bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of chlorinated poly(vinyl chloride) by blending with epoxidized polybutadiene
Authors: Sotiropoulou Dionissia D. , Gravalos Kostas G. , Kalfoglou Nikos K.
Published: April 2003

The 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

Cation 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

The 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

Polymethyl 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

Studies 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

Organosolv 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

The 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

The 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

Gel 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

Effects 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

A 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

Several 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

Styrene‐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

This 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.
A study of curative interactions in cis‐1,4‐polyisoprene. X. The cis‐1,4‐polyisoprene/sulfur/zinc dimethyldithiocarbamate and cis‐1,4‐polyisoprene/sulfur/zinc dimethyldithiocarbamate/ZnO systems
Authors: Kruger F. W. H. , McGill W. J.
Published: April 2003

Aspects of the mechanism of zinc dimethyldithiocarbamate (ZDMC)‐accelerated sulfur vulcanization were discussed. The trends in the efficiency parameter E, confirmed that crosslinking is preceded by the formation of pendent groups RSxSX [R = polyisoprenyl, X = Me2NC(S)] in ZDMC‐based systems. The index x in RSxX was calculated as 5.82 in the cis‐1,4‐polyisoprene (IR)/sulfur/ZDMC/ZnO compound at the initial stages of curing, compared to 3.23 in the absence of ZnO. The high value of x supports the postulation that elemental sulfur and ZDMC react at the early stages of vulcanization, to form the active sulphurating agent XSxSZnSSX. Crosslinks form by either a disproportionation reaction between two α‐methylic or α‐methylenic pendent groups RSxX, or a reaction between a pendent group RSxX and the rubber chain—these routes are the same as that suggested for the IR/tetramethylthiuram disulfide (TMTD)/ZnO compound. The beneficial role of ZnO and zinc stearate is shown, as in the case of ZnO in the IR/TMTD/ZnO system, to be related to their ability to trap dimethyldithiocarbamic acid, which formed in the generation of pendent groups and crosslinks. ZnS is inactive in this regard. The formation of ZnS is characteristic of natural rubber/sulfur/ZDMC/ZnO systems, as opposed to IR/TMTD/ZnO mixtures where little ZnS forms.
A study of the transport properties of acetylene through a highly oriented polyethylene fiber
Authors: Jones R. A. , Orchard G. A. J. , Ward I. M.
Published: April 2003

The transport properties of acetylene in a high modulus polyethylene fiber have been studied in detail over the temperature range of 25 to 65°C. Diffusion coefficients for the fiber are about four orders of magnitude lower than values cited for isotropic high density polyethylene. In keeping with this, a much higher apparent activation energy of diffusion (ca. 80.64 ± 0.53 kJ mol−1) was found. The solubility of acetylene in the fiber (ca. 0.158 cm3 C2H2 STP/cm3 PE @ 76 cm Hg), is lower, but of the same order of magnitude as that expected for isotropic polyethylene. The apparent heat of solution was determined, within experimental limits, to be zero. It is concluded that the acetylene is neither chemically nor physically absorbed onto the fiber, but freely diffuses, according to Fick's law, through the amorphous regions of the polymer.
Preparation and electrical properties of metal sulfides–amidoximated PAN composite film
Authors: Im Sung Soon , Lee Joon Sung , Kang Eun Young
Published: April 2003

To improve the electrical conductivity of polyacrylonitrile (PAN) film, metallic sulfides and PAN composite film were prepared by the chelating method. Dense PAN film and porous PAN film were prepared by dry process and wet process, respectively. These PAN films were treated to NH2OH solution to introduce the amidoxime group coordinated with metallic ion. Cu+2 and Cd+2 ions were adsorbed to amidoximated PAN films, the sulfur ion was treated with metal‐adsorbed PAN films, and thus CuS—and CdS–PAN composite films were prepared. The adsorptive capacity of amidoximated PAN film for the Cu+2 ion was independent of the morphology of the PAN film, but the adsorptive capacity of the Cd+2 ion on amidoximated PAN film was dependent on porosity of the polymer. Adsorptive capacity of amidoximated porous PAN film for Cd+2 was improved about four times than that of amidoximated dense PAN film. The electrical conductivities of CuS–dense and porous PAN composite film were both 10−1 S/cm in optimum condition, but because of the difference in adsorptive capacity, the electrical conductivities of CdS–dense and CdS–porous PAN composite films were 10−9 S/cm and 10−4 S/cm, respectively. Additionally, because CdS was known as a photoconductive material, the photoconductive properties of CdS–porous PAN composite film were investigated.
Recovery of uranium from seawater. X. Pore structure and uranium adsorption of macroreticular chelating resin containing amidoxime groups
Authors: Egawa Hiroaki , Nonaka Takamasa , Abe Syouichirou , Nakayama Morio
Published: April 2003

Eight types of amidoxime–type resin (RNH) were derived from macroreticular acrylonitrile—divinylbenzene copolymer beads, which were synthesized by varying the amount of polymerization initiator. Although these RNH are similar in chemical properties and physical pore structure, they exhibited different adsorption abilities for uranium. The porous structure of RNH in swollen state was analyzed by gel permeation chromatography in aqueous medium. The calibration curves yielded useful information on the pore structure of RNH in the swollen state and it was recognized that the pore structure in the swollen state is important for the improvement of the adsorption rate.
Macromolecular entanglement. III. Textural development of acrylic fibers
Authors: Qian B. J. , Qin J. , Wu Z. Q. , Wu C. X. , Hu P. P. , Zhao J. X.
Published: April 2003

The texture of a polymer (on fiber) is effectively developed by heat and stress. In this article, the chief material studied is acrylics, usually polyacrylonitile copolymer (PAC fiber) produced by Jingshan Jinglun Fiber Production Plant. In industry, the Jinglun acrylic fiber is heat treated, using saturated steam, at a temperature of 120–130°C to enhance its loop strength, reduce shrinkage, and stabilize crimp. At 140°C, the fiber becomes tacky and its good textile properties seem to deteriorate. At 150–160°C, the texture of the fiber seems to be deeply modified. Tested by differential scanning calorimetry (DSC) with the fiber immersed in a swelling agent (usually termed swelling DSC, abbreviated as SDSC), in addition to the entanglement peaks situated on the latter part of the thermogram of the Jinglun fiber, a new endothermic peak before the crystalline peak (actually, paracrystalline in the case of acrylic fiber) was discovered. The elastic recovery properties of the treated fiber under partially swelling conditions were improved. This seems to indicate that this preparacrystalline peak might also be concerned with entanglements.
Universal calibration for thermal field‐flow fractionation
Authors: Yushu Gao , Xiurong Chen
Published: April 2003

Experiments have shown that the thermal diffusion coefficient of a polymer is independent of the sample's molecular weight. According to the relationship between the ordinary diffusion coefficient and polymer molecular weight, a universal calibration method for thermal field‐flow fractionation (FFF) has been created. This method has been examined experimentally by three polymers of different chemical composition with different molecular weight in three organic solvents. It is shown that this method is useful both in terms of calibrating a thermal FFF system with some readily available polymer standard, for use with unknown samples of known thermal diffusivity, and in terms of determining the thermal diffusion coefficient of the unknown sample under conditions where its molecular weight can be measured by other methods.
Preparation of polymer‐supported schiff base iron (III) complexes and their catalytic activity for decomposition of hydrogen peroxide
Authors: Wang Xin , Gu Weihong , Lu Lude , Chen Zhijin , Stevens John G.
Published: April 2003

Polymeric substrates containing salicylidenimine ligands as discrete units can be obtained by reacting chloromethylated divinylbenzene styrene copolymer with amines, followed by condensation with salicylaldehyde. Polymer‐supported Schiff base iron (III) complexes have been prepared and their IR spectra and Mössbauer spectra measured. Catalytic activity of supported complexes have been tested using decomposition of hydrogen peroxide as a model reaction.
Rheology of neck formation in the cold drawing of polymeric fibers
Authors: Coleman Bernard D. , Newman Daniel C.
Published: April 2003

An asymptotic formula has been obtained for the axial tension in nonlinear viscoelastic fibers undergoing inhomogeneous stretch. The formula, which is valid to within an error of the fourth order in diameter, expresses the tension per unit cross‐sectional area in terms of the history of the local axial stretch and its first two derivatives with respect to distance along the fiber axis. The theory obtained by treating the formula as exact is consistent with thermodynamical principles, and permits computation of the stretch field resulting from a specified tensile loading history. Numerical results for creep under static load show that for an appropriate class of materials with slowly fading memory there is a range of applied loads for which an initially homogeneous deformation evolves into a well‐defined neck whose edges, after a period of relatively quiescent incubation, advance rapidly along the fiber and in so doing transform moderately stretched material into highly stretched, i.e., drawn material. The calculated fiber profiles and the predicted dynamics of neck formation are in accord with familiar observations of neck formation in polymeric materials susceptible to cold drawing.
Natural and artificial weathering of low‐density polyethylene (LDPE): Calorimetric analysis
Authors: Sebaa M. , Servens C. , Pouyet J.
Published: April 2003

Studies of the thermal and photodegradation of two commercial polymers, stabilized and unstabilized low‐density polyethylene (LDPE), show the effects of weathering in differential scanning calorimetry (DSC) curves. The shape and the size of the melting peak vary significantly in thermal aging and in accelerated photoirradiation, but no change was observed in natural weathering implying that the crystallinity remains steady in outdoor exposures. The melting temperatures remain steady for all exposure tests. The fall of mechanical properties and the evolution of chemical structure, followed by IR spectroscopy especially near the carbonyl regions, was also performed. The resistance to UV light irradiation as probed by deformation at break was superior in stabilized LDPE compared to unstabilized LDPE. Simple correlations were not observed between the fall of mechanical properties, the rate of oxidation, and the morphology.
Reactive extrusion vs. batch preparation of starch–g–polyacrylonitrile
Authors: Yoon K. J. , Carr M. E. , Bagley E. B.
Published: April 2003

Acrylonitrile (AN) was graft polymerized onto unmodified cornstarch by a continuous reactive extrusion process and, for comparison, by a typical batch reaction process. The effect of AN/starch weight ratios, level of ceric ammonium nitrate (CAN) initiator, starch in water concentration, reaction temperature, reaction time, and extruder screw speed in the reactive extrusion process was studied. Add‐on, reaction efficiency, grafting frequency, weight average molecular weight (MW) and MW distribution of polyacrylonitrile (PAN), and water absorbency of the saponified copolymers were determined. Processing times in the twin‐screw extruder (ZSK) were 2–3 min, and total reaction time was about 7 min before reaction of the extruded material was terminated, compared to a reaction time of 2 h used in the typical batch procedure. The continuous reactive extrusion process was found to be a rapid and efficient means of preparing St‐g‐PAN with high add‐on (% PAN of the grafted product). For example, 42% add‐on was achieved within the 7‐min reaction period using an AN/starch weight ratio of 1.0 (3.5% CAN, starch weight basis), as compared to 38–49% for the 2‐h batch process (0.75–1.5 AN/starch ratio). Percentages of homopolymer of the copolymers were low for both extrusion and batch processes. Grafting frequencies were substantially higher while MWs were significantly lower for grafts from the extrusion process. Water absorbency of the saponified St–g–PAN products was somewhat greater for the products prepared by the batch process.
Studies on characteristics and mechanisms of X–MoO3 synergism in fire‐retarded epoxy resin
Authors: Xiaoming Xu , Shiyuan Cheng , Jianzong Li
Published: April 2003

Molybdenum trioxide was incorporated into epoxy resin, containing halogen additive, and the performance of the system was studied. The results from LOI measurements show that X–MoO3 synergism in fire‐retarded epoxy resin depends on the levels both of halogen and MoO3, and that when Mo/X ratio is 1/3, the maximum fire retardancy is not found in the synergistic combination. The thermal analysis was carried out by thermogravimetry (TG), differential scanning calorimetry (DSC), X‐ray diffraction, and laser Raman spectroscopy. The results indicate that MoO3 acts as a synergist in condensed phase. The mode of X–MoO3 synergism in fire‐retarded epoxy resin in proposed.
Theory‐based improvements of continuous polymer fractionation demonstrated for poly(carbonate)
Authors: Weinmann K. , Wolf B. A. , Rätzsch M. T. , Tschersich L.
Published: April 2003

For the first time, a quantitative theoretical analysis (liquid/liquid phase equilibria treated by means of the continuous thermodynamics) of the operating characteristics of continuous polymer fractionation (CPF) was performed. The results of these calculations were compared with data published for CPF of polyethylene. It turned out that the efficiency of the conventional CPF corresponds to approximately two theoretical plates only. For this reason, several improvements, suggested by theoretical considerations, were realized experimentally, for which purpose the system dichloromethane/diethylene glycol/bisphenol‐A polycarbonate was chosen. The pulsating sieve‐bottom column was replaced by a nonpulsating column filled with glass beads. In this manner, the number of theoretical plates could be raised considerably. A further improvement of the fractionation efficiency results from the reflux of part of the polymer contained in the sol phase. In praxi, this situation was realized by putting a condensor on top of the column and introducing the feed somewhere near its upper third. After predictive calculations and orienting experiments, 125 g of a polycarbonate with Mw = 29 kg/mol and a nonuniformity U = 1.3 were fractionated in four consecutive CPF runs (where the gels were directly used as feed for the next step) into five fractions of approximately equal weight. Except for the lowest‐molecular‐weight fraction, one obtains nonuniformities on the order of 0.1.
Corrosion protection of steel and bond durability at polyphenylene sulfide‐to‐anhydrous zinc phosphate interfaces
Authors: Sugama T. , Carciello N. R.
Published: April 2003

To enhance the performance of high‐temperature polyphenylene sulfide (PPS) coating in protecting steels from corrosion, the cold‐rolled steel surfaces were prepared with anhydrous zinc phosphate (Zn · Ph) conversion coatings containing poly(acid) anhydride as an interfacial tailoring material. The factors contributing to the formation of a good bond at the PPS/Zn · Ph joints were as follows: (1) the chemical reaction of PPS with Fe2O3 in the Zn · Ph layers, (2) PPS‐to‐poly(acid) anhydride interaction, and (3) the mechanical interlocking between PPS and the rough Zn · Ph crystal surfaces. Although such interfacial bond structures provide a superior durability of PPS/Zn · Ph joints against a hot H2SO4 solution, the cathodic reaction, H2O + ½O2 + 2e− = 2OH−, occurring at any defect in the PPS/Zn · Ph joint system when NaCl is present will lead to the delamination of the PPS film from the phosphated steel. This cathodic delamination was due mainly to alkali‐induced dissolution of Zn · Ph layers. However, the rate of delamination for the PPS/Zn · Ph systems was considerably lower compared with that for the PPS/steel system in the absence of Zn · Ph.
Adhesive monomers to dental ceramics. I. Evaluation of N‐substituted 3‐amino‐2‐hydroxypropyl methacrylates as adhesives for calcium metaphosphate crystalline glass‐ceramic
Authors: Kitoh Shinya , Suzuki Kunitomo , Kiyohara Takao , Kurita Keisuke
Published: April 2003

N‐Substituted 3‐amino‐2‐hydroxypropyl methacrylates have been evaluated as adhesives for calcium metaphosphate crystalline glass‐ceramic, a potential esthetic dental restoration material. Although the adhesion to the ceramic was found to be much more difficult and dependent on the kinds of substituents than that of tooth enamel, monomers having a carboxyl group showed specifically high adhesive tensile strength. The strength tended to decrease as the hydrophobicity and molecular bulkiness increased. Surface treatment of the ceramic, especially with sodium hydroxide, proved effective in terms of both strength and durability for the carboxyl‐containing monomers. Scanning electron microscopy analysis confirmed the importance of surface irregularity due to the alkaline treatment.
The effects of functional azo initiator on PMMA and polyurethane IPN systems. II. The influence of the interface and the matrix structure on the mechanical properties
Authors: Roha M. , Dong F.
Published: April 2003

The mechanical properties of materials prepared by a new method for modifying the structure of polyurethane/poly(methyl methacrylate) (PU/PMMA) interpenetrating polymer networks (IPNs) by using a reactive azo initiator were investigated by means of tensile test, tear test, and dynamic mechanical thermal analysis (DMTA) measurement. The structures of these IPNs were similar to the particulate filled elastomers. It was found that the reactive initiator, which could form blocks of PMMA within the PU matrix (rubber), changed both the filler‐matrix interface and the matrix structure. The mechanical properties of these IPNs were dominated by the matrix structure and the interface.
Following of the relaxations in a polymer's behavior part II: Characterization by quasistatic and dynamic forced bending
Authors: Guerrin G. M. , Genevaux J. M.
Published: April 2003

The aim of this work is to quantify the internal loss in polymers, for frequencies near 1 Hz, and including the domain (100 and 3000 Hz). The quasistatic experiment used the double‐pendulum method; the other experiments were forced vibrations in bending. Two materials were tested between 20 and 60°C, PMMA and wood. Owing to the anisotropy of the wood, the different mechanisms that induce internal loss are located in the matrix or in the reinforcement (fiber) of this composite. The results were plotted on the correlation diagrams, presented in the first part of this study.
Adsorption mechanism of heavy‐metal ion by microspherical tannin resin
Authors: Yamaguchi H. , Higasida R. , Higuchi M. , Sakata I.
Published: April 2003

The spherical tannin resin (STR) resulting from the reaction between Mimosa (Acacia Mollissima) tannin (condensed‐type tannin) and formaldehyde was very porous. The specific surface area of the STR made from 37.5% of tannin was 139.2 m2/g (1 g of the resin in this is wet resin corresponding to 1 g of dried resin). Properties such as specific surface area and average pore radius could be controlled by adjusting the tannin concentration. The apparent activation energy of Cu2+ion adsorption by STR was 3 kcal/mol, and that of Cr6+ion was 2 kcal/mol. Since the energy was small, we concluded that the adsorption of metal ions was not influenced significantly by the adsorption temperature. The heat of adsorption for Cu2+ions was only 1.6 kcal/mol, which suggests that the adsorption was a physical phenomenon. It was thought that the diffusion of heavy‐metal ions into the porous resin was the rate‐determining step of the adsorption since the elution profile of the column method was analogous to the profile of active carbon, which adsorbs physically, the heavy metal ions gradually leaking through the column. The surface and cross section of the STR were observed before and after Cu2+ion adsorption with the scanning electron microscope. The pores of the spherical resin were clogged with adsorbed copper, suggesting that the Cu2+ions were adsorbed during the formation of a multimolecular layer. The adsorption may therefore have been due to physical attractive forces. The rate of adsorption and adsorption isotherms of Cu2+ions from copper salts having various anions was found to vary depending on the type of anion. These phenomena were not thought to be due to the properties of the spherical resin but to differences in the hydration state of copper ions.
Response of filled polyethylene membranes to the changes in the environmental conditions
Authors: Islam M. A. , Nikolov N. D.
Published: April 2003

The environmentally sensitive properties of polyethylene membranes filled with SiO2 have been studied. The porous characteristics of the membranes is investigated with the aqueous solutions of pH 1–8 and aqueous electrolyte solutions with concentrations of 10−5–10−1 mol/L. The experimental results are explained by the concept of coagulation‐swelling behavior of the filler under different environmental conditions. The relaxation of membrane resistance with a change in pH is also studied.
High‐temperature stabilization of polyolefines with hydroxides of alkali metals
Authors: Losev Yu. P. , Paushkin Ya. M.
Published: April 2003

Hydroxides of alkali metals are shown to be high‐temperature stabilizers of polyethylene. Potassium hydroxide is found to be most efficient. The reaction mechanism of alkali metal hydroxides as thermal stabilizers is considered.
Study of curative interactions in cis‐1,4‐polyisoprene. XII. The cis‐1,4‐polyisoprene–sulfur–tetramethylthiuram disulphide–ZnO–stearic acid vulcanization system
Authors: Kruger F. W. H. , McGill W. J.
Published: April 2003

Several aspects on the mechanism of vulcanization in the synthetic cis‐1,4‐polyisoprene (IR)‐sulfur‐tetramethylthiuram disulphide (TMTD)–ZnO system were harmonized. The differential scanning calorimetry (DSC) thermograms showed that the vulcanization processes became better resolved on increasing the curative loading in the compound. Two major crosslinking reactions occurred consecutively in the IR (100)–sulfur (9.46)–TMTD (8.86)–ZnO (3.00) mixture, viz the IR–sulfur–TMTD–ZnO and IR–sulfur–zinc dimethyldithiocarbamate (ZDMC) (or IR–sulfur–ZDMC–ZnO) reactions. In the first process poly‐and disulfidic pendent groups RSxSX (R = polyisoprenyl, X = Me2NC (S), x ≥ 1) formed via the IR–XSSxSX reaction, and in the second via the IR–XSSxZnSSX reaction. Thermogravimetric analysis (TGA) and high‐pressure liquid chromatography (HPLC) data showed that dimethyldithiocarbamic acid liberated during the IR–sulfur–TMTD–ZnO reaction was trapped by ZnO to yield ZDMC. Hence ZDMC was a product, and not precursor, of this crosslinking process. A comparison of reactions in IR–sulfur–TMTD–ZnO and poly(ethylene‐co‐propylene)–sulfur–TMTD–ZnO mixtures showed that the participation of IR molecules was essential for ZDMC formation. The ZDMC concentration remained constant at ∼ 38.4 mol % during the later stages of cure, showing that it did not participate in the desulfuration reactions of polysulfidic links. In the presence of stearic acid the stearic acid–ZnO reaction occurred at 87°C as was manifested by an intense crystallization peak of zinc stearate. The vulcanization processes were the same both in the presence and absence of stearic acid.
Instrumented impact testing of a glass swirl mat‐reinforced reaction injection‐molded polyamide block copolymer (NBC)
Authors: Karger‐Kocsis J.
Published: April 2003

The fracture behavior of a reaction injection‐molded (RIM) polyamide block copolymer (NBC) reinforced with a continuous glass strand mat (swirl mat) was studied in instrumented high‐speed impact‐bending tests. Investigations were carried out on Charpy and Izod specimens of different size and notching direction to elucidate specimens' size effects. From the tests performed at ambient temperature and −40°C, fracture mechanical parameters (fracture toughness, fracture energy) andE‐modulus were derived. Changes observed in the above parameters of the matrix were attributed to a molding‐induced skin‐core morphology. Both fracture toughness and energy of the composites depended strongly on the type, i.e., on the ligament width (W) and length‐to‐span ratio (L0/L) of the specimens. Reliable fracture mechanics data can be determined in three‐point bending whenW> 12 mm andL0/L> 1.7 for the specimens. The fracture toughness andE‐modulus increased monotonously, whereas the fracture energy reached a plateau as a function of fiber mat content. Their values were only slightly influenced by the temperature. It was also shown how molding‐and machining‐induced flaw size can be defined. The failure mode of the materials was studied by fractography and the failure events were summarized in a model and discussed.
Preparation of cationic water‐absorbent resin from PEI and PEO
Authors: Qirong Liu
Published: April 2003

Hydrophilic network copolymers containing poly(ethylene oxide) and polyethyleneimine blocks were prepared by cross‐linking polyethyleneimine with poly(ethylene oxide) terminated at both ends with Br atoms in DMSO. The experimental results show that the network density of the copolymer and the water absorption power thereupon can be efficiently controlled by the change of the amount of DMSO in the reaction system. Further modification was obtained by converting these copolymers into quaternary ammonium salts. The resulting quaternary ammonium salts exhibit enormously enhanced water absorption power. The absorption power of these quaternary ammonium salts in several organic solvents and in aqueous solutions containing Na+, Ca2+, Mg2+, or Fe3+ was also examined.
Viscometric behavior of ternary concentrated solutions of hydroxypropyl cellulose and ethyl cellulose in m‐cresol
Authors: Suto Shinichi , Kosaka Masato , Sugiura Terusada
Published: April 2003

The shear viscosity of blend solutions of hydroxypropyl cellulose (HPC) and ethyl cellulose (EC) in m‐cresol (both HPC/m‐cresol and EC/m‐cresol systems form lyotropic liquid crystals) was determined by cone‐plate‐type and capillary‐type viscometers. The textures for the same systems at rest and undergoing shear were also observed with a polarized microscope.

At shear rate of 1 s−1, viscosity exhibited a maximum and a minimum with respect to temperature, and this suggested that the phase of the matrix dominated the viscometric behavior of the ternary systems; the blend composition dependence of the viscosity was not additive, and this suggested that HPC and EC were immiscible. At relatively high shear stress, the blend composition dependence of the viscosity greatly depended on the total polymer concentration of the solutions and was quite different from that at low shear rate; the texture of the anisotropic solutions was also different from that at low shear rate. Our findings suggested that the dependence of viscosity on shear and concentration for pure HPC solution was different from that for pure EC solution.
Experimental relations between physical structure and mechanical properties of a huge number of drawn poly(ethylene terephthalate) yarns
Authors: Heuvel H. M. , Lucas L. J. , Van den Heuvel C. J. M. , De Weijer A. P.
Published: April 2003

The results of a study of the relation between a number of mechanical properties of poly(ethylene terephthalate) (PET) yarns and their physical structure are presented. The relation was studied on a set of 295 drawn yarn samples, resulting from an exceptionally large variety in process conditions applied. The size of this experiment offered a unique opportunity to study the property–structure relation more extensively than ever before. Therefore, our understanding of the mechanical properties could be enriched with several new insights. A selection of seven yarn properties has been investigated. Five of them have been derived from the stress–strain curves and the remaining two are shrinkage and shrinkage force. The physical structure has been described with a set of five, statistically selected, parameters. Most of the yarn properties could very well be described in terms of these structure parameters. This description was performed by means of an artificial neural network, ANN. The type of calculation is completely naive, i.e., without any specific mathematical formulation for the relation concerned. The fitting results have been translated into physical aspects related to the well‐known molecular two‐phase model. The practical importance of a good physical understanding of yarn properties is that the essential possibilities and impossibilities of combinations of properties can far more easily be surveyed and understood. As a result, the efficiency of process developments can be substantially improved.
Synthesis and characterization of saturated and unsaturated copolyesters based on bis‐1,4‐(dicarboxymethoxy) benzene
Authors: Essawy S. A. , El‐Sawy A. A. , Mahmoud A. A. , Badr S. K.
Published: April 2003

Saturated copolyester were prepared by copolyesterification of bis‐1,4‐(dicarboxymethoxy) benzene and phthalic anhydride with diethylene glycol, triethylene glycol, tetraethylene glycol, 1,4‐butane diol, 1,2‐propane diol, and 1,6‐hexamethylene glycol. Also, unsaturated copolyesters were prepared by copolyesterification of bis‐1,4‐(dicarboxymethoxy) benzene and maleic anhydride with the same glycols. All the copolyester resins obtained have been characterized and unsaturated copolyesters in the form of films were determined. IR and 1H‐NMR spectroscopy were used for both qualitative and quantitative analysis of the copolyesters resins and their hydrolyzate products, after curing with styrene. © 1992 John Wiley & Sons, Inc.
DC conduction in butyl rubber (IIR) loaded with carbon black
Authors: Abo‐Hashem A.
Published: April 2003

Current–voltage characteristics of samples of butyl rubber loaded with two different types of carbon black have been studied at different temperatures in the voltage range 10–3 KV. The conduction mechanism was found to follow the conventional band approach followed by the hopping model for isobutylene isoprene rubber (IIR) mixed with 40 phr of fast‐extrusion furnace black (FEF) carbon black and the hopping model for IIR mixed with 50 phr of semireinforcing furnace black (SRF) carbon black. © 1992 John Wiley & Sons, Inc.
Chemical interactions at the interface between a carbon fiber and a boron trifluoride‐catalyzed epoxy matrix
Authors: Wang Shiping , Garton Andrew
Published: April 2003

The cure of a tetrafunctional epoxy resin (largely tetraglycidyldiaminodiphenylmethane, TGDDM), cross‐linked with diaminodiphenylsulphone (DDS) and boron trifluoride/ethylamine (BF3EA) catalyst, is affected in a complex fashion by the presence of an oxidized carbon fiber surface. If the fiber is aged in a humid environment (25°C, 95% humidity) before coating with the matrix, the affinity of the oxidized fiber surface for water leads to destruction of the catalyst and retardation of the cure. This retardation is noticeable at lower humidities if the polymer content of the composite is reduced to > 20%. For oxidized fibers that are stored under ambient conditions (40% humidity), the retarding effect of water is overwhelmed by the catalytic effect of the acidic fiber surface. This activates the latent catalyst, increasing the rate of epoxy consumption and the proportion of the epoxy–epoxy reaction relative to the epoxy–amine reaction. For the low‐humidity case, even though the rate of chemical reaction is increased, vitrification of the matrix is retarded, implying that there is less cross‐linking and more extended epoxy–epoxy sequences in the network. The proposed chemical changes in epoxy/carbon fiber composites were confirmed by analysis of model reactions in solution. © 1992 John Wiley & Sons, Inc.
Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. XI. The influence of polymerization temperature on morphology and properties
Authors: Hourston D. J. , Huson M. G.
Published: April 2003

Polyurethane–poly(methyl acrylate) interpenetrating polymer networks (IPNs) of fixed composition (50/50) were prepared at 200 MPa and a range of temperatures. Decreased synthesis temperatures generally resulted in improved mixing of the two networks, although the sequence of formation of the two polymers was also important. No obvious improvements in physical properties resulted from the enhanced mixing. At high synthesis temperatures, the exothermic heat of polymerization of the methyl acrylate led to excessive temperatures, capable of degrading the already‐formed polyurethane network. This resulted in a deterioration in tensile strength and a decrease in hardness of the IPN. © 1992 John Wiley & Sons, Inc.
The mechanical behavior of blends of polyethylene, polypropylene, and an ethylene–propylene block copolymer at −20°C
Authors: Flaris Vicki , Stachurski Zbigniew H.
Published: April 2003

Compatibilization is necessary for most binary blends which display poor mechanical properties. The addition of an ethylene–propylene block copolymer to a blend of isotactic polypropylene and linear low‐density polyethylene alleviates the problem of poor adhesion at the interface. This was observed through the improvement in overall performance of the blend. It was noted that it is not solely the “interfacial agent” which is responsible for the improvement in impact strength of this blend. © 1992 John Wiley & Sons, Inc.