bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of oxirane groups on curing behavior and thermal stability of vinyl ester resins
Authors: Malik Mona , Choudhary V. , I. K. Varma  
Published: October 2004

AbstractThe effects of oxirane groups in vinyl ester (VE) resin and reactive diluent on curing characteristics and thermal behavior of cured resins are described. Stoichiometric (0.5:1, sample A) as well as nonstoichiometric (0.5:0.85, sample B) ratios of the diglycidyl ether of bisphenol‐A (DGEBA) and methacrylic acid (MA) were used for the synthesis of VE resins. Resin sample B had more residual epoxy groups because of the stoichiometric imbalance of the reactants. VE resins thus obtained were diluted with methyl methacrylate (MMA; 1:1, w/w), and controlled quantities of epoxy groups were introduced by partial replacement of MMA with glycidyl methacrylate (GMA), keeping the overall ratio of resin and reactive diluent constant. Increase of GMA content in resin A or B resulted in a decrease in gel time, indicating that the curing reaction is facilitated by the presence of epoxy groups. An increase in initiator content also reduced the gel time. In the differential scanning calorimetry (DSC) scans, a sharp curing exotherm was observed in the temperature range 107 ± 3–150 ± 1 °C. The onset temperature (Tonset) and peak exotherm temperature (Texo) decreased with increase in GMA content. Heat of curing (ΔH) also increased with increase in GMA content. A broad exotherm was observed after the initial sharp exotherm that was attributed to the etherification reaction. Cured VE resins were stable up to 250–260 °C, and started losing weight above this temperature. Rapid decomposition was observed in the temperature range 400–500 °C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 416–423, 2001
A new metal chelate sorbent for glucose oxidase: Cu(II)‐ and Co(II)‐chelated poly(N‐vinylimidazole) gels
Authors: Salih Bekir , Pekel Nursel , Güven Olgun 
Published: October 2004

AbstractPoly(N‐vinylimidazole) (PVIm) gels were prepared by irradiating a binary mixture of N‐vinylimidazole (VIm)–water in a 60Co‐γ source having 4.5 kGy/h dose rate. In the glucose oxidase (GOx) adsorption studies, affinity gels with a swelling ratio of 1100% for PVIm and 40 and 55% for Cu(II)‐ and Co(II)‐chelated PVIm gels, respectively, at pH 6.5 in phosphate buffer were used. FTIR spectra were taken for PVIm and Cu(II)‐ and Co(II)‐chelated PVIm, and glucose oxidase adsorption on these gels, to characterize the nature of the interactions in each species. The results show that PVIm–glucose oxidase interaction is mainly electrostatic and metal ion–chelated PVIm gel–glucose oxidase interaction is of coordinate covalent nature. Cu(II) and Co(II) ions were chelated within the gels via amine groups on the imidazole ring of the gel. Different amounts of Cu(II) and Co(II) ions [maximum 3.64 mmol/g dry gel for Cu(II) and 1.72 mmol/g dry gel for Co(II)] were loaded on the gels by changing the initial concentration of Cu(II) and Co(II) ions at pH 7.0. GOx adsorption on these gels from aqueous solutions containing different amounts of GOx at different pH was investigated in batch reactors. GOx adsorption capacity was further increased when Cu(II) and Co(II) ions were attached [up to 0.53 g GOx/g dry Co(II)‐chelated PVIm gels]. More than 90% of the adsorbed GOx was desorbed in 5 h in desorption medium containing 1.0M KSCN at pH 7.0 for plain gel and 0.05M EDTA at pH 4.9 for metal‐chelated gel. Nonspecific glucose oxidase adsorption on/in the metal ion–chelated PVIm gel was investigated using 0.02M of phosphate buffer solution. The nonspecific GOx adsorption was determined to be about 18% for PVIm and 8% for the metal ion–chelated PVIm gels. The ionic strength effect was investigated both on PVIm and on the metal ion–chelated PVIm gels for the glucose oxidase adsorption. It was found that ionic strength was more effective on the PVIm gel because of the electrostatic interaction between protonated gel and the deprotonated glucose oxidase side chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 446–453, 2001
Characterization of branched polymers by SEC coupled with a multiangle light scattering detector. II. Data processing and interpretation
Authors: Podzimek S. , Vlcek T. 
Published: October 2004

AbstractThis study deals with the characterization of branched polymers by means of size‐exclusion chromatography coupled with a multiangle light scattering detector (SEC‐MALS). The application of SEC‐MALS is demonstrated on several randomly branched polystyrene and star‐branched poly(benzyl methacrylate) samples. Various methods of the data processing are compared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 454–460, 2001
Master curves and lifetime prediction for the epoxy system badge n = 0/m‐XDA by thermogravimetric analysis
Authors: Fraga F. , Rodríguez Núñez E. 
Published: October 2004

AbstractMaster plots were used to corroborate Rn‐type mechanisms calculated in a previous study, using the method proposed by Criado et al. (Thermochim Acta 1989, 147, 377). Analysis of experimental data seems to belong to the family of decelerated curves (Rn) in the range of conversion studied. The lifetime of the system diglycidil ether of bisphenol A (BADGE n = 0)/m‐xylylenediamine (m‐XDA) for different decelerated mechanisms was calculated using thermogravimetric analysis. From the experimental data it was found that the optimum temperature range of use for this material is 60–100°C for all Rn‐type mechanisms, at which corresponding lifetimes range between 190 years and 1 year. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 461–466, 2001
Solution and interfacial behavior of hydrophobically modified water‐soluble block copolymers of acrylamide and N‐phenethylacrylamide
Authors: Abu‐Sharkh B. F. , Yahaya G. O. , Ali S. A. , Kazi I. W. 
Published: October 2004

AbstractHydrophobically modified water‐soluble block copolymers were prepared by aqueous micellar copolymerization of acrylamide and small amounts (2 and 3 mol %) of a hydrophobe (N‐phenethylacrylamide) that is characterized by a long spacer that places the aromatic ring far away from the backbone, with the objective of investigating the copolymers' rheological behavior and surface and interfacial activities under various conditions such as polymer concentration, shear rate, temperature, and salinity. As expected, the block copolymers exhibit improved thickening properties attributed to intermolecular hydrophobic associations as the solution viscosity of the copolymers increases sharply with increasing polymer concentration. Additional evidence for intermolecular association is provided by the effect of NaCl, the presence of which substantially enhances the viscosity. An almost shear rate–independent viscosity (Newtonian plateau) is also exhibited at high shear rate and a typical non‐Newtonian shear thinning behavior appears at low shear rates and high temperatures. Furthermore, the block copolymers exhibit high air–liquid surface and liquid–liquid interfacial activities as the surface and interfacial tensions decrease with increasing polymer concentration, indicating strong adsorption of the copolymer at the interface. The surface and interfacial tensions exhibited by the copolymers were found to be relatively insensitive to the concentration of salt (NaCl). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 467–476, 2001
Preparation and identification of a soluble copolymer from pyrrole and o‐toluidine
Authors: Li Xin‐Gui , Wang Lin‐Xia , Jin Yi , Zhu Zhi‐Liang , Yang Yu‐Liang 
Published: October 2004

AbstractA series of copolymers were prepared by chemically oxidative polymerization of pyrrole (PY) and ortho‐toluidine (OT) in HCl aqueous medium. The yield, intrinsic viscosity, and solubility of the copolymers were studied by changing the monomer molar ratio. The resulting PY/OT copolymers were identified by FTIR, 1H–NMR, DSC, and WAXD techniques. The experimental results showed that the oxidative polymerization of pyrrole and o‐toluidine is exothermic and the resulting polymers exhibit an enhanced solubility in most organic solvents compared with that of pyrrole homopolymer. The polymer obtained is a real and amorphous copolymer containing pyrrole and o‐toluidine units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 510–518, 2001
Compounding of poly(dimethyl siloxane) to reduce tack in natural rubber
Authors: Pattanakul Wipawee , Magaraphan Rathanawan , Grady Brian P. 
Published: October 2004

AbstractTack in natural rubber latex was reduced by compounding poly(dimethyl siloxane) (PDMS) emulsion in concentrated latex. Sheet and dipped film surfaces were examined with Fourier transform infrared spectroscopy using attenuated total reflection (FTIR–ATR) and by contact angle measurements. Autohesive tack and tensile properties were also determined. For both sheet and dipped film, FTIR–ATR showed that the PDMS concentration was higher at the glass surface than at the air surface. The contact angle of ethylene glycol on the rubber decreased with increasing PDMS content. Autohesive tack for sheet and dipped film also decreased with increasing PDMS amount; however, annealing for 1 week at 70°C in air did cause tack to rise in the sheets. The rubber surface could be made nonadhesive by addition of sufficient PDMS. PDMS caused a decrease in tensile strength for the sheet, especially after annealing; however, PDMS did not cause a substantial decrease in percentage elongation for the sheets, except at relatively high PDMS contents. The tensile strength and percentage elongation for dipped film was not affected by PDMS over the much more limited PDMS concentration range studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 519–526, 2001
Development of a simplified relationship between uniaxial creep, stress relaxation, and constant strain‐rate results for viscoelastic polymeric materials
Authors: Sudduth Richard D. 
Published: October 2004

AbstractThis publication introduces a new mathematical model to describe a definitive relationship between constant strain‐rate, creep, and stress‐relaxation analysis for viscoelastic polymeric compounds. This new concept is especially significant since it adequately describes all the important characteristics of both creep and stress relaxation in the same model. In particular, all three phases of creep (i.e., primary, secondary, and tertiary) can be described adequately using this model. This new model for polymeric materials also indicates that yielding for constant strain‐rate measurements and the inception of tertiary creep appear to be directly related and may, in fact, be manifestations of the same phenomena. The initial buildup of stress followed by the drop off in stress as a function of time for stress relaxation is also adequately described. This new formulation approach also offers a reasonably simple process in which to shift from a constant strain‐rate configuration to a creep calculation or stress‐relaxation configuration without changing formulation considerations. Most importantly, this model can be used to make a transition from one of these stress‐configuration modes to another without stress or strain discontinuities. It is hoped that this analysis approach will open new doors for the design of plastic products for both short‐term and long‐term applications. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 527–540, 2001
Synthesis and air separation of soluble terpolymers from Aniline, Toluidine, and Xylidine
Authors: Li Xin‐Gui , Huang Mei‐Rong , Zhu Li‐Hua , Yang Yuliang 
Published: October 2004

AbstractA series of terpolymers were synthesized by oxidative polymerization of aniline, o‐toluidine, and 2,3‐xylidine with three monomer ratios using ammonium persulfate as an oxidant in two acidic media. The yield and intrinsic viscosity of the terpolymers were studied by changing the polymerization temperature and medium. The resulting terpolymers were characterized by 1H–NMR, wide‐angle X‐ray diffraction, differential scanning calorimetry, thermogravimetry, and constant pressure‐variable volume methods. The results showed that the terpolymers are amorphous and exhibit enhanced solubility, high thermostability, and high char yield, greater than 35 wt % at 900°C in nitrogen. A blend membrane of the terpolymer with ethyl cellulose shows good air‐separation ability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 790–798, 2001
Studies on the composites of cellulose triacetate (prepared from sugar cane pulp) and gelatin
Authors: Rajini R. , Venkateswarlu U. , Rose C. , Sastry T. P. 
Published: October 2004

AbstractSugarcane waste (bagasse) which is hitherto discarded as a waste at sugarcane parlors and jaggery units was recovered and cellulose triacetate (CTA) was prepared from the same, after isolation of cellulose. Using this CTA, CTA–gelatin composites were prepared. The materials prepared (i.e., sugarcane cellulose, CTA, CTA–gelatin composites) were characterized for their mechanical properties, water absorption capacity, infrared spectroscopy, and scanning electron microscopy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 847–853, 2001
Synthesis and characterization of an isocyanurate–oxazolidone polymer: Effect of stoichiometry
Authors: Chian K. S. , Yi S. 
Published: October 2004

AbstractIsocyanurate–oxazolidone polymers were synthesized by using various reactant stoichiometry of a diglycidyl ether of bisphenol‐A (DGEBA) and a polymeric diphenyl methane diisocyanate (pMDI). The reaction was catalyzed by tris‐2,4,6‐dimethylaminoethylphenol (Ancamine K54). The effects of stoichiometry that the reaction had on the molecular structure and mechanical and thermomechanical properties were evaluated. Two main structures obtained from the reaction of DGEBA with pMDI, namely isocyanurate and oxazolidone, were clearly shown by Fourier transformed infrared spectroscopy (FTIR) analyses. It was found that the amount of DGEBA present determines the amount of oxazolidone formed. Where excess DGEBA was used, structural transformation reaction from isocyanurate to oxazolidone was observed. The amount of pMDI, on the other hand, influenced the amount of isocyanurate structure formed. As the relative amounts of isocyanurate and oxazolidone contents changed with stoichiometry of the reactants, the effects on the crosslink density in the samples were clearly shown by both mechanical and thermomechanical measurements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 879–888, 2001
Hydrolysis of aromatic heterocyclic polymers in high temperature water. I. Hydrolysis of polyphenyl‐1,2,4‐triazine
Authors: Yi Xiao‐Bing , Wu Guo‐Shi , Lu Feng‐Cai , Tang Au‐Chin 
Published: October 2004

AbstractThe hydrolytic behaviors of polyphenyl‐1,2,4‐triazine (As–PPT) at high temperatures were investigated both experimentally and theoretically. The hydrolytic experiments of As–PPT film and a reasonably designed model compound for the polymer were carried out in distilled water at 250°C/3.97 MPa under N2atmosphere, respectively. The hydrolytic reactions were monitored by FTIR and UV‐Vis spectra, and their hydrolysates were identified by FTIR, HPLC, and MS. The results confirmed that the two reactions gave the same major hydrolysate, terephthalic acid. In addition, the electronic structure of its model compound, given by ab initio calculation at the 4‐31G level, indicated that the triazine ring is the hydrolytically active part at which the N atoms are to be protonated. On the basis of these results, a hydrolytic mechanism is proposed, which suggests that the cleavage of one CN bond takes place, primarily on the triazine rings, followed by a gradual rupture of the polymer chain and the formation of the intermediate terephthalonitrile, the further hydrolysis of which produces terephthalic acid.© 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82;907–915;2001
Synthesis and properties of polysiloxane containing N,N′‐bis(diphenylsilyl)tetraphenylcyclodisilazane
Authors: Zhou N. , Zhang Z. J. , Xu C. H. , Xie Z. M. 
Published: October 2004

AbstractA new kind of polysiloxane containing N,N′‐bis(diphenylsilyl)tetraphenylcyclodisilazane was prepared by the anionic polymerization with a “seed solution” as initiator. The synthesis of monomers N,N′‐bis(hydroxydiphenylsilyl)tetraphenylcyclodisilazane (BHPTPC), N,N′‐bis(chlorodiphenylsilyl)tetraphenylcyclodisilazane (BCPTPC), and 1,3‐dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) are all reported in this study. The synthesized polysiloxane containing N,N′‐bis(diphenylsilyl)tetraphenylcyclodisilazane was characterized by 1H–NMR, 29Si–NMR, gel permeation chromatography (GPC), and intrinsic viscosity. The thermal stability of the polysiloxane was studied by isothermal gravimetric analysis (IGA). The results demonstrated that the synthesized polysiloxane containing N,N′‐bis(diphenylsilyl)tetraphenylcyclodisilazane had excellent thermal stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 929–933, 2001
Study of microbial polyhydroxyalkanoates using two‐dimensional Fourier‐transform infrared correlation spectroscopy
Authors: Wu Qiong , Tian Ge , Sun Suqin , Noda Isao , Chen Guo‐Qiang 
Published: October 2004

AbstractThe premelting behavior of bacterially synthesized polyester poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate), abbreviated as P(HB‐co‐HHx), was investigated by two‐dimensional Fourier‐transform infrared (2D FTIR) correlation spectroscopy. The temperature‐dependent dynamic spectra were measured over a temperature range of 25–300°C. We focused our study on the thermally induced intensity fluctuations of bands for CO (1700–1760 cm−1), CH (2910–3010 cm−1) and COC groups (1220–1310 cm−1) stretching vibrations. Changes of crystalline conformation due to the thermal perturbation could be detected by the intensity and location variations of those characteristic bands responding to the variations of dipole moments. 2D correlation analysis indicated that the appearance of fully amorphous component did not happen simultaneously with the disappearance of crystalline component, suggesting that there was an intermediate state between ordered crystalline and amorphous states in P(HB‐co‐HHx). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 934–940, 2001
Solution thermodynamics of the dextran/methoxy ethylene glycol system
Authors: Güner Ali , Çatiker Efkan 
Published: October 2004

AbstractThe main thermodynamic parameters were evaluated for the dextran/methoxy ethylene glycol (MEG) system by viscosity measurements at 25, 30, 35, 40, and 45°C. The long‐range and short‐range interaction parameters were determined by extrapolation methods, i.e, Kurata‐Stockmayer‐Fixman, Berry, and Inagaki‐Suzuki‐Kurata equations. Calculated values, as well as the unperturbed root‐mean‐square end‐to‐end distance and hydrodynamic expansion factor, were interpreted mainly on the basis of hydrogen‐bond formation between polymer segments and dextran/MEG molecules in solution. The thermodynamic interaction parameter was also evaluated for the same system. The theta temperatures were obtained from the temperature dependence of the interaction parameter, dependence of (1/2‐χ) and the second virial coefficient in the temperature interval of 25 and 45°C for the system and quite a good accordance was indicated with the calculated values evaluated via extrapolation and interpolation methods. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 948–953, 2001
Study of the actions of BTEX compounds on polypyrrole film as a gas sensor
Authors: Lin C. W. , Liu S. S. , Hwang B. J. 
Published: October 2004

AbstractPolypyrrole (PPy) thin films were prepared electrochemically at a constant potential. Gas‐sensing behaviors, including reproducibility, sensitivity, and response time to various benzene, toluene, ethylbenzene, and xylene (BTEX) compound concentrations, were investigated. BTEX compounds were found to be able to compensate for the doping level of PPy and, hence, decrease the conductivity of PPy on exposure to them. A reasonable reproducibility of the resistance change (ΔR) was obtained. The sensitivity for each compound was 2.3 mω/ppm (benzene), 0.4 mω/ppm (toluene), 8.3 mω/ppm (ethylbenzene), and 2.9 mω/ppm (xylene). An adsorption model correlated well with the experimental results and was used to interpret the sensing behaviors. The parameters of this model, including the adsorption equilibrium constant and the ΔR caused by a pseudomonolayer of the detecting layer {[m(r1 − r0)]/n, where m is the number of active sites on the pseudomonolayer; r1 and r0 are the site resistances when the site is vacant and occupied, respectively; and n is the thickness of the film}, were determined. According to the parameters, toluene vapor had the most prominent effect in undoping PPy film but the poorest affinity to the active sites of the film. On the other hand, ethylbenzene showed the highest affinity to PPy film compared to the other BTEX compounds and consequently led to the highest sensitivity for such a sensor. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 954–961, 2001
Effect of sintering on surface chemistry and surface energy of pigmented latex coatings
Authors: Al‐Turaif H. , Lepoutre P. 
Published: October 2004

AbstractDrying in the absence of water (sintering) of pigmented coatings made of styrene–butadiene (SB) latex and kaolin clay at different levels of pigmentation was investigated. As found from X‐ray photoelectron spectroscopy, sintered coatings showed a higher SB area percent on the surface than did latex with a high glass‐transition temperature (Tg) and dried at room temperature. This was a result of latex spreading at the surface. Sintering the high‐Tg coatings that were dried at room temperature caused a decrease in the surface energy. Drying in the presence of water (wet coalescing) was compared to drying in the absence of water (sintering). Even though sintered coatings were more porous and had higher gloss, no significant difference was found in the SB/clay ratio at the surface or in the surface energy above the critical pigment volume concentration (CPVC). However, at and below CPVC, the sintering process yielded a higher SB content at the surface and a lower surface energy than the wet‐coalescing process. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 968–975, 2001
Optimization of physical and mechanical properties of rubber compounds by a response surface methodological approach
Authors: Sridhar V. , Prasad K. , Choe S. , Kundu P. P. 
Published: October 2004

AbstractResponse surface methodology was used for optimizing the ratio of vegetable oil and carbon black and occluded volume fraction of rubber in the compound. Central composite design for two variables was chosen as the experimental design. The data obtained from measurement of properties was fitted as a two variable second‐order equation, and were plotted as contours using software developed from MATLAB v.5.1. From contours it is observed that at the ratio of 0.06 of vegetable oil and carbon black, there is maximum coupling, and a further increment in vegetable oil and carbon black ratio shows less coupling and more plasticizing effect. The ultimate failure properties like tensile and tear strength and elongation decreases with an increase in occluded volume fraction, reaches a minima at the central region, followed by an increase, whereas 300% modulus and hardness decreases throughout.© 2001 John Wiley & Sons, Inc, J Appl Polym Sci 82: 997‐1005, 2001