bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and structure study of polypropylene/polyamide‐6 gradient materials
Authors: Wen Bian‐Ying , Li Qing‐Chun , Hou Shao‐Hua , Wu Gang 
Published: December 2003

AbstractA polymeric gradient material was prepared by a specific extruding technique in which the weight ratio of two components, polypropylene (PP) and polyamide‐6 (PA6), was changed gradually with the progress of process. This columnar gradient material was formed during a combined extruding and winding operating. The gradient variation of specimens sampled along the radius of columnar gradient material was confirmed and characterized through measurements of DSC melting behavior and elemental analysis. The morphological variation was studied using SEM observation. The results indicate that the content of either polymer shows a monotonous variation along the radius direction. With increasing radius, a gradually decreased percentage of PP was observed, whereas PA6 gradually increased. SEM photographs of the specimens sampled at different radii exhibit that the morphology also evolves gradually with variations in the percentage ratio of two polymers. A phase‐inversion phenomenon was recognized in this polymeric gradient material and a “dual mode” of dispersed morphology was found in the sandwich zone. These results indicate that the PP/PA6 blend with gradient structure was successfully prepared by use of this unique technique. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2491‐2496, 2004
Viscoelastic behavior of Cytec FM73 adhesive during cure
Authors: Hojjati Mehdi , Johnston Andrew , Hoa Suong V. , Denault Johanne 
Published: December 2003

AbstractIn this work, the viscoelastic properties of Cytec FM73 structural film adhesive were characterized. Several resin plates were cured using various process cycles to achieve a range of final cure states. Specimens cut from these plates were tested using a dynamic mechanical analyzer (DMA) and the glass‐transition temperature at each degree of cure was determined. Stress relaxation tests at different temperatures were then performed using DMA in stress relaxation mode and time‐temperature superposition was used to generate master stress relaxation curves and associated shift functions for each degree of cure. Several different constitutive models were examined for their ability to describe relaxation modulus development during cure. A simple three‐parameter model consisting of a stretched exponential with cure‐dependent terms was found to provide the best results. The results indicate that of the parameters used in the model, relaxation time strongly depends on cure state. The empirical DiBenedetto equation was used to obtain an expression for glass‐transition temperature as a function of degree of cure. This expression was in turn used to derive a new relation to describe stress relaxation time as a function of degree of cure. The shift function was modeled using a simplified form of the Vogel equation with cure‐dependent coefficients. Good correlation between measured relaxation modulus and model predictions was observed. © 2003 Wiley Periodicals, J Appl Polym Sci 91: 2548–2557, 2004
Complexation studies of some newly synthesized precursors for substituted dibenzo and dibenzodiaza crown ethers
Authors: Çakir Ümit , Uǧraş H. Ibrahim , Temel Hamdi , Topal Giray 
Published: December 2003

AbstractThis study represents the synthesis of dibenzo and dibenzodiaza crown ether precursors with various functional groups in good yield by employing four different methods using polar protic and aprotic solvents with high boiling points. Also the complexation abilities of all synthesized ligands with Cu2+, Zn2+, and Ag+ were studied by conductometry; thus the conductometric behavior of Cu(NO3)2, ZnCI2, and AgNO3 in 80% dioxane–water mixture was investigated in the presence of these ligands. The order of formation constant for complexes of the ligands with Cu2+, Zn2+, and Ag+ ions was found to be: Cu2+ > Zn2+ > Ag+ for the ligands of VI, VII, XI, and XII; Cu2+ > Ag+ > Zn2+ for the ligands of III and VIII; and Zn2+ > Cu2+ > Ag+ for the ligands of I, II, IV, V, IX, and X. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2497–2501, 2004
Notch sensitivity of aliphatic polyketone terpolymers
Authors: Zuiderduin W. C. J. , Huétink J. , Gaymans R. J. 
Published: December 2003

AbstractThe notch sensitivity of aliphatic polyketone (PK) terpolymers was investigated in this article. The notch‐tip radius was varied between the size of an actual propagating crack tip of 1–2 μm and the largest notch tip of 1000 μm radius. The larger notch‐tip radii (1000–15 μm) were milled into the polymer. The smallest notch‐tip radii of 2 and 15 microns were made with a novel technique with the aid of an Eximer laser. The fracture behavior of the PK‐terpolymer was found to be sensitive toward changes in notch‐tip radius. The fracture energy decreased strongly with decreasing notch‐tip radius even when fractured ductile. Sharper notches were not as effectively blunted as were larger notches in the ductile region. The brittle‐to‐ductile transition temperature (Tbd) was increased with decreasing notch‐tip radius for the larger notches (1000–100 μm). For sharper notches (2 and 15 μm) the Tbd decreased again. This behavior could be explained by the decreasing amount of elastic energy release with sharper notches. The energy release proved to be very important for this material. A mixed‐mode fracture behavior was found to occur with larger notches because of the elastic energy present in the sample before fracture. The notch sensitivity was reduced considerably by the addition of a 10% core‐shell rubber phase. For the blend material the notch‐tip radius had almost no influence on the Tbd. The fracture energy on the other hand was still lowered with a sharper notch. This was attributed to the difference in the crack initiation process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2558–2575, 2004
Kinetics of heterogeneous polymerization of vinylidene chloride. II. Discussion of model
Authors: Lu Qun , Weng Zhi‐Xue , Huang Zhi‐Ming , Cao Xiao‐Hua , Pan Zu‐Ren 
Published: December 2003

AbstractIn the present article, the kinetic model for vinylidene chloride polymerization obtained in the previous article was analyzed and simplified. A series of kinetic experiments was carried out in stainless‐steel batch reactors to evaluate the model. The kinetic parameters were estimated by using these experimental data. The theoretical model prediction was compared with the experimental data. The result shows that the present model is in good agreement with experimental data over nearly the entire conversion range. © 2003 Wiley Periodicals, Inc. J Apply Polym Sci 91: 2582‐2587, 2004
A novel method for the preparation of core‐shell nanoparticles and hollow polymer nanospheres
Authors: Yu Faquan , Liu Yanping , Zhuo Renxi 
Published: December 2003

AbstractA one‐step method to prepare core‐shell nanoparticles and thus hollow nanospheres is reported. The process for the formation of core and shell took place during reaction. Once the core formed, it was covered with the shell substance produced in situ, and thus, the shell hindered the continued growth of the core. Based on this method, we readily obtained core‐shell nanoparticles by choosing AgCl, CuS, or Fe(III) diethyldithiocarbamate (FeDEC)3 as model core substances and the cogel from gelatin and gum arabic as the shell substance. High‐resolution transmission electron microscopy (HRTEM) directly revealed the core‐shell structure. TEM results showed the average particle sizes were under 100 nm, depending on the core substance and the concentration of substances producing cores. After removal of the core materials, hollow nanospheres resulted, which were directly observed by TEM. The observation further verified the core‐shell structure. UV spectrophotometry also gave signals of coated structure and revealed high core content (51.1%) and nearly perfect coating (91.6%). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2594–2600, 2004
Cationized nylon as adsorbent for anionic residual dyes
Authors: Baouab Mohamed Hassen V , Zghida Haïfa , Gauthier Robert , Gauthier Hélène 
Published: December 2003

AbstractFor use as an ion exchanger, a cationized nylon (EPTMAC–nylon) was prepared by reacting nylon‐6,6 with epoxy propyl trimethyl ammonium chloride (EPTMAC), using anhydrous tin chloride (SnCl2) as catalyst in a nonaqueous medium. Evidence of grafting was provided by atomic force microscopy and the exchange capacity of EPTMAC–nylon was evaluated by potentiometric titration. The adsorption of four dyes (Acid Blue 25, Acid Yellow 99, Reactive Yellow 23, and Acid Blue 74) from aqueous solutions using a batch process was studied according to the adsorption capacity of the cationized support. The effect of experimental parameters such as dye concentration and adsorption temperature were analyzed. The adsorption isotherms were determined at different temperatures and modeled using Langmuir, Freundlich, and Jossens equations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2513–2522, 2004
Characteristics of azo‐dye binding sites on wool‐fiber keratin
Authors: Pielesz Anna 
Published: December 2003

AbstractProtein electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulfate is a widely used technique for the analysis of proteins. This article presents research on the binding of model azo‐dyes, based on nongenotoxic benzidine analogs, with wool‐fiber keratin. Protein fractionation, performed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and depending on the protein weight, was conducted on whole wool fibers, on fibers descaled in formic acid, and on lyophilized formic acid extracts. Dyes were bound with the proteins from the high‐sulfur‐protein area or high‐tyrosine‐protein area, depending on the level of dye dissolution. Fluorescence microscopy and transmission electron microscopy were used to illustrate the extent of the penetration of the model azo‐dyes into the wool fibers. Scanning electron microscopy was used to detect changes in the fiber topography resulting from the chemical treatments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2629–2641, 2004
Structural control and properties of low‐dielectric‐constant poly(hydrogen silsesquioxane) precursors and their thin films
Authors: Liu Wei‐Chih , Yu Yang‐Yen , Chen Wen‐Chang 
Published: December 2003

AbstractThe precursors of poly(hydrogen silsesquioxane) (PHSSQ) were synthesized from triethoxysilane (TES) through variations in the pH and molar ratio of water to TES (R1). The molecular structures of the prepared PHSSQ precursors were controlled by the reaction conditions, including the molecular weight, the content of SiOH end groups, and the cage/network ratio. The effect of the reaction conditions on the PHSSQ structure was quite different from that previously reported for poly(methyl silsesquioxane) (PMSSQ). The SiOH content and cage/network ratio of the prepared PHSSQ precursors increased with increasing R1 and pH. The molecular weight of the prepared PHSSQ precursors first increased with increasing R1 or pH and then decreased at high values of R1. These results were explained by the effects of R1 and pH on the hydrolysis and condensation reactions. The cage/network ratio of the prepared PHSSQ films decreased with increasing curing temperatures and resulted in an increasing refractive index or dielectric constant. The steric effect from the side groups yielded PMSSQ films that had a smaller refractive index or dielectric constant than the PHSSQ precursors. PHSSQ films have potential applications as low‐dielectric‐constant materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2653–2660, 2004
Microencapsulation of capsaicin by the complex coacervation of gelatin, acacia and tannins
Authors: Xing Fubao , Cheng Guoxiang , Yang Bingxing , Ma Linrong 
Published: December 2003

AbstractWith gelatin and acacia as walls and capsaicin as the core substance, microcapsules were prepared through the mixing of two solutions of oppositely charged polymers and were then treated with tannins. The processing factors included the stirring rate and the types and dosages of the surfactants used in the preparation of the microcapsules. The morphology and size distribution of the microcapsules were analyzed with optical microscopy, environmental scanning electron microscopy, and laser particle size analysis. The microcapsules had a mean diameter of 20–30 μm, a maximal drug loading content of 19.84%, and an encapsulation efficiency of 88.21% with a good dispersion, even distribution, and round shape. The influence of the tannins on the morphology and structures of the microcapsules was also investigated, and their interaction mechanism was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2669–2675, 2004
Composition, tensile properties, and dispersion of polypropylene composites reinforced with viscose fibers
Authors: Paunikallio T. , Suvanto M. , Pakkanen T. T. 
Published: December 2003

AbstractThe reinforcement mechanics of viscose‐fiber‐reinforced polypropylene (PP) composites were studied. The effect of the coupling agent, maleated polypropylene (MAPP), was of special interest. The fibers, coupling agent, and PP were extruded and injection‐molded. The composition, mechanical properties, fracture morphology, and dispersion of the composites were examined. Thermogravimetric analysis showed that the fiber content in the tensile specimens varied slightly with the sample location; however, the differences in the values were within 1.0%. Scanning electron microscopy images of the fracture surfaces of the composites showed that the surfaces of the composites without MAPP were covered with fibers pulled out from the matrix. A lack of adhesion further appeared as a cracked matrix–fiber interface. A new scanning thermal microscopy method, microthermal analysis, was used to study the dispersion of the fibers in the composites. Local thermal analyses gave further information about the location of the fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2676–2684, 2004
Volumetric study of aqueous solutions of poly(ethylene glycol) from 283.15 to 313.15 K and at 0.1 MPa
Authors: Cruz Raphael Da C. , Martins Rosana J. , Cardoso Márcio J. E. De M. , Barcia Oswaldo E. 
Published: December 2003

AbstractDensity measurements of binary aqueous solutions of poly(ethylene glycol), with a nominal average molecular weight of 6000, were used to determine the specific volumes of the solutions with solute‐to‐solvent mass ratios (mass of the solute/mass of the solvent) of 0.0483–0.5493 and at seven different temperatures (283.15, 285.15, 293.15, 298.15, 303.15, 308.15, and 313.15 K). The difference between the specific volume of a solution and the specific volume of a pure solvent, at a given temperature, was expanded by a virial‐type equation, in terms of the solute concentration. The first‐order coefficient was the partial specific volume of a solute at infinite dilution. The higher order coefficients corresponded to the contribution of pairs, triplets, and higher order solute aggregates according to the constant‐pressure theory of solutions. The functional dependence of the virial coefficients on the temperature was examined in terms of solute–solute and solute–solvent interactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2685–2689, 2004
An analysis of the influence of the accelerator/sulfur ratio in the cure reaction and the uniaxial stress–strain behavior of SBR
Authors: Marzocca A. J. , Goyanes S. 
Published: December 2003

AbstractVulcanized styrene butadiene rubber (SBR) with different cure systems was prepared and analyzed by using the model of rubber elasticity based on the tube concept, applied to the treatment of the stress–strain measurements. Samples with several ratio accelerators to sulfur, Λ, between 0.22 and 3.0 cured at 433 K were studied. The network chain density and the crosslink density of the samples were evaluated. By means of normalized rheometer curves, the kinetics of cure of these samples were evaluated by considering the model of isothermal curing proposed by Kamal and Sourour. In this frame, the parameters of the kinetics model were obtained. A correlation between the order of the kinetic equation, n, and the network chain density of the cure samples was established. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2601–2609, 2004
Synthesis and polymerization of the bromoacrylated plant oil triglycerides to rigid, flame‐retardant polymers
Authors: Eren Tarik , Küsefoğlu Selim H. 
Published: December 2003

AbstractSimultaneous addition of bromine and acrylate to the double bonds of fatty acids in triglycerides was achieved. In the first part of the study, methyl oleate was bromoacrylated in the presence of acrylic acid and N‐bromosuccinimide as a model compound for the application of the reaction to the triglycerides. Next, soybean oil and high oleic sunflower oil were bromoacrylated by using the same procedure. The products were characterized by GC, IR, 1H‐NMR, 13C‐NMR, and mass spectrometry. The bromoacrylation yields for soybean oil and sunflower oil were 75 and 55%, respectively. A rigid thermoset polymer was prepared from the radical copolymerization of bromoacrylated soybean oil with styrene. The bromoacrylated sunflower oil–styrene copolymer showed semirigid properties. The crosslinked network structure of the copolymers was examined by their swelling behavior in different solvents. Glass‐transition temperatures were also determined and soybean oil–based polymer and sunflower oil–based polymer showed a glass transition at 55–65 and 20–30°C, respectively. The storage moduli of the soybean‐based and sunflower‐based polymers at room temperature were approximately 1.0 × 1010 and 1.1 × 108 Pa, respectively. Photopolymerization was also carried out by using 2,2‐dimethoxy‐2‐phenyl‐acetophenone as initiator. The response of the cured polymers to the thermal energy produced by a small flame was also tested by the ignition respond index method according to ASTM D 3713‐78 and was found to be 5 B at 2.00 mm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:2700–2710, 2004
Control of particle morphology and film structures of carboxylated poly(methyl methacrylate)/poly (n‐butylacrylate) composite latex particles
Authors: Kirsch S. , Stubbs J. , Leuninger J. , Pfau A. , Sundberg D. 
Published: December 2003

AbstractParticles with a hard core of 66% poly(methyl methacrylate)/34% poly(n‐butyl acrylate) copolymer and a soft shell of pure poly(n‐butyl acrylate) were synthesized via a two‐stage emulsion polymerization process. The particle morphology and the surface structure of the dispersion films were analyzed by atomic force microscopy (AFM). The results, concerning single particle structure and the corresponding films, are correlated to macroscopic properties similar to the minimum expected from the kinetic side. The different morphologies are compared to the findings reported in a previous article, where the corresponding soft‐core/hard‐shell dispersions were analyzed (Kirsch et al. Colloid Surf A 2001, 183–185, 725). The key parameters to tailor the particle morphology are thermodynamic factors, for example: (i) the stage ratio and (ii) the phase compatibility and kinetic factors affecting the polymer chain mobility (e.g., cross‐linking and polymer glass transition temperature). In this work, we used a core material which is in the glassy state at room temperature, however, above the polymer glass temperature (Tg) at polymerization temperature. The diffusion of the second‐stage polymer chains is therefore strongly affected. From this point of view, the major influence for the current system is expected from the kinetic side. The different morphologies of the single particles are discussed qualitatively and the effects of reaction parameters and our results from previous work are compared to the results of computer simulation work and other results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2610–2623, 2004
Evolution of peroxide‐induced thermomechanical degradation of polypropylene along the extruder
Authors: Machado A. V. , Maia J. M. , Canevarolo S. V. , Covas J. A. 
Published: December 2003

AbstractAn experimental study of the peroxide‐induced degradation of polypropylene in a corotating twin‐screw extruder, operating under various conditions, was reported. Runs were performed without and with peroxide in different concentrations. The evolution of the chemical reactions along the extruder was characterized by on‐line rheological measurements and by determination of the molecular weight of samples collected at the same locations. The results evidenced the relationships between peroxide concentration and processing conditions with rheological properties and molecular structure of the modified materials. The concept of chain‐scission distribution function elucidated the mechanisms involved in the thermomechanical degradation of PP, which is by chain scission and is dependent on the level of stress imposed by the screw elements, temperature, and concentration of hydrogen‐abstracting agents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:2711–2720, 2004
Positively charged composite nanofiltration membrane prepared by poly(N,N‐dimethylaminoethyl methacrylate)/polysulfone
Authors: Du Runhong , Zhao Jiasen 
Published: December 2003

AbstractPoly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) can be crosslinked by quaternization to develop a positively charged dense network structure. According to this mechanism, PDMAEMA/polysulfone (PSF) positively charged nanofiltration membrane was developed by interfacial crosslinking polymerization using PSF plate microfiltration membrane as support layer, PDMAEMA aqueous solution as coating solution, and p‐xylylene dichloride/n‐heptane as crosslinking agent. Technique and condition of developing membrane such as concentration of coating solution, coating time, pH value of coating solution, content of low molecular weight additive in coating solution, concentration of crosslinking agent, crosslinking time, and number of coatings were studied. FTIR, SEM, and X‐ray photoelectron spectroscopy were used to characterize the structure of membranes. This membrane had rejection to inorganic salts in water solution, the rejection rate to MgSO4 (1 g/L water solution at 0.8 MPa and 30°C) was about 90%, and permeation flux was about 10–20 L m−2 h−1. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2721–2728, 2004