bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of mid‐ and near‐infrared techniques as tools for characterizing blends of copolymers of styrene–butadiene and acrylonitrile–butadiene
Authors: Shield Stephanie R. , Ghebremeskel Ghebrehiwet N. 
Published: March 2003

AbstractThere is increased technological interest in using blends of various dissimilar elastomers in applications for which service, material availability, or cost of a single elastomer do not provide the necessary processing, vulcanizate, or economic properties. The properties of these polyblends are sensitive to small variations in the amounts of the individual polymers used. Accurately estimating the elastomer composition of blends is of vital importance to the elastomer industry. This study illustrates the feasibility of using mid‐infrared (MIR) and near‐infrared (NIR) spectroscopy to estimate the amount of styrene–butadiene and acrylonitrile–butadiene copolymers in blends composed of varying ratios of the two elastomers. Sometimes it is difficult to obtain a film of an elastomer amenable to IR analysis; to address this problem, several techniques were developed in this study [MIR transmission of a film, attenuated total internal reflection (ATR)‐FTIR of a chunk, and NIR using a fiber‐optic probe]. A plot of the absorbance ratio (absorbance of the characteristic peak for styrene–butadiene rubber or acrylonitrile–butadiene rubber/absorbance of the CC stretching vibration of polybutadiene) versus the amount of each elastomer in the blend was used to predict the blend composition. In addition, the blends were also characterized by ATR‐FTIR using a plot of the characteristic peak absorbance versus the polymeric content for a series of standards. A partial least‐squares algorithm was used to develop a calibration curve for the NIR region. Finally, the accuracy of the test methods developed in this work is compared to results obtained by pyrolysis‐GC/MS and thermogravimetric analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88:1653–1658, 2003
Dynamic rheological properties for HDPE/CB composite melts
Authors: Wu Gang , Song Yihu , Zheng Qiang , Du Miao , Zhang Peijun 
Published: March 2003

AbstractA study on the dynamic viscoelastic properties of carbon black (CB)‐filled high‐density polyethylene (HDPE) in the molten state was carried out. When the temperature was above 180°C in an air atmosphere, the storage modulus G′, loss modulus G″, and loss tangent δ showed particular characteristics. In the low‐frequency region, the modulus increased with increase of the testing time while the tan δ obviously decreased. Also, the higher the temperature, the more notable was the change. We can detect these changes from the deviation of G′ (G″) against ω plots from the linearity and the appearance of a characteristic plateau phenomenon. The width and height of the modulus plateau increased with increase of the temperature. When temperature was below 180°C, the testing time and the temperature had no effect on the viscoelastic parameters of HDPE. However, if we used 99% nitrogen gas as the atmosphere, substituting for air, the viscoelastic parameters revealed an undiscernible change, different from that in an air atmosphere. No changes were found under the protection of the antioxidant B215. This phenomenon indicated that HDPE can be oxidized at a temperature higher than 180°C. Nitrogen gas and an antioxidant agent can prevent HDPE from crosslinking. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2160–2167, 2003
Preparation of microcellular poly(ethylene terephthalate) and its properties
Authors: Guan Rong , Wang Biqin , Lu Deping 
Published: March 2003

AbstractEngineering plastics poly(ethylene terephthalate) (PET) is relatively difficult to process microcellularly compared to general thermal plastics because of its low melting viscosity. A new method was developed to microcellularly process PET in this study with a general hydraulic press above PET's crystallization temperature and below its melting temperature within times of a few minutes. A processing window existed in which to prepare microcellular PET under certain foaming time, pressure, temperature, and foaming reagent content scope. The effects of foaming time, temperature, pressure, and foaming reagent content on the thermal, mechanical, and dynamic mechanical thermal properties of microcellular PET foam were investigated. Differential scanning calorimetry (DSC) analysis showed that the transition temperature and crystallinity of microcellular PET had small changes with increasing foaming time. Under some processing conditions used in this study, the tensile strength and breaking extension of microcellular PET foam were both increased at the same time, indicating strengthening and toughening effects. The variation of storage modulus, loss modulus, and tan δ under dynamic mechanical thermal analysis was in accord with DSC analysis and mechanical measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1956–1962, 2003
New polyimide–silica organic–inorganic hybrids
Authors: Huang Yi , Gu Yi 
Published: March 2003

AbstractA series of polyimide–silica hybrid films with silica contents up to 30 wt % were successfully prepared by the sol‐gel reaction of tetraethoxysiliane in the presence of poly(amic acid) containing pendent hydroxyl groups. The films were yellow and transparent when the silica content was less than 11 wt %. The chemical structure of the films was characterized by Fourier transform infrared spectroscopy, and the morphology of the films was investigated by scanning electronic microscopy and atomic force microscopy. Thermogravimetric analysis, differential scanning calorimetry, and stress–strain tests were used to measure the performance of the films. The results indicate that the glass‐transition temperatures and decomposition temperatures of the hybrid films increased with increasing silica content, whereas the tensile strength had a maximum with the variety of silica contents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2210–2214, 2003
Chemical modification process of an atactic polypropylene by p‐phenylen‐bismaleamic acid in the melt
Authors: García‐Martínez J. M. , Cofrades A. G. , Areso S. , Collar E. P. 
Published: March 2003

AbstractThis study was concerned with the chemical modification process of an atactic polypropylene from polymerization reactor byproducts with p‐phenylen‐bismaleamic acid to obtain a new grafted polymer supposed to play an important role as an interfacial agent in heterogeneous systems based on polymers. The grafting process was undertaken with the aid of the Box–Wilson experimental worksheet, with two independent variables (or controlled factors), the level of polar monomer to be grafted in the polymer and the concentration of the initiator, and with the agitation rate kept constant. Each item of the experimental design was performed at four different reaction times. This latter let us ascertain the transient nature of the process and the existence of a critical point in the concentration of both reactants conducting the system to the maximum grafting yield. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2202–2209, 2003
Synthesis and characterization of copolyimides with high solubility
Authors: Leu Tsu‐Shang , Wang Chun‐Shan 
Published: March 2003

AbstractA series of copolyimides were prepared from various diamines (polysiloxane and isophorone units) with aromatic tetracarboxylic dianhydrides via a two‐step (thermal imidization) method. The monomers and polymers were produced in high yields, and the copolyimides containing SiOC bonds and asymmetric meta catenation in the polymer backbone exhibited good solubility. The glass‐transition temperatures (Tg's) of all the copolyimides were found to be 201–262 and 215–258°C by differential scanning calorimetry (DSC) and dynamic mechanical analysis, respectively. Thermogravimetric analyses indicated that the polymers were fairly stable up to 502–578°C (10 wt % loss in N2) and 490–574°C (10 wt % loss in air). The char yields at 800°C in N2 and air atmospheres were 26–59 and 20–53%, respectively. The copolymerization results, determined with 1H‐NMR and DSC, indicated a random copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1963–1970, 2003
Toward an understanding of the role of water‐soluble oligomers in the emulsion polymerization of styrene–butadiene–acrylic acid. Function of carboxylic acid
Authors: Yuan Xue‐Yi , Dimonie Victoria L. , Sudol E. David , El‐Aasser Mohamed S. 
Published: March 2003

AbstractIn a further effort to understand the role of water‐soluble oligomers formed during the emulsion terpolymerization of styrene/butadiene/acrylic acid (St/Bu/AA), the reaction temperature, initiator concentration, and ionic strength were varied and the kinetics and resulting oligomers were characterized as a function of reaction time. The rate of polymerization (Rp) was observed to increase with increasing temperature and initiator concentration; the reasons for this vary. The increase in Rp with increasing initiator concentration is mainly attributed to the increase in the number of oligomeric radicals formed and, subsequently, the resulting number of particles (Np). Increasing the temperature increases the water solubility of both monomers and polymers, which results in changes in the composition and molecular weight of the oligomeric radicals being formed. The primary reaction locus in the St/Bu/AA system was noted to shift to the aqueous phase after most of the styrene and butadiene had reacted, based on the unreacted AA profile. The role of water‐soluble oligomers (both oligomeric radicals and dead oligomers) during the emulsion polymerization of St/Bu with acrylic acid can be described by three periods: (1) particle generation and (2) before and (3) after the critical surface saturation concentration (CSSC) is reached during the particle growth period. The incorporation of AA monomer into the oligomer chains after the CSSC may cause destabilization of the latexes through a bridging flocculation mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1988–1999, 2003
Polymer blends of poly(trimethylene terephthalate) and polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers
Authors: Huang Jieh‐Ming 
Published: March 2003

AbstractThe compatibilizing effects of styrene‐glycidyl methacrylate (SG) copolymers with various glycidyl methyacrylate (GMA) contents on immiscible blends of poly(trimethylene terephthalate) (PTT) and polystyrene (PS) were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and 13C‐solid‐state nuclear magnetic resonance (NMR) spectroscopy. The epoxy functional groups in the SG copolymer were able to react with the PTT end groups (COOH or OH) to form SG‐g‐PTT copolymers during melt processing. These in situ–formed graft copolymers tended to reside along the interface to reduce the interfacial tension and to increase the interfacial adhesion. The compatibilized PTT/PS blend possessed a smaller phase domain, higher viscosity, and better tensile properties than did the corresponding uncompatibilized blend. For all compositions, about 5% GMA in SG copolymer was found to be the optimum content to produce the best compatibilization of the blend. This study demonstrated that SG copolymers can be used efficiently in compatibilizing polymer blends of PTT and PS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2247–2252, 2003
Technique development and measurement of Poisson's ratio, lateral creep behavior, and thermal and hygroscopic expansion of individual layers in magnetic tapes
Authors: Ma Tiejun , Bhushan Bharat 
Published: March 2003

AbstractAn experimental technique was developed to measure the Poisson's ratio (lateral contraction over longitudinal elongation), lateral creep, and both thermal and hygroscopic expansion of thin polymeric films. A so‐called profile‐matching method was developed to measure the lateral and longitudinal deformation with the help of a laser scan micrometer. A thermomechanical analyzer was used to measure the coefficient of thermal expansion (CTE). The laser scan technique was also used to measure the coefficient of hygroscopic expansion (CHE). The measurements were performed on magnetic tapes, substrates, and tapes with front coat or back coat, or with both coats stripped. A model based on the rule of mixtures was developed to determine the Poisson's ratio, lateral and longitudinal deformation behavior, and thermal expansion of the front coat and back coat. To investigate the mechanical degradation of the substrates during tape manufacturing, the data for substrate with the front and back coats removed from the tape, were compared with the data for the never‐coated virgin film. The relationship between the molecular structure and the degradation mechanism of the substrates is discussed. The magnetic tapes used in this research include two metal particle (MP) tapes and two metal evaporated (ME) tapes that use polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates. Longitudinal and lateral deformation tests were performed at 25 ± 0.5°C and 50 ± 2%RH, and thermal expansion was measured from 15 to 70°C. The CHE was measured at 25 ± 0.5°C and 15–80%RH. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2082–2096, 2003
Coral communities of Biscayne Bay, Florida and adjacent offshore areas: diversity, abundance, distribution, and environmental correlates
Authors: Lirman Diego , Orlando Beth , Maciá Silvia , Manzello Derek , Kaufman Louis , Biber Patrick , Jones Tahzay 
Published: March 2003

Abstract
Hardbottom habitats of Biscayne Bay, a shallow lagoon adjacent to the city of Miami, Florida, USA, contain a limited number of coral species that represent a small subset of the species found at nearby offshore hardbottom and reef habitats of the Florida Reef Tract. Although the physical characteristics of this basin make it a marginal environment for coral growth, the presence of dense populations of Siderastrea radians and Porites furcata indicate that these, as well as other corals that are found at lower densities, are able to tolerate extreme and fluctuating conditions. Three factors, temperature, sedimentation, and salinity, appear to limit coral abundance, diversity, and distribution within Biscayne Bay.
Temperatures exhibit high frequencies of extreme high and low values known to cause coral stress and mortality elsewhere. Similarly, sedimentation rates are very high and sediment resuspension caused by currents, storms and boating activities commonly bury corals under sediment layers. Sediment burial was shown experimentally to influence growth and mortality of S. radians.
The salinity of Biscayne Bay is influenced by freshwater inputs from canal, sheetflow and groundwater sources that create a near‐shore environment with low mean salinity and high salinity fluctuation. Coral communities along this western margin have the lowest coral density and species richness. Chronic exposure to low salinity was shown experimentally to cause a decrease in the growth of S. radians.
The location of Biscayne Bay, downstream of a large restoration effort planned for the Everglades watershed, highlights the need to understand the relationship between the physical environment and the health of benthic communities. The data presented here provide the type of scientific information needed so that management decisions can take into account the potential impacts of human activities on the health of coral populations that are already near their tolerance limits for temperature, salinity, and sedimentation.
Copyright © 2003 John Wiley & Sons, Ltd.
Trabecular rod thickness by direct measurement from 3D SEM anaglyphs
Authors: Vijayapalan Vinotha , Sutton‐Smith Peter , Parkinson Ian H. , Martin R. Bruce , Fazzalari Nicola L. 
Published: March 2003

AbstractThis study presents a methodology for measuring the thickness of trabecular rods directly from anaglyphs. Macerated sagittal slices of T12 vertebral bodies from 15 subjects were examined by scanning electron microscopy (SEM). Two digital images (the second image tilted 5°) were recorded, and a 3D anaglyph was created. The thickness of the trabecular rods (Tb.Th(rods)), and the anatomical orientation of the trabecular rods were measured using an image analyser. Conventional 2D histomorphometry was performed on adjacent bone slices. A total of 1,559 rod measurements were made from the 15 vertebral bone slices, with a mean Tb.Th(rods) of 123 ± 36μm. The rod thickness in males (128 ± 34 μm) was significantly greater than that in females (119 ± 37 μm, P < 0.001). Tb.Th(rods) changed significantly with age in the males: the thicker rods in the younger men reduced with age to a thickness similar to that in women. 3D measurements were significantly larger than the 2D estimates, and there was no correlation between the two methods of measurement. An inverse correlation was found between the number of rods and the bone volume fraction (BV/TV), indicating that decreased BV/TV is associated with an increased number of rods. The vertical rods (132 ± 39 μm) were significantly thicker than the horizontal rods (116 ± 33 μm, P < 0.001). The determination of rod numbers, and their orientation and individual thicknesses enables a greater understanding of cancellous bone architecture in both individuals and populations, and will allow more reliable finite element modelling. Direct measurements from 3D anaglyphs of intact specimens provide new data that show previously unrecognised age‐ and sex‐related changes. Anat Rec Part A 271A:286–290, 2003. © 2003 Wiley‐Liss, Inc.
Connexin43 is expressed in mouse fetal ovary
Authors: Pérez‐Armendariz E. Martha , Sáez Juan C. , Bravo‐Moreno J. Francisco , López‐Olmos Victoria , Enders George C. , Villalpando Irma 
Published: March 2003

AbstractDevelopmental studies have shown that connexin43 (Cx43) is expressed in the ovary from the first day of life and throughout the rest of postnatal development. In both mouse embryonic ovaries and testes, target‐directed deletion of Cx43 gene induces a significant decrease in germinal cells, but the exact mechanism determining this reduction remains unknown. Moreover, recently we found that Cx43 is abundantly expressed in mouse testes from the earliest stages of its fetal development. In the present work we investigate whether Cx43 transcript and protein are expressed in mouse embryonic ovaries. Total RNA was analyzed with specific Cx43 oligonucleotides in RT‐PCR studies. A Cx43 PCR product was detected in ovaries at 16.5 and 18.5 days postcoitum (dpc). Bands of 43‐45 kDa, characteristic of Cx43, were detected in immunoblots of total homogenates of ovaries at 14.5 and 18.5 dpc. Cell type‐specific expression of Cx43 was investigated using double‐labeled sections incubated with specific antibodies against Cx43 and the enzyme 3β‐hydroxysteroid dehydrogenase (3βHSD) or a germ cell nuclear antigen (GCNA1), which are cell markers of steroidogenic and germinal cells, respectively. At 18.5 dpc, Cx43 was found in conglomerates of 3βHSD‐positive cells. Cx43 was also localized at homocellular junctions between parenchyma pregranulosa cells, and at heterocellular junctions between pregranulosa and germinal cells. At these two latter localizations, Cx43 was traced back to 12.5 dpc. In conclusion, this study demonstrates for the first time that from the earliest stages of embryonic ovary development, Cx43 is expressed in principal cell types involved in control of female fertility. These data suggest that the gap junctions formed with Cx43 between somatic and germinal cells may be necessary for prenatal expansion of germinal cells at initial stages of fetal gonadal development. Anat Rec Part A 271A:360–367, 2003. © 2003 Wiley‐Liss, Inc.
Computerized measurement of magnetic resonance imaging erosion volumes in patients with rheumatoid arthritis: A comparison with existing magnetic resonance imaging scoring systems and standard clinical outcome measures
Authors: Bird Paul , Lassere Marissa , Shnier Ron , Edmonds John 
Published: March 2003

AbstractObjectiveOne of the major aims of therapy in rheumatoid arthritis (RA) is to prevent erosive disease and subsequent disability. One of the important goals of therapy assessment must therefore be the accurate measurement of damage progression. We undertook this study to assess the feasibility, reliability, and validity of measuring magnetic resonance imaging (MRI) erosion volumes and synovial volumes in the wrists of RA patients with the use of a semiautomated computerized method.MethodsTwelve subjects with seropositive RA were chosen to reflect a spectrum of RA severity as determined by the clinical Joint Alignment and Motion (JAM) Scale. MRI of the dominant wrist was performed at the same time of day at baseline and at 48 hours. Images were transferred to a workstation. Erosion volumes and synovial volumes were measured on the coronal images using OSIRIS imaging software. All images were reread in random order at 72 hours by 1 observer. The results were compared with erosion scores and global synovitis scores obtained by the same observer using the Outcome Measures in Rheumatology Clinical Trials MRI RA scoring system. Radiographs were performed at baseline and were read on 2 occasions by 1 observer using the Scott modification of the Larsen method.ResultsTotal erosion volume per subject ranged from 0 cm3 to 4.7 cm3. The total synovial membrane volume per subject ranged from 0.1 mm3 to 12.1 cm3. Intraclass correlation coefficients for erosion volumes and synovial volumes demonstrated excellent intraobserver reliability and interoccasion reliability. There was a strong positive correlation between the total erosion volume and the total erosion score. The correlation between the synovial volumes and synovitis score was less favorable (r = 0.53–0.86). Positive correlations were demonstrated between the erosion volumes, the JAM score, and the modified Larsen scores. No significant correlation was demonstrated between the erythrocyte sedimentation rate, C‐reactive protein level, swollen joint count, tender joint count, or the Disease Activity Score in 28 swollen and 28 tender joints and the synovial volumes or synovitis scores.ConclusionThis study is the first to demonstrate the feasibility, reliability, and validity of computerized MRI erosion volume measurements in the wrists of RA patients. The method will require further evaluation in terms of interobserver reliability, with examination of responsiveness in longitudinal studies, but the method demonstrates excellent interoccasion and intraobserver reliability and compares favorably with existing RA clinical outcome measures. Synovial volume measurements demonstrated good intraobserver reliability and appeared to be more responsive to synovial change over a 48‐hour period in this group of patients.