bluuebunny/crossref_metadata_2025 huggingface dataset:
PVC filled with vacuum pyrolysis scrap tires‐derived carbon blacks: An investigation on rheological, mechanical, and electrical properties
Authors: Dufeu J. B. , Roy C. , Ajji A. , Choplin L.
Published: April 2003

Pyrolysis of scrap tires produces oil and carbon black (CB). The purpose of this work is to compare pyrolytic CBs with commercial grades as fillers for poly(vinyl chloride) (PVC). Blending of PVC with CB was performed in the melt at 180°C. The compositions prepared were 1,5,10,20, and 30 wt % of CB. The dynamic rheological, mechanical, and electrical properties of the PVC–CB composites were investigated. The results obtained for the storage modulus and complex viscosity of the composites of PVC with the pyrolytic CBs were between those of a high‐grade (Monarch 1100) and a low‐grade (Sterling R) commercial CBs. Intermediate tensile modulus, elongation at break, and electrical conductivity were also obtained. The specific surface area of the CB was shown to influence the composite properties. Reduction of the volatile matter and ash contents of the pyrolytic CB led to better properties of the PVC composites. © 1992 John Wiley & Sons, Inc.
Preparation of polymeric initiators of the anionic polymerization of lactams from polyetherdiols
Authors: Stehlíĉek J. , Chauhan Ghanshyam S. , Znáŝiková M.
Published: April 2003

The kinetics of alcoholysis of bis(N‐acyl‐6‐hexanelactams) and bis(N‐carbamoyl‐6‐hexanelactams) was studied for the purpose of the preparation of bifunctional polymeric initiators of the anionic polymerization of 6‐hexanelactam used in the production of polyamide block copolymers by reactive processing. The reaction was carried out with 1‐octanol as a model alcohol and with poly(propylene oxide)diol, without catalysis or using anionic and polyesterification catalysts, and in 6‐hexanelactam as a solvent. Applicability of this functionalization method is discussed with respect to a broad spectrum of formed products, competition of lactam oligomerization in the presence of basic catalysts, preparation of the initiator component for two‐component polymerization systems, and in situ functionalization during polymerization. © 1992 John Wiley & Sons, Inc.
Mechanical properties of complexed α,ω‐diamino polybutadiene
Authors: Tant M. R. , Song J. H. , Wilkes G. L. , Charlier P. , Jerome R.
Published: April 2003

α,ω‐Dipiperazino polybutadiene (PBD) was complexed with the hydrated forms of copper chloride, iron chloride, and nickel chloride in methanol. The polymers were recovered and compression molded into films and properties investigated. In particular, the tensile stress‐strain behavior as well as stress relaxation behavior were monitored with time at ambient conditions. It was observed that the polybutadiene material showed a strong association with copper providing a pseudo network behavior. The association for the iron and nickel components were considerably weaker than that of copper. Comparisons of the data obtained from these systems were also made with earlier data obtained from the same laboratory on carboxylated or sulfonated telechelic ionomers based on polyisoprene and polyisobutylene. It was concluded that the copper complex with the α,ω‐dipiperazino polybutadiene has comparable or better behavior than some of the carboxylate systems. © 1992 John Wiley & Sons, Inc.
Preparation and characterization of 2‐cyanoacrylate copolymers
Authors: Stein Michael
Published: April 2003

Butyl and ethoxyethyl 2‐cyanoacrylate and mixtures thereof in different molar ratios were subjected to polymerization at pH 2.0, 3.0, 4.0, 5.5, and 6.9 and characterized by X‐ray diffraction, hot‐stage microscopy, and NMR analysis. The polymers were in an X‐ray amorphous state. Their softening temperatures increased with ascending pH during polymerization. In all cases, the temperatures of the ethoxyethyl polymers were below those of the butyl polymers. Softening temperatures between those of the pure polymers could by achieved by copolymerization. The molar composition of the polymers was checked by NMR analysis. © 1992 John Wiley & Sons, Inc.
Thermal conductivities of blends of polyethylene/SEBS block copolymer and polystyrene/SEBS block copolymer
Authors: Agari Y. , Ueda A. , Nagai S.
Published: April 2003

Thermal conductivities of two series of blends of polystyrene and styrene–ethylene/butyrene–styrene block copolymer (PS/SEBS), and polyethylene and styrene‐ethylene/butylene‐styrene block copolymer (PE/SEBS) were measured. Here the PS part and hydrogenated polybutadiene (EB; ethylene‐butene‐1 copolymer) part of SEBS were confirmed to be miscible in PS and PE homopolymers, respectively, by the differential scanning calorimetry. The thermal conductivity of PS/SEBS increased, while that of PE/SEBS blends decreased monotonically, with increasing SEBS content. No significant changes in the range where microphases usually occur were noted. The thermal conductivities of PS/SEBS and PE/SEBS were explained by modifications of our equation for composites. Thermal conductivity of EB in SEBS was estimated from that of PS/SEBS blend as 4.9 × 10−4 cal/s cm °C. Further, the thermal conductivity of PE/SEBS could be predicted by substituting the obtained value of EB into the modified equation. Therefore, the modified equations were confirmed to be applicable to thermal conductivities of PE/SEBS and PE/SEBS blends. © 1993 John Wiley & Sons, Inc.
IR spectroscopy approach for the study of interactions between an oxidized aluminium surface and a poly(propylene‐g‐acrylic acid) film
Authors: Romero M. A. , Chabert B. , Domard A.
Published: April 2003

In this paper, we report the study of the interactions between a poly(propylene‐g‐acrylic acid) and an oxidized aluminium surface by IR spectroscopy. A deposit of a pure poly(acrylic acid) on the same surface is used as a model. Under free acid form (COOH) we demonstrate the formation of hydrogen bondings between the acrylic carboxyl groups and OH functions located at the surface of alumina. This is characterized by an IR absorption [v(co)] at 1733 or 1743 cm−1 when we observe the metal surface either after peeling of a PPg(OH) film initially pressed on it or after a deposit of PAA(OH). Under the carboxylate form (COO−), we observe two modes of interaction, the one purely ionic between COO− and Al3+ with an absorption located near 1550 cm−1 and the other of complex form between COO− and Al3+ giving a band near 1610 cm−1. The water molecules can play a major part, in particular in the first case (COOH) where they destroy hydrogen bondings in favor of the formation of COO− groups, interacting with the metal surface according to ionic or complex modes as above. © 1993 John Wiley & Sons, Inc.
Determination of polymer‐solvent interaction parameters using piezoelectric crystals, with reference to the sorption of chemical warfare agents
Authors: Charlesworth John M. , Riddell Stuart Z. , Mathews Robert J.
Published: April 2003

Polymeric materials which show sensitivity to certain classes of organic vapors and give minimal responses from interferents are being sought for use as coatings on piezoelectric mass detection devices. The present work illustrates some simple methods for the determination of fundamental properties such as polymer‐solvent interaction parameters and diffusion constants, and relates these to the sensitivity and response time of the sensor. Polymers with a controlled variation in crosslink density were exposed to a variety of common solvents and vapors covering a range of solubility parameters. Seven non‐crosslinked amorphous polymeric materials were also assessed for their suitability as selective coatings for the detection of a range of chemical warfare vapors. Gross differences in the response characteristics of coated crystals immersed in liquids can be predicted, and an approximate guide to the relative rates of solvent penetration can also be obtained. More accurate predictions are hampered by the lack of knowledge of the specific interactions which occur within polymer–solvent pairs. Crosslinking the polymer film to enable operation in strongly solvating liquids has the effect of reducing the extent of swelling to a larger degree than expected on the basis of existing theories. The operation of coated crystals in the gas phase at very high vapor concentrations leads to a dual site adsorption process which can be described by the BET equation. At much lower vapor concentrations Henry's law appears to determine the response, and a simple solution model developed from partition theory for stationary phases in gas–liquid chromatography can be used to interpret the sensitivity of three non‐crosslinked amorphous polymeric films to DMMP, GA, GB, and GD. While adequately describing the responses of the organophosphorus esters, the model is not as satisfactory in predicting the interactions with HD. © 1993 John Wiley & Sons, Inc.
Study on the synthesis of perfluorovinyl‐sulfonic functional monomer and its copolymerization with tetrafluoroethylene
Authors: Kostov G. K. , Kotov St. V. , Ivanov G. D. , Todorova D.
Published: April 2003

Tetrafiuoroethylene (TFE) and hexafluoropropylene (HFP) were subjected to reactions with freshly distilled sulfur trioxide to obtain 1‐fluorosulfonyldifluoro‐acetylfluoride (FSDFAF, yield 65–70%) and pentafluoro‐2‐propenylfluorosulfate (PPFS, yield up to 50%). A subsequent reaction of FSDFAF with PPFS under anhydrous conditions led to a preparation of 2‐(1‐pentafluoro‐2‐propenyloxy)tetrafluoroethanesulfonyl fluoride (PPOTESF, yield 40–41%) whose structure was proved by both infrared (IR) spectroscopy and nuclear magnetic resonance (19F NMR). TFE was copolymerized with PPOTESF in bulk by using a free radical initiator of the hydrocarbon type at a temperature of 50°C. Various TFE/PPOTESF mole ratios were employed and the presence of sulfonyl fluoride (SO2F) functional groups in the copolymers was proven by IR spectroscopy. The copolymers were subjected to alkaline hydrolysis and the SO2F content was found not to exceed 0.70–0.80 mEq/g with polymer yields in the range of 11–31%. The reactivity ratios r1 and r2 related to TFE and PPOTESF, respectively, were determined by using the Fineman‐Ross method. A random distribution of PPOTESF units along the polymeric chain, consisting mainly of TFE fragments, was found to exist. The copolymers had melting temperatures 40–45°C lower than polytetrafluoroethylene and were thermally stable to 305–315°C. © 1993 John Wiley & Sons, Inc.
Preparation and characterization of aromatic polyimides and related copolymers
Authors: Li Shaohua , Karasz Frank E.
Published: April 2003

Copolyimides containing BTDA‐3DDS and BTDA‐4ODA units have been synthesized by solution imidization methods. The copolyimides have high Tg's (267–283°C) and high decomposition temperatures (540–575°C; nitrogen); both properties are dependent on composition. Those copolymides with low concentrations of BTDA‐4ODA are generally soluble in organic solvents, whereas those copolyimides with higher BTDA‐4ODA content are only partially soluble or insoluble. However, all the copolyimides prepared can be compression molded. It has also been found that segmental motion above Tg is heavily suppressed in the BTDA‐4ODA homopolymer relative to that in the BTDA‐3DDS homopolymer. This reduction in molecular motion may severely hinder the solubility and fusibility of the BTDA‐4ODA homopolymer. © 1993 John Wiley & Sons, Inc.
Kinetic analysis of high‐resolution TGA variable heating rate data
Authors: Salin I. M. , Seferis J. C.
Published: April 2003

Isothermal and constant heating rate thermogravimetric analysis (TGA) experiments have been performed for examining decomposition of polymers and composites. In practice, low heating rates are necessary to obtain good resolution under nonisothermal conditions thus increasing the time required for experiments. A novel TGA mode, high‐resolution TGA (Hi‐ResTM TGA), provides a means to remarkably increase the resolution while often decreasing the time required for experiments. In this variable heating rate mode of Hi‐ResTMTGA, the heating rate is continuously and dynamically varied to maximize resolution. Thus, traditional methods cannot be directly utilized to determine kinetic parameters. Accordingly, in this work, variable heating rate experiments were run on ethylene‐vinylacetate (EVA) copolymer, poly(ether ether ketone) (PEEK), and carbon‐fiber‐reinforced bismaleimide (BMI), whose kinetics have been quantitatively described with traditional isothermal and nonisothermal experiments. Comparison of the different techniques led to the development of a simplified method by which the activation energy, preexponential factor, and reaction order can be extracted from variable heating rate TGA experiments. The technique, based on the principle that maximum weight loss rate is observed at minimum heating rate, gave kinetic results that were in excellent agreement with values that have been determined by traditional isothermal and dynamic experiments. © 1993 John Wiley & Sons, Inc.
Studies on fiber formation of thermotropic copolyesters
Authors: Mehta Sanjay , Deopura B. L.
Published: April 2003

Thermotropic copolyesters PET/60 PHB and PET/80 PHB fibers are melt spun at different extrusion temperatures and at different draw‐down ratios. The flow behavior of PET/60 PHB is studied at different temperatures and shear rates. The melt of (PET/60 PHB) at temperatures above 265°C exhibit low viscosity and low activation energy of flow. The modulus and strength for both PET/60 PHB and PET/80 PHB fibers increase with the increase in extrusion temperature and draw‐down ratio in the ranges studied. High birefringence, indicating the presence of mesophase is observed between 265 and 300°C on a hot stage polarizing microscope. X‐ray diffraction patterns show that the molecular orientation increased with increasing draw‐down ratio. Scanning electron microscopy of these fibers shows a well‐developed highly oriented fibrillar structure. Superior mechanical performance of fibers spun at around 275°C are attributed to the presence of nematic mesophase in the polymer melt. © 1993 John Wiley & Sons, Inc.
Wavelength sensitivity of the photodegradation of poly(methyl methacrylate)
Authors: Mitsuoka Takuya , Torikai Ayako , Fueki Kenji
Published: April 2003

Poly(methyl methacrylate) (PMMA) was photolyzed with monochromatic light of wavelengths 260, 280, 300, 320, 400, and 500 nm in vacuo by the use of the Okazaki Large Spectrograph. UV spectral changes, the quantum yields of main‐chain scission (ϕcs), and effects of wavelength were investigated. UV spectral changes around 280 nm were observed with irradiation at 260 nm. The ϕcs has a maximum value in case of irradiation with 300 nm light. It turned out that photodegradation of PMMA took place by irradiation of 260–320 nm light but did not by irradiation with the light longer wavelength than 340 nm. The average values of ϕcs obtained in this work were 0.84 × 10−4, 1.06 × 10−4, 4.21 × 10−4, 1.23 × 10−4, 0, and 0 for irradiations at 260, 280, 300, 320, 400, and 500 nm, respectively. It was found that the photo‐induced side‐chain scission initiates the main‐chain scission of PMMA by irradiation of 260 and 280 nm light. © 1993 John Wiley & Sons, Inc.
Surface and interfacial FTIR spectroscopic studies of latexes. IV. The effect of surfactant structure on the copolymer–surfactant interactions
Authors: Thorstenson Timothy A. , Urban Marek W.
Published: April 2003

The interactions between sodium dodecylbenzene sulfonate (SDBS) and the components of an ethyl acrylate/methacrylic acid (EA/MAA) copolymer latex were examined and the influences of using D2O as the synthetic suspension medium were investigated. Whereas it is found that D2O has no detectable influence on the fully coalesced latex films, the film coalescence conditions are shown to significantly affect the nature of surfactant interactions within the film matrix. When films are prepared and stored under controllable low atmospheric water‐vapor concentrations, hydrogen‐bonding interactions between the surfactant SO3−Na+ groups and the copolymer acid functionality dominate. However, coalescence and storage of the films under higher relative humidity conditions results in a displacement of these interactions in favor of the hydrated form of the surfactant. It is also shown that the presence of an aromatic ring adjacent to the surfactant sulfonate group exerts an influence on the nature of the SO3− ··· HOOC interactions within the copolymer matrix. Relative to sodium dioctyl sulfosuccinate (SDOSS), the aromatic group near hydrophilic end of SDBS increases the strength of the SO bond in the presence of acid interactions. © 1993 John Wiley & Sons, Inc.
Laser‐irradiation effect on poly(vinyl alcohol) films doped with nanometer‐sized CdS particles: Ablation and third‐harmonic generation
Authors: Nosaka Yoshio , Tanaka Kazunori , Fujii Nobuyuki
Published: April 2003

Ultrasmall CdS particles, whose average size was controlled by thiols to range from 2 to 4 nm, were embedded in poly(vinyl alcohol) films. Shift of the fluorescence peak associates with the shift of the absorption threshold of the films, and the fluorescence intensity increases with the decrease in the size of CdS. Laser ablation at 308 nm was investigated by monitoring the emission spectra. Third‐harmonic generation was measured for various sizes of CdS particles, and the optical nonlinearity in the nonresonance region was found to remain almost constant in the diameter range studied. © 1993 John Wiley & Sons, Inc.
Cyclohexanone oxime‐blocked polyisocyanates
Authors: Kothandaraman H. , Thangavel R.
Published: April 2003

Cyclohexanone oxime‐blocked isophorone diisocyanate and cyclohexanone oxime‐blocked toluene diisocyanate were synthesized and analyzed by infrared spectra, nuclear magnetic resonance spectra, elemental analysis, etc. Decomposition temperatures of the blocked isocyanates were determined by thermogravimetry. The solubilities of blocked isocyanates in various polyols were tested. © 1993 John Wiley & Sons, Inc.
Fracture toughness of high‐impact polystyrene based on threej‐integral methods
Authors: Lee Chang‐Bing , Lu Ming‐Luen , Chang Feng‐Chih
Published: April 2003

ThreeJ‐integral methods and their modified versions have been used to characterize the fracture toughness of high‐impact polystyrene (HIPS) with different thicknesses. TheJcvalues obtained were highest from the E813–87 method, followed by the E813–81 method, then by the hysteresis method. The hysteresis method based on the steep rising of hysteresis energy under constant displacement‐controlled loading inJcdetermination has many advantages over the ASTM E813–81 or the E813–87 method. The requirement of crack growth length measurements is no longer necessary and the controversial issue on the crack blunting line can also be avoided. The E813–87 method resulted in significantly higherJcvalues for polymers, but the modified version of E813–87, by moving the offset line from the original 0.2 to 0.1 mm, resulted in comparableJcvalues. Since crazes as the main failure mechanism for HIPS, well‐defined crack blunting does not expect to occur and theJcobtained by the original E813–81 based on the theoretically predicted blunting line is indeed slightly higher. The modified version of E813–81 by neglecting the blunting line inJcdetermination is believed to be more reasonable for HIPS. The nature of polymers will determine whether the crack tip will be blunted, partially blunted, or not blunted. ASTM E813–81 is appropriate for those polymers with a well‐defined blunted crack tip (such as elastomer‐modified polycarbonate), whereas the modified version of ASTM E813–81 seems better for those polymers with craze as the main failure mechanism (such as HIPS). Experimental results indicated that this hysteresis method is able to inherently adjust the crack blunting effect and therefore can be applied to any type of ductile polymer. © 1993 John Wiley & Sons, Inc.
Structural, mechanical, and thermal properties of extruded sheets of a liquid crystalline copolyester
Authors: Kyotani Mutsumasa , Kaito Akira , Nakayama Kazuo
Published: April 2003

Structural, Mechanical, and thermal properties of extruded sheets of a liquid crystalline copolyester containing p‐hydroxybenzoic acid and 2‐hydroxynaphthoic acid were investigated using X‐ray diffraction measurements, differential scanning calorimetry, rheovibron measurements, and scanning electron microscopic observation. The extruded sheets of the thermotropic copolyester are composed of layered structures containing skin and core layers. A skin layer comprises fine fibrils oriented almost parallel to the extrusion direction. A core layer contains poorly oriented thicker fibrils or platelike structures. The orientation function of sheets and their tensile dynamic modulus parallel to the extrusion direction increase with increasing draw‐down ratio of the sheet. Annealing of the sheet caused the increases in the temperature and the heat of crystal—mesophase transition, the heat‐resistance to the mechanical tensiles properties, and the inherent viscosity of the polymer. The effect of annealing on the structural properties of the extruded sheet was discussed. © 1993 John Wiley & Sons, Inc.
The crystallization kinetics of filled poly(ethylene terephthalate)
Authors: Cheng Sen , Shanks Robert A.
Published: April 2003

The crystallization kinetics of poly(ethylene terephthalate) was measured under isothermal conditions by DSC in the presence of various fillers and with varying filler concentrations. The fillers used were carbon, titanium dioxide, glass fiber, and calcium carbonate. The kinetics was calculated using the slope of the crystallization vs. time plot, the times for 10% and 50% reduced crystallization, and the Avrami equation. Activation energies were determined from measurements under different isothermal temperatures. The fillers caused athermal nucleation to be inhibited as shown by the increased values of the Avrami exponent, n. Interactions between the polyester and filler were interpreted to reduce the mobility of the polymer in the melt. This decreased the rate of crystallization and increased its activation energy. The order of the filler effect in reducing crystallization was the following: no filler < carbon < titanium dioxide < glass fiber < calcium carbonate. The concentrations of filler were above those typically used for nucleation and more in the range expected for reinforcement or dilution of the polymer. © 1993 John Wiley & Sons, Inc.
The effects of high‐energy radiation on the surface chemistry of polystyrene: A mechanistic study
Authors: Onyiriuka E. C.
Published: April 2003

Irradiation of polystyrene by 15 Mrad gamma or exposure to a 254 nm ultraviolet (UV) light source leads to surface oxidation of the polymer to depths greater than 10 nm as opposed to ∼ 3 nm depth offered by either plasma or corona‐discharge treatment. Oxidation increases linearly with UV irradiation time. More carboxyl (OCO) acid functionality, which increases with depth, was detected for UV‐treated polymer. With 3 Mrad gamma irradiation, only hydroxyl (CC) groups were detected by XPS as the surface‐oxidized species. ADXPS, GPC, and static SIMS data suggest that chain scission is the dominant degradation mechanism for polystyrene exposed to high gamma and UV radiation, respectively. © 1993 John Wiley & Sons, Inc.
Surface modification of epoxy resin with fluorine‐containing methacrylic ester copolymers
Authors: Kasemura T. , Oshibe Y. , Uozumi H. , Kawai S. , Yamada Y. , Ohmura H. , Yamamoto T.
Published: April 2003

To improve oil and water repellency, fluorine‐containing block copolymers, which were composed of methyl methacrylate (MMA), glycidyl methacrylate (GMA), and 1H, 1H, 2H, 2H‐heptadecafluorodecyl acrylate (PFA), were blended with an epoxy resin. It was expected that a glycidyl group would mesh with the epoxy resin by primary bonding, and the low surface energy fluorocarbon segment would absorb and orient to the exterior to fluorinate the surface. X‐ray photoelectron spectroscopy, contact angle, and peel strength of pressure‐sensitive adhesives for modified epoxy resin surface were determined. The amount of fluorine obtained via angular‐dependent ESCA investigation in the modified resin surfaces increased with the shallowing of the sampling depth. With increasing modifier content, the amount of fluorine in the modified resin surface layer increased, and the critical surface tension of modified resin surfaces and the peel strength of a silicone pressuresensitive adhesive affixed to the modified epoxy resin, decreased. A considerable amount of fluorine in the resin surface modified with GMA‐containing block copolymers remained after Soxhlet extraction, whereas in the surface modified with copolymer without GMA, more fluorine was extracted. It was extracted. It was shown that these copolymers were good surface modifiers to improve oil and water repellency. © 1993 John Wiley & Sons, Inc.
Application of SIMS in polymers and lignocellulosic materials
Authors: Hua Xujun , Kaliaguine Serge , Kokta Bohuslav V.
Published: April 2003

Secondary Ion Mass Spectrometry (SIMS), a new surface analysis technique, has begun to be applied to the studies of organic macromolecule surface either for chemical imaging and functional group analysis or for the determination of molecular weight distribution. The instrumental conditions that are critical for obtaining a meaningful spectrum are discussed for polymers which have properties similar to lignocellulosic materials, i.e., they are thermally fragile and electrically insulating. Examples are given for qualitative and quantitative analyses. Possible uses of SIMS for characterization of lignocellulosic materials are suggested. © 1993 John Wiley & Sons, Inc.
Measurements of craze velocities in polystyrene‐polybutadiene blends
Authors: Spiegelberg Stephen H. , Argon Ali S. , Cohen Robert E.
Published: April 2003

Normally brittle polystyrene (PS) can be toughened effectively by the inclusion of a few weight percent of low molecular weight polybutadiene (PB). The PB, which can be made to phase separate into submicron sized, randomly dispersed pools, locally plasticizes the glassy phase in the vicinity of a growing craze; the resulting reduction in craze flow stress and increased craze velocity lead to significant enhancement of toughness when strain rates are below approximately 10−1 s−1. Craze velocities were measured in PS containing 1 to 5 wt % of a low molecular weight PB (2300 g/mol). The results were compared to a version of the interface convolution mechanism for craze growth that has been modified to account for the localized plasticization effect of the low molecular weight diluent. Addition of 5 wt % PB led to craze velocities that are three orders of magnitude larger than observed for pure PS. The model deviated significantly from the experimental data at the higher and of the PB concentration range studied here, but it did exhibit the general form of the observed dependence of craze velocity on PB content. © 1993 John Wiley & Sons, Inc.
Catalytic grafting: A new technique for polymer‐fiber composites. III. Polyethylene‐plasma‐treated KevlarTM fibers composites: Analysis of the fiber surface
Authors: Wang Qi , Kaliaguine Serge , Ait‐Kadi Abdellatif
Published: April 2003

In this article, plasma‐treated KevlarTM fiber‐polyethylene composites prepared by the catalytic grafting technique were studied. The reactive groups COOH, OH, NH2 generated on the Kevlar fiber surface by oxygen plasma treatment were used to chemically anchor Ziegler‐Natta catalyst, which was then followed by ethylene polymerization on the fiber surface. The surface structure of the Kevlar fibers, untreated or treated by oxygen plasma, catalyst grafted, or ethylene polymerized, was characterized by X‐ray photoelectron spectroscopy (XPS), attenuated total reflection (ATR), and scanning electron microscopy (SEM). The morphology, interfacial behavior, and mechanical properties of the high‐density polyethylene (HDPE) composites reinforced by either catalytic grafted or ungrafted Kevlar fibers were investigated by means of differential scanning calorimetry (DSC), polarized light optical microscopy, tensile testing, and SEM. Special attention was devoted to the tensile properties of the composites in the direction transverse to the fibers. The experimental results show that oxygen plasma treatment increases the reactive site concentration on the fiber surface significantly and that the composites reinforced by catalytically grafted Kevlar fibers exhibit higher tensile strength both parallel and transverse to the fibers. The improved interfacial adhesion is attributed to the interfacial chemical bonding established by catalytic grafting. © 1993 John Wiley & Sons, Inc.
The transverse elastic modulus of fiber‐reinforced composites as defined by the concept of interphase
Authors: Sideridis E.
Published: April 2003

A theoretical expression for the prediction of the transverse elastic modulus in fiber‐reinforced composites was developed. The concept of interphase between fibers and matrix was used for the development of the model. This model considers that the composite material consists of three phases, that is, the fiber, the matrix, and the interphase. The latter is the part of the polymer matrix lying at the close vicinity of the fiber surface. In the present investigation it was assumed that the interphase is inhomogeneous in nature with continuously varying mechanical properties. Different laws of variation of its elastic modulus and Poisson ratio were taken into account in order to define the overall modulus of the composite. Thermal analysis method was used for the estimation of the thickness of the interphase. The results obtained were compared with the respective values of other models as well as with experimental data. © 1993 John Wiley & Sons, Inc.
pH‐sensitivity of hydrogels based on complex forming chitosan: Polyether interpenetrating polymer network
Authors: Yao Kang De , Peng Tao , Goosen M. F. A. , Min Ji Mei , He Yu Yin
Published: April 2003

This article deals with a novel, semi‐interpenetrating polymer network (semi‐IPN), composed of crosslinked chitosan (cr‐CS) with glutaraldehyde (GA) and polyether. The pH responsibility of swelling data shows that swelling reaches a maximum at pH = 3.19 and a minimum at pH = 13. The concentration of chitosan acetic acid solution, the amount of crosslinking agent, and polyether, have effects on the swelling behavior of the network. Stimulating‐response of the semi‐IPN, induced by abrupt changes of pH between 1 and 13, is discussed as well. © 1993 John Wiley & Sons, Inc.
A kinetic study of the hydrolytic degradation of polyethylene terephthalate at high temperatures
Authors: Campanelli John R. , Kamal M. R. , Cooper D. G.
Published: April 2003

The hydrolytic depolymerization of molten PET in excess water was studied using a 2 L stirred pressure reactor at temperatures of 250, 265, and 280°C. Rate constants for hydrolysis are calculated from the initial rate data. At initial water: PET charge ratios (w/w) exceeding 5.1, essentially complete depolymerization to monomer is possible at 265°C. At lower water: PET initial charges, an equilibrium is established. The equilibrium constants are calculated for 2 g water/g PET at three temperatures. A kinetic model is proposed to describe the hydrolysis reaction. The model is shown to fit experimental data and to yield good predictions for the equilibrium concentration of carboxyl groups. Carboxyl‐group concentrations are measured using an end‐group analysis technique. Potentiometric titrations are carried out in one of two solvent systems, dimethylphenol:chloroform or dimethylsulfoxide, depending on the extent of hydrolysis. © 1993 John Wiley & Sons, Inc.
Gamma‐radiation induced grafting of acrylonitrile onto guar gum: Influence of reaction conditions on the properties of the grafted and saponified products
Authors: Lokhande H. T. , Varadarajan P. V. , Nachane Nayana D.
Published: April 2003

In the gamma‐radiation induced grafting of acrylonitrile onto guar gum, the influence of different concentration of the monomer acrylonitrile on the PAN add‐on, the number average molecular weight of the PAN side chains, and the grafting frequency of the PAN side chains are reported. At 0.3 Mard dosage, the PAN add‐on were 32.4, 48.5, and 66.2% and the number average molecular weight of the PAN side chains were 59,700, 132,200, and 238,900, respectively, at three different reaction conditions. The frequency of grafting also showed considerable variation at 0.2 Mrad dosage, for all three sets of samples. The viscosity of the aqueous dispersions of the saponified samples at different concentrations are also reported. The water absorbency of the saponified samples were evaluated and the values were around 250 g/g. The fall in viscosity of the aqueous dispersions on storage were also evaluated. The observed fall in viscosity was lower in the case of the product with higher PAN content. © 1993 John Wiley & Sons, Inc.
External lubrication of high‐temperature thermoplastic polymers
Authors: Stolarski T. A.
Published: April 2003

External lubrication of high‐temperature thermoplastic polymers was studied experimentally. It was found that the nature of the lubrication fluid has a pronounced effect upon the behavior of the contact. It is postulated that premature failure of PEEK‐lubricated contacts is caused by the migration of linear carboxylic acids into the polymer matrix at elevated temperatures, thereby producing significant plasticization. A sequence of events leading to failure is given and some rationale for it provided. © 1993 John Wiley & Sons, Inc.
Low temperature slow rate penetration test: Evidence for its sensitivity to the thermomechanical relaxations in the case of ethylene–vinyl acetate copolymers
Authors: Porzucek K. , Lefebvre J. M.
Published: April 2003

The sensitivity of a low temperature slow rate penetration test to the dynamic mechanical response of ethylene‐vinyl acetate (EVA) copolymers with different compositions is clearly evidenced. The β‐molecular relaxation process occuring around −10°C controls the slow puncture behavior. The penetration resistance reaches a maximum value at this temperature and the type of rupture involved in the perforation mechanism varies on both sides of this critical temperature (brittle or ductile rupture). The parallel variations of the slow puncture resistance and of the high speed tensile impact strength with temperature, as well as with the vinyl acetate content, point to the reliability of the low temperature slow rate penetration test. This test thus appears as an efficient tool to simulate static mechanical deformations undergone by polymer films used in the sealed packaging of frozen food. © 1993 John Wiley & Sons, Inc.
Cross‐linking of bisepoxide with divalent metal salts of p‐aminobenzoic acid and diamine
Authors: Takechi Shigetoshi , Matsuda Hideaki
Published: April 2003

Cross‐linking of bisepoxide with divalent metal salts of p‐aminobenzoic acid and 4,4′‐diaminodiphenylmethane (4,4′‐methylenedianiline) was investigated. As the bisepoxide, bisphenol A diglycidyl ether was used. Mg and Ca were used as the divalent metal. The metal salts showed catalytic activities for the cross‐linking reaction and also for etherification of epoxy groups. In this case, the salt containing Ca with the lower electronegativity exhibited higher catalytic activities than that containing Mg. Hence, the cross‐linking reaction was supposed to proceed via an ionic mechanism. As for the physical properties of the cured resins, compressive strength was higher in the metal‐containing cured resins than in the resin without metal. Heat‐distortion temperature showed a tendency to decrease with increase in the metal content. However, glass transition temperature determined by dynamic mechanical properties were not influenced by the metal content. The metal‐containing cured resins exhibited low weight gain and changes in dimension and external appearance against boiling water. In addition, thermal decomposition was accelerated by the incorporated metal. © 1993 John Wiley & Sons, Inc.
Water‐soluble copolymers. XLV. Ampholytic terpolymers of acrylamide with sodium 3‐acrylamido‐3‐methylbutanoate and 2‐acrylamido‐2‐methylpropanetrimethylammonium chloride
Authors: McCormick Charles L. , Salazar Luis C.
Published: April 2003

Water‐soluble, low charge density polyampholytes have been synthesized by free‐radical terpolymerization of acrylamide (AM) with sodium 3‐acrylamide‐3‐methylbutanoate (NaAMB) and 2‐acrylamido‐2‐methylpropanetrimethylammonium chloride (AMPTAC). Terpolymer compositions obtained by 13C‐NMR reflect monomer feed concentrations. Molecular weights and second virial coefficients range from 3.43 to 19.4 × 106g/mol and from 1.63 to 3.61 mL mol/g‐2, respectively, as determined by low‐angle laser light scattering. Ionic associations were explored by investigating the dilute solution properties as a function of terpolymer concentration, terpolymer charge density, and added electrolytes. Terpolymers with 0.5, 2.5, and 5.0 mol % of both of the cationic (AMTAC) and anionic (NaAMB) monomers were soluble in deionized water, whereas those with 10 and 15 mol % of each monomer required electrolyte addition. The higher‐density terpolymers undergo a 700% increase in intrinsic viscosity upon changing NaCl concentration from 0.05 to 1M. Polyelectrolyte behavior could be induced by decreasing solution pH below the pKa of the NaAMB mer. Intermolecular ionic associations resulting in gel networks were studied utilizing dynamic mechanical analysis. © 1993 John Wiley & Sons, Inc.
Efficiently activated carbon fiber derived from grafted novoloid fiber
Authors: Shimada Machiko , Takigami Shoji , Nakamura Yoshio , Abe Yukio , Iizuka Toshi , Makiyama Nobusuke
Published: April 2003

Graft copolymerization of methyl methacrylate onto novoloid fiber was carried out by the electron beam mutual irradiation method. The characteristics of the grafted fiber were almost the same as those of the original novoloid fiber. The grafted fiber was carbonized and activated to yield an efficiently activated carbon fiber. The yield and the specific surface area of the activated carbon fiber, derived from the grafted novoloid fiber, were much greater than those derived from the original novoloid fiber. This is because grafted poly(methyl methacrylate) decomposes into monomer and gaseous products, forming pores on the surface and inside of the novoloid fiber on heating. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of polyester‐imides from imidodicarboxylic acid monomers and ethylene glycol
Authors: Kishanprasad V. S. , Gedam P. H.
Published: April 2003

Two monoimidodicarboxylic acids and four diimidodicarboxylic acids were synthesized from trimellitic anhydride and amino compounds, viz., glycine, p‐aminobenzoic acid, 4,4'‐diaminodiphenyl sulfide, 4,4'‐diaminodiphenyl ether, 4,4'‐diaminodiphenyl methane, and 4,4'‐diaminodiphenyl sulfide, and characterized by IR and 1H‐NMR spectroscopies and melting‐point determination. These functional monomers were condensed in N‐methyl‐2‐pyrrolidone solvent with ethylene glycol by a transesterification reaction to obtain the novel polyester‐imides with backbones of alternate imide‐ester linkages or imide‐imide‐ester‐ester linkages with SO2, O, CH2, or SS bridges in between. All the polymers were characterized by IR and 1H‐NMR spectroscopies, X‐ray diffraction, solution viscosity, solubility and solubility parameters, and differential thermal analysis. Most of the polymers possess amorphous structure and fairly high decomposition temperatures (450–485°C). These polymers having solubility parameters in the range δ 11.44–11.85, as determined by the group contribution technique, are soluble at room temperatures in aprotic polar solvents. © 1993 John Wiley & Sons, Inc.
Polymeric photoinitiators bearing side‐chain acyldiphenylphosphinoxide moieties for uv surface coatings
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo , Lelli Nicola , Rolla Pier Angelo
Published: April 2003

Polymeric photoinitiators bearing side‐chain acyldiphenylphosphinoxide moieties have been prepared by reacting poly(methacryloyl chloride) and methacryloyl chloride/methyl methacrylate copolymers with methoxydiphenylphosphine. The activity of the above polymeric systems has been checked in the UV curing of both clear and pigmented coating formulations and compared with that of the low molecular weight analog pivaloyldiphenyl‐phosphinoxide. The stability to light and to different hydrolitic conditions of the polymeric photoinitiators with respect to pivaloyldiphenylphosphinoxide has also been tested. The data concerning activity and stability are discussed in terms of structural features of the above systems. © 1993 John Wiley & Sons, Inc.
Investigations on vinylene carbonate. VI. Immobilization of alkaline phosphatase onto poly(vinylene carbonate) ‐jeffamine® hydrogel beads
Authors: Chen Guohua , Does Leen Van Der , Bantjes Adriaan
Published: April 2003

Hydrogel‐like polymers with reactive cyclic carbonate (CCA) groups have been obtained by the cross‐linking reaction of poly(vinylene carbonate) (PVCA) with Jeffamines®. By this reaction, microspheric hydrogel beads with a high water content and a high concentration of reactive CCA groups were prepared. The beads were used as a matrix for the immobilization of the enzyme alkaline phosphatase (ALP) and showed a considerable capacity to couple ALP and a reasonable retention of activity for the immobilized ALP, depending on the reaction conditions. The immobilized ALP exhibited a better thermal stability than did native ALP and a high residual activity was found after repeated use. © 1993 John Wiley & Sons, Inc.
Starch urea‐formaldehyde matrix encapsulation. IV. Influence of solubility and physical state of encapsulant on rate and mechanism of release
Authors: Shukla P. G. , Rajagopalan N. , Sivaram S.
Published: April 2003

The influence of the physical state and solubility of the encapsulant on the rate and mechanism of release and swelling of the cross‐linked starch‐urea formaldehyde (St‐UF) matrix has been studied by encapsulating model organic compounds. The release and swelling data have been analyzed in terms of the generalized equation Mt/M∞ = ktn applicable for swellable controlled‐release systems. This matrix system shows and an inverse relationship of release rate with the cross‐link ratio for all the encapsulants studied. The solid encapsulants have n values in the range of 0.22–0.41, indicating a Fickian or anomalous mechanism. Further, the release rate increases with solubility of the encapsulant. The liquid encapsulants have n values in the range of 0.5–1.5, indicating Case II transport mechanism. The release rates for liquid encapsulants are lower by one to three orders of magnitude than those for solid encapsulants and are not influenced by encapsulant solubility. This indicates a polymer chain relaxation‐controlled mechanism of release for liquid encapsulants. © 1993 John Wiley & Sons, Inc.
Radiation grafting of acrylic and methacrylic acids onto poly(tetrafluoroethylene‐hexafluoropropylene‐vinylidene fluoride) TFB films
Authors: Dessouki A. M. , Taher N. H. , El‐Arnaouty M. , Khalil F. H.
Published: April 2003

A study has been made for the preparation of membranes by the direct radiation grafting of acrylic and methacrylic acids onto poly(tetrafluoroethylene‐hexafluoropropylene‐vinylidene fluoride) TFB films. The appropriate reaction conditions were selected under which the graft polymerization was carried out successfully. In this grafting system, ammonium ferrous sulfate (Mohr's salt), ferric chloride, and cuppric chloride were used as inhibitors to minimize the homopolymerization of acrylic acid and methacrylic acid. Also, the effect of monomer concentration on the rate of grafting was investigated. The dependence of the grafting rate on monomer concentration was found to be of the order of 1.1 and 1.0 for acrylic acid and methacrylic acid, respectively. This grafting system was proceeded by a front mechanism. Some selected properties of the grafted films such as swelling behavior, dimensional change, and mechanical and electrical properties were investigated. It was found that the grafted membranes possess good hydrophilic properties that may make them promising in some practical applications. © 1993 John Wiley & Sons, Inc.
Preparation of high molecular weight monodisperse polystyrene latexes by concentrated emulsion polymerization
Authors: Sun Fuming , Ruckenstein Eli
Published: April 2003

The preparation of high molecular weight monodisperse polystyrene (PS) latexes by the concentrated emulsion polymerization is investigated. The PS latexes thus obtained have diameters in the range of 0.1–0.3 μm. The average size and the dispersity of the latexes are dependent on the concentration of surfactant (SDS), the monomer volume fraction, and the amount of monpolymerizable additive (decane). The ionic strength does not seem to affect the size but affect the dispersity of the latexes. Under proper conditions, monodisperse particles can be prepared with a quite small standard deviation. © 1993 John Wiley & Sons, Inc.
Aqueous ring‐opening metathesis polymerization of exo‐7‐oxabicyclo [2.2.1] hept‐5‐ene‐2,3‐dicarboximide
Authors: Viswanathan Tito , Jethmalani Jagdish
Published: April 2003

The aqueous ring‐opening metathesis polymerization of the exo‐Diels‐Alder adduct of furan and maleimide was accomplished using an “activated Ruthenium” catalyst present in the supernatant of a RuCl3‐catalyzed aqueous polymerization of furan‐dimethylacetylene dicarboxylate adduct. The polymer was characterized by solution 1H− and 13C‐NMR, IR, DSC, and viscometry. Characterization revealed an intact imide group and the possibility of high‐temperature applications. © 1993 John Wiley & Sons, Inc.
The dependence of fracture properties on cure temperature in a DGEBA/DDS epoxy system
Authors: Min B.‐G. , Hodgkin J. H. , Stachurski Z. H.
Published: April 2003

The glass transition temperature (Tg), water‐ and solvent‐absorption characteristics, fracture toughness, and tensile properties of a diglycidyl ether of bisphenol‐A (DGEBA) ‐based epoxy resin (Epikote 8283) cured with an aromatic amine curing agent, 4,4' ‐diaminodiphenyl sulfone (DDS), were studied as a function of cure temperature and cure cycle (one‐step or two‐step cure). The glass transition temperature (which depends on the extent of cure) shows a linear increase with increasing cure temperature and levels off toward the cure temperature of 200°C. Water and solvent uptake tended to increase with increasing cure temperature and, hence, with cross‐linking level. Fracture toughness, tensile strength, strain to break, and tensile fracture energy also increased significantly with increasing final cure temperature regardless of cure cycle. In contrast, the small strain properties such as modulus, yield stress, and yield strain were not influenced greatly by cure temperature and cure cycle. From these results, we infer that the large strain properties of the resin are not inversely proportional to the cross‐link density of the network as reported in many publications, 1 but, rather, that they are dependent on other structural parameters such as free volume and the flexibility of the cross‐linked chains. © 1993 John Wiley & Sons, Inc.
Interrupted plasma treatment of EPDM‐40 rubber
Authors: Kondyurin A. V.
Published: April 2003

The glow discharge plasma treatment of EPDM‐40 rubber has been studied using the IRMATR spectroscopy. A mathematical model for the kinetics of rubber surface oxidation processes has been suggested. The interrupted plasma treatment was proposed as the most efficient technique of polymer surface activation. It was noted that the rubber oxidation processes occurs during the contact with air after the plasma treatment, but not during the discharge. © 1993 John Wiley & Sons, Inc.