bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and deformation of an elastomeric propylene–ethylene copolymer
Authors: Poon B. C. , Dias P. , Ansems P. , Chum S. P. , Hiltner A. , Baer E. 
Published: January 2007

AbstractThe elastic behavior of a propylene–ethylene copolymer was investigated. An initial “conditioning” tensile extension up to 800% strain resulted in an elastomer with low initial modulus, strong strain hardening, and complete recovery over many cycles. Structural changes that occurred in the low crystallinity propylene–ethylene copolymer during conditioning, and that subsequently imparted elastomeric properties to the conditioned material, were investigated. Thermal analysis, wide and small angle X‐ray diffraction, and atomic force microscopy measurements were performed at various strains during the conditioning process. Conditioning transformed crystalline lamellae into shish‐kebab fibers by melting and recrystallization. The fibers, accounting for only 5% of the bulk, were interconnected by a matrix of entangled, amorphous chains that constituted the remaining 95%. It was proposed that the shish‐kebab fibers acted as a scaffold to anchor the amorphous rubbery network. Entanglements of the amorphous chain segments acted as network junctions and provided the elastic response. The stress–strain response of materials conditioned to 400% strain or more was described by the classical rubber theory with strain hardening. The extracted value of Mc, the molecular weight between network junctions, was intermediate between the entanglement molecular weights of polypropylene and polyethylene. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 489–499, 2007
Catalytic effects of copper oxides on the curing and degradation reactions of cyanate ester resin
Authors: Hong Shinn‐Gwo , Yeh Chin‐Sen 
Published: January 2007

AbstractThe catalytic effect of copper oxides on the curing and degradation behaviors of the cyanate ester resin is studied with infrared spectroscopy, attenuated total reflection infrared spectroscopy (ATR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The result of infrared spectroscopy and DSC analyses indicates that accelerated curing effects from different additives are in the order of zinc octoate > cuprous oxide > cupric oxide. The exothermic characteristics of the cyanate ester resin during cure are drastically affected by the presence of the copper oxides. In addition, it is obtained from TGA analyses that the thermal stability and degradation mechanism of cyanate ester resins are also significantly affected by the addition of copper oxides whereas the extent of degradation from the cupric oxide is greater than that from the cuprous oxide. These results are attributed to the differences in catalytic effects and surface areas of two copper oxides on the cyanate ester resin in contact during the thermal exposure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 442–448, 2007
New crosslinked polymer from a rapid polymerization of acrylic acid with triaziridine‐containing compound
Authors: Chen Po‐Cheng , Wang Shih‐Chieh , Huang Chia‐Yu , Yeh Jen‐Taut , Chen Kan‐Nan 
Published: January 2007

AbstractA triaziridine containing compound, trimethylolpropane tris(1‐aziridinepropionate) (TMPTA‐AZ), is prepared from a Michael addition of aziridine (AZ) with trimethylolpropane triacrylate (TMPTA). A rapid polymerization of acrylic acid (AA) with TMPTA‐AZ occurred at ambient temperature without catalyst. This polymerization process involves three subsequent reactions are proposed: (1) An exothermic neutralization takes place between AA and TMPTA‐AZ. (2) That neutralization heat triggers AZ ring‐opening reaction and that carboxyl group (of AA) plays as a nucleophile and results in an amino ester bond formation. (3) A final crosslinked polymer is obtained from that amino group reacts with its acrylic double bond via an intermolecular Michael addition reaction. These new crosslinked polymers with various performance properties are obtained from a mixture of AA and TMPTA‐AZ in different ratios and post‐heating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 809–815, 2007
Thermal analysis of merino wool fibres without internal lipids
Authors: Martí M. , Ramírez R. , Manich A. M. , Coderch L. , Parra J. L. 
Published: January 2007

AbstractMerino wool is made up of cuticle and cortical cells held together by the cell membrane complex (CMC), which contains a small amount of internal lipids (IWL) (1.5% by mass). IWL have been extracted from wool on account of their considerable dermatological interest owing to their proportion of ceramides. IWL have been extracted by different methods and solvents, methanol and acetone at laboratory and pilot plant levels. Thermal analysis of these extracted wool fibers is presented using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG provides a measurement of the weight loss of the sample as a function of time and temperature. DSC gives information about possible structure modification of extracted wool fibers. Thermoporometry was applied to evaluate the pore size distribution of extracted wool fibers. The results showed that the extraction process increased the pore size distribution and the cumulated pore volume, which is consistent with some changes in the extracted wool CMC. Extracted fiber becomes more hydrophilic and absorbs a large amount of water. We can conclude that the lipid extraction of wool produced no relevant changes in the crystalline fraction when extracted with acetone. However, part of the amorphous keratin material was extracted with methanol, the rest of the crystalline material becoming more stable. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 545–551, 2007
Evaluation and characterization of ammoniumpolyphosphate–pentaerythritol‐based systems for intumescent coatings
Authors: Andersson Anna , Lundmark Stefan , Maurer Frans H. J. 
Published: January 2007

AbstractIntumescent coatings are increasingly used as a method of passive fire protection on steel constructions. By forming a carbon network and releasing a blowing agent, the thin intumescent film swells 100‐fold at elevated temperatures. The highly insulating foam effectively prevents the load bearing steel from reaching its critical temperature at which it looses its mechanical properties and collapses. The role of the carbon donor in intumescent coatings has been studied. Comparison in temperature development, foaming ratios, and rheological behavior has been performed between formulations containing pentaerythritol (penta), di–penta, and tri–penta. A simulated fire test, in which the temperature development during intumescence was studied, showed that the formulations containing penta were considerably more efficient in keeping a low temperature throughout the process. A more rapid temperature development was displayed when using di–penta and tri–penta as the carbon donor. Rheometer tests indicate that penta formulations enter the intumescent process at a lower temperature and stays in it for a longer time than di–penta and tri–penta formulations. Furthermore, the crossover temperature and maximum phase angle are shifted towards higher temperatures by replacing penta with di–penta and with tri–penta in the formulations, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 748–753, 2007
Polyethylenes/PET blend compatibilization with maleic anhydride modified polyethylenes obtained by a UV preirradiation process
Authors: Martínez J. G. , Benavides R. , Guerrero C. 
Published: January 2007

AbstractThe compatibilization of HDPE/LDPE/LLDPE/PET blend during reactive extrusion, using compatibilizing agents, such as modified high, low, and lineal low density polyethylenes with maleic anhydride, was carried out. The agents were prepared in our laboratory by using a UV preirradiation process, containing different grafting and crosslinking degrees. The materials were compared with same maleic anhydride modified polyethylenes prepared by the traditional peroxide method in our laboratory and with a commercial maleic anhydride modified lineal low density polyethylene. The mechanical and thermal properties, as well as their morphology, were evaluated in the compatibilized blends and changes in crystallization phases recorded. The elongation at break and impact strengths increased with compatibilization level and morphology was markedly more homogenous. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 560–567, 2007
Dynamic mechanical properties of Al2O3/poly(ether ether ketone) composites
Authors: Goyal R. K. , Tiwari A. N. , Mulik U. P. , Negi Y. S. 
Published: January 2007

AbstractThe dynamic mechanical properties of high‐performance polymer matrix composites based on semicrystalline poly(ether ether ketone) (PEEK) and aluminum oxide (Al2O3) were evaluated in the temperature range of 30–250°C with a three‐point‐bending mode at a frequency of 1 Hz. The storage modulus and loss modulus changed significantly with the variation of the Al2O3 content in the PEEK matrix. The Al2O3 reinforcement was more pronounced above the glass‐transition temperature (Tg). A composite containing 60 wt % (33 vol %) Al2O3 exhibited about a 78% increase in the storage modulus at 50°C and about a 200% increase at 200°C. However, there was no significant change in the mechanical loss factor and Tg associated with the peak of the mechanical loss factor or loss modulus with the addition of Al2O3. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 568–575, 2007
Characterization of a superabsorbent polymer
Authors: Bakass M. , Bellat J. P. , Bertrand G. 
Published: January 2007

AbstractWe studied an amorphous polymer superabsorbent, able to absorb until 1000 times its weight of water. It is consisted of macromolecular chains, dependent between them by chemical bonds. The swelling of the product in the presence of water gives rise to a polyelectrolytic gel. The chemical analysis of polymer by energy dispersive spectrometry and photoelectrons spectroscopy with a microsounder X showed that the product is homogeneous. It contains carbon, oxygen, and sodium. The measurements of specific surface of the product show that the polymer is nonporous and present a weak surface of about 2.1 m2/g. The thermal study of polymer showed that, under the effect of the temperature and with atmospheric pressure, the polymer is degraded only at temperatures higher than 200°C and becomes porous. When the material is heated at higher temperature of 200°C, its surface becomes increasingly porous with also an increase in the size of the pores. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 782–786, 2007
Coloring effect of the organic hybrid of polyamide 6 and N,N′‐ethylene‐bis(tetrabromophthalimide)
Authors: Deng Xin , Dai Wen‐Li , Zheng Yun‐Long 
Published: January 2007

AbstractColoring study in organic hybrid of polyamide (PA6) and N,N′‐ethylene‐bis(tetrabromophthalimide) (EPT), where the chromophore was self‐assembled by hydrogen bonding formed between PA6 molecular chains and EPT compound, have been characterized by several techniques. CS930 double wavelength lamella scanner was employed to measure the change of color. The existence of hydrogen bonding in PA6/N‐N′‐ethylene‐bis (tetrabromophthalimide) (PA6EPT) was investigated with Fourier transform infrared (FTIR), the results of which were compared with that of PA6 with the same thermal history. FTIR spectra at room temperature revealed that there is essentially hydrogen bonding between PA6 and EPT. The crystallization behavior of PA6EPT affected by hydrogen bonding was studied by using FTIR. The temperature‐dependent behavior of both PA6 and PA6EPT was studied by temperature‐FTIR spectroscopy and differential scanning calorimetry (DSC). With temperature increasing, changes in sensitive, high‐resolution absorbance spectra are observed as dissolve‐volatilizing thin film. Temperature‐FTIR results showed that the hydrogen bonding in PA6EPT attenuated and dissociated considerably at a smaller rate than PA6, that is to say, hydrogen bonding in PA6EPT is more stable than that in PA6. DSC showed that the melting temperature of PA6EPT and PA6 are similar. However, the crystalline degree and crystalline temperature and melting enthalpy of PA6 and PA6EPT are different. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 594–600, 2007
Quantitative assessment of relationship between pressure performances and material mechanical properties of medical graduated compression stockings
Authors: Liu R. , Kwok Y. L. , Li Y. , Lao T. T. , Zhang X. 
Published: January 2007

AbstractGraduated compression stockings (GCSs) have been widely applied for prophylaxis and treatment of venous disorders. Their pressure performances and medical functions depend largely upon the mechanical properties of stocking knitted fabrics. In the present study, the multiple fabric mechanical behaviors of GCSs with different pressure levels and medical functions were examined by using Kawabata standard evaluation system. On the basis of pressure ranges advised by the European Committee for Standardization, the definitive quantitative relationships between pressure performances and key mechanical properties of GCS fabrics were developed and evaluated. The results show that GCS fabrics with different pressure performances produced significant differences in tensile, shearing, and bending properties (P < 0.001). GCS fabrics generating lighter pressure possessed higher values in tensile strain, tensile energy at a given force, and lower values in shearing stiffness and bending rigidity, while stronger pressure levels are produced by the GCS fabrics with higher resistance to the mechanical deformations. Pressure magnitude performances of GCSs are an integrative action performed by multiple fabric mechanical properties. The developed relationships between pressure levels and material mechanical properties provide a rational and practical approach for assessing and predicting pressure functional performances of GCSs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 601–610, 2007
Characterization of nanoscale wool particles
Authors: Cheng Y. F. , Yuen C. W. M. , Li Y. , Ku S. K. A. , Kan C. W. , Hu J. Y. 
Published: January 2007

AbstractNanoscale wool particles were prepared from wool fibers by a special pretreatment with the aid of specially designed machinery and techniques. Scanning electron micrographs showed that the particle sizes of wool powders produced from wool fibers approximately 8–20 μm in diameter decreased from a microscale to a nanoscale after three stages of pulverization, which were further confirmed with a laser particle size analyzer. Fourier transmission infrared analysis showed that there were no substantial changes in the chemical structure of the wool after the pulverization processes. The wool powders after the second and third pulverizations slightly differed from that of the wool fiber and the particles after the first pulverization, with greater amounts of the secondary amine groups, amide groups, CS stretching vibrations, and OH bonds. X‐ray diffraction analysis showed that the crystallinity of the wool powders decreased when the particle sizes decreased, particularly at nanoscales. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 803–808, 2007
Morphology development in polypropylene/polystyrene blends during coalescence under shear
Authors: Li Yun‐Yan , Chen Zi‐Qi , Huang Yi , Sheng Jing 
Published: January 2007

AbstractMorphology development during the coalescence under shear in polypropylene/polystyrene blends was studied in this article. The coalescence was performed by decreasing the shear rate after a fine morphology is obtained at higher shear rate. Time resolved SEM performance indicates that, because of the smaller capillary number, particles of the minor phase are almost spherical during the whole coalescence process. An original sizing method based on SEM is used to describe the time evolution of particle size and their distribution. Initially, the volume–average particle size increases rapidly and levels off before a steady state is obtained, while the number–average particle size increases slowly but monotonously during the whole coalescence process. This two‐step increase in volume average particle size is discussed in terms of coalescence efficiency. Further, an examination of scaling behavior shows that a master curve for particle growth with different compositions is observed by plotting the relative increase in particles size versus the shear strain, confirming that the evolution of particle size could be described by a scaling law. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 666–671, 2007
Plasticized/graphite reinforced phenolic resin composites and their application potential
Authors: El‐Tantawy Farid 
Published: January 2007

AbstractPlasticized graphite (PG)/phenolic resin composites are candidates for positive temperature coefficient resistivity (PTCρ) thermistors, which are used for self‐recoverable elements that provide protection from overcurrents, gasoline sensors, and electrostatic charge and electromagnetic wave shielding in many kinds of electrical devices. The morphology and network structure of PG/phenolic resin composites have been characterized with scanning electron microscopy and with measurements of the crosslinking density, bound resin content, degree of crystallinity, viscosity, surface energy, thermal conductivity, enthalpy, and glass‐transition temperature. In addition, mechanical properties such as the tensile strength, Young's modulus, Shore A hardness, and elongation at break for resins filled with PG have been studied. The electrical properties of the composites have been measured to relate the PG volume fraction to the electrical conductivity. A large PTCρ value has been observed for all samples. The mechanism of the PTCρ effect in the materials is related to the thermal expansion and highest barrier energy of the composites. Switching behaviors of the current and voltage for all samples have been observed. The applicability of PG/phenolic resin composites for temperature controllers and gasoline gas sensors has been examined. The antistatic charge dissipation and dielectric constant as functions of the PG content have been studied. Finally, the experimental electromagnetic interference of the PG/phenolic composites has been investigated in the frequency range of 1–15 GHz and compared with a theoretical model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 697–709, 2007
Acid wash in determining cellular uptake of Fab/cell‐permeating peptide conjugates
Authors: Kameyama Shouju , Horie Mayo , Kikuchi Takeo , Omura Takao , Tadokoro Akiko , Takeuchi Toshihide , Nakase Ikuhiko , Sugiura Yukio , Futaki Shiroh 
Published: January 2007

AbstractSuccessful intracellular delivery of various bioactive molecules has been reported using cell‐permeating peptides (CPPs) as delivery vectors. To determine the effects of CPPs on the cellular uptake of immunoglobulin Fab fragment, conjugates of a radio‐iodinated Fab fragment with CPPs (CPP‐125I‐Fab) derived from HIV‐1 TAT, HIV‐1 REV, and Antennapedia (ANP) were prepared. These vectors are rich in basic amino acids, and their strong adsorption on cell surfaces often results in overestimation of internalized peptides. Cell wash with an acidic buffer (0.2M glycine–0.15M NaCl, pH 3.0) was thus employed in this study to remove cell‐surface adsorbed CPP‐125I‐Fab conjugates. This procedure enabled clearer understanding of the methods of internalization of CPP‐125I‐Fab conjugates. The kinetics of internalization of REV‐125I‐Fab conjugate was rapid, and a considerable fraction of REV‐125I‐Fab was taken up by HeLa cells as early as 5 min after administration. It was also shown that cellular uptake of these conjugates was significantly inhibited in the presence of endocytosis/ macropinocytosis inhibitors, in the order REV‐125I‐Fab ≥ TAT‐125I‐Fab ≥ ANP‐125I‐Fab; this order was the same as for effectiveness of intracellular delivery. Simultaneous cell washing with phosphate‐buffered saline (PBS) and this acidic buffer effectively separated the internalized conjugates from the cell‐surface‐adsorbed ones, and considerable differences were observed in these amounts dependent on the employed CPPs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 98–107, 2007.This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Structural flexibility of the nucleosome core particle at atomic resolution studied by molecular dynamics simulation
Authors: Roccatano Danilo , Barthel Andre , Zacharias Martin 
Published: January 2007

AbstractComparative explicit solvent molecular dynamics (MD) simulations have been performed on a complete nucleosome core particle with and without N‐terminal histone tails for more than 20 ns. Main purpose of the simulations was to study the dynamics of mobile elements such as histone N‐terminal tails and how packing and DNA‐bending influences the fine structure and dynamics of DNA. Except for the tails, histone and DNA molecules stayed on average close to the crystallographic start structure supporting the quality of the current force field approach. Despite the packing strain, no increase of transitions to noncanonical nucleic acid backbone conformations compared to regular B‐DNA was observed. The pattern of kinks and bends along the DNA remained close to the experiment overall. In addition to the local dynamics, the simulations allowed the analysis of the superhelical mobility indicating a limited relative mobility of DNA segments separated by one superhelical turn (mean relative displacement of approximately ±0.2 nm, mainly along the superhelical axis). An even higher rigidity was found for relative motions (distance fluctuations) of segments separated by half a superhelical turn (approximately ±0.1 nm). The N‐terminal tails underwent dramatic conformational rearrangements on the nanosecond time scale toward partially and transiently wrapped states around the DNA. Many of the histone tail changes corresponded to coupled association and folding events from fully solvent‐exposed states toward complexes with the major and minor grooves of DNA. The simulations indicate that the rapid conformational changes of the tails can modulate the DNA accessibility within a few nanoseconds. © 2007 Wiley Periodicals, Inc. Biopolymers 85: 407–421, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com