bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoselective modification of poly(vinyl chloride) in a twin screw extruder
Authors: Mijangos C. , Cassagnau P. , Michel A. 
Published: April 2003

AbstractContinuous chemical modification of poly(vinyl chloride) (PVC) with sodium benzene thiolate (NaBT) in a counter‐rotating twin screw extruder has been studied. The course of the reaction is analyzed, taking into account the physical changes of the polymer along the length of the screw. From the results, it is concluded that the modification reaction is associated with the fusion–gelation process. The reaction kinetics are determined as a function of the mean residence time with the aid of a UV tracer. Temperature profile, flow rate, and premixing are some of the processing parameters influencing the reaction, kinetics. The continuous modified polymer is analyzed in terms of thermal behavior, molecular weight, and stereochemical structure, and the results are compared with those obtained by a discontinuous melt process (Haake–Rheocord). It is confirmed that the same stereoselective substitution mechanism occurs as that in discontinuous melt with no side reactions.
Phase equilibria of modified ethylene glycol–maleic anhydride–phtalic anhydride polyester resins
Authors: Hyršl Jan , Podzimek Štěpán , Eichler Josef 
Published: April 2003

AbstractThis paper describes the influence of a termination of ended carboxyl groups of ethylene glycol–maleic anhydride–phtalic anhydride polyesters with cyclohexanole on a position of phase interface of the unsaturated polyester–styrene system. At given temperatures, optimal molecular weights were determined for the achievement of maximal miscibility of this polymer with styrene. Simultaneously, a model implicit equation was proposed, which is based on the assumption that the dependence of the interaction parameter χ on number‐average molecular weights is similar to that dependence of the interaction parameter χ on temperature. Solution of these implicit equation are isotherms in the phase diagram Mn−ϕ2−Tcloude point.
Crystal size and distortion parameter of natural pure mysore silk fibers (Bombyx Mori)
Authors: Somashekar R. , Urs R. Gopalkrishna , Madhava M. S. 
Published: April 2003

AbstractCrystal size and lattice distortion parameters were determined experimentally by recording X‐ray diffraction patterns of natural silk fiber (pure Mysore silk, Bombyx Mori) using Fourier cosine coefficients of the intensity profile of an X‐ray (210) reflection. Also, the crystal size distribution along [210] direction is given.
Effect of methanol on optical property of irradiated poly(methyl methacrylate)
Authors: Lin C. B. , Lee Sanboh 
Published: April 2003

AbstractThe effect of methanol on optical property of irradiated poly(methyl methacrylate) (PMMA) has been investigated. The gamma irradiation enhances the methanol transport in PMMA. The activation energies of diffusivity for case I and velocity for case II decreases with increasing gamma ray dose. For the same wavelength, in the range 350–800 nm, the transmittance decreases with increasig gamma ray dose. The equation of transmittance I with gamma ray dose ϕ at the wavelength 405 nm is I = I0 exp(−0.06ϕ1/2), where I0 is the transmittance of virgin PMMA. When the irradiated PMMA is immersed into methanol bath, the yellow color fades out gradually. The recovery of transmittance increases with methanol content in irradiated PMMA. The boundary to separate the outer region (solvent affected zone) from the inner region (no solvent‐affected zone) is also studied. The rate of boundary movement increases with gamma ray dose.
Diffusion of water into a photopolymer film
Authors: Best Margaret Evans , Moylan Christopher R. 
Published: April 2003

AbstractSorption of water vapor into thin films of a crosslinked dimethacrylate UV‐cured polymer was measured by means of a quartz crystal microbalance apparatus. The diffusion coefficient and solubility were obtained. An upper limit to the water vapor diffusion coefficient, namely, the diffusion coefficient for liquid water in intimate contact with the sample, was measured for reference purposes by both gravimetric and infrared spectral techniques. A water uptake value for thick films was obtained gravimetrically as a reference for the thin film value. Measurement of the diffusion coefficient allows the determination of the length of time that the photopolymer could act as an effective water vapor barrier.
Application of poly(butadiene‐co‐acrylic acid)–sucrose as gel in the separation of different substances
Authors: Alvarez C. , Bertorello H. , Strumia M. 
Published: April 2003

AbstractThe synthesis of a new hydrophobic gel by reacting cooligomer of butadiene and acrylic acid (Mw 4500) with sucrose crosslinking in best conditions is described. Application of this new gel swelled in different organic solvents is studied. Separation of organic substances in benzene was achieved with higher retention of more polar substances. By this way, cholesterol was separated from lecithin, acrylic acid from polybutadiene with terminal carboxylic groups, and metals such as copper from organic solvents.
Effect of barbituric acid on the self‐polymerization reaction of bismaleimides
Authors: Pan Jing‐Pin , Shiau Gwo‐Yuh , Lin Song‐Shiang , Chen Ker‐Ming 
Published: April 2003

AbstractBarbituric acid (BTA) was used as an initiator for the homopolymerization of bismaleimide (BMI). The reaction was controlled by the amount of barbituric acid and ended up with solvent‐soluble oligomers. The effects of varying the amounts of BTA, as well as the reaction time, on BMI's self‐polymerization reaction were investigated. The thus‐formed oligomers were characterized by gel permeation chromatography (GPC), infrared spectra (IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The degree of reaction increased proportionally to the concentration of BTA or the length of the reaction time. Thus, solvent‐soluble BMI oligomer can be controlled and obtained.
Development of potentially degradable materials for marine applications. III. Polyethylene‐polyethylene oxide blends
Authors: Gonsalves K. E. , Patel S. H. , Trivedi D. H. 
Published: April 2003

AbstractThe effect of a simulated marine environment on unstabilized polyethylene‐polyethylene oxide blends, having varying polyethylene oxide content (up to 40% by weight), with or without a metal catalyst (e.g., cobalt (III) acetylacetonate) and a metal containing plasticizer (e.g., aluminum stearate), has been studied for 10 weeks exposure time. In the absence of metal catalyst and plasticizer, phase separation of polyethylene oxide was quite evident visually after melt mixing and subsequent regular compression molding of polyethylene‐polyethylene oxide blends. However, these blends rendered better and uniform mixing in the presence of metal catalyst and plasticizer. Since polyethylene oxide is a water soluble component of the system, % weight loss increased significantly with increase in its content after exposure to brine. These blends have been further characterized by tensile properties, optical and scanning electron microscopy, and thermal analysis in order to monitor mechanical as well as morphological changes.
Creep of polycarbonate: Experiments and correlation with relaxation
Authors: Malkin Alexander Ya. , Teishev Albert E. , Kutsenko Michael A. 
Published: April 2003

AbstractThe correctness and reliability of different methods of creep function calculations from relaxation curves were investigated by the computational experiment method. It was shown that an adequate description of some initial (relaxation) curve was not sufficient for the correct determination of the proper creep function. The best results can be achieved by the method of expansion of a relaxation curve into the discrete sum of exponents; some other procedures of analytical approximation of relaxation curves can lead to considerable unexpected errors in calculated creep functions.The experiments were done with polycarbonate (PC) in the linear stress range and also at high stresses. The limits of linear viscoelastic behavior were determined.
Modification of chlorinated poly(vinyl chloride) by blending with epoxidized polybutadiene
Authors: Sotiropoulou Dionissia D. , Gravalos Kostas G. , Kalfoglou Nikos K. 
Published: April 2003

AbstractThe compatibility of epoxidized poly(cis‐1,4‐butadiene) (EPB) with chlorinated polyvinylchloride (CPVC) was investigated. Blends studied covered the complete composition range using EPB at two degrees of epoxidation: 20 and 43 mol % oxirane units. Tensile properties of EPB (63)/CPVC were also studied at the 50/50 composition. Dynamic mechanical analysis (DMA) showed that both sets of blends were miscible at the segmental level except for the rich CPVC compositions. All blends showed good tensile properties. even those where DMA indicated phase separation. This may be attributed to strong segmental interactions of the donnor‐acceptor type between the oxirane and acidic‐hydrogen‐containing groups of these complementary dissimilar blend partners.
Uphill and selective transport of uranyl ions through 2,3‐epithiopropyl methacrylate–2‐acrylamide‐2‐methyl propane sulfonic acid copolymer membranes
Authors: Nonaka Takamasa , Ogawa Hirofumi , Morikawa Masateru , Egawa Hiroaki 
Published: April 2003

AbstractCation exchange membranes were prepared with 2,3‐epithiopropyl methacrylate (ETMA)‐2‐acrylamide‐2‐methylpropane sulfonic acid (AMPS) copolymers. Transport of uranyl ion against its concentration gradient through the membranes was investigated by using a system containing carbonate solution (left side) and uranyl ion (and other metal ion) solution (right side). ETMA–AMPS copolymer membranes transported UO2+2 against its concentration gradient. Na2CO3 solution was most effective as receiving solution for the uphill transport of UO2+2. The transport was greatly affected by the composition of the copolymer membranes. Highly selective transport of UO2+2 from the solution containing UO2+2 and other metal ions was observed by using Na2CO3 solution in the left side. The main driving force for this transport of UO2+2 is the high complex‐formation ability of UO2+2 with CO2−3.
Polymerization of methyl methacrylate in water and water–ethylene glycol mixtures
Authors: Badran A. S. , El‐Hakim A. A. Abd , Ayoub M. M. H. , Younan A. F. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate (MMA) was carried out in water and in water‐ethylene glycol (EG) mixtures using sodium bisulfite as initiator. The rate of polymerization was found to be dependent on the initiator, the monomer, and ethylene glycol concentrations to the powers 0.68, 1.08, and 1.5, respectively. Addition of ethylene glycol increased both the rate of polymerization and the viscosity average molecular weights of the obtained polymers, while the rate of polymerization was found to decrease with temperature. The apparent activation activation energies were found to be 13.79 and 10.45 kJ/mol in water and in water‐ethylene glycol mixture (50/50) (v/v), respectively.
Effects of injection temperature on the mixing level and properties of injection‐mixed PMMA–phenoxy blends
Authors: Erro R. , Gaztelumendi M. , Nazabal J. 
Published: April 2003

AbstractPolymethyl methacrylate‐phenoxy blends have been obtained in an injection machine at different injection temperatures in order to determine the possibility of direct blending in these processing machines and also the effect that different blending levels have in the mechanical properties of these miscible blends. High injection temperatures, but in the range used in production of the components, provided fairly well homogenized blends comparable both in transparency and mechanical properties to those obtained by kneading and subsequent compression molding. Very good mechanical properties, although less transparent, were obtained when processing at low injection temperatures.
Synthesis of starch‐g‐poly(acrylamide‐co‐sodium allylsulfonate) and its application of flocculation to Kaolin suspension
Authors: Yao K.‐J. , Tang Y.‐B. 
Published: April 2003

AbstractStudies were conducted on grafting of acrylamide (AM) and sodium allylsulfonate (SAS) onto cornstarch utilizing Ce(IV) as initiator. The influence of synthetic variables on percent grafting and grafting efficiency have been discussed. The starch‐g‐poly(AM‐co‐SAS) samples prepared by this method were characterized by IR spectroscopy, scanning electron micrograph, and elemental analysis. These graft copolymers may induce the flocculation of Kaolin suspension and showed excellent ability in both the rates of sedimentation and the clearing of supernatant liquid in the presence of NaCl.
Light scattering of acetylated lignin
Authors: Merkle Gerhard , Auerbach Sabine , Burchard Walther , Lindner Albert , Wegener Gerd 
Published: April 2003

AbstractOrganosolv lignin was fractionated on a Sephadex G 75 column with 0.1M aqueous NaOH resulting in 14 fractions. These fractions were acetylated and a high‐molecular‐weight fraction (F3) was investigated by means of combined static and dynamic light scattering (LS) in solvents acetone, tetrahydrofuran (THF), and trifluoroethanol (TFE). The measurements were found to be reproducible, and recycling of lignin by freeze drying caused slight but unessential changes in solution properties. Depending on the solvent used, weight average molecular weights Mw between two and ten million were found. By contrast, Mn of the fractions, measured by vapor pressure osmometry (VPO), was in the range of a few thousands only. Analysis of the angular dependence in static LS by means of a Casassa–Holtzer plot and the fractal dimensions showed the presence of chain stiffness, most distinct in TFE. Also, the dynamic light scattering results in TFE are typical for semiflexible chains, while in THF, and to some extent in acetone, the dynamic measurements including viscosity suggest the presence of spherical structures. These findings are being explained by large lignin clusters that consist of stiff subunits.
Effect of wood sawdust on the aqueous polymerization of methyl methacrylate
Authors: El‐Awady M. M. 
Published: April 2003

AbstractThe effect of different woods such as water‐treated Eucalypt Sawdust (ESD), alkali‐treated ESD, and untreated white pine SD in the presence and absence of Cu2+ ions on the aqueous polymerization of methyl methacrylate (MMA) was studied. It was found that the percent conversion was considerably higher in the presence of treated ESD and white pine SD. The percent conversion was further increased upon copper‐treated ESD. The highest conversion values (> 95%) were those obtained in the presence of copper leached from alkalitreated ESD and the least conversion values (> 16%) were those obtained in the absence of copper in the untreated ESD.
Effect of diameter and surface treatment of fiber on interfacial shear strength in glass fiber/epoxy and HDPE
Authors: Moon Chang Kwon , Lee Jang‐Oo , Cho Hyun Hok , Kim Kyoo Sung 
Published: April 2003

AbstractThe effect of fiber diameter and the surface treatment of fiber on the interfacial shear strength between glass fiber and matrix (epoxy and high‐density polyethylene) has been investigated. Pullout experiments for measuring the interfacial shear strength have been carried out through use of microbonding and the solution microbond test methods for the epoxy and HDPE composite systems, respectively. From this study, it has been found that the interfacial shear strength decreased with the increasing fiber diameter regardless of the type of fiber surface treatment for both resin systems.
Use of GPC‐UV to determine the location of functional groups in styrenic polymers
Authors: Warner Sandra L. , Howell Bob A. , Smith P. B. , Dais V. A. , Priddy D. B. 
Published: April 2003

AbstractGel permeation chromatography (GPC) is one of the most important characterization tools of the polymer chemist. The coupling of GPC with ultraviolet (UV) spectroscopy (GPC–UV) increases the power of the tool even further. This article describes the use of GPC–UV to determine the location of functional groups in polymers. This information is important for characterization of functionalized polymers being used as building blocks for making block and graft copolymers, and for the elucidation of polymer degradation mechanisms. The use of GPC–UV for quantitation of the level of functional groups is hampered by the inability to achieve complete conversion of some UV transparent functional groups (e.g., hydroxyl and carbonyl) to the uniquely absorbing derivative needed for the analysis. Attempts to quantitatively derivatize polymer‐bound functional groups using conditions developed for model compounds failed. However, the use of GPC–UV to locate functional groups in polymers (pendant vs. chain‐end) is clearly demonstrated.
Isothermal physical aging of poly(methyl methacrylate): Localization of perturbations in thermomechanical properties
Authors: Venditti R. A. , Gillham J. K. 
Published: April 2003

AbstractEffects of isothermal physical aging on poly(methyl methacrylate) (PMMA) were investigated for isothermal aging temperatures (Ta) from Tg−13 to Tg−128°C using a freely oscillating torsion pendulum (TBA). A single PMMA‐glass fiber specimen, the effects of the thermal history of which could be erased by heating above Tg (=116°C, 0.7 Hz), was used for all experiments; this facilitated comparison of the unaged and aged specimen. The modulus was observed to increase linearly with the logarithm of isothermal aging time. Thermomechanical properties of the aged versus unaged specimen showed perturbations (e.g., increased modulus) principally in the vicinity of Ta. This suggests that different intermediate portions of the relaxation spectrum are specifically involved in the process of aging for different values of Ta.
Synthetic resins. XII. Synthesis and characterization of the resins derived from resacetophenone–substituted benzoic acids–furfural
Authors: Senapati M. , Burma S. P. N. S. , Nayak P. L. 
Published: April 2003

AbstractA number of resin copolymers have been synthesized by condensing resacetophenone with substituted benzoic acids and furfural in the presence of some base as catalyst. The resins have been characterized by IR spectra of the characteristic groups. The number‐average molecular weights of the resins have been determined by the conductance method. The solubility and viscosity behavior of the resins have been determined. Cu2+, Ni2+, Co2+, Mn2+, Zn2+, and Mg2+ chelates have been prepared. The resins were shown to be selective ion exchangers for certain metal ions. The batch equilibrium method was used to study the selectivity of the metal ions. The thermal behavior of the resins has been determined. The values of energy of activation of the degradation of the resins were computed by using the Freeman‐Anderson and Broido methods. The biological assays of some of the resins have been evaluated, and some of them were found to be highly sensitive to the bacteria studied.
A study of curative interactions in cis‐1,4‐polyisoprene. VIII. Network maturing reactions in the cis‐1,4‐polyisoprene/tetramethylthiuram disulfide/ZnO system
Authors: Kruger F. W. H. , McGill W. J. 
Published: April 2003

AbstractSeveral aspects concerning the network maturing reactions of the cis‐1,4‐polyisoprene (IR)/tetramethylthiuram disulfide (TMTD)/ZnO curing system, were evaluated with reference to previously published literature. The crosslink density increased progressively from 1.42 × 10−5 mol cm−3 rubber at 140.0°C, to 8.30 × 10−5 mol cm−3 at the higher temperature of 190.0°C, which tied in with the fact that natural rubber (NR) or IR/TMTD/ZnO systems show negligible reversion provided sufficient ZnO is present. The increase in the crosslink density value was accompanied by a systematic buildup of monosulfidic crosslinks, and a substantial decrease in the concentration of tetramethylthiuram monosulfide (TMTM). Calculations showed, in addition, that the increase in the concentration of zinc dimethyldithiocarbamate (ZDMC) and the decrease in the TMTM concentration, were interdependent. It is shown that TMTM, rather than ZDMC, was involved in the crosslink shortening reactions.
Functional polymers for colloidal applications (III): Structural effects of lipophile‐modified styrene‐maleic anhydride copolymers on dispersing polar and nonpolar particles
Authors: Kuo Ping‐Lin , Ni Sheng‐Chung , Lai Chien‐Chi 
Published: April 2003

AbstractStyrene‐maleic anhydride copolymer (SMA) with the molecular weight (MW: 7100) suitable for acting as a dispersant was synthesized and then ring‐opened with alkylamine to prepare the n‐butyl and n‐dodecyl‐substituted SMA. The prepared lipophile‐modified SMA copolymers were used as dispersants to disperse both polar and nonpolar particles (TiO2 and carbon black). Upon dispersing TiO2 and carbon black, the antibridging effect (a larger optimum concentration and a less sharp increase after optimum concentration) was observed for SMA as well as n‐butylamide‐substituted SMA as compared to sodium polyacrylate. The bridging effect, however, is obvious for n‐dodecylamide highly substituted SMA (12N45). For dispersing TiO2, both for n‐butyl and n‐dodecylamide‐substituted SMA, the curve of viscosity vs. concentration increases less sharply after optimum concentration except for 12N45. In the case of dispersing carbon black, the n‐butylamide‐substituted SMA shows a pronounced antibridging effect, while the n‐dodecylamide‐substituted SMA shows a significant bridging effect. The minimum viscosity and the optimum concentration for both n‐butyl and n‐dodecylamide‐substituted SMA are correlated to conclude that: (a) at low percentage of alkylamide in SMA, both for n‐butyl and n‐dodecyl group cause bridging phenomena and increase the viscosity; (b) as the percentage of alkylamide in SMA increase, the adsorption effect is more important for n‐butylamide‐substituted SMA (e.g., 4N45), and the bridging effect is more important for n‐dodecylamide‐substituted SMA (e.g., 12N45); (c) the decrease in optimum concentration for 12N45 can be interpreted by the bridging effect.
Studies of the effects of the organometallic coupling agents on adhesion of the glass fiber–BMI composites
Authors: Chou S. , Chen H.‐C. , Lee K.‐S. 
Published: April 2003

AbstractThis work investigates the increase of adhesion between glass fiber and BMI. Five kinds of organometallic coupling agents of Ti, Zr, and Zr/Al are used to treat the fiber surface and then to reinforce BMI. A more efficient way is to mix the coupling agents directly into BMI and then reinforce by glass fiber. Then compare the adhesion of resulting composites, which are made by two methods described as above. As a result, the mechanical properties of the latter is slightly lower than the former. The Ti coupling agents are most effective, followed by Zr coupling agents and then Zr/Al coupling agents. Mixing Ti coupling agent directly into BMI, the degree of curing measured by DSC is 90%, the shear strength of the GFRP increases 31.9%, the flexural strength increases 30.8%, and the tensile strength increases 34.0%. Analyzing the chemical bonding by FT‐IR, we found that choosing the organometallic coupling agent of type [RO–Ti (OX–R'NH2)3] and adding it to BMI can most effectively improve the adhesion. TGA shows that directly mixing coupling agent into BMI only changes a little of its thermal cracking temperature. Observed by SEM, we know that using coupling agent can promote adhesion between BMI and glass fiber.