bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Slab 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

A 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

Electrically 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

Chloroprene (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

Photopatternable 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

Experiments 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.
Methyl nadimide resins: Synthesis and characterization
Authors: Alam Sarfaraz , Kandpal L. D. , Varma I. K.
Published: April 2003

This article describes the synthesis and characterization of several methyl nadimides endcapped resins based on tris(3‐aminophenyl)phosphine oxide. These resins were prepared by reacting methyl‐5‐norbornene 2,3‐dicarboxylic anhydride (methyl nadic anhydride) (MNA), pyromellitic dianhydride (PMDA)/3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6F), and tris(3‐aminophenyl)phosphine oxide (TAP) in glacial acetic acid/acetone. Structural characterization of the resins was done by elemental analysis, IR, and 1H‐NMR. Thermal characterization of uncured resins using DSC and TGA techniques revealed an exothermic transition accompanied by a weight loss in the temperature range of 200–350°C. Residual weight at 800°C in nitrogen was found to be 47–55%. Isothermal curing of the resins was done at 340°C for 1 h in an air atmosphere. The cured resins were stable up to 400 ± 20°C. © 1994 John Wiley & Sons, Inc.
The film formation of acrylic latexes: A comprehensive model of film coalescence
Authors: Eckersley Sarah T. , Rudin Alfred
Published: April 2003

A comprehensive model of film formation that was proposed in an earlier article by the present authors was evaluated for latexes having a wide range of physical properties. In this model, capillary force and interfacial forces act in tandem to promote film coalescence. The emulsion polymers studied were all based on poly(methyl methacrylate‐co‐butyl acrylate). The viscoelastic nature of the copolymer was varied by the addition of molecular weight modifiers (CBr4 chain‐transfer agent and ethylene glycol dimethacrylate cross‐linking monomer) during synthesis. In contrast to the simplifications of the previous analysis, the experimental system was well characterized. The effect of water plasticization was investigated. The surface energetics of the system were studied. Also, drying kinetics were considered. Results showed that the degree of coalescence ranged from complete fusion to superficial fusion. The minimum film temperature was found to increase with increasing polymer rigidity, as is expected. Comparison of the model predictions and experimental observations validated the model. © 1994 John Wiley & Sons, Inc.
Effect of compatibility on specific volume of molten polyblends
Authors: Wang Y. Z. , Hsieh K. H. , Chen L. W. , Tseng H. C.
Published: April 2003

The specific volume of polymer blends with different degree of compatibility has been measured at high pressure, up to 2000 kg/cm2, in the molten state by a dilatometer. The specific volume and thermal expansion coefficient of the molten homopolymers at zero pressure were satisfactorily fitted to a simplified Simha–Somcynsky equation. The specific volume of styrene–butadiene (SBR) random copolymer, which is considered to be a compatible system, at a constant styrene composition can be calculated by an semiempirical equation based on the Tait equation. The temperature dependence of excess specific volume of SBR with different styrene content at zero pressure was estimated by a combining rule in terms of self‐and cross interactions. The concentration‐dependent equation is derived to estimate the specific volume of SBR with various styrene contents. Both the thermal and dynamic mechanical analysis of the blend from the two polystyrene (PS) and polybutadiene (BR) homopolymers show a low degree of compatibility. The weight fractions of each domain consisting of PS blending with BR and those of the components in each domain can be calculated from the mass balance on the two domains and the rearranged Couchman equation. The specific volume of PS–BR composed of two phases obeys the principle of additivity from the weight fractions of the specific volume of the corresponding phases. © 1994 John Wiley & Sons, Inc.
Morphological study of hydrogels of cellulosic super water absorbents by CRYO‐SEM observation
Authors: Yoshinobu Masahiro , Morita Mitsuhiro , Higuchi Mitsuo , Sakata Isao
Published: April 2003

The structures of the hydrogels of the partially hydrolyzed cellulose‐graft‐polyacrylamide copolymers as super water absorbents were examined by use of a cryogenic scanning electron microscope. The hydrogel of the wood pulp graft copolymer that had been not hydrolyzed (P/PULP‐AM) formed a spongelike structure with numerous circular micropores. The highly swollen hydrogel of the partially hydrolyzed wood pulp graft copolymer (P/PULP‐AM‐Hyd), on the other hand, formed a honeycomblike structure with polygonal pores surrounded with membraneous walls. A hydrogel of a crosslinked polyacrylamide (PAM) formed a similar structure to that of P/PULP‐AM, but the honeycomblike structure shown in P/PULP‐AM‐Hyd was not observed in the partially hydrolyzed PAM. The pore size of the honeycomblike structure of the hydrogel of P/PULP‐AM‐Hyd decreased with an increase in the amount of the crosslinker added at graft copolymerization. For the hydrogel of the P/PULP‐AM‐Hyd with less addition of the crosslinker, however, the honeycomblike structure had been broken. The hydrogel of the P/PULP‐AM‐Hyd without the addition of the crosslinker did not show a honeycomblike structure. In spite of no addition of the crosslinker, the cellulosic film and nonwoven fabric graft copolymers formed honeycomblike structures. © 1994 John Wiley & Sons, Inc.
A morphological examination of ceric ion and preirradiation acrylic acid‐grafted rayon fibers
Authors: Gupta B. S. , McDowall D. J. , Stannett V. T.
Published: April 2003

Using the ceric ion and preirradiation methods, acrylic acid was grafted to rayon. The fiber used was large denier (50) continuous filament, particularly suited for examining changes in morphology and properties. The grafted fiber was given decrystallization treatments involving ZnCl2 and NaOH. Optimization studies conducted to seek maximum graft with minimum homopolymer formation has been published elsewhere.1 Also published earlier were the results of changes in mechanical and physical properties of the fiber resulting from the grafting and decrystallization treatments.2 Presented in this article are the results on the effects of these treatments on the structure and the morphology of the fiber. The structural features examined were the molecular orientation, crystallinity and crystalline orientation, and the surface morphology. Based on the results of this study and those of the earlier2, it was possible to develop and propose a model of fiber structure that fits the present fiber. © 1994 John Wiley & Sons, Inc.
Quartz crystal microbalance study for chemical synthesis of polypyrrole
Authors: Ayad Mohamad M.
Published: April 2003

The quartz crystal microbalance was used to monitor the deposition of a smooth film of the conductive polypyrrole (PP) using a purely chemical method. The film was grown from the oxidative polymerization of pyrrole with potassium persulfate in aqueous solution. A comparison was made between the growth rate of PP films and the PP formed in the bulk at the same molar ratio of the reactants. The kinetics of the PP film formation were found to be governed by the concentration of the reactants in the bulk. The effect of HCl on the growth rate of PP films was also investigated. © 1994 John Wiley & Sons, Inc.
Curing studies on the epoxides of carbono‐ and thiocarbonohydrazones
Authors: Thangamathesvaran P. M. , Jain S. R.
Published: April 2003

The curing behavior of a new class of NN bonded epoxy resins has been analyzed using the simultaneous DTA‐TG, dynamic mechanical analysis (DMA), and thermomechanical analysis (TMA) techniques. The resin systems, viz, diglycidyl ether of furfuraldehydecarbonohydrazone (DGFCH), diglycidyl ether of furfuraldehydethiocarbonohydrazone (DGFTCH), and tetraglycidyl ether of vanillinthiocarbonohydrazone (TGVTCH) with the curative, diaminodiphenylmethane (DDM), taken in stoichiometric amounts have been examined. The curing exotherm could be resolved from the decomposition exotherm qualitatively using DTA‐TG analysis. The DMA has been carried out in both the dynamic and isothermal mode to follow the curing process of the systems DGFCH/DDM and TGVTCH/DDM. The storage modulus (G′), loss modulus (G″), complex viscosity (η) and creep factor (tan δ) were measured simultaneously. The crossover point of G′ and G″, taken as the gelation point in isothermal runs, was determined to obtain time to gelation at that temperature. The isothermal runs at different temperatures have been used to calculate activation energy of the curing process up to gelation. For the difunctional resin DGFTCH, the activation energy value was found to be 18.7 kcal/mol. The thermomechanical analysis (TMA) has been used to find the glass transition (Tg0, and melt transition (Tm) temperatures. The cured tetrafunctional TGVTCH/DDM system as expected, has higher Tg than those of the two difunctional resin systems. © 1994 John Wiley & Sons, Inc.
Polyamides and polyimides prepared from diaminomaleonitrile and their cross‐linking to thermally stable resins
Authors: Mikroyannidis John A.
Published: April 2003

Unsaturated cyano‐substituted polyamide and polyimides were prepared from the reactions of diaminomaleonitrile with terephthaloyl dichloride and tetracarboxylic dianhydrides such as pyromellitic dianhydride and benzophenone tetracarboxylic dianhydride. The polymers were characterized by inherent viscosity measurements, by FTIR and 1H‐NMR spectroscopy, as well as by DTA and TGA. They were soluble in polar aprotic solvents and certain strong inorganic and organic acids. Upon curing at 300°C for 70 h, cross‐linked polymers were obtained that were stable up to 397–426°C in N2 or air and afforded anaerobic char yield of 56–61% at 800°C. Their glass transition temperatures as determined by the thermal mechanical analysis (TMA) method were 210–249°C. © 1994 John Wiley & Sons, Inc.
Radiation‐initiated inverse emulsion polymerization of vinylpyrrolidone
Authors: Taylor M. B. , Gilbert R. D. , Stannett V. T. , Williams J. L.
Published: April 2003

The radiation‐induced inverse emulsion polyerization of vinylpyrrolidone using an isoparaffinic hydrocarbon and nonionic emulsifier blend is described. High molecular weight polyvinylpyrrolidone (PVP) (1 million to 2 million Mv) was readily obtained at rapid polmerization rates (Rp ∼ 10–35 mol 1−1 s−1) to high conversions (90–95%). The polydispersity of the polymer varied from 2.6 to 4.4, suggesting that chain transfer to the polymer had occurred. Adding a polymeric surfactant to the nonionic blend modified the polymerization rate and particle‐size distribution. © 1994 John Wiley & Sons, Inc.
Graft‐copolyamide molecular composites
Authors: Aharoni Shaul M.
Published: April 2003

A novel family of graft‐copolyamides was prepared in which several chains of high molecular weight polycaproamide (nylon 6) are grafted onto the backbone of each stiff aromatic polyamide chain. The unique feature of the present graft‐copolyamides is that the side chains are connected through amide groups directly to the aromatic rings in the stiff chain, and not to the amide groups in the backbone of the stiff chain. Because they are miscible with linear nylon 6, blends of the graft‐copolymers and nylon 6 are easily prepared. Electron microscopy, x‐ray diffraction scans, DSC runs, and solid‐state NMR relaxation and spin diffusion experiments all indicate that the aromatic stiff polyamide chains are molecularly dispersed in the graft‐copolyamides and their blends with nylon 6. In an ungrafted blend of the stiff aromatic and flexible aliphatic nylon 6, the stiff chains tend to agglomerate into small hydrogen‐bonded sheaf‐like aggregates the size of which increases upon annealing above the melting point of the flexible polyamide. The NMR results point to a substantial flexibility of the stiff chains in the graft‐copolyamides, helping to explain the levels of reinforcement reflected in the tensile properties of these materials. In the ungrafted blends, the aromatic‐chain stiffness is greatly enhanced when these chains are phase separated in the minute sheaf‐like particles. The tensile properties of the graft‐copolymers and their mixtures with pure nylon 6 are far superior to those of the ungrafted blends. The reinforcement of the flexible matrix by the stiff polyamide chains is explained in terms of the Halpin—Tsai formulation. © 1994 John Wiley & Sons, Inc.
Development and control of a blend morphology by In situ cross‐linking of the dispersed phase
Authors: De Loor A. , Cassagnau P. , Michel A. , Vergnes B.
Published: April 2003

The development of the morphology of a reactive blend along a twin‐screw extruder has been experimentally studied. A transesterification reaction activated by a catalyst allowed a cross‐linking of the dispersed phase during the flow in the extruder. In comparison with the nonreactive system (without catalysts), the resulting morphologies were characterized by larger dimensions. Influence of screw speed and feed rate were similar for both systems, whereas the changes along the screws were more pronounced for the reactive blend. It appeared that the local morphology was strongly dependent on the extent of the reaction. At low extent, the equilibrium between breakup and coalescence was shifted toward coalescence, whereas at high extent, the classical mechanisms were largely modified and replaced by a “coagulation” mechanism. It was shown that, for the fully cross‐linked dispersed phase, the final morphology remained remarkably stable during successive extrusion steps. For such products, the observation of a low‐frequency plateau of the elastic modulus suggested the formation of a copolymer at the interface with the matrix. © 1994 John Wiley & Sons, Inc.
Cross‐linked polymer brushes. II. Formation and properties of poly(isobutyl vinyl ether)‐b‐poly[2‐(vinyloxy)ethyl cinnamate] brushes
Authors: Liu Guojun , Xu Xiuqi , Skupinska Krystyna , Hu Nanxing , Yao Hong
Published: April 2003

A diblock copolymer, i.e., poly(isobutyl vinyl ether)‐b‐poly[2‐(vinyloxy)ethyl cinnamate] (PIBVE‐b‐PVEC), has been shown to form polymer brushes quickly on the surface of solid substrates by deposition from a solvent selectively poor for PVEC. The resultant brush could be cross‐linked photochemically by initiating the dimerization between VEC groups of different polymer chains and the cross‐linking was extremely efficient. Crosslinked polymer brushes, as expected, were resistant to organic solvent, such as chloroform, and nitric acid attacks. Important industrial applications are expected of cross‐linked brushes. © 1994 John Wiley & Sons, Inc.
Solid‐state NMR studies of relaxations in modified duroplastic low‐stress materials
Authors: Domke W.‐D. , Halmheu F. , Schneider S.
Published: April 2003

Duroplastic low‐stress molding materials, based on epoxy novolak resins with different siloxane modifications have been investigated with respect to the mobility of different structural elements and the morphology of the resulting polymers. Different solid‐state NMR relaxation experiments have been used to probe the mobility in a wide range of motional frequencies. Spin diffusion experiments allowed the estimation of domain sizes even in the case of highly filled polymers and indicate that the effect of low‐stress modification is correlated with microphase separation. © 1994 John Wiley & Sons, Inc.
Permeation of gases across the poly(chloro‐p‐xylylene) membrane
Authors: Tanioka Akihiko , Fukushima Noriaki , Hasegawa Koichi , Miyasaka Keizo , Takahashi Noboru
Published: April 2003

Gas permeabilities across poly(chloro‐p‐xylylene) (parylene C) films are measured with different thicknesses of 20.2, 10.0, 8.9, 4.6, 3.4, and 1.0 μm. Measurements were carried out below 1 atm and between 10 and 80°C, which are under the glass transition temperature. The temperature and pressure dependencies of the permeability and the apparent diffusion coefficients were measured. If the membrane thickness is larger than 8 μ, the gas‐transport mechanism is solution–diffusion, which implies that it is pinhole‐free, because the pressure dependency of the permeability cannot be found and the apparent activation energy of permeation and diffusion are observed. If the membrane thickness is less than 8 μ, the gas transport mechanism is pore flow combined with solution–diffusion flow because gas may penetrate both the porous area and the polymer matrix. The thinner the membrane, the higher is the permeability coefficient, since the diameter and number of pores increase with decrease of the membrane thickness. The gas permeability coefficient has different values at the same pressure or temperature. As this film is in the glassy state, it should be explained using the average ordering parameter (ξ), which is a function of temperature, pressure, gas concentration, and time. © 1994 John Wiley & Sons, Inc.
Degradability testing of radiation‐vulcanized natural rubber latex films
Authors: Thiangchanya Adul , Makuuchi Keizo , Yoshi Fumio
Published: April 2003

The degradability under various conditions of five kinds of radiation‐vulcanized natural rubber latex (RVNRL) films was studied. The treatments were leaching in methanol, leaching in 1% ammonia solution, mixing with tris(nonylated phenyl)phosphite (TNP) antioxidant, blending with poly(methyl methacrylate) (PMMA), and grafting with PMMA, Comparisons were made with sulfur‐vulcanized natural rubber latex (SVNRL) film. RVNRL films SVNRL film can be kept for a long time when indirectly exposed to sunlight at room temperature. However, the former degraded much more rapidly than did the latter. TNP was found to be very suitable as an antioxidant to prolong the life of RVNRL films under dry conditions. PMMA, either blended or grafted with RVNRL, was ineffective in the prevention of deterioration of RVNRL films. The rapid degradation of RVNRL products could be an advantage over SVNRL products in environmental and wildlife conservation. © 1994 John Wiley & Sons, Inc.
Effect of molecular orientation on the dielectric properties of spin‐coated polyimide films
Authors: Lin Linda , Bidstrup Sue Ann
Published: April 2003

The effect of molecular orientation on the dielectric properties of spin‐coated polymide films has been studied in Situ for pyromellitic dianhydride with 4,4′‐oxydianiline (PMDA/ODA) and biphenyldianhydride with p‐phenylendiamine (BPDA/PPD). The degree of molecular orientation is characterized by the optical anisotropy between the in‐plane and the through‐plane, refractive indices. The through‐plane dielectric properties are measured by fabricating parallel‐plate capacitors directly onto the silicon substrate. Both the birefringence and the dielectric constant of PMDA/ODA polyimide vary with film thickness; however, these properties are independent of film thickness for BPDA/PPD films. To confirm that the measured dielectric constant obtained from the parallel‐plate structures is free from a significant edge effect, finite element modeling of the electrstatic potential within the dielectric edge effect, finite element modeling of the electrostatic potential within the dielectric is performed. Models for both isotropic and anisotropic dielectric properties indicated that the fringing effects are indeed negligible for the film thicknesses examined. Thus, the changes observed in the measured dielectric constant are attributed to the variations in the molecular orientation. The optical anisotropy observed for the polyimides suggests a corresponding dielectric anisotropy in the films. An estimation using the Maxwell relation indicates that the dielectric anisotropy at 105 Hz is 0.31 for PMDA/ODA and 0.85 for BPDA/PPD. © John Wiley & Sons, Inc.
On the in situ generation of reinforcing fibers
Authors: Qin Yimin
Published: April 2003

A study has been made of the formation of the microstructure of a polypropylene (pp) and liquid crystal polymer (LCP) blend. The pp/LCP mixture was fed into a single‐screw melt extruder, and polyblend fibers were made by extrusion of the melt through a spinneret plate. Samples of the melt were taken from various sections of the screw barrel, before and after the metering pump, before and after the mesh filter, before and after the die head, and in the as‐made fibers. The microstructure of the LCP phase in the blend was studied with a hot‐stage microscope. It was found that the dispersion of the LCP phase in the pp matrix was well completed before the metering pump. Planar flow and compressional strain in the metering pump had little influence on the LCP phase structure, but elongational strain in the mesh filter produced fine dispersion of the LCP phase. It was found that the LCP phase existed largely in spherical particles before the die‐head entrance. Although the extensional flow in the die entrance deformed the LCP particles into thin droplets, further elongational strain below the die head is essential if thin and long LCP fibrils are required in the polyblend fibers. © 1994 John Wiley & Sons, Inc.
Pervaporation performance of polyetherimide membranes spin‐ and dip‐coated with polydimethylsiloxane
Authors: Page C. A. , Fouda A. E. , Matsuura T.
Published: April 2003

The pervaporation performance of polydimethylsiloxane (SR) spin‐ and dip‐coated polyetherimide (PEI) membranes was inmvestigated for acetic acid/water mixture. The spincoating technique was used to produce a thin, uniaform coating, and compared to the dipcoating technique in terms of pervaporation performance, thickness, and uniformity of the coatiing layer. It was fould that the PEI membranes studied were water‐selective and that the water selectivity of PEI membranes increased when spin‐coated with a SR solution. It wal also fould that the water selectivity increased when the PEI membranes were conated with SR solutions of increassing concentration, Althought the permeate flux noticeably decreased. The coating thickness was measured by the weighting techniquo and the results were compared with the thickless estimation by two versins of the resistance model. It was determined that the spin‐coating technique can provide a thinner and more uniform coating than the dip‐coating technique, and that the coating solution penetrates the mem brane pores beofre coating the surface. © 1994 John Wiley & Sons, Inc.
Preparation and characterization of perlite‐filled high‐density polyethylenes. I. Mechanical properties
Authors: Akin‐öktem Gülsu , Tincer Teoman
Published: April 2003

Four different types of high‐density polyethylenes (HDPE) were blended with perlite at different concentrations. Silane coupling agent γ‐aminopropyltriethoxv silane (γ‐APS, A‐1100) was used to enhance the adhesion between perlite and HDPEs. Ultimate tensile strength and elastic modulus increased as the perlite content increased, while ultimate elongations decreased with the increasing amount of perlite. Exceptional variations in the measured properties are explained in terms of the differences in polyethylenes used in the composites. The biggest improvement in ultimate tensile strength was observed in the highly crystalline polyethylene; on the other hand, in the absence of sialane coupling agent the high molecular weight polyethylene showed the least improvement in tensile strength. The effect of branching in HDPE composites was demonstrated. The enhancement of interfacial adhesion by using a coupling agent was also examined by scanning electron microscopy (SEM). © 1994 John Wiley & Sons, Inc.
Characterization of alicyclic polyimides based on cyclobutane ring dianhydride and aromatic diamine
Authors: Tsujita Y. , Tanaka H. , Yoshimizu H. , Kinoshita T. , Abe T. , Kohtoh N.
Published: April 2003

Films of alicyclic polyamic acid and polyimide containing cyclobutane ring in dianhydride moiety and aromatic ring with p‐ or m‐linkages in diamine moiety were characterized by infrared (IR) spectroscopy, dynamic viscoelasticity, differential‐scanning calorimetry (DSC), density, and wide‐angle X‐ray diffraction analyses. Partially and fully imidized polyimides were obtained by varying the imidization temperature, e.g., 150°C, 250°C, and 350°C. It was found from the results of IR spectra, dynamic viscoelasticity, and DSC measurements that the imidization of alicyclic polyamic acid was reduced at about 150°C and needed a higher imidization temperature than aromatic polyamic acid. Alicyclic polyimide with m‐linkage in the diamine moiety had a higher density and a much more ordered structure than with p‐linkage. © 1994 John Wiley & Sons, Inc.
Compatibility studies of solution‐blended poly(acrylonitrile)/poly(n‐butyl methacrylate)
Authors: Somanathan N. , Senthil P. , Viswanathan S. , Arumugam V.
Published: April 2003

Poly(acrylonitrile) (PAN) was solution blended with poly(n‐butyl methacrylate) (PnBMA) in various proportions. Compatibility in these blend systems was analyzed using ultrasound. The ultrasound velocity and attenuation results show that the two polymers formed a compatible blend. Viscosity and other derived parameters like free volume and internal pressure of the blends show that PAN form into an ideal blend with PnBMA in the compositions of 60 : 40 and 40 : 60. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of styrene‐based microbeads possessing amine functionality
Authors: Cousin P. , Smith P.
Published: April 2003

Microbeads possessing amine functionality at the surface have been prepared by two methods: In the first method, poly(4‐vinylpridine/styrene) P(4VP/S) copolymer microbeads containing 13–69 mol % 4‐vinylpridine (4VP) were synthesized from the monomers. In the second method, animated polystyrene (PS) particles were prepared by postpolymerization reactions on cross‐linked PS and polychloromethylstyrene particles to obtain poly(aminomethylstyrene/styrene) and polydiethylaminomethylstyrene particles, respectively. Scanning electronic microscopy of P(4VP/S) microbeads showed regular and spherical particles having a diameter between 80 and 200 nm depending on 4VP content. The chemical structure of the various particles made was studied using Fourier transform infrared spectroscopy, electron spectroscopy for chemical analysis (ESCA), and elemental analysis, whereas thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. © 1994 John Wiley & Sons, Inc.
Swelling of hydrophilic polymers. III
Authors: Ogawa Ikuko , Yamano Hideki , Miyagawa Kinjiro
Published: April 2003

The total volume change included gel and surrounded water with the swelling of five types of speherical cross‐linked dextran (Sephadex) that are either nonionic (G) or possess one of four different ionic groups in the same molecular skeleton: CM: sodium carboxymethyl, SP: sodium sulphopropyl, DEAE: diethylaminoethyl chloride, and QAE: diethyl‐(2‐hydroxypropyl) aminoethyl chloride. All have been studied by dilatometry. The total volume decreased with the swelling of all Sephadexes. The maximum changes of total volume with the swelling in water were all negatives of CM, G, SP, (DEAE, QAE), which decrease in that order. These values did not depend on the concentration of sodium chloride and were closely related to the maximum heats of swelling. Total volume changes occurred by the dissociation of the ionic group of dextran derivatives that subtracted the total volume change due to hydration of Sephadex skeleton from the total volume change: −21.6 ± 3.1 μL mmol−1 for CM, −2.8 ± 8.0 μL mmol−1 for SP, +13.2 ± 4.4 μL mmol−1 for DEAE, and +15.4 ± 4.6 μL mmol−1 for QAE. These values are assumed to be reflected in the quantities of ions‐water interaction of Sephadexes. © 1994 John Wiley & Sons, Inc.
Stereoblock polypropylene/isotactic polypropylene blends. I. Phase organization
Authors: Canevarolo S. , De Candia F.
Published: April 2003

The phase organization of stereoblock polypropylene/isotactic polypropylene blends has been analyzed. The different samples were prepared by a two‐stage process, that is, solvent casting followed by pressure molding. The analysis was carried out using techniques such as X‐ray diffraction, differential scanning calorimetry (DSC), and thermomicroscopy. The experimental results show that both the components segregate a crystalline phase and that the overall crystallinity, as well as the crystallinity of each component, is affected by the sample composition. Some evidence of co‐crystallization, at least for samples at low content in isotactic polypropylene, has been found. © 1994 John Wiley & Sons, Inc.
Tensile yield in phenolphthalein polyether ketone
Authors: Han Yanchun , Yang Yuming , Li Binyao , Feng Zhiliu
Published: April 2003

Uniaxial tension tests to the yield point were performed on phenolphthalein polyether ketone (PEK‐C) from room temperature to near the glass transition temperature (Tg) at a constant rate of 0.02 min−1. At room temperature, some measurements were also made at strain rates from 0.002 min−1 to 2 min−1. Yield stress was a linear function of temperature and log strain rate. The temperature and the strain rate dependence of yield stress could be modeled using Eyring theory. Yield energy was found to be a linear function of temperature. Young's modulus, yield strain, elastic strain, and plastic strain all decreased with temperature. © 1994 John Wiley & Sons, Inc.
Distributions of functionality and of molecular weights in an hydroxyl‐terminated polybutadiene by dual‐detection size exclusion chromatography
Authors: Bielsa R. O. , Brandolini M. C. , Akcelrud L. , Meira G. R.
Published: April 2003

The article deals with data treatment problems associated with the estimation (via dualdetection size exclusion chromatography) of the independent distributions of molecular weight and functionality in a derivatized hydroxyl‐terminated polybutadiene. Calculations are based on an approach originally developed for linear copolymers and include corrections for (a) effect of functional groups on instantaneous mass and molecular weights, (b) dependence of refractive index with molecular weight, and (c) instrumental broadening. Compared to other more laborious analytical methods, the proposed technique is simple and provides accurate results. © 1994 John Wiley & Sons, Inc.
Miniemulsion polymerization of vinyl acetate with nonionic surfactant
Authors: Wang S. , Schork F. J.
Published: April 2003

The stability of vinyl acetate miniemulsions employing polyvinyl alcohol (PVOH) as the surfactant, and hexadecane and/or various polymers as the cosurfactant, were studied. Shelf lives (to phase separation) and monomer droplet sizes were measured. The results indicate that it is possible to prepare stable miniemulsions using a nonionic surfactant (PVOH) and hexadecane as the cosurfactant. Polymeric cosurfactants do not create stable miniemulsions but retard Ostwald ripening to an extent that allows predominant droplet nucleation. The polymerization behavior of these miniemulsion systems was investigated using on‐line conductance measurements to differentiate droplet versus micellar/homogeneous nucleation. The effect of cosurfactant concentration on the reaction rate was compared for hexadecane and polymeric cosurfactants. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of a new block copolymer: Poly(butylene terephthalate‐co‐olefin) application on PP/PBT blend and PBT homopolymer
Authors: Boutevin B. , Khamlichi M. , Pietrasanta Y. , Robin J. J.
Published: April 2003

The synthesis of a new block copolymer was investigated by the condensation of terephthaloyl chloride, hydrogenated α,ω‐dihydroxy polybutadiene and butanediol. The resulting (PBT) product is termed as the hard segment, and the hydrogenated α,ω‐dihydroxy poly‐butadiene is termed as the corresponding soft segment. This block copolymer was characterized by FTIR, 1H and 13C‐NMR, DSC, and SEC. Quantitative estimations of the contents of block segments have been carried out by NMR. The product was used either to increase the properties of PBT/PP blends or the impact strength of PBT. In both cases the mechanical properties are described. © 1995 John Wiley & Sons, Inc.
Crystallization kinetics of a PEEK/LCP blend
Authors: de Carvalho Benjamim , Bretas Rosario E. S.
Published: April 2003

The crystallization kinetics of a polyetheretherketone (PEEK)/liquid crystalline polymer (LCP) blend was studied by using differential scanning calorimetry. Nonisothermal runnings were performed on heating and on cooling at different rates. Isothermal crystallization experiments at 315, 312, 310, and 307°C, from the melt state (380°C) were performed in order to calculate the Avrami parameters n and k and the fold surface free energy, σe. Polarized light optical micrographs were also obtained to confirm the Avrami predictions. It was observed that the LCP retarded the PEEK crystallization process and that the PEEK melting temperature decreased with the amount of LCP, but the LCP melting temperature increased with the amount of PEEK. Probably the PEEK improves the perfection of the LCP crystalline domains. A spherulitic morphology in pure PEEK and its blends was predicted by the Avrami analysis; however this morphology was only observed for pure PEEK and for the 80/20 composition. The other compositions presented a droplet and fibrillar‐like morphology. The overall crystallization rate was observed to decrease with the crystallization temperature for all compositions. Finally, σe was found to decrease with the increase of LCP in the blends, having unrealistic negative values. Thus, calculations were made assuming σe constant at all compositions. It was observed that δ, the interfacial lateral free energy, decreased but still remained positive. It was concluded that in these blends neither σe nor σ could be considered constant. © 1995 John Wiley & Sons, Inc.
Concentration and separation of aqueous solutions of Cu2+, Ni2+, Fe3+ by dextran
Authors: Şolpan D. , Şahan M.
Published: April 2003

The effects of water‐soluble polymers on the concentration and separation of the aqueous solutions of the metal ions have been studied. The separation of metal ions can be possible by ultrafiltration‐complexation process. The effect of Dextran, which is a water‐soluble polymer, on the concentration and separation of metal ions (Cu2+, Ni2+, Fe3+) have been investigated by using EC‐PEG 4000 alloy membranes. The permeability of these membranes for metal ions has been rrecorded at constant pressure but different pH values. It has been notices that the highest water‐permeable membrane is also permeable towards Cu2+ and Ni2+, but has shown a considerable retention for Fe3+ as a result of the hydrolysis of Fe3+. The retentions of metallic ions and metallic‐ion‐Dextran couples have been determined at constant pressure but different pH and polymer concentration values. It has been shown that Fe3+/Ni2+ and Fe3+/Cu2+ couples can be separated by using Dextran. © 1995 John Wiley & Sons, Inc.
Stereoblock polypropylene/isotactic polypropylene blends. II. Mechanical behavior
Authors: Canevarolo S. V. , De Candia F. , Russo R.
Published: April 2003

The mechanical properties of stereoblock polypropylene/isotactic polypropylene blends have been analyzed at different temperatures and at large deformations. The samples at a lower content of isotactic polypropylene show good elastic properties, both in terms of deformation reversibility and in terms of energy dissipation in the hystersis cycles. Considering the dependence of the elastic behavior on the temperature, the model that can be suggested is based on the presence of a physical network in which the cross‐linking is due to cocrystallization between the matrix (the stereblock polypropylene) and the crystalline domains of isotactic polypropylene. © 1995 John Wiley & Sons, Inc.
Miscibility and transesterification in bisphenol‐a polycarbonate/ethylene terephthalate–caprolactone copolyester blends
Authors: Zhang Ruiyun , Luo Xiaolie , Ma Dezhu
Published: April 2003

The miscibility and microstructure of blends of bisphenol‐A polycarbonate (PC) with ethylene terephthalate (ET)‐caprolactone (CL) copolyesters (TCL) were studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR) and phase contrast microscopy (PCM). The DSC results showed that PC were immiscible or partially miscible with the copolyesters having ethylene terephthatate contents higher than 60 (wt %), and miscible with the copolyesters having ET contents lower than 60(wt %). After annealing at elevated temperature, homogenization will take place in the immiscible or partially miscible blends of PC with higher ET‐content copolyesters. The IR and PCM results revealed that the homogenization of the blend are caused by the transesterification between the PC and copolyesters. © 1995 John Wiley & Sons, Inc.
Sorption and polymerization of methyl isopropenyl ketone in low‐density polyethylene
Authors: Agarwal Mini , Choi Kyu Yong
Published: April 2003

The polymerization of methyl isopropenyl ketone (MIPK) inside low‐density polyethylene beads has been studied with lauroyl peroxide as the initiator. The reaction was carried out by first immersing the polymer beads in a liquid solution of MIPK monomer and initiator for 5 h at 55°C and then draining the excess liquid. The temperature of these monomersoaked beads was increased to a reaction temperature (85°C) and the monomer was polymerized in the solid resins. The bulk polymerization of MIPK and the sorption characteristics of MIPK and initiator were also investigated through experimentation and model simulation. It has been observed that the monomer uptake in the solid polymer increased considerably in the presence of the lauroyl peroxide initiator in the liquid phase during the sorption stage. The differential scanning calorimetry study also indicated that some changes in the polymer morphology have occurred due to the incorporation of poly‐MIPK into the polyethylene resins. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of end‐alkoxysilylated polystrene and the grafting behaviors onto inorganic pigments. I. Utilization of 4‐isopropoxydimethylsilyl‐α‐methylstyrene
Authors: Ohata Masatoshi , Yamamoto Masaharu , Isono Yoshinobu
Published: April 2003

Novel end‐functional polystyrene having isopropoxydimethylsilyl (IPS) groups at the end part of the chain was prepared. IPS groups were introduced by the reaction between the living polystyryl anion and 4‐isopropoxydimethylsilyl‐α‐methylstyrene (1) in THF at 195 K. The resultant polymer was characterized by GPC, 1H‐NMR, and TLC. It was confirmed that the polymer had several units of 1 at the chain end and a fairly narrow molecular weight distribution. IPS groups in the polymer can be hydrolyzed with strong acid such as mono‐n‐butylphosphate (MBP) but not with weak acid and base. Grafting behaviors of the polymer onto silica and alumina were studied in toluene in the presence of MBP as a catalyst. The polymer was grafted onto silica effectively. However, it cannot be grafted onto alumina because of predominant adsorption of MBP onto alumina having a basic surface. © 1995 John Wiley & Sons, Inc.
A differential scanning calorimetry study of plasma irradiation grafting of nascent polyethylene reactor powder
Authors: Tian Jun , Lin Xiao , Xu Jiping , Huang Baotong
Published: April 2003

The melting behavior of poly(methyl methacrylate)‐grafted nascent polyethylene reactor powder by plasma irradiation was studied by differential scanning calorimetry (DSC). The grafting yield ranged from 11 to 190% Grafting was found to lower both melting point and heat of fusion during the first run of DSC determination. The heat of fusion was used to calculate the apparent grafting yield of the samples. There was little strain induced by plasma‐irradiated grafting on the surface of the polyethylene crystals. A method to determine the covalent grafting yield in the graft copolymer systems was developed. © 1995 John Wiley & Sons, Inc.
Injection molding of semicrystalline polymers. I. Material characterization
Authors: Isayev A. I. , Chan T. W. , Shimojo K. , Gmerek M.
Published: April 2003

Various material data for an isotactic polypropylene were acquired for the simulation of the injection molding of this material. Viscosity as a function of shear rate and temperature was measured using a capillary rheometer at high shear rates and a cone‐and‐plate rheometer at low shear rates. Heat‐flow properties, characterizing kinetics and induction time of quiescent crystallization, were obtained from DSC measurements. Material data characterizing shear‐induced crystallization were obtained from extrusion experiments through a slit die with subsequent quenching of the material in the die after various rest times. The thickness of the shear‐induced crystallization layer was measured along with the birefringence in this layer. A model of shear‐induced crystallization developed by Janeschitz‐Kriegl and co‐workers was used to fit the kinetic data. Thus, kinetic parameters such as the limiting shear rate below which no shear‐induced crystallization can occur and the characteristic time for the relaxation of birefringence were obtained. © 1995 John Wiley & Sons, Inc.