bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of curing accelerators on physical properties of epoxy molding compound (EMC)
Authors: Ogata Masatsugu , Kinjo Noriyuki , Eguchi Shuji , Hozoji Hiroshi , Kawata Tatsuo , Sashima Hiroki
Published: April 2003

The effects of various curing accelerators on the physical properties of epoxy molding compounds (EMCs) were investigated. Such properties as elasticities in rubbery and glassy regions, glass transition temperature, thermal expansion coefficient, and water absorption at 60°C of neat epoxy resins using various curing accelerators were found to be directly reflected in the properties of the EMCs that were prepared by using each resin system. However, volume resistivity and saturated water absorption at 120°C were not reflected. This was attributed to differences in the catalytic reactivity of accelerators causing different melt viscosity for the EMC, which resulted in different densities (packing degrees) and affected physical properties of molded EMC. On the other hand, it was found that the density of molded EMC was also affected by the molding conditions. To improve the physical properties of the molded EMC, in addition to proper selection of accelerators, it was very important to set the melt viscosity of the EMC as high as possible within the moldable range and to select suitable molding conditions.
Adsorption of anionic surfactants and related compounds from aqueous solution onto activated carbon and synthetic adsorbent
Authors: Ihara Yasuji
Published: April 2003

The adsorption isotherms of two anionic surfactants and sodium alkyl sulfonates with various carbon numbers onto activated carbon and synthetic adsorbent were measured in aqueous solutions. The adsorption affinities remarkably increased with an increase in the length of alkyl group in the adsorbates for both adsorbents. Furthermore, the amount of adsorption increases with addition of sodium chloride into the solutions. These behaviors suggested that the effect of hydrophobic interactions seem to play an important role on adsorption of both adsorbents.
Polymer compatibility and biodegradation of starch–poly(ethylene‐co‐acrylic acid)–polyethylene blends
Authors: Shogren R. L. , Thompson A. R. , Felker F. C. , Harry‐Ókuru R. E. , Gordon S. H. , Greene R. V. , Gould J. M.
Published: April 2003

X‐ray diffraction, CP/MAS C‐13 NMR, DSC, FTIR and fluorescence microscopy have been used to study the structure, compatibility, and morphology of films made from starch, poly(ethylene‐co‐acrylic acid) (EAA), and polyethylene (PE) before and after exposure to a mixture of highly amylolytic bacteria. The components of starch, amylose and amylopectin, interact with EAA via the formation of V‐type inclusion complexes and hydrogen bonds. PE appears to be immiscible with the starch–EAA complex, with each forming sheetlike domains. The amylopectin in the films is susceptible to digestion by the bacterial consortium while the crystalline EAA–amylose complex is resistant. Digestion begins at the film surface and then proceeds inwards with sheetlike areas of starch removed. The good compatibility between starch and EAA as well as migration of EAA to the film surface explains the resistance of such films to digestion by conventional amylases.
In situ compatibilization of polystyrene/polyethylene blends using amino‐methacrylate‐grafted polyethylene
Authors: Song Zhiqiang , Baker Warren E.
Published: April 2003

Blends of a styrene–maleic anhydride copolymer (SMA) with polyethlene (PE) or polyethylene melt grafted with tertiary (PE‐g‐DMAEMA) or secondary (PE‐g‐tBAEMA) amino methacrylate were prepared by blending in a batch melt mixer. The morphology of these blends at various compositions was examined with a scanning electron microscope (SEM) and related to their tensile and impact properties. The SMA/PE blends are found to have the typical coarse morphology of incompatible blends and poor mechanical properties, while their reactive conterparts, SMA/PE‐g‐DMAEMA or SMA/PE‐g‐tBAEMA blends, show finer morphology and modestly improved tensile and impact strength. This was attributed to chemical interaction of the acidic anhydride and the basic amino groups. The greater improvement in morphology for SMA/PE‐g‐tBAEMA than for SMA/PE‐g‐DMAEMA suggests a stronger interaction between the secondary amino groups and the anhydride groups, possibly with the formation of SMA‐g‐tBAEMA‐g‐PE graft polymer through amide covalent bonds. The amide formation appears to occur at the interfacial region in the blends and is too little to be detected by Fourier transform infrared (FTIR) spectra. However, differential scanning calorimeters (DSC) and the viscosity measurements indicate crystallinity and molecular weight changes for the SMA/PE‐g‐tBAEMA blends, supporting an argument for the formation of SMA‐g‐tBAEMA‐g‐PE grafts at the phase interface.
Photocrosslinked norbornene–thiol copolymers: Synthesis, mechanical properties, and cure studies
Authors: Jacobine A. F. , Glaser D. M. , Grabek P. J. , Mancini D. , Masterson M. , Nakos S. T. , Rakas M. A. , Woods J. G.
Published: April 2003

A number of norbornene‐functionalized resins were prepared and their photoinitiated crosslinking reaction with a multifunctional thiol was studied. Access to these novel resins can be gained by several synthetic routes. The most general of these routes is the [4π + 2π] cycloaddition reaction (the Diels–Alder reaction) of the corresponding multifunctional acrylate ester with cyclopentadiene (CPD) monomer. The photocrosslinking reaction of these resins with multifunctional thiols such as pentaerythritol tetramercaptopropionate (PETMP) is quite rapid and sensitive to low UV dose as well as dose rate. FT‐IR cure studies also indicated that the cure rate slows down dramatically as the conversion approaches the calculated gel points for the systems under study. Mechanical properties of cured thin films of these materials exhibited a wide range of tensile and dynamic mechanical properties, which depended on the structure of starting materials used in the preparation of the norbornene resin and the crosslinking thiol.
Crystallinity and isotactic index of polypropylene samples prepared by VOCI3 and aluminum alkyls
Authors: Pandya M. V. , Maryam G. , Desai M. R. , Kumar K. Suresh
Published: April 2003

The X‐ray crystallinity and the isotactic index [II(%)] values were measured for polypropylene (PP) samples prepared by VOCI3 and various aluminum alkyls. The reaction parameters, such as aging time, temperature, reaction medium, and additives, have some effect on the crystallinity of the samples. Among the three systems studied, a combination of VOCI3 + Et2AICI was found to give PP with higher crystallinity and II. In general, the tacticity of the samples prepared were much lower than the samples prepared with α‐, β‐, γ‐TiCl3 as the catalyst.
Application of the blister test to the study of polymer–polymer adhesion
Authors: Chu Y. Z. , Durning C. J.
Published: April 2003

This article demonstrates the use of the blister test for measuring the fracture energy, Ga, of the interface between two incompatible polymers. We describe an apparatus in which a fluid was injected at constant rate at the interface between a solid, glassy polymer, and a thin rubbery overcoating to create a “blister.” The fluid pressure and blister geometry were measured as functions of time. An energy balance analysis reveals three independent methods for the calculation of Ga from the data. The method was applied to the system of polyisoprene/poly(methylmethacrylate). We used a sequential debonding procedure to obtain reproducible data following the theoretical predictions. The self‐consistency of the data suggested that the adhesion energy could be calculated reliably from the pressure alone, without using the blister geometry.
Buffer effects on aqueous swelling kinetics of polyelectrolyte gels
Authors: Chou Loretta Y. , Blanch Harvey W. , Prausnitz John M. , Siegel Ronald A.
Published: April 2003

Electrolytes are often added to a gel‐swelling medium under the assumption that the important conditions which characterize swelling rates are the solution pH and ionic strength, with little emphasis on the nature of the electrolyte. Previous research by Siegel et al. has indicated that the presence of the un‐ionized acidic form of an electrolyte buffer is a primary rate determinant for swelling of a polybase gel. A systematic swelling study on two separate gels, 2‐hydroxyethyl methacrylate copolymerized with methacrylic acid (HEMA/MAA) and N,N‐dimethylaminoethyl methacrylate (HEMA/DMA), has been performed to investigate the influence of the concentration of the un‐ionized buffer by three principal factors: (1) total buffer concentration, (2) solution pH, and (3) buffer pKa. Swelling and deswelling kinetics were obtained. In the presence of an electrolyte buffer, a dramatic swelling rate increase is observed for the HEMA gels, with substantial gains in rate obtained as total buffer concentration rises. Results also emphasize that to enhance swelling kinetics, the pH must be such that the buffer is essentially un‐ionized.
Structure of microporous polypropylene sheets containing CaCO3 filler
Authors: Nagō Satoshi , Nakamura Shunichi , Mizutani Yukio
Published: April 2003

The microporous polypropylene sheets were prepared by biaxially stretching polypropylene sheets containing CaCO3 filler (particle size, 0.08–3.0 μm), when the CaCO3 filler content was 59% by weight and the stretching ratio was 2.8 × 1.8. The microstructure of the sheets were investigated in relation to the CaCO3 particle size by a N2 gas permeation method. (1) Effective porosity increases with decreasing mean particle size of filler. (2) The tortuosity factor of the pore is in the range of 25–40 and becomes relatively smaller with decreasing mean particle size of filler. (3) The equivalent pore size becomes relatively smaller with decreasing mean particle size of filler.
A new process for fabricating nonwoven fibrous‐reinforced elastomer composites
Authors: Epstein M. , Shishoo R. L.
Published: April 2003

A new type of mold was developed and tested for structural reaction injection molding (SRIM) of elastomer composites having polymer matrices made from a mixture of two components. These mixtures had short pot lives and relatively high viscosity. Channel systems for polymer feeding and vacuum application were investigated. The mold cavity was provided with up to 24 polymer feeding holes and 38 vacuuming holes. The cavity and channels were made from transparent materials that allowed easy observation and video recording of the polymer matrix flow. In addition, some design parameters were studied such as channel layout. Investigations were carried out on the mechanism of polymer matrix flow and fiber breakage during the formation of fiber‐reinforced composites made of non‐woven fiber reinforcement structures with considerably longer fiber lengths than reported earlier. Other studies included determination of the effects of fiber type, fiber dimensions, and fiber/matrix v/v ratio on the matrix flow during impregnation. © 1992 John Wiley & Sons, Inc.
Preparation and properties of negatively charged ultrafiltration membrane: Photografted sodium styrene sulfonate onto brominated polyacrylonitrile membrane
Authors: Kobayashi Takaomi , Fujii Nobuyuki
Published: April 2003

Charged ultrafiltration membranes were prepared by photografting sodium styrene sulfonate onto photosensitive polyacrylonitrile membrane containing bromine atoms. The degree of the photografting was characterized by contact angles of air or n‐octane in water and FTIR spectra for the negatively charged membrane. Permeations of dextran and dextransulfate through the negatively charged membranes were studied by ultrafiltration in the aqueous solutions of both solutes. With an increase of photoirradiation, the permeability of the solutes decreased. Also, an electrostatic repulsion of the solute and the membrane was confirmed by direct comparison between the permeability of the solutes, dextran, and dextransulfate, each having similar molecular size.
Preparation of conducting polyacrylonitrile/polypyrrole composite films by electrochemical synthesis and their electrical properties
Authors: Park Yun Heum , Han Myeong Hee
Published: April 2003

Electrically conducting polyacrylonitrile (PAN)/polypyrrole (PPy) composite films were prepared by electrochemical polymerization of pyrrole in an insulating PAN matrix under various polymerization conditions and their electrical properties were studied. The conductivities of PAN/PPy composite films peeled off from the platinum electrode he lie in the range of 10−2–10−3 s/cm, depending on the preparation conditions: The conductivity increased with the concentrations of the electrolyte and the monomer, but it decreased with the polymerization temperature of pyrrole and the applied potential.
Studies on the mechanism of the instability of polymers in tensile testing
Authors: Cao Jinan
Published: April 2003

This study deals with the mechanism of the instability of tensile force occurring in tensile testing for polymer materials. It was found that through a proper transformation of inertia coordinates, a tensile test can be described in the same governing differential equations with the same boundary conditions as those employed in melt spinning. This fact suggests that the nature of the instability is simply due to draw resonance rather than any other cause. The effects of extension rate in tensile testing and the specimen dependence on the instability of tensile force were experimentally investigated by using specimens with various molecular orientations. The results are interpreted by applying the principles of draw resonance in melt spinning.
Mechanical properties and morphology of high‐density polyethylene/linear low‐density polyethylene blend
Authors: Gupta A. K. , Rana S. K. , Deopura B. L.
Published: April 2003

The binary blend of high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE) in the range of composition from 100% HDPE to 100% LLDPE has been investigated for tensile and flexural properties and the morphology in the deformed state on tensile fracture. Tensile properties (initial modulus, yield stress, and elongation‐at‐yield, ultimate tensile strength and elongation‐at‐break, and work of yield and work of rupture) and flexural properties (flexural modulus and flexural yield stress) are studied as a function of blend composition. Behavior, in terms of these properties, is distinguishable in three zones of blend composition, viz. (i) HDPE‐rich blend, (ii) LLDPE‐rich blend, and (iii) the middle zone. In zones (i) and (ii), the variations of these properties are more or less linear, whereas in the middle region [i.e., zone (iii)], there is a reversal of trends in variation or sometimes a behavior opposite to the expected one. The results are explained on the basis of the effects of cocrystallization and the presence of octene‐containing segments in the amorphous phase. Scanning electron micrographs of the tensile fracture surfaces are presented to illustrate the occurrence of transverse bands interconnecting the fibrils.
Thermal and mechanical characterization of partially miscible blends of poly(ether ether ketone) and polyethersulfone
Authors: Malik Tariq M.
Published: April 2003

The miscibility behavior of poly(ether ether ketone) (PEEK) and polyethersulfone was studied by differential scanning calorimetry (glass transition temperature) and tensile properties: Young's modulus and ultimate tensile strength. A single glass transition temperature was observed over the entire composition range. The glass transition temperature of blends, however, did not follow any of the theoretical equations. Utracki and Jukes equation was used with K = 11 to fit the experimental data that indicate partial miscibility. Up to 30 wt % PEEK, the blends showed amorphous behavior with the glass transition temperature very close to that of polyethersulfone. Because of partial miscibility, blends showed mechanical compatibility. Both the modulus and strength increased significantly with an increasing concentration of PEEK in the blends, reaching a maximum around 40%. Electron microscopic results revealed phase separation but strong adhesion between the phases.
Unsaturated polyester containing myrcene–maleic anhydride Diels–Alder adduct
Authors: Abate Diane Wolfer , Stevens Malcolm P.
Published: April 2003

Myrcene–maleic anhydride Diels–Alder adduct and the corresponding diacid were used as monomers for unsaturated polyesters. The polyesters exhibited air‐drying properties on cross‐linking with styrene.
Transport of small molecules in polyolefins. I. Diffusion of irganox 1010 in polyethylene
Authors: Földes Enikõ , Turcsányi Béla
Published: April 2003

Transport properties of antioxidants in polymers have a very important role in their effectiveness. Lifetime of a product is strongly influenced by the physical loss of the stabilizer. The diffusion coefficient (D) and solubility (S) of Irganox 1010 in low‐density polyethylene (LDPE) were studied at 45 and 80°C, changing the physical state of the antioxidant in the additive source. Irganox 1010 is a polymorphous material; its actual morphology depends on the thermal history. It was proved that the morphology of the additive has a determining effect on the measured D and S values. Contradictions in the literature data can be explained by the differences in the experimental conditions, i.e., in the physical state of the penetrant in the additive source and the crystallinity and orientation of the polymer.
Gas permeability studies on poly(vinyl chloride) based polymer blends intended for medical applications
Authors: Pal S. N. , Ramani A. V. , Subramanian N.
Published: April 2003

Plasticized PVC finds applications in a wide range of medical products. However, plasticizer leaching, known to take place from these conventional materials, is not desirable. A number of approaches to overcome this problem are mentioned in the literature. We suggest pursuing the polyblend approach. Plasticized PVC containing different amounts of plasticizer, binary polyblends of plasticized PVC (PPVC) with acrylonitrile–butadiene rubber (NBR1), and compounded graft polymer of vinyl chloride and ethylene–vinyl acetate copolymer (EVAPVC), and ternary blends of PPVC, NBR1, and EVAPVC, were formulated. In this article, we report our results of studies on water vapor, O2, CO2, and N2 permeabilities. Increased plasticization for PVC was found to increase permeability for water vapor, O2, CO2, and N2. Rise in temperature increased the permeability for water vapor and the change became faster as the materials crossed the region of Tg. A simple model suggested for permeability worked satisfactorily. The binary and ternary blends, based on PPVC, had lower O2, CO2, and N2 permeability. This improvement in property is of great practical significance and interest and the results indicate that PVC‐based polyblends can be investigated further for potential applications in medicine
A mechanical model for the deformational behavior of the polymeric membranes operating in pressure‐driven processes
Authors: Islam M. A.
Published: April 2003

A mechanical model consisting of three elements (elastic, viscoelastic, and plastic) is proposed to describe the deformational behavior of a polymeric membrane operating in a pressure‐driven process. The changes in the membrane thickness are proposed to be calculated from the experimentally obtained flux data. The advantages of a mechanical model over the conventional method of hysteresis area measurement as the mechanical stability of the polymeric membranes are discussed. © 1992 John Wiley & Sons, Inc.
Empirical estimation method of intrinsic loss spectra in transparent amorphous polymers for plastic optical fibers
Authors: Takezawa Yoshitaka , Taketani Noriaki , Tanno Seikichi , Ohara Shuichi
Published: April 2003

We have developed a novel simulation to estimate the intrinsic loss spectrum of a plastic optical fiber (POF) having a transparent amorphous polymer as its core. Loss for POF is divided into four elements, that is, αe, αv, αR, and αj Here, αe means the electronic transition absorption loss, αv the absorption loss due to harmonics of molecular vibrations, and αR Rayleigh scattering loss. These three losses cause attenuation loss intrinsically and determine the lower limit of loss in the POF. The αi is the extrinsic loss due to fabrication process and contaminating dust, etc., and as such can be decreased to a negligible amount. We clarified the relationship between the chemical structure of polymer repeating unit and the three intrinsic losses and derived empirical equations to estimate the losses. The spectra estimated by this simulation agreed well with experimental ones. © 1992 John Wiley & Sons, Inc.
Characterization of water vapor plasma‐modified polyimide
Authors: Goldblatt R. D. , Ferreiro L. M. , Nunes S. L. , Thomas R. R. , Chou N. J. , Buchwalter L. P. , Heidenreich J. E. , Chao T. H.
Published: April 2003

To enhance polyimide‐to‐polyimide adhesion, we have investigated the effect of surface modification in water vapor plasma. The use of a water vapor plasma to treat a fully cured polyimide (PMDA–ODA) surface before subsequent layers of polyimide are applied results in dramatically enhanced interfacial adhesion. The polyimide‐to‐polyimide interfacial adhesion strength attained following water vapor plasma treatment exceeds the cohesive strength of the applied polyimide layer. The effect of surface modification in water vapor plasma on metal‐to‐polyimide adhesion has also been investigated. The use of a water vapor plasma to treat a fully cured polyimide (PMDA–ODA) surface prior to metallization results in increased metal‐to‐polymer interfacial adhesion. A study of both electroless and vacuum‐deposited metal was conducted. The use of contact‐angle measurements, peel tests, Fourier transform infrared spectroscopy, optical emission spectroscopy, nuclear forward scattering, and X‐ray photoelectron spectroscopy has led us to a preliminary understanding of the resulting surface modification and the subsequent effect of adhesion promotion. © 1992 John Wiley & Sons, Inc.
Coconut husk lignin. III. Reactivity of alkaline extracts with formaldehyde
Authors: Vázquez‐Torres H. , Canché‐Escamilla G. , Cruz‐Ramos C. A.
Published: April 2003

In this article we report results of the evaluation of the reactivity of polyphenolic extracts of coconut husk with formaldehyde in both acidic and alkaline media. The objective of this evaluation was to determine if the extracts could be used in the preparation of phenol–formaldehyde‐type resins. Extracts were obtained using aqueous solutions of NaOH (with and without anthraquinone) and NH4OH. Because of their low Stiasny's Number values, these extracts are not suitable for phenol–formaldehyde resin preparation in acidic conditions unless they are mixed with phenol or phenolic derivatives. Nevertheless, extracts obtained with NaOH, especially at 100 and 120°C, showed sufficient reactivity with form‐aldehyde in basic conditions and may therefore be considered suitable for resin preparation in an alkaline medium. The resins were characterized using infrared spectroscopy (IR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). A transition temperature prior to decomposition was not detected; their thermal stability was similar to phenol–formaldehyde‐type resins. © 1993 John Wiley & Sons, Inc.
Physical aging in the glassy state of a thermosetting system vs. extent of cure
Authors: Wang Xiaorong , Gillham John K.
Published: April 2003

The physical aging behavior of a high‐Tg amine/epoxy thermosetting system has been investigated vs. change of chemical structure induced by cure and vs. aging temperature (Ta) using the Torsional Braid Analysis (TBA) technique. The chemical structure was changed systematically from monomer to highly crosslinked polymer by curing in the equilibrilium state (T > Tg). The aging temperatures ranged from just below the glass transition temperature to deep in the glassy state (Ta > Tg). In the absence of chemical reaction, the physical aging rate at a given temperature, Ta, passes through a minimum with increasing chemical conversion (i.e., change of chemical structure). Analysis of this behavior is simplified by using Tg as an index of measurement of extent of cure. There is a superposition principle for normalizing the physical aging behavior of the thermosetting glasses, which involves a shift of Tg–Ta and a shift of C(Ta) (a function of aging temperature), regardless of chemical structure. Analysis reveals that: (1) this behavior is the consequence of the Tg and Tβ transitions, (2) the segmental mobility (1/τ) is a function of the deviation from equilibrium (as measured by Tg–Tg and the aging time), (3) the segmental mobility, which is involved in the physical aging process in the glassy state, is insensitive to the extreme changes of chemical structure (from monomer, to sol/gel polymer, and to highly crosslinked polymer), and (4) physical aging deep in the glassy state affects both segmental mobility and cohesive energy density. © 1993 John Wiley & Sons, Inc.
Efficiency of metal activators of accelerated sulfur vulcanization
Authors: Ducháček Vratislav , Kuta Antonín , Pr̆ibyl Pavel
Published: April 2003

The effects of copper, mercury, nickel, zinc, cadmium, indium, magnesium, and calcium stearates on the course of N‐cyclohexyl‐2‐benzthiazylsulphenamide‐accelerated sulfur vulcanization of natural rubber have been investigated on the basis of curemeter measurements at 145°C. The differences in the efficiencies of these metal activators of accelerated sulfur vulcanization have been discussed from the points of view of the electron configurations of the metals and their affinities to sulfur. We attempted to determine why zinc oxide is generally accepted as the best metal vulcanization activator. © 1993 John Wiley & Sons, Inc.
Lignocellulose–polymer composite. III
Authors: Mansour Olfat Y.
Published: April 2003

A linear relationship was achieved between the polymer load and the monomer concentration up to 200% when china clay or talc replaced the glass in the initiating system, sodium bisulfite–soda lime glass, for the free‐radical graft polymerization reactions using semichemical pulp of bagasse as substrate. The results showed that china clay is better than talc, which may be contributed to the difference in their network structure. The properties of the composites prepared from the cografted semichemical pulp–polymethyl methacrylate revealed that the china clay leads to composites with high compression strength and hardness. Deformation percent increased with increasing polymer load. However, decreasing or increasing the polymer load affects the properties of the composites up to a limit, where there is a maximum or minimum for both compression strength and hardness at china clay ratio of 2 or 3. Composites were also prepared from poly(methyl methacrylate)‐cografted‐pith of bagasse using the initiating system sodium bisulfite in the absence or presence of soda lime glass. Compression strength, deformation percent, and hardness increased on decreasing the glass ratio from 1 to 0, at nearly the same polymer load. The presence of waxes and resins decreased the compression strength of the composites prepared by impregnation of the lignocellulose in polymer solution. The hardness of these composites increased on removing waxes and resins. Removal of part of hemicellulose by alkali treatment of the lignocellulose has increased the effect on hardness. Alkali treatments of the substrates lead to a high deformation percentage. The compression strength of alkali‐treated lignocellulose are lower than the untreated ones. The change of compression strength to deformation percent and the compressibility due to complete removal of waxes and resins by the extraction with methanol–benzene or partial removal of the waxes, resins, and hemicellulose through alkali treatment followed the change of both the compression strength and percent of deformation. Water uptake of the composites prepared in this work was ranged between 6.8 and 7%. After 48 h the water uptake increased to the range 8.5–14.1%. Impregnation of the composites in water for 72 h increased the water uptake to the range 10.2–18.1%. © 1993 John Wiley & Sons, Inc.
Temperature effect on PI/Cu interface
Authors: Wang Tsung‐Hsiung , Ho Shy‐Ming , Chen Ker‐Ming , Hung Aina
Published: April 2003

The interfacial reaction and peel strength of polyimide with copper foil at various cure schedules have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), and peel test to determine the temperature effect on polyimide/copper interface diffusion and adhesion. SEM studies indicate that the polyimide/copper interfaces are fairly smooth for all samples studied in this experiment. The TEM microstructure reveals the existence of a copper‐polyimide interaction zone at the interface when it is cured at a temperature higher than 250°C, which also results in a high peel strength. XPS spectra revealed higher copper and carbonyl carbon contents at the polyimide interface when it is cured at a high‐temperature schedule (350°C). From the results of these interface studies, it is concluded that chemical bonding resulting from the interaction of copper oxide and polyimide carbonyl group provides the binding force for polyimide and copper foil. © 1993 John Wiley & Sons, Inc.
Surface modification of polyethylene by photochemical grafting with 2‐hydroxyethylmethacrylate
Authors: Edge Stephen , Walker Susan , Feast W. James , Pacynko Witold F.
Published: April 2003

The photochemical grafting of 2‐hydroxyethylmethacrylate onto low‐density polyethylene film is described. The grafting technique employed involved irradiating a solution of 2‐hydroxyethylmethacrylate and benzophenone in acetone spread between films of poly(ethylene terephthalate) or glass and low‐density polyethylene. After irradiation for 2 min, the contact angle of the polyethylene films with water fell from 97° to about 50°. The contact angle of the poly(ethylene terephthalate) substrate also fell during grafting. X‐ray photoelectron spectroscopy was consistent with the presence of poly(2‐hydroxethylmethacrylate) at the surface of the polyethylene. The effect of solvent on the photochemical grafting of 2‐hydroxyethylmethacrylate onto low‐density polyethylene is discussed. © 1993 John Wiley & Sons, Inc.
Solution properties of methyl methacrylate–acrylonitrile copolymers
Authors: Asaduzzaman A. K. M. , Rakshit A. K. , Devi Surekha
Published: April 2003

Characterization of methyl methacrylate‐acrylonitrile copolymers is done through viscosity, swelling, and differential refractometric studies. Viscosities of the copolymers and homopolymers were determined at 30, 40, and 50°C. The activation parameters of viscous flow, voluminosity, and shape factor were also calculated. The average shape factor was observed to be 2.5 ± 0.005 for all copolymer systems. Viscosity molecular weights were calculated, and from intramolecular expansion factor (α), it was observed that copolymers are less flexible than are homopolymers. dn/dc values obtained from differential refractometry are in good agreement with those calculated theoretically. © 1993 John Wiley & Sons, Inc.
Two‐dimensional artificial extracellular matrix: Bioadhesive peptide‐immobilized surface design
Authors: Kondoh Akihiro , Makino Keisuke , Matsuda Takehisa
Published: April 2003

A novel artificial extracellular matrix derivatized with a cell adhesive peptide, Arg—Gly—Asp—Ser (RGDS) tetrapeptide, which is the central peptidyl sequence of the adhesive site of fibronectin, was designed. RGDS coupling was achieved via isocyanation of surface hydroxyl groups of poly(vinyl alcohol) (PVA) film and subsequent conversion to activated ester. The surface‐modified PVA film was quantitatively analyzed by ESCA. The surface density of RGDS was partly controlled by the degree of isocyanation of the PVA film. Bovine endothelial cells (ECs) adhered and grew well on the RGDS‐derivatized PVA film, irrespective of the presence or absence of the serum. The adhesion and growth of ECs were enhanced with an increase in the surface density of RGDS. When a sufficient amount of RGDS was added to the medium, the adhered ECs were delaminated. This indicated that the adhesion of ECs on an RGDS‐derivatized PVA surface is mediated by the RGD—ligand/receptor interaction. Thus, a peptidyl artificial matrix via surface derivatization was developed. © 1993 John Wiley & Sons, Inc.
The influence of the surface cross‐linking of the high‐density polyethylene induced by plasma treatment on the durability of treatment efficiency
Authors: Yao Yaoguang , Liu Xeushu , Zhu Yufen
Published: April 2003

The structure of the surface cross‐linking layer of high‐density polyethylene (HDPE) produced by plasma treatment was studied by DSC, X‐ray diffraction, elemental analysis, and infrared analysis. The relationship between the cross‐linking and the durability of the modification efficiency provided by the plasma treatment was investigated. The results of the structure analysis indicated that the polar groups introduced by the plasma just locate on the upper surface of the cross‐linking layer and the chemical constitution and structure of the inner part of the cross‐linking layer is similar to that of the uncross‐linking HDPE. The cross‐linking density of the gel decreases from the surface to the inside with a large gradient and the average cross‐linking degree of the whole gel is rather low. Nevertheless, the experiment proved that this cross‐linking layer can limit the mobility of the molecules in the cross‐linking layer and hinder the decay of the treatment efficiency significantly. When the surface cross‐linking induced by plasma reaches a certain extent, the treatment efficiency will remain relatively constant in storage. © 1993 John Wiley & Sons, Inc.
Gas transport properties of poly(3‐hydroxyoxetane)
Authors: Aguilar‐Vega M. , Paul D. R. , Vandenberg E. J. , Mullis J. C.
Published: April 2003

Gas transport properties for poly(3‐hydroxyoxetane) (PHO) were measured for five gases at 35°C. While PHO has very low gas permeability coefficients, they are larger than those reported for polyacrylonitrile (PAN), poly(vinyl alcohol) (PVA1) and copolymers of ethylene / vinyl alcohol (EVAL) for all gases tested except He. The permeability coefficients for PHO and EVAL are well correlated with the density of hydroxyl groups along the chain. Extrapolations to PVA1 give values that agree well with those estimated by Salame using the Permachor method. It is suggested that some of the reported experimental values for PVA1 are in error. © 1993 John Wiley & Sons, Inc.
Structure of the epoxy–chelate metal‐containing matrices: Theoretical aspects
Authors: Kurnoskin A. V.
Published: April 2003

A theoretical analysis has been carried out of the structure of metalliferous epoxy–chelate polymers (MECP) based on diglycidyl ether of bisphenol‐A (DGEBA) hardened with metal complexes of the formula [M(L)n(X)p], where M is the cation of the transition metal; R, a nitrogen‐containing ligand; X, the anion of an organic acid; n, the number of the ligands in the complex molecule (n = 1 or 2), and p, the metal valency (p = 2 or 3). On the basis of the correlations between the tensile strength (σt) and tensile modulus (Et), and flexural strength (σf) and flexural modulus (Ef), of MECP, σt = f(Et)and σf = f(Ef), and supposing that when the condition \documentclass{article}\pagestyle{empty}\begin{document}$ \sigma _{_{t_A } }= \sigma _{_{t_B } } ,{\rm}\sigma _{_{f_A } }= \sigma _{f_B } ,{\rm}E_{t_A }= E_{t_B } ,{\rm}E_{f_A }= E_{f_B } $\end{document} is fulfilled, where A and B are complex hardeners of different structures but of the same class, the epoxy–chelate matrices have similar structures. The influence of the structural fragments of the hardener molecule (the metal, ligand, and anion) on the polymer properties was evaluated and it was found out that the biggest contribution to these properties belongs to the metal, the alteration of which changes the thermal stability (ΔM is the polymer mass loss after thermal treatment in air), deformability (ε), σf, Ef, and deflection temperature (DT) significantly. By this, the effect of the hardener structure change on the alteration of the MECP properties is maximal for ΔM, is minimal for the compressive strength (σc), and decreases in the series: ΔM > ε > DT > σf > Ef > σc. The type of the anion affects σc significantly, but the ligand type contributes the least to the polymer properties. The obtained dependencies of the MECP properties on the structural fragments of the complex hardeners allow preliminary evaluation of the structure of the chelates and epoxy–chelate compositions necessary to produce epoxy polymers with required properties. The new method of the theoretical investigation of the effect of the structural fragments (method of TIESF) of the polymer matrix on the polymer properties can be used to analyze the structures of the polymers of other classes and to predict the optimal structures, promising the production of the materials with the optimal properties. © 1993 John Wiley & Sons, Inc.
Silane cross‐linking of PVC. I. Grafting of mercaptoalkylalkoxysilanes onto PVC: Properties of the grafted and cross‐linked product
Authors: Kelnar I. , Schätz M.
Published: April 2003

The reaction of poly(vinyl chloride) (PVC) with mercaptoalkyltrialkoxysilanes yielded silane‐grafted PVC that can be cross‐linked by the hydrolytic mechanism. The grafting of the silanes on the plasticized and unplasticized PVC was carried out at 180° C during processing in the presence of basic lead‐containing stabilizers. The reaction is favorably affected by the presence of plasticizers and lubricants containing polar, preferably ester, groups. The silane‐grafted and cross‐linked polymers have satisfactory thermal stability. The results of strength measurements at elevated temperatures after cross‐linking by water indicate that the material obtained has greatly improved parameters that are suitable for a number of applications. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of poly(ether urethane)‐nylon 6 block copolymer
Authors: Seo Seung Won , Ha Wan Shik
Published: April 2003

poly(ether urethane) (PEU) prepolymer terminated with isocyanate at both ends was prepared by controlling the mol ratio of poly(tetramethylene glycol) and methane diphenyl‐4,4'‐diisocyanate. Using this prepolymer as an activator, the anionic polymerization of ϵ‐ caprolactam was carried out to obtain PEU‐nylon 6 block copolymer. The phase structure of the block copolymers was characterized on the basis of molecular interaction. The results of dynamic mechanical and thermal analyses revealed that the block copolymer films prepared via melt pressing and subsequent quenching had a one‐phase structure. The equilibrium melting temperatures determined by a Hoffman‐Weeks plot showed that the two blocks are miscible in the melt state. N‐Trifluoroacetylation of the block copolymer led to the conclusion that this miscible behavior is due mainly to the specific interaction between urethane groups in PEU block and amide groups in nylon 6 block through hydrogen bonding. © 1993 John Wiley & Sons, Inc.
Reactive extrusion of styrene polymers
Authors: Michaeli W. , Höcker H. , Berghaus U. , Frings W.
Published: April 2003

Reactive extrusion is the term used to denote a plastics processing method in which an extruder is used as a reactor for the continuous synthesis and modification of polymers. This paper describes the manufacture of polystyrene and styrene‐isoprene copolymers by a reactive extrusion process: anionic “living” s‐butyllithium‐initiated bulk polymerization was performed in a co‐rotating closely intermeshing twin‐screw extruder. The results of the process analysis show that living polymerization of styrene can be performed in a screwtype reactor, despite the high reaction temperatures of over 200°C. The polystyrene melt can be modified in bulk with comonomers or coupling reagents immediately after polymer synthesis. Depending on the raw material, formulation, and process parameters, the process variants developed and analyzed at the Institut für Kunststoffverarbeitung for homopolymerization of styrene, copolymerization of styrene‐isoprene mixtures, and sequential polymerization of styrene and isoprene resulted in styrene polymers with widely differing structural characteristics and properties. For example, the copolymerization of styrene‐isoprene monomer mixtures produced poly [isoprene‐co‐styrene)‐b‐styrene]. The sequential polymerization of styrene and isoprene led to poly(styrene‐b‐isoprene) contaminated with partly cross‐linked low molecular weight polyisoprene. The polyisoprene content is presumably formed by side reactions due to the high reaction temperatures. © 1993 John Wiley & Sons, Inc.
Crosslinking of HDPE during reactive extrusion: Rheology, thermal, and mechanical properties
Authors: Kim K. J. , Kim B. K.
Published: April 2003

The effect of peroxide and coagent, alone and together, on the crosslinking of HDPE during melt extrusion was studied. The melt flow index decreased rapidly with peroxide (1,3‐bis (t‐butylperoxy‐isopropyl) benzene), and smoothly with trimethylolpropanetriacrylate (TMPTA), but showed a small increase with parabenzoquinone (PBQ).

Melt viscosity of 0.3 phr peroxide‐treated PE responded elastically, whereas that of 0.3 phr TMPTA showed yield behavior. Tm (crystalline melting temperature) and Tc (crystallization temperature) increased with peroxide, Tm decreased, and Tc increased with TMPTA. ΔHf (heat of fusion) increased at 0.05 phr followed by a sharp drop, more with peroxide and less with TMPTA. Hardness and preyield properties increased with TMPTA, and peroxide (except hardness) with the loss of elongation at break. The most significant improvement was obtained with impact strength, over 5 times with peroxide and 7 times with TMPTA.

When the TMPTA was used in combination with peroxide, more redution in MI, followed by a further increase of hardness, modulus, and strength, was obtained, but impact strength was decreased below that of TMPTA alone. © 1993 John Wiley & Sons, Inc.
Influence of the experimental conditions on the photooxidation of poly(vinyl chloride)
Authors: Gardette J. L. , Gaumet S. , Philippart J. L.
Published: April 2003

The photooxidation of poly(vinyl chloride) involves complex reactions in which photooxidation and photodiscoloration by the formation of polyenes compete. These reactions are now fairly well understood, and on the basis of the mechanisms formerly reported, it appears possible to investigate the influence of irradiation parameters such as the thickness of the samples, the temperature, or the external pressure of oxygen. This objective requires the distribution of the photoproducts through the irradiated polymer matrix to be analyzed at the microscopic level. The shapes of the profiles that are determined show that the overall behavior of the polymer results from oxygen‐starvation effects. The diffusion of oxygen controls the rate of the photooxidation of the matrix, the rate of the photooxidative bleaching of the polyenes, and the rate of absorption of the light by the residual polyenes that have not been oxidized. © 1993 John Wiley & Sons, Inc.
In situ modification of microporous membranes
Authors: Gabriel E. M. , Gillberg G. E.
Published: April 2003

Under proper conditions, in situ polymerizations of acrylic acid monomer solutions were performed within the microporous structures of a hydrophobic membrane, Celgard ® 2500. poly(acrylic acid) modified pores have been characterized to be permanently wettable by aqueous solutions, to be capable of gelling water to withstand increased transmembrane pressure gradients, and also to possess a higher transmembrane electrical resistance. In cases of less concentrated acrylic acid monomer solutions, a cross‐linker was employed to facilitate polymer permanency within the infrastructure of the hydrophobic membranes. © 1993 John Wiley & Sons, Inc.
Concentration and separation of metallic ions from aqueous solutions by using EC‐PEG 4000 alloy membranes
Authors: Solpan D. , Sahan M.
Published: April 2003

The concentration and separation of some metallic ions have been achieved by complexing these species with suitable macromolecules or with water‐soluble polymers in ultrafiltration. The effect of water‐soluble poly(vinyl alcohol) (PVA) on the concentration and separation of Cu2+, Ni2+, and Fe3+ ions have been investigated by using EC‐PEG4000 alloy membranes in ultrafiltration experiments. The water permeability of the membranes has been measured at various pressures. The permeability of these membranes for metal ions, however, has been recorded at constant pressure but at different pH values. The highest water‐permeable membrane is also permeable for Cu2+ and Ni2+, but it shows a considerable retention for Fe3+, probably as a result of the hydrolysis of Fe3+. The retentions of metallic ions and metallic ion‐PVA couples have been determined at constant pressure but varying pH and polymer concentration values. It has been shown that Fe3+/Ni2+ pairs can well be separated by using PVA. © 1993 John Wiley & Sons, Inc.
Thermal and mechanical properties of copolymers of methyl methacrylate with N‐phenyl maleimide
Authors: Bharel Renu , Choudhary Veena , Varma I. K.
Published: April 2003

Structural modification of PMMA was done by copolymerizing it with low mole fraction (≤ 0.1) of N‐phenyl maleimide (NPM) using benzoyl peroxide as an initiator. Four copolymers were prepared by changing the mole fraction of NPM in the monomer feed from 0.025 to 0.1. The copolymer composition was determined by 1H‐NMR. An increase in NPM content resulted in an increase in Tg of copolymers. Tensile stress and % elongation decreased, whereas modulus increased with an increase in NPM content. The Flexural strength was not affected by the NPM content. The dynamic mechanical properties were also evaluated in the temperature range of–20 to 100°C. © 1993 John Wiley & Sons, Inc.
Self‐crosslinkable plastic‐rubber blend system based on poly (vinyl chloride) and acrylonitrile‐co‐butadiene rubber
Authors: Manoj N. R. , De P. P. , De S. K.
Published: April 2003

That the melt‐mixed blend of poly (vinyl chloride) and acrylonitrile‐co‐butadiene rubber becomes crosslinked during high‐temperature molding is evident from Monsanto rheometric, solvent swelling, and infrared spectroscopic studies. Dynamic mechanical analysis shows that such a self‐crosslinkable plastic‐rubber blend is miscible in different blend ratios. The degree of crosslinking depends on the blend ratios and the molding conditions. The cross‐linking reaction involves the allylic chlorine sites in poly (vinyl chloride) and the CN group in the nitrile rubber. © 1993 John Wiley & Sons, Inc.
Transport properties of poly(vinyl alcohol) membranes of different degrees of crystallinity. I. Pervaporation results
Authors: Gref R. , Nguyen Q. T. , Schaetzel P. , Néel J.
Published: April 2003

Dense poly (vinyl alcohol) (PVA) membranes of different crystallinities were prepared and studied in pervaporation of water‐ethanol mixtures. High selectivities to water were obtained with all types of membranes. Permeation fluxes increase exponentially with the water content in the liquid mixture. At a given water content, the membrane permeability decreases drastically when its crystallinity increases. When the pervaporation temperature increases, the permeation flux increases according to the Arrheniuslike law, with a permeation acti‐vation energy that depends strongly on the crystallinity of the membrane. A permeation model, in which the volume fraction of amorphous polymer intervenes in both the sorption and the diffusion laws, was proposed and validated by the experimental data. With the obtained values of the parameters, the permeation Olux can be calculated for membranes of a given crystallinity at any temperature and composition of the water‐alcohol mixture. © 1993 John Wiley & Sons, Inc.