bluuebunny/crossref_metadata_2025_split huggingface dataset:
Release of model compounds from modified lactone copolymers
Authors: Karjalainen Teija , Rich Jaana , Seppälä Jukka 
Published: October 2004

AbstractThe applicability of three different P(ϵ‐caprolactone‐co‐DL‐lactide) copolymers for injection‐molded controlled release devices was evaluated. The copolymers of ϵ‐caprolactone and DL‐lactide were polymerized in bulk using Sn(II) octoate as the catalyst. Glycerol, polyethylene glycol 1000, and polyethylene glycol 4000 were used as initiators. Copolymers were characterized by size exclusion chromatography, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy measurements. The release of two model compounds, theophylline and propranolol hydrochloride, at different loadings (2–30 wt %) was studied. The solubility of the model compounds into the matrices was confirmed to be low by DSC measurements. Increasing the hydrophilicity of the copolymer matrix increased the release rates of both model compounds. The results clearly demonstrate that the desired release rates of these model compounds can be tailored by varying the compound loading or modifying the hydrophilicity of the matrix copolymer. The copolymers were found to be relatively stable during the 4‐month hydrolysis. Addition of hydrophilic polyethylene glycol blocks into the backbone of the copolymer chain increased water absorption and thus the degradation was faster. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2118–2126, 2001
Synthesis and properties of poly(butylene succinate) with N‐hexenyl side branches
Authors: Jin Hyoung‐Joon , Kim Duck‐Soo , Kim Mal‐Nam , Lee Ick‐Mo , Lee Han‐Sup , Yoon Jin‐San 
Published: October 2004

AbstractN‐hexenyl side branches were introduced into poly(butylene succinate) (PBS) by polymerization of succinic acid (SA) with 1,4‐butanediol (BD) in the presence of 7‐octene‐1,2‐diol (OD). Thermal properties and biodegradability of the aliphatic polyesters were investigated before and after epoxidation of the pendant double bonds. The glass‐transition temperature (Tg) decreased with the branching density to give a minimum at 0.03 mol of branching units per mole of structural units. Thereafter, Tg increased due to the in situ crosslinking of the unsaturated groups during the differential scanning calorimetry (DSC) measurements. N‐Hexenyl side branches decreased melting temperature (Tm) more significantly than ethyl side branches, but the effect was on par with that by n‐octyl branches. Epoxidation of the double bonds decreased Tm and melting enthalpy (ΔHm), but increased Tg of the aliphatic polyester. Biodegradability was enhanced to some extent by the presence of n‐hexenyl side branches. However, the epoxidation of the unsaturated groups did not notably affect the biodegradability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2219–2226, 2001
Miscibility behavior of metallocene polyethylene blends
Authors: Chen Fei , Shanks Robert , Amarasinghe Gandara 
Published: October 2004

AbstractVery‐low‐density polyethylenes (VLDPEs) with short branches, formed by metallocene or Ziegler–Natta catalysts, were blended with low‐density polyethylenes (LDPEs) or VLDPEs with long branches. The crystallization and melting behavior of these blends were examined by differential scanning calorimetry (DSC). The blends of metallocene‐catalyzed VLDPE1 and LDPEs showed a smooth change in both crystallization and melting peak temperatures, indicating that there was co‐crystallization and, hence, partial miscibility at all compositions. However, the blends of VLDPE1 and long‐chain branched VLDPE2 co‐crystallized at 50% or less VLDPE2 content, whereas Ziegler–Natta‐catalyzed VLDPE3–VLDPE2 blends showed co‐crystallization at 50% or higher VLDPE2 compositions. It is concluded that either complete or partial miscibility has occurred between the two polyethylenes in each of the blends with VLDPE2. Nevertheless, VLDPE2 did not cause a significant change in the morphology of VLDPE1, perhaps because of the reduced number of long branches present in VLDPE2 compared with LDPEs. The molar masses or melt flow indices of the polyethylenes were not significant in controlling the morphology; only the distribution of branches along the chains was important. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2227–2236, 2001
Effects of moisture on properties of epoxy molding compounds
Authors: Lu M. G. , Shim M. J. , Kim S. W. 
Published: October 2004

AbstractIn this article the effects of moisture on a novel epoxy molding compound, including the mechanical properties, temperature transition, and thermal degradation behavior, are studied. The experimental results reveal that the absorbed water acts predominantly as a crazing agent, continuously decreasing the mechanical strength with the time in water. The glass‐transition temperature decreases at the early stage and is finally equilibrated. The thermal degradation behavior of the materials is not greatly influenced by the hydrothermal age. The decomposition of samples in oxygen is composed of two independent steps: the thermal degradation and oxidation at high temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2253–2259, 2001
Degradation of the mechanical properties of composite vulcanizates loaded with paraffin wax
Authors: Abu‐Abdeen M. 
Published: October 2004

AbstractA composite of Styrene Butadiene Rubber (SBR) and Natural Rubber (NR) loaded with 40 phr of High Abrasion Furnace (HAF) carbon black is loaded with different concentrations of paraffin wax. From the stress–strain curves, Young's modulus was found to decrease with increasing the amount of added paraffin wax. The modified Mooney‐Revlin equation was used to calculate the parameters C1 and C2. A plot between the true tensile stress as a function of (λ2 − λ−1) was used to calculate two parameters σ0 and G, and then both the average molecular weight between crosslinks and the number of effective plastic chains per unit volume were also calculated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2265–2270, 2001
Effect of heat treatment on the structural and conformational changes of regenerated Antheraea pernyi silk fibroin films
Authors: Kweon Haeyong , Woo Soon Ok , Park Young Hwan 
Published: October 2004

AbstractRegenerated Antheraea pernyi silk fibroin films prepared from calcium nitrate solution were treated with heat for crystallization. The structural and conformational changes caused by heat treatment were investigated with X‐ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The temperature and treatment time of heat greatly influenced the conformation of the regenerated films. The conformational change was caused by heat treatment over 230°C, and the transition was enhanced by increasing time and temperature. The contents of α‐helix, β‐sheet, and random‐coil conformations were calculated and examined to investigate the effect of heat treatment on the conformational changes. The β‐sheet structure could be transformed from a random‐coil conformation on heat treatment, whereas the content of α‐helix structure was nearly unchanged, regardless of heat‐treatment conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2271–2276, 2001
Investigation into the rheological properties of PES/NMP/nonsolvent membrane‐forming systems
Authors: Li Zhansheng , Jiang Chengzhang 
Published: October 2004

AbstractFrom the perspective of a polymer solution, the rheological properties of the popular polyethersulfone (PES)/N‐methyl‐2‐pyrrolidone (NMP)/nonsolvent (NS) membrane‐forming system were investigated thoroughly with a controlled stress rheometer (HAAKE RS75, Germany). The scope of the study included measurements of the controlled‐stress flow curve, creep recovery, and dynamic oscillation. H2O, 1‐butanol, ethylene glycol, and diethylene glycol were used as NS additives. The effects of the polymer concentration and the quality of the solvent mixture, as characterized by the approaching ratio, on the rheological behavior of the dopes were studied. Up to 38 wt % PES and extremely adjacent to the phase separation (i.e., the approaching ratio of the dope was 0.95), the viscous property dominated all the dopes, which behaved as Newtonian fluids. Moreover, all the membrane‐forming dopes investigated were in the crossover regime in the semidilute region, in which the chains were overlapping but unentangled. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 283–291, 2001
Dextran–rare earth ion interactions. I. Dynamics in aqueous solutions
Authors: Mazi H. , Zümreoğlu‐Karan B. , Güner A. 
Published: October 2004

AbstractThe interaction of light‐lanthanoid cations (La3+, Ce3+, and Nd3+) with dextran in aqueous solutions was studied by viscosimetric, turbidimetric, and conductimetric methods. The effects of the type of the cation and the concentration of the cation on the interaction mechanism were investigated. Viscosity behavior of the solutions was interpreted using the Huggins and Kraemer equations; intrinsic viscosities and the slopes were calculated. The results found from the Huggins and Kraemer approaches accorded well. The order of interaction was determined as La3+ > Ce3+ > Nd3+. In all experimental methods applied, a critical concentration of the Ln3+ ion (≈0.08 mol Ln3+/L) was noted at which the observed property showed a significant change. Up to this critical concentration, viscosities of the dextran/Ln3+ solutions decreased and after making an outstanding turn at this point increased toward higher concentrations. Turbidimetric and precipitation experiments gave opposite results as expected but the same order for the cation and the same value of critical concentration. The results obtained from the application of a mathematical model to the precipitation data verified the conclusions attained by viscosimetry and conductimetry. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 323–329, 2001
Nonisothermal crystallization of isotactic polypropylene blended with poly(α‐pinene). I. Bulk crystallization
Authors: Di Lorenzo Maria Laura , Cimmino Sossio , Silvestre Clara 
Published: October 2004

AbstractThe influence of a natural terpene resin, poly(α‐pinene) (PαP), on the nonisothermal crystallization process of isotactic polypropylene (iPP) was investigated. The solidification process strongly depends on cooling rate, composition, and miscibility of the system. For the blends containing PαP up to 30 wt %, the overall nonisothermal crystallization rate is depressed with respect to plain iPP. This is probably the result of the diluting effect of the polyterpene because the two components are miscible. The 50/50 blend presents, instead, two amorphous phases: an iPP‐rich phase and a PαP‐rich phase. For this composition, solidification starts at temperatures higher than those for plain iPP and blends with lower PαP content, given that the diluting effect of PαP in the iPP‐rich phase is counterweighted by an increased number of nuclei that originate from the polyterpene‐rich phase domains. PαP also influences the morphology of iPP spherulites, which are spherical in plain iPP and become more irregular with increasing PαP content. The number and dimension of iPP spherulites depend on blend composition and miscibility of the components. Moreover, the nonisothermal crystallization kinetics of iPP/PαP blends was analyzed with the Ozawa equation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 358–367, 2001
Studies on SLS doped polyaniline and its blend with PC
Authors: Jeevananda T. , Siddaramaiah  , Annadurai V. , Somashekar R. 
Published: October 2004

AbstractElectrically conductive polyaniline (PANI) and its blend with polycarbonate (PC) was prepared by one‐step emulsion polymerization technique in which sodium lauryl sulfate (SLS) acts as surfactant and as a protonating agent for the resulting polymer. The prepared PANI and its blends were characterized by density, percentage of water absorption, and electrical conductivity. PANI–PC blend exhibits a conductivity value of 4.70 × 10−2 S/cm (PANI–PC1) and 5.68 × 10−5 S/cm (PANI–PC3) with a change in dopant from p‐toluene sulfonic acid (TSA) to SLS, respectively. By using a more general method, which takes into account the presence of disorder of the second kind in polymers proposed by Hosemann, crystal size (〈N〉) and lattice strain (g in %) values were estimated. The variation of conductivity in doped PANI and PANI–PC blend has been explained on the basis of these microcrystalline parameters. TGA thermograms of PANI and PANI‐PC blend show three‐step degradation behavior. Thermal stability of PANI was improved after blending with PC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 383–388, 2001
Surface modification of LDPE film by chemical processes with Ni2+ and ammonium persulfate
Authors: Bandopadhay D. , Panda A. B. , Pramanik P. 
Published: October 2004

AbstractChemical modification of the surface of low‐density polyethylene (LDPE) film was performed with an aqueous solution of ammoniacal ammonium persulfate in the presence of Ni2+ ions, where the polar groups were generated on the surface of the LDPE film. The surface of the LDPE film was modified chemically with an ammoniacal solution of ammonium persulfate (1.1M) and Ni(SO4)2 (0.02M) heated at about 70°C for 3 h. The morphologies of the surfaces were studied with scanning electron microscopy and infrared spectroscopy; electron spectroscopy for chemical analysis revealed the introduction of polar groups on the surface, which improved printability and adhesion properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 406–415, 2001
Polypropylene/polystyrene blends—Preliminary studies for compatibilization by aromatic‐grafted polypropylene
Authors: Mustafa S. J. Syed , Nor Azlan M. R. , Ahmad Fuad M. Y. , Mohd Ishak Z. A. , Ishiaku U. S. 
Published: October 2004

AbstractThe blends of Polypropylene (PP), that is a semicrystalline and nonpolar thermoplastic polymer with a polar and amorphous polymer such as Polystyrene (PS), are known to be immiscible. This article investigates the use of an aromatic vinyl monomer (AVM)‐grafted PP (PPA) as a potential compatibilizer for such an immiscible blend system (PP/PS blend). PPA was prepared by grafting a monofunctional aromatic vinyl monomer onto PP using an organic peroxide at 180°C for 10 min in a Brabender mixer. Using a twin‐screw extruder, blends of PP/PS in various composition containing different amount of PPA were prepared. Results obtained from tensile and impact strength, heat deflection, and melt flow index measurements shows some improvement in the properties of the blends indicating some compatibilization effects in the blend system. However, the scanning electron microscopy (SEM) micrographs strongly suggested a significant compatibilization between PP and PS. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 428–434, 2001
Synthesis and in situ transformation of poly(oxybutylene)amides by butoxylation
Authors: Lin Jiang‐Jen , Wu Jeng‐Jaw , Ho Yung‐Sheng 
Published: October 2004

AbstractA family of gasoline detergents was prepared by a two‐step process—(1) preparation of amide initiators by reacting hydrophilic amines with ethyl acetate at high temperature; (2) consecutive butoxylation of the initiators with 1,2‐epoxybutane (BO) to obtain oil‐soluble products. The process led to the preparation of amide‐initiated butoxylates, which were characterized by FTIR, NMR, and amine titration. During the butoxylation, it was found that the unexpected ester by‐products were generated via an amide/ester exchange. The reaction profile was studied. The amide/ester exchange reaction, characterized by IR absorption of amide (1650 cm−1) vs. ester (1735 cm−1), reached equilibrium during the process of butoxylation to 1600 Mw. Steric hindrance of the amide structures is an important factor controlling the formation of these ester byproducts. Selective hydrolysis to remove the ester by‐products is necessary to render the final product with an improved engine performance of octane requirement. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 435–445, 2001
FEG–ESEM investigation of micromechanical deformation processes in ultrafine monospherical SiO2 particle‐filled polymer composites
Authors: Kim G.‐M. , Lee D.‐H. 
Published: October 2004

AbstractMicromechanical deformation processes responsible for toughening mechanisms in ultrafine monospherical inorganic particle‐filled polyethylene were investigated in situ by a field‐emission gun‐environmental scanning electron microscope (FEG–ESEM) with low‐voltage techniques. In general, the ultimate properties of polymer composites are largely dependent on the degree of dispersion of filler particles into the matrix. Very often, the agglomeration is one of inevitable occurrences in polymer composites, mixed with ultrafine filler particles. In the present work, the effects of agglomerates, consisting of ultrafine monospherical filler particles, were reexamined in polymer composites on the toughening mechanism. The results show that the dominant micromechanical deformation processes are the multiple debonding processes inside agglomerates, in which the ratio of the matrix strand and the size of agglomerate plays a great role of matrix yielding. In the specimen, where the agglomerates are isolated in the matrix, deformation begins at the equatorial region of agglomerates and propagates through them. However, in the case of closely placed agglomerates, deformation occurs homogeneously within the whole area inside the agglomerates. In both cases, in conjunction with the multiple debonding processes, the major part of energy during the deformation dissipates through the shear‐flow processes of the matrix material. In particular, the micromechanical deformation processes observed in this work confirm that the agglomerates do not always have negative effects on the mechanical properties—at least, in the shear deformable semicrystalline polymer matrices. The agglomerates may be effectively used for the improvement of toughness. Furthermore, the FEG–ESEM with low‐voltage techniques offers an extremely promising and efficient alternative method to study the morphology as well as in situ micromechanical deformation processes in nonconducting polymer systems. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 785–789, 2001
Preparation and properties of functionalized polyorganosiloxanes
Authors: Yahaya G. O. , Brisdon B. J. , Maxwell M. , England R. 
Published: October 2004

AbstractA series of linear functionalized polyorganosiloxanes of the type Me3SiO[MeSiO(CH2)nR]x(Me2SiO)ySiMe3, where n = 2, R = —(CH2)NMe2; n = 1, R = —(CH2)OEt; n = 4, R = —(CH2)COOEt; n = 3, R = —(CH2)Me, have been prepared and characterized. Functional group loadings of ∼4 mol % (x = 1, y = 25), ∼11 mol % (x = 3, y = 23), and ∼30 mol % (x = 8, y = 18) were obtained by reacting commercially available copolymers Me3SiO(MeSi{H} O)x(Me2SiO)ySiMe3 with the appropriate ratios ofx:y, with the required quantities of HO(CH2)nR, using dichloro(1,5‐cyclooctadiene)platinum(II) as catalyst. Amine, ether, ester, and alkyl functionalized siloxanes were obtained in good yields after purification, and each fluid polymer has been characterized by 1H and 13C‐nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectral measurements, elemental analysis, viscosity, surface tension, and density measurements. The functionalized polymers exhibit Newtonian behavior over the range of shear rates 0.4–79.4 s−1, and significant viscosity enhancements were observed for all functionalized polymers compared with poly(dimethylsiloxane) fluids of similar chain lengths. The functionalized siloxanes exhibited in almost all cases an increase in both viscosity and density as the functional group loading increased. The surface tensions of the polymers have also been determined and lie within the range 18.8–22.3 mN m−1. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 808–817, 2001
Synthesis and the magnetic properties of novel metal(II) complexes of polyamides
Authors: Liu Jiageng , Sun Weilin , Lu Fengcai 
Published: October 2004

AbstractNovel polyamides DTPA and DTPyA are prepared from 2,2′‐diamino‐4,4′‐bisthiazole and aromatic polycarbonyl chloride. The complexes of Fe(II) and Cu(II) metal of the polyamides are also prepared. The complexes as well as the polyamides are characterized through IR and EPR, and the magnetic property of each complex are measured through MPMS. It is found the Fe(II) complexes of both DTPA and DTPyA reveal magnetization ability, especially the Fe(II) DTPA complex. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 818–822, 2001
The production of a high‐functionality RBD palm kernel‐based polyester polyol
Authors: Badri K. H. , Ahmad S. H. , Zakaria S. 
Published: October 2004

AbstractIn the previous article, a diol‐based RBD palm kernel polyol was prepared. It has been found that the polyurethane foam produced is only giving a good compressive strength property at 45 kg/m3 molded density. The combination of sorbitol into the polyol system resulted in a better dimensional stability and improved thermal conductivity as well as enhanced the compressive strength. These were obtained by increasing the functionality of the polyol (functionality of 4.5) through introduction of high molecular weight and branching polyhidric compound. Direct polycondensation and transesterification methods were used for the syntheses. The hydroxyl value, TLC, and the FTIR were determined to study the completion of the reaction. A comparative study of the mechanical properties and morphological behavior was carried out with the diol‐based polyol. From the water‐blown molded foam (zero ozone depletion potential ODP) with density of about 44.2 kg/m3 and closed‐cell content of 93%, it resulted in a compressive strength of 222 kPa, dimensional stability of 0.09, 0.10, and 0.12% at the length, width, and thickness of the foam, respectively, conditioning at −15°C for 24 h. The thermal conductivity improved to an initial value of 0.00198 W/mK, tested at 10°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 827–832, 2001
Influence of the molecular structure on slow crack growth resistance and impact fracture toughness in Cr‐catalyzed ethylene‐hexene copolymers for pipe applications
Authors: Stephenne V. , Daoust D. , Debras G. , Dupire M. , Legras R. , Michel J. 
Published: October 2004

AbstractIn this study we correlate parameters describing molecular structure (molar mass distribution, short chain branching content, intermolecular heterogeneity) of different ethylene‐hexene Cr‐catalyzed copolymers, with slow crack growth and rapid crack propagation resistances, respectively measured with Bent Strip and Charpy tests. The PTREF technique, coupled with classical techniques, was used. Two new indices were proposed to correlate mechanical properties and molecular structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 916–928, 2001
Vulcanization characteristics of asphalt/SBS blends in the presence of sulfur
Authors: Wen Guian , Zhang Yong , Zhang Yinxi , Sun Kang , Chen Zhiyong 
Published: October 2004

AbstractThe vulcanization of asphalt/styrene–butadiene–styrene (SBS) triblock copolymer blends in the presence of elemental sulfur was followed with a strain‐controlled rheometer. The vulcanization of the blends took place at temperatures greater than 140°C. From 150 to 180°C, the curing rate of the blends increased significantly with increasing temperature, and the apparent activation energy of vulcanization was 45.2 kJ mol−1. A suitable processing temperature for good mechanical and thermally stable properties was between 170 and 180°C. Both the structure of SBS and the sulfur level had important effects on the vulcanization of the blends. A plot of the electric current versus time showed the process of the dynamic vulcanization of the blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 989–996, 2001