bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue contributions to sex and race: Differences in tooth crown size of deciduous molars
Authors: Harris Edward F. , Hicks Joseph D. , Barcroft Betsy D. 
Published: August 2002

AbstractThis study describes size of constituent deciduous tooth crown components (enamel, dentine, and pulp) to address the manner in which males characteristically have larger teeth than females, and the observation that teeth of American blacks are larger than those of American whites. Measurements were collected (n = 333 individuals) from bitewing radiographs using computer‐aided image analysis. Tissue thicknesses (enamel, dentine, pulp) were measured at the crown's mesial and distal heights of contour. Deciduous mesiodistal molar crown length is composed of about 1/7 enamel, 1/3 dentine, and 1/2 pulp. Details differ by tooth type, but males typically have significantly larger dentine and pulp dimensions than females; there is no sexual dimorphism in marginal enamel thickness. Males scale isometrically with females for all variables tested here. Blacks significantly exceed whites in size of all tissues, but tissue types scale isometrically with blacks and whites with one exception: enamel thickness is disproportionately thick in blacks. While the absolute difference is small (5.56 mm of enamel in blacks summed over all four deciduous molar tooth types vs. 5.04 mm in whites), the statistical difference is considerable (P < 0.001). Aside from enamel, crown size in blacks is increased proportionately vis‐à‐vis whites. Principal components analysis confirmed these univariate relationships and emphasizes the statistical independence of crown component thicknesses, which is in keeping with the sequential growth and separate embryonic origins of the tissues contributing to a tooth crown. Results direct attention to the rates of enamel and dentine deposition (of which little is known), since the literature suggests that blacks (with larger crowns and thicker enamel) spend less time in tooth formation than whites. Am J Phys Anthropol 115:223–237, 2001. © 2001 Wiley‐Liss, Inc.
Phase equilibria of precursor‐derived Si–(B–)C–N ceramics
Authors: Seifert Hans Jürgen , Peng Jianqiang , Golczewski Jerzy , Aldinger Fritz 
Published: August 2002

AbstractPhase equilibria and phase reactions of precursor‐derived ceramics of the Si–C–N and the Si–B–C–N systems at temperatures higher than 1700 K are described. CALPHAD (CALculation of PHAse Diagrams) results confirm quantitatively the data from thermogravimetry and differential thermal analysis of precursor‐derived Si–C–N ceramics. A model for explanation of the thermal stability of specific Si–B–C–N precursor ceramics was developed. Phase reactions of polymeric precursors of the Si–C–N–H system were calculated and compared with analyses concerning the composition of the solid ceramic and gaseous products from thermolysis at a temperature of 1323 K. The results­show that a semi‐quantitative description of­the thermolysis process is possible. Copyright­© 2001 John Wiley & Sons, Ltd.
Superstructure and mechanical properties of poly(ethylene terephthalate) fibers zone‐drawn under critical necking tension
Authors: Suzuki Akihiro , Kawada Takashi 
Published: August 2002

AbstractThe superstructure and mechanical properties of poly(ethylene terephthalate) fibers zone‐drawn under a critical necking tension (σc) were studied. σc was defined as the minimum tension needed to generate a neck at a given drawing temperature (Td) and was measured over a temperature range of 70–120°C. The σc value increased rapidly with decreasing Td in the temperature range below 85°C, but the temperature dependence of σc was small above 85°C. The neck profile relied on Td, becoming more shapely with decreasing Td. A neck with a gradual decrease in diameter was observed in the fibers drawn at 100°C and above. The draw ratio increased significantly with increasing Td above 90°C, but birefringence decreased. Density decreased gradually with increasing Td, and fiber drawn at 120°C had a density of 1.347 g/cc. Wide‐angle X‐ray diffraction photographs of the fibers drawn at 100°C and below showed reflections due to crystallites, but a photograph of the fiber obtained at 120°C showed a ring‐like amorphous halo. The storage modulus (E′) at 25°C increased progressively with decreasing Td, and the fiber drawn at 70°C had the maximum E′ value among the fibers drawn at a series of Td's. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 179–185, 2002
Effects of a Nd—Fe—B magnetic filler on the crystallization of poly(phenylene sulfide)
Authors: Guschl Peter C. , Kim Hyun Seog , Otaigbe Joshua U. 
Published: August 2002

AbstractThe crystallization of poly(phenylene sulfide) (PPS) in a polymer–magnetic Nd—Fe—B powder suspension was studied. Isothermal crystallization behavior was analyzed by way of differential scanning calorimetry, and the kinetics were described via the Avrami equation. The Avrami parameters and the crystallization times were strongly affected by both the particle size and the presence of a coupling agent coated on the filler particles. The small Nd—Fe—B particles exhibited long induction and half‐times, whereas the large particles tended to have short crystallization times. Particles ranging from 38 to 150 μ appeared to have similar crystallization times and to have no significant change in the value of Avrami index with melt crystallization temperature. As a result of these analyses, the dynamic mechanical properties were determined to correlate the fundamental polymer crystallization characteristics and the physical properties of the PPS binder. The enhancement of the wetting of the filler to the binder was promoted through the coupling agent, as confirmed by dynamic mechanical testing performed on the samples. The storage modulus typically decreased because of the presence of the uncoated small particles. Conversely, the loss modulus was enhanced because of the presence of the coated small particles in the PPS binder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1091–1102, 2002
Blends of high‐density polyethylene with solid silicone additive
Authors: Muñoz P Ma. Patricia , Werlang Moisés M. , Yoshida I. Valéria P. , Mauler Raquel S. 
Published: August 2002

AbstractSilicone masterbatch (SMB) is a pelletized formulation containing 50% of an ultrahigh molecular‐weight polydimethylsiloxane dispersed in polyethylene. This SMB is designed to be used as an additive in polyethylene‐compatible systems to impart benefits such as processing improvement and modification of surface characteristics. In this work, binary blends of high‐density polyethylene (HDPE) and SMB were prepared by melt‐mixing technique to study the influence of this masterbatch on the processing and mechanical properties of HDPE. Ternary blends were also prepared by the addition of silane‐grafted polyethylene (HDPE‐VTES) as compatibilizer. The blends were analyzed by melting flow rate (MFR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile tests. Data of final torque and MFR showed that SMB improved the processability of pure HDPE. DSC results showed differences in crystalline behavior between binary and ternary blends. In the former, the degree of crystallinity increased up to 10 wt % of SMB content; beyond this concentration, it decreased. In ternary blends, a reverse behavior was observed. The morphologic study showed silicone particles uniformly distributed in HDPE matrix. With high SMB concentration, the addition of HDPE‐VTES significantly reduced the size of silicone particles. In the range of SMB composition studied, the mechanical properties of blends lower slightly compared to pure HDPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2347–2354, 2002
Effect of polycarbonate–poly(methyl methacrylate) graft copolymer as a modifier improving the surface hardness of polycarbonate
Authors: Okamoto Masaya 
Published: August 2002

AbstractWith the use of macromonomers that have a dicarboxyl group, polycarbonate–poly(methyl methacrylate) (PC–PMMA) graft copolymers were prepared, and the relationship between the length of PMMA branches and Vickers hardness of the graft copolymer was investigated. With the use of the PC–PMMA graft copolymer as a modifier to improve the surface hardness of PC, Vickers hardness of PC/PC–PMMA blend polymers was examined. PC/PC–PMMA blend polymers are more transparent than PC/PMMA blend polymers. PC/PC–PMMA blend polymers are superior in Vickers hardness to PC/PMMA blend polymers, although the content of PMMA in PC/PC–PMMA blend polymers is smaller than that of PC/PMMA blend polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2774–2779, 2002; DOI 10.1002/app.10252
Enhancement of the luminescent intensity of the novel system containing Eu3+‐β‐diketonate complex doped in the epoxy resin
Authors: Parra Duclerc Fernandes , Brito Hermi Felinto , Matos Jivaldo Do Rosário , Dias Luís Carlos 
Published: August 2002

AbstractPhotoluminescent properties of the europium tris(thenoyltrifluoroacetonate) dihydrate [Eu(TTA)3(H2O)2] incorporated in epoxy resin in the solid state are reported. The polymeric Eu3+ complex and the precursor compound were characterized by elemental analysis, thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy, nuclear magnetic resonance (NMR), and electronic spectroscopy. Due to efficient energy transfer from the polymer to the rare earth ion, the polymer phosphorescence intensity was observed to decrease with an increase of the Eu3+ ion concentration. High values of the Ω2 intensity parameter were obtained, reflecting the hypersensitive character of the 5D0 → 7F2 transition and indicating that the Eu3+ ions are in a highly polarizable chemical environment. This is consistent with systems containing epoxy resin that generally show a higher value for the Ω4 parameter as a consequence of the difference in the basicity of the oxygen donor from the polymer. Lifetime measurement (τ = 0.442 ms) suggests that the Eu3+ luminescence has a higher efficiency than in the case of hydrated compound (τ = 0.260 ms). The emission quantum efficiency shows higher luminescence for the polymer containing 1% of Eu3+‐β‐diketonate complex. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2716–2726, 2002
Wetting properties of polystyrene ionomers treated with plasma source ion implantation
Authors: Kim Joon‐Seop , Hong Min‐Chul , Nah Yeon Hwa , Lee Yeonhee , Han Seunghee , Lim Hyun Eui 
Published: August 2002

AbstractThe wetting properties of polystyrene‐based ionomers treated with plasma source ion implantation (PSII) were investigated by the measurement of water contact angles. When sulfonated ionomers were aged for a few days, the hydrophobic recovery for the ionomers became much slower than that for the nonionic polymers. However, when the samples were aged over 20 days, the water contact angle of the ionomers converged with that of the nonionic polymer. Thus, it was concluded that the ionic interaction between the ionic groups and the presence of ionic groups together resulted in the slow hydrophobic recovery and that the aging effect was significant for the ionomers. For the methacrylate ionomer of low ion content, on the other hand, it was found that the PSII treatment produced only a small change in hydrophobic recovery behavior. Thus, it was suggested that the low ionic content coupled with the small size of the ionic unit might cause changes only of a very insignificant degree in hydrophobic recovery behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2500–2504, 2002
Influence of mechanical stresses on the hydrolytic aging of standard and low styrene unsaturated polyester composites
Authors: Autran M. , Pauliard R. , Gautier L. , Mortaigne B. , Mazeas F. , Davies P. 
Published: August 2002

AbstractStandard and low styrene emission glass fiber‐reinforced unsaturated polyester (FRP) composites were aged by immersion under flexural and tension loads, to evaluate modifications to the mechanical properties as a function of exposure time under stress. The application of a mechanical load does not modify either the quantity of the absorbed water or the diffusion coefficients significantly. For an applied stress of less than 10% of the fiber strength, the influence on aging is small, but for larger applied stresses, the rate of reduction in the mechanical properties is accelerated and, in some cases, premature rupture is observed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2185–2195, 2002
Formation of integrally skinned asymmetric polyetherimide nanofiltration membranes by phase inversion process
Authors: Kim In‐Chul , Yoon Hyung‐Gu , Lee Kew‐Ho 
Published: August 2002

AbstractIntegrally skinned asymmetric polyetherimide (PEI) membranes were prepared by the phase inversion process from casting solution containing dimethylformamide (DMF) as a solvent and 1,4‐dioxane as a cosolvent. Deionized water was used as a coagulation medium in preparing asymmetric membranes. The effect of 1,4‐dioxane was investigated by measuring casting solution properties, permeation properties, and membrane structures. Various effects of polymer concentration, evaporation time, and coagulation bath temperature were also studied. Low miscibility of 1,4‐dioxane with coagulant (water) resulted in reducing membrane pore size. The molecular weight cutoff values of asymmetric membranes could be controlled by changing the amount of 1,4‐dioxane in the casting solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1300–1307, 2002; DOI 10.1002/app.10452
Preparation and adsorption behavior for metal of chitosan crosslinked by dihydroxy azacrown ether
Authors: Yang Zhikuan , Zhuang Li , Tan Gongrong 
Published: August 2002

AbstractA new type of crosslinked chitosan was prepared using Dihydroxy azacrown ether as the crosslinking agent. Its structure was confirmed by elemental analysis, Fourier transform infrared (FTIR) spectra analysis, solid‐state 13C nuclear magnetic resonance (NMR) analysis, and X‐ray diffraction analysis. Its static adsorption properties for Ag+, Cd2+, Hg2+, and Co2+ were studied. The experimental results showed that the Dihydroxy azacrown ether crosslinked chitosan has good adsorption capacities and high selectivity for adsorption of Ag+ with the coexistence of Hg2+ and Co2+. The selectivity coefficients of crosslinked chitosan are k/ = 5.47, k/ = 4.64, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 530–535, 2002
Quantitative analysis of star‐branched polymers by multidetector size‐exclusion chromatography
Authors: Balke Stephen T. , Mourey Thomas H. , Robello Douglas R. , Davis Tammy A. , Kraus Alexander , Skonieczny Krzysztof 
Published: August 2002

AbstractThe object of this study is to develop multidetector size‐exclusion chromatography (SEC) methods to determine the number of arms per molecule across the molecular size distribution of star‐branched polymers. An empirical fit between the intrinsic viscosity molecular contraction factor g‘ and the number of arms f is used as an alternative to converting g‘ values to root mean square radii ratios used by random walk models. The quantitative analysis of star polymer distributions by SEC is then reduced to understanding factors unique to the accurate measurement of g‘ across the molecular size distribution. Two methods of analyzing SEC data are then tested: (1) the “conventional method” utilizing values of weight‐average molecular weight and intrinsic viscosity at each retention volume and (2) the method of component chromatograms. The latter is a new method useful when only a few different types of branching are present. It depends on fitting each detector's chromatograms as the sum of component chromatograms. Plotting the intrinsic viscosity of the branched polymer versus that of the linear polymer at the same molecular weight was useful for diagnosing problems. The conventional method was defeated by axial dispersion in the narrow chromatograms and the homogeneity of branching in the samples. The component chromatogram method avoids the axial dispersion problem but its value depends on how accurately the component peaks reflected the true situation. In this study, the method provided the most reasonable values when component peaks were grouped together. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 552–570, 2002
Synthesis and properties of poly(ester ether) multiblock copolymers/organomontmorillonite hybrid nanocomposite
Authors: Li Chun‐Cheng , Zhang Dong , Li Zhen‐Yi 
Published: August 2002

AbstractIn this article, poly(ester ether) multiblock copolymer/organomontmorillonite hybrid nanocomposites were prepared via an intercalation polymerization process. The resulting hybrid nanocomposites were characterized by X‐ray diffraction, differential scanning calorimeter, and transmission electron microscopy. The results proved that the organomontmorillonite (organo‐MMT) could be exfoliated into ∼ 50‐nm thickness and dispersed in the poly(ester ether) multiblock copolymer (TPEE) matrix during the intercalation polymerization process. TPEE/organo‐MMT nanocomposites showed excellent mechanical properties compared with the unfilled TPEE. When the organo‐MMT content was about 3–5 wt %, MMT could enhance the strength, modulus, and hardness of TPEE without sacrificing its elongation at break. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1716–1720, 2002; DOI 10.1002/app.10552
Mechanical and morphological properties of white rice husk ash filled polypropylene/ethylene‐propylene‐diene terpolymer thermoplastic elastomer composites
Authors: Siriwardena S. , Ismail H. , Ishiaku U. S. , Perera M. C. S. 
Published: August 2002

AbstractThe performance of white rice husk ash (WRHA) as filler for polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) thermoplastic elastomer (TPE) composites was investigated. The composites with different filler loadings were prepared in a Brabender plasticorder internal mixer. Both unvulcanized and dynamically vulcanized composites were prepared. Mixing and vulcanization processes of the composites were monitored through the typical Brabender torque‐time curves. The mechanical properties and morphology of the composites were also studied. The Brabender torque curves revealed that the dynamic vulcanization process employed was successful and incorporation of filler has no adverse effect on the processibility of the composites. Incorporation of WRHA improves the tensile modulus and flexural modulus and lowers tensile strength, elongation at break, tear strength, and toughness of both types of composites. Dynamic vulcanization significantly enhances the mechanical and TPE properties of the composites. Dynamic mechanical analysis (DMA) study revealed the existence of two phases in both types of composites. It further shows that neither dynamic vulcanization nor filler agglomeration has played a prominent role in the compatibility of the composites. Thermogravimetric investigation shows that dynamic vulcanization or WRHA loading has not adversely affected the thermal stability of the composites. The scanning electron micrographs provide evidence for the tendency to form filler agglomerates with increasing filler loading, better filler dispersion of dynamically vulcanized composites over unvulcanized composites, and effective vulcanization of elastomer phase of the composites in the presence of filler. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 438–453, 2002
Three‐dimensional imaging of large compressive deformations in elastomeric foams
Authors: Kinney J. H. , Marshall G. W. , Marshall S. J. , Haupt D. L. 
Published: August 2002

AbstractSpecimens of silica‐reinforced polysiloxane foam pads were three‐dimensionally imaged during axial compressive loading to densification. The foams' behavior was highly nonlinear and showed the three characteristic regions of linear elastic, elastic buckling, and densification. A finite‐element technique, based upon conversion of the image voxels to finite elements, was used to calculate the mechanical properties of the foams. The results were compared with conventional mechanical testing and theory. The finite‐element calculations were in excellent agreement with experimental stress–strain data over the entire range of compressive loading. Theoretical models, on the other hand, overestimated the stiffness of the foam above the elastic buckling stress by not correctly predicting the abruptness of the transition from elastic buckling to densification. Three‐dimensional analysis of the deformed microstructures indicated that there was a critical foam density beyond which the cell morphology suddenly changed from open‐celled to closed‐celled and that this “phase”‐like transition was responsible for the abrupt increase in stiffness near densification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1746–1755, 2001
Synthesis and properties of organosoluble polyimide/clay hybrids
Authors: Hsiao Sheng‐Huei , Liou Guey‐Sheng , Chang Li‐Ming 
Published: August 2002

AbstractA soluble polyimide prepared from 7,7′‐bis(4‐aminophenoxy)‐4,4,4′,4′‐tetramethyl‐2,2′‐spirobichroman and 4,4′‐hexafluoroisopropylidenediphthalic anhydride was mixed with organo‐modified montmorillonite or synthetic mica in N,N‐dimethylacetamide. The content of the clay minerals was 1, 2, and 4 wt %, respectively. Transparent, flexible, and tough films could be cast from the hybrid solutions. The hybrid films were characterized with wide‐angle X‐ray scattering (WAXS), transmission electron microscopy, thermomechanical analysis, thermogravimetric analysis, and differential scanning calorimetry. The WAXS results revealed that the montmorillonite was dispersed more homogeneously than the synthetic mica in the polyimide matrix. In both polyimide/clay hybrids the addition of clay caused thermal expansion coefficients to decrease, and the thermal stability was slightly enhanced. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2067–2072, 2001
Crystallization and nematic–isotropic transition activation energies measured using the Kissinger method
Authors: Sha W. 
Published: August 2002

AbstractThe activation energies for crystallization in poly(3‐hydroxybutyrate) and for nematic–isotropic transition in liquid–crystalline polyesters have been calculated based on data obtained with a dielectric method and differential scanning calorimetry (DSC), respectively. This study explores the feasibility of using a modified Kissinger method to calculate the activation energies of these transitions. It has been found that the activation energy for crystallization in poly(3‐hydroxybutyrate) is 109 kJ/mol. The activation energy for nematic–isotropic transition in the liquid crystals is 487 kJ/mol. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2535–2537, 2001
Polymerization of methyl methacrylate with a thermal iniferter: Diethyl 2,3‐dicyano‐2,3‐di(p‐tolyl)succinate
Authors: Qin Shu‐Hui , Qiu Kun‐Yuan , Westmoreland David G. , Lau Willie , Wu Shuguang , Swift Graham 
Published: August 2002

AbstractA hexa‐substituted ethane type compound, diethyl‐2,3‐dicyano‐2,3‐di(p‐tolyl)succinate (DCDTS), was successfully synthesized and used for initiation of methyl methacrylate (MMA) polymerization. The reaction demonstrated the characteristics of a “living” polymerization; i.e., both the yield and the molecular weight of the resulting polymers increased linearly with increasing reaction time, the molecular‐weight distribution of PMMA obtained was ∼1.60 and almost unaffected by the conversion, and the resultant polymer can be chain extended by adding fresh MMA. End group analysis of the resultant PMMA confirmed that DCDTS behaves as a thermal iniferter for MMA polymerization. A block copolymer was prepared from the resultant PMMA, which contains a hexa‐substituted CC bond functional end group. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2566–2572, 2001