bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cure kinetics of different molar ratios of 4,4′‐bismaleimidodiphenylmethane and bisphenol A dicyanate
Authors: Hong Jin‐Long , Wang Cherng‐Kuo , Lin Rong‐Hsein 
Published: April 2003

AbstractBismaleimide‐triazine (BT) resins are thermosets derived from the addition polymerization of different molar ratios of 4,4′‐bismaleimidodiphenylmethane (BM) and bisphenol A dicyanate (BA). The possible cross‐linking reactions involved in the formation of BT resins are addition polymerization of BM, cyclocrimerization of BA, and heteropolymerization between BM and BA. Fourier‐transform infrared spectroscopy reveals that cyclotrimerization of BA occurs during the cure of a 1 : 2 molar ratio of BM to BA (as 1M2A). No sign of cyclotrimerization is observed for the case of the 1 : 1 molar ratio of BM to BA (as 1M1A). A dynamic differential scanning calorimeter (DSC) is employed to study the cure kinetics. The apparent activation energy evaluated from the Prime method is increased with the content of the BM component in the starting mixture. The different pattern of activation energy with fractional conversion (α) indicates the different chemical nature for the cure reactions of 1M1A and 1M2A. The empirical rate functions thus evaluated are 2.32 × 105 + 5.62 α 105α − 8.61 × 105α2 and 6.07 × 105 + 1.06 × 106α − 1.66 × 106α2s−1 for the cure reactions of 1M1A and 1M2A, respectively. © 1994 John Wiley & Sons, Inc.
Application of ionically crosslinked latex membranes to the separation of ethanol–water mixtures by pervaporation
Authors: Wei Yi , Huang Robert Y. M. 
Published: April 2003

AbstractIonically crosslinked latex membrane is prepared by treating the latex membrane containing carboxyl groups with salt solutions. Pervaporation separation with these membranes shows that the ionic crosslinking raises the permeability, with the selectivity being maintained or increased. Ionically crosslinked membranes also have a higher pervaporation separation efficiency than the nontreated membranes. Permeability and selectivity increase with increasing ethanol content in feed. The temperature dependence of permeability can be correlated by the Arrhenius relationship. © 1994 John Wiley & Sons, Inc.
100% solids ultraviolet curing acrylated chlorinated rubber coatings
Authors: Thames Shelby F. , He Z. Alex 
Published: April 2003

AbstractAcrylated chlorinated rubber (ACR) has been synthesized from masticated natural rubber and characterized with Fourier transform infrared spectroscopy (FTIR), solid state nuclear magnetic resonance spectroscopy (NMR), and differential scanning calorimetry (DSC). The ACR products have been used as prepolymers in formulations of 100% solids ultraviolet (UV) cured coatings. The UV cured ACR‐based coatings show excellent performance and attractive appearance. Formulation examples and coating performance are reported. © 1994 John Wiley & Sons, Inc.
Enantioface differentiation by chiral polymers containing dimethylaminobornyl moieties
Authors: Liu Jui‐Hsiang 
Published: April 2003

AbstractChiral monomers cis,endo‐3‐dimethylamino‐2‐bornyl methacrylate (DABM) and N,N‐dimethyl[cis,endo‐2‐(2‐vinyloxy‐ethoxy)‐3‐bornyl]amine (DVEBA) were synthesized from (+)‐camphor. The homopolymerization of both DABM and DVEBA, and the copolymerization of both chiral monomers with achiral methylmethacrylate (MMA) and styrene (St) were carried out with 2,2‐azobisisobutyronitrile (AIBN) in various organic solvents. Effects of temperature, solvents, reagent molar ratio and reaction time on the polymerizations were studied. Dependences of the feeding concentration and reaction conditions on the specific rotation of the chiral copolymers were investigated. Enantioface differentiation by using the chiral polymers having dimethylaminobornyl moieties synthesized in this investigation were investigated. Effects of temperature and solvent on the asymmetric induction were also studied. © 1994 John Wiley & Sons, Inc.
Fractionated crystallization in polyolefins–nylon 6 blends
Authors: Tang Tao , Huang Baotong 
Published: April 2003

AbstractThe crystallization behavior of polyolefins–nylon 6 polymer blends was studied by differential scanning calorimetry (DSC) measurements. In these blends, the crystallization of the minor component often starts with distinctly deeper supercooling than that of the pure polymer, and proceeds in several separate steps. The origin of this phenomenon was studied and was related to the volume fraction of the dispersed phase and the compatibility between the dispersed phase and the matrix. © 1994 John Wiley & Sons, Inc.
Thermoplastic elastomers from iPP/EPR blends: Crystallization and phase structure development
Authors: D'Orazio L. , Mancarella C. , Martuscelli E. , Sticotti G. , Ghisellini R. 
Published: April 2003

AbstractThe phase morphology and structure of thermoplastic elastomers obtained from isotactic polypropylene (iPP) and ethylene—propylene random copolymer (EPR) blends by means of the dynamic curing of EPR rubbery component carried out during its melt mixing with iPP in a Banbury mixer at 180°C were investigated. Samples obtained by compression molding and by using isothermal crystallization conditions of the iPP phase were analyzed by means of differential scanning calorimetry, of optical, scanning, and transmission electron microscopy, and of wide‐angle and small‐angle X‐ray diffraction. The influence of cooling below the melting point and of EPR molecular structure on the kinetic and thermodynamic parameters related to crystallization process of the iPP phase was also studied. It was found that the process of dynamic curing of the EPR component dramatically affects the development of the phase morphology and structure in the material. As a matter of fact, the blend containing the uncured EPR is characterized by the presence of iPP domains randomly distributed in the EPR rubbery matrix, whereas in the blend containing the cured EPR the iPP phase becomes the continuous phase crystallizing in a structure that resembles a cobweb tending to surround the EPR cured particles; moreover such an iPP cobweb appears to be contituted by row structures of stacked lamellae. It was found that the addition of EPR phase interferes dramatically with the crystallization process of the iPP, thus inducing drastic modification in its intrinsic morphology (size, neatness, regularity of spherulites, inner structure of spherulites, etc.). Such interference was found to be comparatively stronger when the iPP phase crystallizes in presence of cured EPR. The elastic behavior of the thermoplastic elastomer material was accounted for by applying the “leaf spring model” to the morphology and structure of the iPP phase crystallized in presence of cured EPR. © 1994 John Wiley & Sons, Inc.
Studies on preparation and ion‐exchange properties of weakly acidic cation exchange fiber by preirradiation‐induced graft copolymerization with electron beam
Authors: Yun Lu , Zhu Zhang , Hanmin Zeng 
Published: April 2003

AbstractWeak acidic cational exchange fibers were obtained by means of preirradiation‐induced graft copolymerization of methacrylic acid, acrylic acid, and diglycol acrylate onto polypropylene nonwoven fabric with electron beam. Effects that influence grafting and the exchange adsorptive property of the ion‐exchange fibers obtained toward transition and rare‐earth metal ions have been investigated. © 1994 John Wiley & Sons, Inc.
PBI powder processing to performance parts
Authors: Hughes O. R. , Chen P. N. , Cooper W. M. , DiSano L. P. , Alvarez E. , Andres T. E. 
Published: April 2003

AbstractA new route (“direct forming”) was developed for forming dense PBI shapes from PBI powder. The new process affords the possibility of automated PBI powder shaping (“cold compaction”) and densification in batches of multiple parts by a “powder‐assisted hot isostatic pressing” process. Direct forming is a more productive alternative to hot compression molding. Two developments enable PBI direct forming: (1) the discovery that PBI powders that are porous and plasticized with moisture can be shaped by compaction at ambient temperatures (cold‐compacted), and (2) a finding that cold‐compacted shapes can be densified in large batches by a powder‐assisted hot isostatic pressing. The porous PBI powder is formed from PBI in solution by a spray‐precipitation process. When plasticized with moisture, this powder is cold‐compactible to PBI shapes with densities up to 94% of that of ultimate density of PBI. These shapes, which have sufficient strength to be handled, are then further consolidated via powder‐assisted hot isostatic pressing to shapes with excellent thermal and mechanical properties and densities of about 99% of the ultimate. © 1994 John Wiley & Sons, Inc.
Composition depth profiles of plasma‐fluorinated poly(ethylene terephthalate) fibers
Authors: McCaulley James A. , Goldberg Harris A. 
Published: April 2003

AbstractComposition depth profiles of the outer 50 Å of plasma‐fluorinated poly(ethylene terephthalate) fibers were obtained by angle‐dependent X‐ray photoelectron spectroscopy (XPS). The effect of sample geometry on XPS sampling depth and the depth distribution function (DDF) was determined theoretically for cylindrical and hemispherical surfaces. The theoretical DDFs are nonexponential. For cylindrical surfaces, the effect is small, a 22% increase in surface sensitivity. The average XPS sampling depth for smooth, properly oriented fibers is shown to vary, as it does for a planar surface, as the sine of the nominal takeoff angle. The DDF appropriate for cylindrical surfaces was incorporated into a computer program for inversion of angle‐dependent XPS data to obtain composition depth profiles of the fibers. Plasma‐fluorinated PET fibers were used to demonstrate the use of angle‐dependent XPS on fibers. XPS results indicate that most fluorination occurs within the top few “monolayers,” attack is preferentially at the phenyl ring, both CHF and  CF2  moieties are formed, and fluorination causes partial loss of aromaticity. © 1994 John Wiley & Sons, Inc.
Synthesis, characterization, and processing of aromatic copolyesters with different monomer sequences
Authors: Makhija S. , Jaffe M. 
Published: April 2003

AbstractTwo aromatic copoyester compositions were prepared from p‐hydroxybenzoic acid, hydroquinone, and isophthalic acid with compositions 2 : 1 : 1 (HIQ50) and 1 : 1 : 1 (HIQ33). For each of these compositions, one random copolyester and one known sequence copolymer was prepared. The random compositions were prepared by melt condensation, whereas controlled sequence polymers were prepared by low‐temperature solution polymerization. For the 1 : 1 : 1 composition, the controlled sequence polymer had higher crystallinity than that of the random, whereas the 2 : 1 : 1 composition random copolymer had higher crystallinity. The difference in crystallinity is attributed to the sequence distributions in the copolymers. All compositions were thermotropic in nature. © 1994 John Wiley & Sons, Inc.
Synthesis and randomization of well‐defined sequence, wholly aromatic copolyester/esteramides
Authors: Choe Eui‐Won , Borzo Marie 
Published: April 2003

AbstractWell‐defined sequence, wholly aromatic copolyester/esteramides have been synthesized by an interfacial polycondensation of a preformed triad diacid chloride monomer, di(para‐chlorocarbonylphenyl)isophthalate, with the disodium salt of hydroquinone or of deuterated hydroquinone, or with meta‐phenylene diamine. Carbon‐13 nuclear magnetic resonance (NMR) spectroscopy provided unequivocal evidence for regularly alternating polymer structures, and coupled with statistical methods, for randomization on heating in the case of regularly alternating poly(p‐oxybenzoate‐co‐p‐phenylene isophthalate). Polymers synthesized using standard high‐temperature melt‐polymerization techniques were shown by statistical/carbon‐13 NMR methods to have essentially random structures. Thermal properties of copolymer powders and films were found to vary with monomer sequence distribution as well as with composition. © 1994 John Wiley & Sons, Inc.
Measurement of polar orientation in poled side‐chain NLO polymers using infrared spectroscopy
Authors: Carr P. L. , Davies G. R. , Ward I. M. 
Published: April 2003

AbstractInfrared spectroscopy has been used to provide an independent estimate of dipole orientation in poled films of a side‐chain polymer based on poly(methyl methacrylate) with an oxynitrostilbene side group attached via an aliphatic spacer. In particular, we used the dichroism of the absorption band assigned to the NO2 symmetric stretching vibration as a measure of the orientation of the nitrostilbene group. This yields 〈P2(cos θ)〉, where θ is the angle between the transition dipole moment and the symmetry axis of the sample. We then used a Langevin‐type model to calculate 〈cos θ〉 from 〈P2(cos θ)〉 and concluded that values of 〈cos θ〉 as high as 0.5 are being achieved. We find, however, that 〈P2(cos θ)〉 obtained by comparison of normal incidence measurements on unpoled and poled films does not agree with 〈P2(cos θ)〉 obtained from tilted‐film measurements on poled films. We propose that this discrepancy arises because the local field in a poled sample affects the polarizability of the molecules. To confirm this, we applied high fields to unpoled films in the infrared spectrometer at room temperature. The results clearly show a large reduction in absorbance with the applied field when the infrared electric field vector has a component perpendicular to the plane of the film. A major error therefore occurs as a consequence of the internal field in poled samples if 〈P2(cos θ)〉 is derived from the tilted film measurements, whereas 〈P2(cos θ)〉 derived from normal incidence measurements is essentially correct. © 1994 John Wiley & Sons, Inc.
Nonlinear optical polymers in advanced photonics
Authors: Jacobson S. , Landi P. , Findakly T. , Stamatoff J. , Yoon H. 
Published: April 2003

AbstractDevelopment of advanced photonic devices requires extensive integration of several technologies. Electrooptical devices must simultaneously satisfy several materials properties including: high nonlinear optical activity, thermal stability, mechanical strength, and optical transparency. In addition, the device materials must be amenable to fabrication, and must be compatible in a multi‐layered configuration. We have recently developed polymers which meet these complex requirements. Indeed, electrooptical devices have been demonstrated using these polymers. This paper is a comprehensive review of the development of such devices, from design of the molecular architecture to waveguide design and fabrication. The critical issues in each aspect of device development are discussed. © 1994 John Wiley & Sons, Inc.
Mechanical failure in thin‐film nonlinear optical polymers: Structure and processing issues
Authors: McCulloch Iain , Man Hong‐Tai , Song Kigook , Yoon Hyun 
Published: April 2003

AbstractStress developed during the spin‐coating process often initiates cracks leading to failure in nonlinear optical devices. The primary intrinsic reasons for this were shown to be a lack of a secondary relaxation process below the glass transition as well as an insufficiently large molecular weight to enhance toughness by chain entanglement, as detected by dielectric measurements and viscoelastic shear moduli, respectively. A detailed systematic synthetic effort was undertaken to increase the chain length through improved free‐radical methods. Results showed that as the molecular weight was raised chain entanglements were observed and film toughness was improved as evidenced by the thicker, crack‐free film attained. As well as thermal stresses, solvent stress cracking was identified as a major source of fabrication defects in the multilayer spin‐coating process. A plasma polymer layer deposited on the film surface was successful as a barrier layer preventing solvent penetration and crack formation. © 1994 John Wiley & Sons, Inc.
Silicon phthalocyanine/methyl methacrylate copolymer slab directional couplers for all‐optical switching
Authors: Sounik J. R. , Norwood R. A. , Popolo J. , Holcomb D. R. , Ghatani S. S. 
Published: April 2003

AbstractSlab waveguide directional couplers were fabricated from the third‐order nonlinear optical polymer silicon phthalocyanine/methyl methacrylate 2/98 copolymer as the active material and poly(methyl methacrylate) as the cladding layer. The monomethacrylate copolymer was synthesized, device fabrication conditions determined, and five‐layer slab directional couplers fabricated. Completed couplers demonstrated waveguide loss on the order of 5 dB/cm and coupling lengths of 0.5 mm at 1.29 μm. These vertically coupled devices may be useful for all‐optical switching. © 1994 John Wiley & Sons, Inc.
Preparation and thermal properties of acrylic polymers with pendant spirobislactone groups
Authors: Pawlikowski Gregory T. , Brady Robert F. 
Published: April 2003

AbstractA series of acrylic terpolymers containing varying concentrations of crosslinkable glycidyl, spirobislactone, and hydroxyl pendant groups was prepared by radical chain polymerization. The glass‐transition temperatures and weight average molecular weights of the terpolymers span broad ranges and can be independently selected by control of monomer composition. Cross‐linking at 210°C was monitored by infrared spectroscopy. The rate and extent of reaction of spirobislactone groups were found to be greater than those for glycidyl groups. The activation energies of the spirobislactone and glycidyl reactions in the range between 160 and 210°C were calculated by Arrhenius treatment of the curing kinetics and found to be 31.0 ± 1.1 kJ mol−1 and 59.1 ± 1.2 kJ mol−1, respectively. The double ring opening reaction of the spirobislactone groups has no effect on the volume of the cross‐linked polymers. © 1994 John Wiley & Sons, Inc.
Conducting rubberlike copolymer–carbon fiber composites
Authors: Ruckenstein Eli , Hong Liang 
Published: April 2003

AbstractElectrically conductive rubberlike copolymer–carbon fiber composites have been prepared by either a solution method or a concentrated emulsion method. In the former procedure, carbon fibers were introduced with stirring in a copolymer–toluene solution, and the polymer–fiber composites were precipitated by extracting the solvent with methanol. In the latter procedure, a pastelike concentrated emulsion of copolymer–toluene solution in an aqueous solution of sodium dodecylsulfate (SDS) was first formed, and the carbon fibers were mechanically blended with the concentrated emulsion. The polymer–carbon fiber composites were precipitated by extracting the toluene and water with methanol. Four kinds of rubberlike copolymers have been used: styrene/ethylene–butylene/styrene triblock copolymer (SES), styrene/butadiene/styrene triblock copolymer (SBS), ethylene/propene/ethylene triblock copolymer (EPE), and ethylene/vinylacetate copolymer (EVA). Short (L = 0.1 mm)‐ and medium (L = 5 mm)‐length carbon fibers were employed. The composites were hot‐pressed in a Laboratory Press to form a sheet. The effects of the two methodologies on the electrical conductivity and mechanical properties of the sheets were investigated by changing the type of polymer, the size of the carbon fibers, the volume fraction of the carbon fibers in the composites, and the hot‐pressing temperature. Composites with electrical conductivities in the range of 5–14 S/cm, tensile strengths in the range of 10–17 MPa, and elongations at break point larger than 200% were obtained. The conductivities of the composites prepared with the short fibers were by two orders of magnitude smaller than those prepared with medium‐size fibers. © 1994 John Wiley & Sons, Inc.
Syntheses of copolymers of chloroprene with ethylmethacrylate and glycidylmethacrylates
Authors: Park Choon Keon , Ha Chang Sik , Lee Jin Kook , Cho Won Jei 
Published: April 2003

AbstractChloroprene (2‐chloro‐1,3‐butadiene; CP) was prepared by dehydrochlorination of 3,4‐dichloro‐1‐butene (DCB) in aquous solution of sodium hydroxide in the presence of tetrahydrofurfuryl alcohol (THFA) at 60°C. The copolymers of CP with ethylmethacrylate (EMA) and glycidylmethacrylate (GMA) were prepared by radical solution polymerization in benzene. The copolymers, poly(CP‐co‐EMA) and poly(CP‐co‐GMA), were characterized by FT‐IR and 1H‐NMR spectrophotometers and differential scanning carolimetry (DSC). It was observed that the copolymers were amorphous and had glass transition temperatures of about −34.5 and −16.4°C, respectively. The monomer reactivity ratios were given as r1(CP) = 2.14 and r2(EMA) = 0.18 in the copolymerization of CP and EMA, and as r1(CP) = 4.02 and r2(GMA) = 0.12 in copolymerization of CP and GMA, respectively. For comparison, the graft copolymers of EMA or GMA onto CR(poly(CR‐g‐EMA) and poly(CR‐g‐GMA)) were also prepared. © 1994 John Wiley & Sons, Inc.
High temperature stable photopatternable copolymers: Synthesis, optical properties, and photopatterning process studies
Authors: Kawatsuki Nobuhiro , Watanabe Rikuji , Tokuhara Toshiaki , Uetsuki Masao , Nagata Shiro , Ichimura Hidejiro 
Published: April 2003

AbstractPhotopatternable copolymers and photopatterning processes for high temperature stable optical elements have been studied. The photopatternable copolymers were synthesized from methyl methacrylate and methacrylic ester comprising a nonconjugate carbon–carbon double bond side chain and epoxy side chain. Their optical properties were investigated on film samples doped with m‐benzoylbenzophenone (BBP). After irradiating with UV light, insoluble polymer was formed in a high yield at higher temperature, resulting in changes in thickness and refractive index, which were precisely controlled by the exposure energy of UV light. The two step photopatterning processes were carried out by means of UV irradiations with and without a photomask bearing a grating pattern followed by removal of unreacted BBP to draw an optical pattern on the polymer material with cross‐linking. Further photoreaction was also performed to cure the polymer by exposure with a high energy UV lamp containing shorter wavelength light after the patterning process. By a combination of the patterning process and the postcuring process, an optical grating fabricated from these copolymers showed a heat stability up to 160°C. © 1994 John Wiley & Sons, Inc.
Studying the storage maturation of freshly mixed rubber compounds and its effects on processing properties
Authors: Leblanc J. L. , Staelraeve A. 
Published: April 2003

AbstractExperiments were performed to study the variation upon storage at room temperature of both the bound rubber and the rheological properties of filled rubber compounds, prepared either with high cis‐1,4 polybutadiene or with natural rubber and various levels of a reinforcing carbon black. It was found that the bound rubber and the rheological properties vary upon storage according to a two‐stage model. Depending on the chemical nature of the rubber, several hundred hours storage are necessary before constant properties are measured. These variations are related to changes occuring in the rubber‐black morphology of the compounds. Large strain rheological tests are most sensitive to storage maturation which suggests an explanation for well‐known hardening effects observed on the factory floor. © 1994 John Wiley & Sons, Inc.