3419, 2006
Reaction‐induced phase separation in poly(vinyl acetate)/polyester blend
Authors: Bulliard X. , Michaud V. , Månson J.‐A. E.
Published: August 2006

In blends of unsaturated polyester (UP), poly (vinyl acetate) (PVAc), and styrene, a reaction‐induced phase separation occurs upon curing that is due to the crosslinking between styrene and the UP molecules. The evolution of the morphology was observed by optical microscopy on a heated stage. Light transmission was used in parallel to precisely detect the onset of phase separation and the formation of microvoids. Using Fourier transform IR spectroscopy in the same conditions, the conversions at phase separation and at microvoiding were evaluated. Phase separation occurs at a very low degree of conversion and microvoiding develops at around 60% of conversion. The final morphology of the blend was investigated by scanning electron microscopy. The relative influences of the cure temperature, the concentration in PVAc, and the molecular weight of PVAc were investigated. It was confirmed that the early stages of the reaction at high temperature determine the final morphology of the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3877–3888, 2006
Synthesis and properties of ethylene/styrene copolymers produced by metallocene catalysts
Authors: Haider N. , Expósito M. T. , Muñoz‐Escalona A. , Ramos J. , Vega J. F. , Méndez L. , Martínez‐Salazar J.
Published: August 2006

Ethylene/styrene copolymers were synthesized under constant polymerization conditions using six different metallocene catalysts activated with methylaluminoxane. For all the catalysts used, the activity and molecular weight of the copolymers produced decreased with the amount of styrene in the reactor feed, but the styrene content of the copolymers increased. Catalysts with carbon bridges and bulky ligands gave rise to copolymers with higher styrene content. As a result of the increased styrene content of the copolymer, the melting temperature decreased. This effect was ascribed to a decrease in the crystallinity of the copolymers. It was also found that lamellar thickness could be significantly diminished by the incorporation of comonomers. The copolymers showed a broad spectrum of mechanical properties as a function of the comonomer ratio. At low styrene contents, they behaved like typical semicrystalline thermoplastics, and at higher styrene contents, they exhibited the properties typical of elastomers. Of the catalysts tested, [rac‐ethylenebis(4,5,6,7‐tetrahydro‐1‐indenyl)]zirconium dichloride emerged as the most promising for the production of ethylene/styrene copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3420–3429, 2006
Mechanistic study of boron trifluoride catalyzed ε‐caprolactone polymerization in the presence of glycerol
Authors: Jiang G. , Walker G. S. , Jones I. A. , Rudd C. D.
Published: August 2006

Boron trifluoride catalyzed ε‐caprolactone polymerization in the presence of glycerol can produce poly(ε‐caprolactone) with a high weight‐average molecular weight and a broad molecular weight distribution. This article reports an investigation of the polymerization mechanism to determine the formation of these molecular weight features through a study of the polymerization kinetics and the molecular structure with NMR. The polymerization proceeds via an activated monomer mechanism, resulting in polymer molecules with hydroxyl chain ends. The broad molecular weight distribution can be attributed to the etherification reactions between hydroxyl chain ends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3900–3906, 2006
Surface relief gratings on azo polymer films through reversible photoisomerization by the irradiation of a monochromatic light
Authors: Alam Md. Zahangir , Ohmachi Tomoko , Ogata Tomonari , Nonaka Takamasa , Kurihara Seiji
Published: August 2006

Surface relief gratings were induced on azobenzene‐functionalized polymer films by exposure to s‐polarized and circularly polarized Ar+‐laser (488‐nm) irradiation through a photomask. The surface relief structures were investigated with atomic force microscopy. A very regularly spaced surface grating with a modulation depth of about 400 nm was obtained after 30 min of circularly polarized Ar+‐laser irradiation. The diffraction efficiency was measured after irradiation by an Ar+ laser, and an efficiency of about 2% was achieved. The polymer films also showed a very high period of recording. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3123–3126, 2006
Atomic force microscopy analysis of cellulose triacetate surface modified in low temperature argon plasma and its adhesion behavior
Authors: Koo Kang , Mi Park Young , Yeong Yu Jae
Published: August 2006

The surface of cellulose triacetate (CTA) film was modified with gaseous plasma of several discharge power in the presence of Argon (Ar) gas at 0.5 torr pressure. After gas plasma etching, the surface structure of the films is analyzed by atomic force microscopy (AFM) and measured with peel strength. Furthermore, the wetting properties of the CTA film treated with Ar plasma are studied by contact angle measurement. Peel strength after plasma treatment was increased with increasing plasma treatment time. However, treatments of plasma greater than 7 min did not find an additional increase in peel strength, similarly to roughness and morphological changes of AFM. The water contact angle decreased for an initial treatment time due to the improved wettability of the film, but showed an increasing trend for a higher treatment time (7 min). These results show that Ar plasma treatment is a convenient tool for improving the adhesive properties of CTA film. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3963–3971, 2006
Thermal behavior of poly(acrylic acid)–poly(vinyl pyrrolidone) and poly(acrylic acid)–metal–poly(vinyl pyrrolidone) complexes
Authors: Moharram M. A. , Khafagi M. G.
Published: August 2006

Thermal analysis (TGA and DTA) of samples of PAA, PVP, PAA–PVP complexes, containing different weight fractions of PAA and ternary polymer–metal–polymer complexes, were studied. The activation energy parameters for the thermal degradation were also calculated. The study of the effect of FeCl3, NiCl2, and Ni(NO3)2 on the TGA and DTA curves of the complexes showed that the decompositions are dependent on the concentrations and the nature of the metal ions. The DTA traces of PAA–PVP complex containing FeCl3, NiCl2, and Ni(NO3)2 showed that the treatment of the complex with these metal ions causes considerable changes in the thermal decomposition of PAA–PVP complex. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4049–4057, 2006
Cure kinetics and rheology characterization of soy‐based epoxy resin system
Authors: Liang G. , Chandrashekhara K.
Published: August 2006

A novel soy‐based epoxy resin system was synthesized by the process of transesterification and epoxidation of regular soy bean oil, which has the potential to be widely usable in various composite manufacturing processes. Cure kinetics and rheology are two chemical properties commonly required in process modeling. In this work, the cure kinetics and rheology of the soy‐based resin system were measured by means of differential scanning calorimetry (DSC) and viscometer. DSC was used to measure the heat flow of dynamic and isothermal curing processes. The cure kinetics models of the different formulations were thus developed. A Brookfield viscometer was used to measure the change in viscosity under isothermal conditions. A novel neural network‐based model was developed to improve modeling accuracy. The models developed for cure kinetics and rheology for soy‐based epoxy resin system can be readily applied to composite processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3168–3180, 2006
Crystallization behavior of PVDF in PVDF‐DMP system via thermally induced phase separation
Authors: Gu Minghao , Zhang Jun , Wang Xiaolin , Ma Wenzhong
Published: August 2006

The crystallization behavior of PVDF (poly (vinylidene) fluoride) in PVDF‐dimethylphthalate(DMP) system was investigated in the liquid–liquid (L–L) phase separation region, solid–liquid (S–L) phase separation region and different quenching conditions via thermally induced phase separation (TIPS). Differential scanning calorimetry (DSC) indicated the crystallinity of PVDF in PVDF‐DMP system increased in the early stage of phase separation and polymer‐rich phase crystallized completely in the late stage of phase separation. The scanning electron microscopy (SEM) showed the different quenching temperatures had effects on the spherulite size of polymer rich phase and the ultimate membrane structure in the different phase separation regions. The wide angle X‐ray diffraction (WAXD) was used to quantify the crystal structure of PVDF in PVDF‐DMP system. The α‐phase PVDF was obtained when the system quenched to different temperatures above 40°C, and the area of diffraction peaks changed when quenching temperatures changed. While the β‐phase PVDF was formed when PVDF‐DMP system was quenched form liquid nitrogen and crystallized for 24 h in 25°C water bath. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3714–3719, 2006
Effects of nanoparticle treatment on the crystallization behavior and mechanical properties of polypropylene/calcium carbonate nanocomposites
Authors: Wan Weitao , Yu Demei , Xie Yunchuan , Guo Xiusheng , Zhou Wandi , Cao Jiping
Published: August 2006

Effects of nanoparticle surface treatment on the crystallization behavior and mechanical properties of polypropylene (PP)/CaCO3 nanocomposites were investigated by using differential scanning calorimetry (DSC), polarized optical microscope (POM), X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results demonstrated that the interfacial interaction formed between PP and nanoparticles significantly influenced the thermal and mechanical properties of nanocomposites. It was found that CaCO3 nanoparticles modified by a single aluminate coupling agent (CA‐1) could improve the onset crystallization temperature more effectively than that modified by a compound surface‐treating agent (CA‐2) could. However, there is no significant difference in total rate of crystallization for the two PP/CaCO3 nanocomposites (PPC‐1 and PPC‐2), which contained CA‐1 and CA‐2, respectively. In contrast, CA‐2 modified nanoparticles could cause smaller spherulites and induce much more β‐phase crystal in nanocomposites than that of CA‐1 modified nanoparticles. This may be explained by a synergistic effect of aluminate coupling agent and stearic acid in CA‐2, which also resulted in an improved toughness for PPC‐2. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 3480–3488, 2006
Use of radiation grafting of polyethylene‐coated polypropylene nonwoven fabric by acrylamide for the removal of heavy metal ions from wastewaters
Authors: Ibrahim Sayeda M. , El‐Salmawi Kariman M. , El‐Naggar A. A.
Published: August 2006

The graft copolymerization of acrylamide (AAm) monomer onto polyethylene‐coated polypropylene (PE‐co‐PP) nonwoven fabric was carried out by the mutual irradiation method. The general peculiarities of the grafting have been studied by gravimetric, scanning electron microscope (SEM), mechanical properties, and Fourier transform infrared (FTIR) methods. The influence of absorbed dose, dose rate, as well as the monomer concentration on the degree of grafting has been determined. Metal ions uptake of Cu2+, Co2+, Ni2+ by the grafted fabrics was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3240–3245, 2006
Kinetics of the effect of ageing on tensile properties of a natural rubber compound
Authors: Ngolemasango E. F. , Bennett M. , Clarke Jane
Published: August 2006

Natural rubber (NR) undergoes chemical changes on heat and air ageing. These changes affect its physical properties and as such, affect the service life of the rubber compound. In this study, a vulcanized NR compound of a typical engine mount composition was subjected to thermo‐oxidative ageing at temperatures from 70 to 110°C, to assess the effect on the tensile properties. The kinetics of degradation of the rubber compound, in terms of changes in these properties, was investigated. A fractional rate law was used to describe the kinetics of ageing in terms of its effect on modulus. Rates of ageing, in terms of effect on modulus, passed through a minimum at about 80°C, indicating the danger of trying to extrapolate in‐service ageing behavior from high temperature ageing data. The activation energy of ageing in terms of its effect on modulus, determined for temperatures of 90–110°C, was 151 kJ mol−1. A second order rate law was used to describe the kinetics of ageing in terms of its effect on tensile strength and elongation at break, with activation energies of 88.32 and 74.3 kJ mol−1, respectively. According to Ahagon's (Ahagon et al., Rubber Chem Technol, 1990, 63, 683) classification of ageing mechanisms, Type I and Type III ageing mechanisms were predominant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3732–3740, 2006
Structure and mechanical properties of poly(trimethylene terephthalate)/poly(hydroxy ether of bisphenol A) blends
Authors: González I. , Eguiazábal J. I. , Nazábal J.
Published: August 2006

Compatible poly(trimethylene terephthalate) (PTT)/poly(hydroxy ether of bisphenol A) (Phenoxy) blends were obtained by direct injection molding throughout the composition range. Two amorphous phases with minor amounts of the other component were found in the blends. Reactions occurred in PTT‐rich blends. By comparing the miscibility level of these blends with that of other blends based on polyalkylene terephthalates, it is proposed that a miscibility limit delimited by a 3/1 methylene–carbonyl ratio in the polyalkylene terephthalate exits in these blends. The synergism in the Young's modulus of the blends is discussed as a consequence of the changes in the crystallinity of PTT, the specific volume and the orientation produced by blending. Ductility is approximately proportional to blend composition, indicating compatibility, and is attributed to the combined effects of a small particle size and a good adhesion level, the latter being a consequence of the partially miscible nature of the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3246–3254, 2006
Synthesis and characterization of water soluble poly(N‐acetyl)iminoethylene and poly(ethyleneimine) by ion‐exchanged clay montmorillonite
Authors: Hachemaoui Aïcha , Yahiaoui Ahmed , Belbachir Mohammed
Published: August 2006

The cationic polymerization of 2‐méthyl‐2‐oxazoline was carried out at 0°C in acetonitrile using an acid‐exchanged montmorillonite as acid solid ecocatalyst (Maghnite‐H+). The effect of the amount of catalyst, solvent, and times of polymerization on yield and viscosity of polymer was studied. A typical reaction product (PMOX) was analyzed by infrared and nuclear magnetic resonance spectroscopy as well as by gel‐permeation chromatography and MALDI‐TOF MS. The polymers presented similar spectrometric results and narrow molecular weight distribution. The poly(N‐acetyl)iminoethylene was hydrolyzed in acid medium obtaining a linear poly(ethyleneimine). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3741–3750, 2006
Effect of compatibilizer and silane coupling agent on physical properties of ethylene vinyl acetate copolymer/ethylene‐1‐butene copolymer/clay nanocomposite foams
Authors: Kim Dong‐Woo , Park Keun‐Wan , Chowdhury Subhendu Ray , Kim Gue‐Hyun
Published: August 2006

In this study an attempt was made to obtain lower density of ethylene‐vinyl acetate copolymer (EVA)/ethylene‐1‐butene copolymer (EtBC) foams without sacrificing mechanical properties. For this purpose EVA/EtBC/clay nanocomposite foams were prepared. To investigate the effect of compatibilizer and silane coupling agent on the physical properties of the EVA/EtBC/clay foams, maleic anhydride‐grafted EtBC (EtBC‐g‐MAH) and the most commonly used silane coupling agent in rubbers, bis(3‐triethoxysilylpropyl) tetrasulfide (Si‐69) were used in the preparation of EVA/EtBC/clay nanocomposite foams. The formation of EVA/EtBC/clay nanocomposite foams was supported by X‐ray diffraction results. And, using a compatibilzer and silane coupling agent, lower density of EVA/EtBC/clay nanocomposite foams were obtained without sacrificing mechanical properties except compression set. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3259–3265, 2006
Intercalation of epoxy resin in organically modified montmorillonite
Authors: Hutchinson John M. , Montserrat Salvador , Román Frida , Cortés Pilar , Campos Lourdes
Published: August 2006

Various methods of preparation of epoxy resin/clay mixtures, before the addition of the crosslinking agent and curing to form epoxy‐based polymer layered silicate (PLS) nanocomposites, have been investigated to determine their effect on the nanostructure. Organically modified montmorillonite clay was used, and the mixtures were prepared by both simple mixing and solvent‐based methods. X‐ray diffraction shows that intercalation of the resin into the clay galleries occurs for all clay loadings up to 25 wt % and for both preparation methods, but the dispersion of the clay in the resin, observed by optical microscopy, is significantly better for the solvent preparation method. Differential scanning calorimetry (DSC) shows that the intercalated resin has the same molecular mobility as the extra‐gallery resin, but suggests that the intercalated resin does not penetrate completely into the galleries. Prolonged storage of the resin/clay mixtures at room temperature leads to changes in the DSC response, as well as in the response to thermogravimetry, which are interpreted as resulting from homopolymerization of the epoxy resin, catalyzed by the onium ion in the modified clay. This confirms and explains the earlier observation of Benson Tolle and Anderson (J Appl Polym Sci 2004, 91, 89) that “conditioning” of the resin/clay mixtures at ambient temperature has a significant effect when the crosslinking agent is subsequently added, and indicates that the preparation method has important consequences for the nanostructure development in the PLS nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3751–3763, 2006
Structural modification and characterization of lignosulfonate by a reaction in an alkaline medium for its incorporation into phenolic resins
Authors: El Mansouri Nour‐Eddine , Farriol Xavier , Salvadó Joan
Published: August 2006

We studied the enhancement of lignin reactivity in an alkaline medium, using sodium hydroxide in a microreactor set. The chemical composition and structural characterization of the reacted lignosulfonate in terms of the phenolic hydroxyl groups, aromatic protons, weight‐average molecular weight, number‐average molecular weight, and lignosulfonate content of all reacted lignins were determined. The techniques that we used were ultraviolet spectroscopy, proton nuclear magnetic resonance spectroscopy, and aqueous gel permeation chromatography. Using response surface methodology, we studied how the temperature and reaction time affected the lignin properties. The reaction conditions were temperatures between 116 and 180°C and reaction times between 18 and 103 min. Modeled response surfaces showed that the two factors affected the lignin properties within the studied ranges. The phenolic hydroxyl groups, aro matic protons, and lignosulfonate content increased when the severity of the treatment increased. The weight‐average molecular weight, number‐average molecular weight, and solid yield (%) decreased when the severity of the treatment increased. The reactivity of the modified lignins was studied with a formaldehyde reactivity test: more severe conditions produced greater improvements in the formaldehyde reactivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3286–3292, 2006
Electrical conductivity modeling of carbon‐filled liquid‐crystalline polymer composites
Authors: Keith Jason M. , King Julia A. , Barton Rodwick L.
Published: August 2006

Electrically conductive resins are needed for bipolar plates used in fuel cells. Currently, the materials for these bipolar plates often contain a single type of graphite powder in a thermosetting resin. In this study, various amounts of two different types of carbon, carbon black and synthetic graphite, were added to a thermoplastic matrix. The resulting single‐filler composites were tested for electrical conductivity, and electrical conductivity models were developed. Two different models, the Mamunya and additive electrical conductivity models, were used for both material systems. It was determined how to modify these models to reduce the number of adjustable parameters. The models agreed very well with experimental data covering a large range of filler volume fractions (from 0 to 12 vol % for the carbon black filled composites and from 0 to 65 vol % for the synthetic graphite filled composites) and electrical conductivities (from 4.6 × 10−17 S/cm for the pure polymer to 0.5 S/cm for the carbon black filled composites and to 12 S/cm for the synthetic graphite filled composites). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3293–3300, 2006
Environmental effects on poly‐p‐phenylenebenzobisoxazole fibers. I. Mechanisms of degradation
Authors: Walsh Peter J. , Hu Xianbo , Cunniff Philip , Lesser Alan J.
Published: August 2006

This is the first of a two‐part series investigating the degradation mechanisms of PBO fiber and approaches to alleviating degradation and improving fiber properties. Poly‐p‐phenylenebenzobisoxazole (PBO) fiber is a high strength and modulus fiber with remarkable thermal stability. Recent in‐service failures of this fiber have revealed that the fiber degrades rapidly in relatively mild environmental conditions of moisture and heat. In this work the mechanisms of degradation due to moisture, the presence of acid, and the effect of radiation from the UV–vis spectrum are investigated. It is found that exposure to moisture results in the loosening of the fiber morphology leading to an increase in the number and size of defects. The presence of aqueous acid causes both loosening of the fiber structure and hydrolysis of the oxazole ring structure. The effect of UV–vis radiation is primarily hydrolysis of the material near the fiber surface with attendant formation of amide linkages. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3517–3525, 2006
Synthesis, characterization, and antimicrobial properties of oligo‐4‐[(pyridine‐3‐yl‐methylene) amino] phenol
Authors: Kaya İsmet , Bilici Ali , Saçak Mehmet
Published: August 2006

The oxidative polycondensation reaction conditions of 4‐[(pyridine‐3‐yl‐methylene) amino]phenol (4‐PMAP) were studied using H2O2, atmospheric O2, and NaOCl oxidants in an aqueous alkaline medium between 30°C and 90°C. Synthesized oligo‐4‐[(pyridine‐3‐yl‐methylene) amino] phenol (O‐4‐PMAP) was characterized by 1H‐, 13C NMR, FTIR, UV–vis, size exclusion chromatography (SEC), and elemental analysis techniques. The yield of O‐4‐PMAP was found to be 32% (for H2O2 oxidant), 68% (for atmospheric O2 oxidant), and 82% (for NaOCl oxidant). According to the SEC analysis, the number–average molecular weight, weight–average molecular weight, and polydispersity index values of O‐4‐PMAP was found to be 5767, 6646 g mol−1, and 1.152, respectively, using H2O2, and 4540, 5139 g mol−1, and 1.132, respectively, using atmospheric O2, and 9037, 9235 g mol−1, and 1.022, using NaOCl, respectively. According to TG and DSC analyses, O‐4‐PMAP was more stable than 4‐PMAP against thermal decomposition. The weight loss of O‐4‐PMAP was found to be 94.80% at 1000°C. Also, antimicrobial activities of the oligomer were tested against B. cereus, L. monocytogenes, B. megaterium, B. subtilis, E. coli, Str. thermophilus, M. smegmatis, B. brevis, E. aeroginesa, P. vulgaris, M. luteus, S. aureus, and B. jeoreseens. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3327–3333, 2006
Corn oil‐based composites reinforced with continuous glass fibers: Fabrication and properties
Authors: Lu Yongshang , Larock Richard C.
Published: August 2006

Novel thermosetting composites have been successfully developed using glass fibers to reinforce regular corn oil (COR) and conjugated corn oil (CCOR) resins prepared by cationic copolymerization with styrene (ST) and divinylbenzene (DVB). The dependence of morphology and physical properties of the composites on the contents of glass fibers and DVB was determined by scanning electron microscopy, dynamic mechanical analysis, thermogravimetric analysis and tensile testing. The glass fiber loading and polymer matrix composition play an important role in improving the mechanical properties and thermal stability of the resulting composites. As the glass fiber content increases from 0 to 45 wt %, the COR‐based composites show an increase in Young's modulus from 4.1 to 874 MPa and tensile strength from 1.7 to 8.4 MPa. Furthermore, the composites exhibit good damping properties and are suitable for applications where reduction of both unwanted noise and vibration is important. Compared with the composites from COR, the CCOR‐based composites exhibit slightly higher thermal stabilities and mechanical properties, due to higher reactivity of CCOR with comonomers. Increasing the DVB content improves the crosslink density of the polymer matrix, leading to a significant improvement in the thermal stabilities and mechanical properties of the resulting composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3345–3353, 2006