bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the notch tip damage zone in biaxially oriented polypropylene
Authors: Snyder J. , Hiltner A. , Baer E.
Published: April 2003

The circular notch tip damage zone in biaxially oriented polypropylene has been analyzed using a thickness correction to the elastic stress distribution for a sharp‐notched tension specimen. The size and shape of the damage zone as a function of applied stress followed a critical mean stress criterion, independent of specimen thickness. Also, the damage zone only grew while σ3 was greater than zero. Close observations of sections through the damage zone revealed that the circular zone, which consisted of many delamination crazes, had a distinctive pattern when viewed across the thickness difection. Large crazes grew into a triangular pattern with smaller crazes in between them. The shape developement of the triangular profile as well as the smaller crazes was explained using a stress‐redistribution argument. The growth path of the delamination crazes in the x‐z plane appeared to be in a direction perpendicular to the direction of σ3. © 1994 John Wiley & Sons, Inc.
Blend structure of commingled plastic from recycled polyethylene and polystyrene
Authors: Li T. , Henry S. , Silverstein M. S. , Hiltner A. , Baer E.
Published: April 2003

The hierarchical morphology of commingled plastic waste in the form of thick beams prepared by the ET‐1 process has been examined. Blends of recycled high‐density polyethylene (RHDPE, New Jersey Curbside Tailings) with 25 and 35 wt % expanded polystyrene (EPS) were compared with blends of a virgin high‐denisty polyethylene resin (VHDPE). At the macroscale, observed with the optical microscope, the beams consisted of a solid skin that extended about one‐third of the distance to the center of the beam and a voided core with about half the density of the skin. The phase morphology of the skin at the microscale was characterized by examining etched cryogenic fracture surfaces in a scanning electron microscope. The blends of RHDPE and VHDPE exhibited a gradient morphology with highly elongated EPS domains near the edge and spherical or co‐continuous EPS domains closer to the core. The morphology gradient was created by the competition between the relaxation rate of the melt‐flow morphology and the cooling rate in the mod. In addition to high‐density polyethylene, a variety of other components were identified in RHDPE by photoacoustic infrared and thermal analysis. These included polypropylene, polystyrene, poly(ethylene terephthalate), and chunks of nonpolymeric material. As a result of the heterogeneous composition, the crystallinity of RHDPE was significantly lower than that of VHDPE. © 1994 John Wiley & Sons, Inc.
Electrical, thermal, and photo properties of poly(phenylene vinylene) precursors. II. Microwave‐induced elimination reactions in precursor polymer films
Authors: Torries‐Filsho Afranio , Lenz Robert W.
Published: April 2003

Microwave radiation (MWR) was used to induce the elimination reaction of the poly(phenylene vinylene)–polyelectrolyte precursors polymer (PPV precursor) into the fully conjugated polymer. The process was applied mainly to the unsubstituted PPV and was followed by infrared spectroscopy. The extent of the elimination process was also determined from the amount of residual sulfur in the film after the irradiation process. The microwave‐induced elimination process was also attempted using PPV precursor films that had been impregnated with anionic compounds containing iron. The molecular mechanisms for the observations are discussed and comparison with the elimination reaction induced by other energy sources is also made. © 1994 John Wiley & Sons, Inc.
The surface modification of polyethylene by solution‐phase photochemical grafting using short irradiation times
Authors: Hamilton L. M. , Green A. , Edge S. , Badyal J. P. S. , Feast W. J. , Pacynko W. F.
Published: April 2003

The surface modification of low‐density polyethylene by solution‐phase photochemical grafting with acrylic acid and acrylamide is described. After irradiation for 3 min, the contact angles of the modified surfaces with water were ca. 20, 30, and 40°C and ca. 40, 40, and 80°C for grafting solutions containing 2M, 1M, and 0.1M of acrylamide and acrylic acid respectively. X‐Ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATRIR) of the modified polyethylene surfaces were consistent with the presence of grafts of polyacrylamide or poly(acrylic acid). Grafting using low concentrations of monomers, that is, 0.1M, resulted in a small, 20° decrease in contact angle for grafting with acrylic acid but a larger, 60°C decrease for acrylamide. © 1994 John Wiley & Sons, Inc.
Synthesis and polymerizations of monomers bearing phosphonated groups. I. Applications on acrylates and methacrylates
Authors: Boutevin B. , Hamoui B. , Parisi J. P.
Published: April 2003

The synthesis of (meth)acrylic monomer bearing phosphonic esters, phosphonic acids, and semisalts is presented. This synthesis was performed in four steps. The first concerns the phosphonylation of allyl bromide by Arbuzov reaction. Second is the monoaddition of 2‐mercapto ethanol onto the allyl double bond, whereas the third consists of the acrylation of the previous phosphonated alcohol. The fourth step involves the dealkylation of the phosphonated ester by the mean of trimethyl halosilane and then the hydrolysis of the obtained silyl ester. Finally, the salification of the diacid is performed in order to stabilize the diacid. In the last part of this work two applications of these monomers in the field of additives for adhesives cured by UV or EB were studied. The results clearly show the superiority of phosphonic acid about the homologous esters. Moreover, the number of acid group and the neighbouring of this acid play an important part in adhesion phenomenon. © 1994 John Wiley & Sons, Inc.
Analysis on the surface adsorption of PEO/PPO/PEO triblock copolymers by radiolabelling and fluorescence techniques
Authors: Amiji Mansoor M. , Park Kinam
Published: April 2003

We have examined the adsorption of poly(ethylene oxide)/ poly(propylene oxide)/poly(ethylene oxide) (PEO/PPO/PEO) triblock copolymers (Pluronics™) on dimethyldichlorosilane‐treated glass (DDS‐glass). The surface concentration of 125I‐labeled Pluronic F‐68(76/30/76) reached a maximum of 0.3 μg/cm2 when the bulk concentration in the adsorption solution was 3.0 mg/mL. Above 5.0 mg/ml, the surface Pluronic F‐68 concentration started to decrease and reached 0.17 μg/cm2 when the bulk concentration for adsorption was 10 mg/mL. The surface concentration of Pluronic F‐108 (129/56/129), on the other hand, increased to 4.0 μg/cm2 at the same bulk concentration. Fluroscence spectroscopic studies using pyrene suggested that the Pluronic F‐68 molecules self‐associated at the bulk concentration of 5.0 mg/mL and above. Because the aggregates are expected to expose the hydrophilic PEO segments to water, they may have lower affinity to DDS‐glass. Aggregation of Pluronic F‐68 also decreases the number of individual Pluronic molecules for adsorption. Pyrene fluorescence in Pluronic F‐108 solution, however, suggests that Pluronic F‐108 molecules do not form aggregates. It appears that the high surface concentrations of Pluronic F‐108 may result from the preferential adsorption of individual molecules in multilayers. This explains the high effectiveness of Pluronic F‐108 in preventing protein adsorption and platelet adhesion when adsorbed on to be hydrophobic surface. © 1994 John Wiley & Sons, Inc.
Chemical structure and physical properties of antheraea assama silk
Authors: Freddi Giuliano , Gotoh Yoko , Mori Tadasu , Tsutsui Ichihiko , Tsukada Masuhiro
Published: April 2003

This work deals with the chemical composition, physical structure, and thermal behavior of Antheraea assama silk fibers. The amino acid composition is characterized by the high content of alanine, glycine, and serine. Among the amino acid residues with polar side chains, aspartic acid, arginine, and tyrosine prevail. The birefrigence and isotropic refractive index values are 0.030 and 1.557, respectively. The stress‐strain curve shows a yield point at 5% elongation, followed by a region of gradual extensibility. Blongation at break is about 40%. The X‐ray diffraction pattern is typical of β silks, with–(ala)n–repeats in the polypeptide sequences of the crystalline regions. The differential scanning calorimetry curve shows two minor endotherms at 230 and 300°C, before final thermal decomposition at 362°C. The maximum extent of contraction exhibited by the thermomechanical analysis curve is 2%. The surface of degummed fibers shows the presence of longtitudinal strations. The fiber cross section is mostly relliptical. Raw Fibers taken from cocoons show the presence of several crystalline deposits on the surface, identified as crystals of calcium oxalate. © 1994 John Wiley & Sons, Inc.
Cyclotrimerization of isocyanate groups. I. Catalyzed reactions of phenyl isocyanate
Authors: S̆pírková Milena , Kubín Miroslav , S̆pac̆ek Pavel , Krakovský Ivan , Dus̆ek Karel
Published: April 2003

Cyclotrimerization of phenyl isocyanate in the presence of various catalysts was studied. All reactions were carried out in 1,4‐dioxane at 30–50°C. Reaction products were determined by reverse‐phase liquid chromatography. 1,3,5‐Triphenyl isocyanurate was formed and also traces of 1,3‐diphenylurea and 1,3,5‐triphenylbiuret were found. The catalytic activity decreased in the following series: quaternary ammonium salt > organic acid salt ≫ tertiary amine. Apparent rate constants of cyclotrimerization were calculated and the overall reaction order is discussed. © 1994 John Wiley & Sons, Inc.
Influence of the controlled rheology process (vis‐breaking) on additive effectiveness in polypropylene
Authors: Tollefson Norris M.
Published: April 2003

Controlled rheology or VIS‐breaking is the process whereby polypropylene, peroxide, and other additives such as stabilizers are extruded to simultaneously shorten polymer chain length by chemical action of the peroxide and to blend in additives. Although the influence of additives on the VIS‐breaking process has been studied, little attention has been paid to the role of additives present during VIS‐breaking on the final resin properties. The effectiveness of a light mineral oil used as a costabilizer for radiation resistance and Irgafos 168 as a melt stabilizer was determined in polypropylene resins prepared with different peroxide levels. It was found that exposure of Irgafos 168 to peroxide during the VIS‐breaking process did not hinder the action of Irgafos 168 as a melt stabilizer during injection molding. At low levels of peroxide, the presence of oil led to an improvement of radiation resistance compared to resins that contained no oil. However, at higher peroxide levels, oil‐containing resins showed less resistance to radiation than did those without oil. These results were interpreted as an interaction of peroxide with the function of oil in the final resins. © 1994 John Wiley & Sons, Inc.
Mechanical properties of the rubber‐toughened polymer blends of polycarbonate (PC) and poly(ethylene terephthalate) (PET)
Authors: Liao Zhi‐Li , Chang Feng‐Chih
Published: April 2003

The intrinsically impact‐brittle PC/PET blends can be effectively toughened, in terms of lower ductile brittle transition temperature (DBTT) and reduced notch sensitivity, by incorporating butylacrylate core‐shell rubber. The rubber particles are distributed exclusively in the PC phase. Varying the PC melt flow rate (MFR) is more important than varying the PET I.V. to vary the low temperature toughness of the blends. PC with MFR = 3 is essential to produce the toughest PC/PET/rubber blend. The presence of rubber slightly relieves the strain rate sensitivity on yield stress increase. Lower MFR PC in the blend results in smaller activation volume and, therefore, higher strain rate sensitivity, because a greater number of chain segments are involved in the cooperative movement during yielding. Two separate modes, localized and mass shear yielding, work simultaneously in the rubber toughening mechanism. The plane‐strain localized shear yielding dominates the toughening mechanism at lower temperatures and brittle failure, while the plane‐stress mass shear yielding dominates at higher temperatures and ductile failure. The critical precrack plastic zone volume has been used to interpret the observed phenomenon. © 1994 John Wiley & Sons, Inc.
Thermoplastic interpenetrating polymer networks based on a poly(styrene‐b‐butadiene) copolymer and an ionically‐terminated polybutadiene ionomer
Authors: Ali S. A. M. , Hourston D. J.
Published: April 2003

Thermoplastic interpenetrating polymer networks (IPN) are mixtures of two physically crosslinked polymers. Thermoplastic IPNs were prepared by blending an SBS triblock elastomer with a 1,2‐polybutadiene that was ionically‐terminated at both ends. The morphologies of these IPNs were studied using differential scanning calorimetry and dynamic mechanical thermal analysis. It was concluded that the ionomer was incompatible with the SBS elastomer, since the Tgs of both the 1,2‐polybutadiene from the ionomer and the essentially 1,4‐polybutadiene from the SBS component were observable at temperatures that were close to those of the individual components. The addition of the polybutadiene material had, however, an influence on the relaxation processes of the polystyrene blocks. The polystyrene glass transition in the pure SBS copolymer is broadened by the interfacial region between polystyrene and polybutadiene. The low temperature shoulder was much more pronounced when the ion‐terminated polybutadiene was present, indicating it has a preference to be located in these interfacial regions. © 1994 John Wiley & Sons, Inc.
Studies on selective adsorption resins. XXXIII. Behavior of macroreticular chelating resins containing phosphinic and/or phosphonic acid groups in the adsorption of trivalent lanthanides
Authors: Egawa Hiroaki , Yamabe Kazunori , Jyo Akinori
Published: April 2003

The effect of the crosslinking and the porosity of the chelating resins containing phosphinic and/or phosphonic acid groups (RSP and RCSP) on uptake of trivalent lanthanides was studied; RSP and RCSP were prepared by hydrolysis of condensation products of phosphorus trichloride with styrene–divinylbenzene copolymer beads (RS) and with chloromethylated RS, respectively. From a series of RSs synthesized by systematically changing the amount of the crosslinker (divinylbenzene) or the porogen (2,2,4‐trimethylpentane), RSPs and RCSPs with different degrees of crosslinking and with different porosities were derived. Measurements of their uptake of La(III), Gd(III), or Yb(III) have clarified that RSP and RCSP with moderately crosslinked highly porous structures exhibit high capacities toward the lanthanides. Using these optimized RSP and RCSP and their respective oxidized derivatives RSPO and RCSPO, the distribution of all lanthanides (III) except for Pm(III) from aqueous hydrochloric acid solutions (0.1–1M) was examined. The distribution of each lanthanide(III) at a given concentration of the acid increases in the order RCSPO ≈ RCSP < RSPO < RSP. Their lanthanide selectivity patterns resemble one another; the selectivity increases with increasing the atomic number of the lanthanides except for the elements from Sm to Ho. In order to illustrate usefulness of these resins in the separation of lanthanides, the chromatographic separation of La(III), Nd(III), and Sm(III) was conducted using columns packed with RCSP. The three lanthanides were successfully separated by the elution with 0.5M hydrochloric acid solution without use of any organic complexing reagents, such as EDTA. © 1994 John Wiley & Sons, Inc.
On the analysis of positron annihilation lifetime spectroscopy data in semicrystalline miscible polymer blend systems
Authors: Simon G. P. , Zipper M. D. , Hill A. J.
Published: April 2003

A free volume probing technique, positron annihilation lifetime spectroscopy (PALS) is used to characterize miscible blends of amorphous polycarbonate with a semicrystalline copolyester at room temperature. The paper describes the analysis required to use the PALS technique to probe the amorphous regions in which the miscibility of the blends occurs. Analysis of the raw PALS data in this system involves taking account of the influence of crystallinity on the PALS results. The results demonstrate that the PALS technique is able to discriminate between free volume in the amorphous regions of as‐molded and annealed samples. This difference in free volume between samples of differing thermal history is assigned to the influence of polymer crystals on the stress state of the miscible amorphous regions. © 1994 John Wiley & Sons, Inc.
Characterization of electropolymerized graphite fiber–polyacrylamide composites
Authors: Iroh J. O. , Suhng Y. , Labes M. M.
Published: April 2003

The synthesis of a series of graphite fiber‐polyacrylamide composites was performed electrochemically in dilute sulfuric acid (0.125M)‐acrylamide (2M) solution, 1 : 1 sulfuric acid (0.25M) : acetone‐acrylamide (2M) solution, and 1 : 1 sulfuric acid (0.25M) : 2‐propanol‐acrylamide (2M) solution, respectively, using graphite fiber bundles as the working electrode. The graphite fiber‐polyacrylamide composites, synthesized in a 1 : 1 2‐propanol : sulfuric acid‐acrylamide solution, were more easily characterized than those synthesized from the sulfuric acid‐acrylamide solution that contained no alcohol. Composites that were synthesized in a dilute sulfuric acid solution were, however, more readily crosslinked. (Fourier transform infrared spectroscopy, FTIR, confirmed the formation of inter‐chain and intrachain imide functional groups after the resin was cured at ≈ 200°C.) Polymer weight gain analysis, coupled with surface morphology studies using scanning electron microscopy, showed that the thickness of the coatings, and hence the volume fraction of the resin in the composites, varied linearly with the time of electropolymerization. Scanning electron microscopy revealed an open and folded chain surface structure, which permitted unrestricted permeation of the monomer onto the electrode surface. Differential scanning calorimetry of the electropolymerized resins confirmed a glass transition temperature of between 180 and 207°C. © 1994 John Wiley & Sons, Inc.
Synthesis of bifunctional ion‐exchange resins through the Arbusov reaction: Effect on selectivity and kinetics
Authors: Trochimczuk Andrzej W. , Alexandratos Spiro D.
Published: April 2003

Bifunctional ion‐exchange resins are synthesized from vinylbenzyl chloride—styrne copolymers. The two types of functional groups are introduced by an Arbusov reaction followed by sulfonation. The effect of ligand ratios, macroporosity, and matrix rigidity on the complexation of Eu (III) from solutions of low pH is quantified. It is found that ion complexation kinetics and selectivity are maximized with resins having both sulfonic and phosphonic acid ligands. Maximum metal ion complexation rates depend on a balance between chemical interactions (i.e., a bifunctional network interacting with a given substrate through an access and a recognition mechanism) and physical parameters (i.e., matrix porosity and rigidity). Structural integrity must be maintained through an appropriate crosslink level in order for the advantage of bifunctionality to be maintained in low‐pH solutions. © 1994 John Wiley & Sons, Inc.
Effect of copper oxides on the thermal oxidative degradation of the epoxy resin
Authors: Hong S. G. , Wang T. C.
Published: April 2003

The effect of copper oxides on the thermal oxidative degradation of a brominated epoxy resin–dicyandiamide system was studied using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The addition of small amounts of Cu2O or CuO fillers to the epoxy resins affected the relative amounts of highly reacted cyclic species formed during thermal aging and induced catalytic degradation of the epoxy resins. The overall and initial activation energies of the degradation process were found to decrease, and the order in the degradation kinetics of the epoxy resin changed from a near zero order to negative domain (autocatalytic nature) in the presence of copper oxides. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of hydroxamic acid resin of poly(4‐vinyl‐2′‐carboxybenzophenone)
Authors: Kamble K. J. , Patkar D. N.
Published: April 2003

The synthesis and characterization of poly(hydroxamic acid) ion‐exchange resin from a poly(carboxylic acid) resin is described and its exchange properties for Cu(II), Ni(II), and Fe(III) are studied. The metal polychelates are investigated by magnetic measurements, diffuse reflectance spectroscopy, and infrared spectroscopy. © 1994 John Wiley & Sons, Inc.
Flexibility improvement of epoxy resin by using polysiloxanes and their derivatives
Authors: Tong Jiangdong , Bai Ruke , Zou Yingfang , Pan Caiyuan , Ichimura Shigeki
Published: April 2003

A study of increasing the flexibility and lowering the internal stress of the cured epoxy resing was carried out by using polysiloxanes capped with functional groups and premaking polysiloxane particles with d = 1.1 μm and narrow distribution. Polysiloxanes capped with functional groups were prepared by the reaction of X‐22‐163B with bisphenol‐A, hexanedioic acid, and decanedioic acid. Poly(dimethylsiloxane‐b‐arylester) was synthesized by the reaction of poly(dimethylsiloxane) (X‐22‐162C) with arylester oligomers. Polysiloxane particles were obtained by cycling the mixture of polysiloxanes containing a vinyl group and aSi–H group, respectively, emulsifier, and water in homogenizer. When oily polysiloxanes were used to improve the flexibility of epoxy resin, good compatibility of polysiloxanes with epoxy resion, and high molecular weight capped with epoxy group favor the formation of small‐sized particles and homogeneous dispersion in the cured matrix. Comparisons were made among the epoxy resing modified with oily polysiloxanes capped with different functional groups. The results indicate that lightly crosslinked polysiloxane particles with d = 1.1 μm and narrow distribution have the greatest increase of elongation and biggest decrease of internal stress. The reason for this is discussed. © 1994 John Wiley & Sons, Inc.
Measurements of ultrasonic velocity and attenuation in biaxially oriented polypropylene films using fast fourier transform
Authors: Malinarič Svetozár
Published: April 2003

The first part of this study deals with the design of a new instrument for measuring the velocity and attenuation of ultrasonic waves propagating in thin polymeric films. The experimental results indicate a large anisotropy. In addition, a strong velocity and attenuation dependence on both frequency and temperature has been observed. The results are explained by means of phenomenological theory. © 1994 John Wiley & Sons, Inc.
Silicon contamination of substrates in fluorocarbon plasmas produced in glass reactors
Authors: Denes Ferencz , Sarmadi Majid , Hop C. E. C. A. , Buncick Milan , Young Raymond
Published: April 2003

Extensive research has been carried out in recent years using fluorocarbon plasmas for modification and depositions on polymer substrates. In some cases anomalous results have been obtained that are not explainable based on conventional fluorine chemistry. In this investigation pure polypropylene films were exposed to carbon tetrafluoride plasmas in a Pyrex glass reactor. At short reaction times (less than 1 min) significant amount of silicon was detected by ESCA on the surface of the films. Analysis of liquid nitrogen trapped fluorocarbon plasma gases and molecular fragments indicated high concentrations of silicon and carbon containing species, the former indicative of ablation and etching reactions of the glass reactor walls. The production of a relatively high quantity of fluorosilicon derivatives was explained by the greater affinity of silicon for fluorine than for carbon, with the tendency to readily form SiF4. These fluorosilicon radical and ionic species generated under cold plasma conditions can easily react with polymeric substrates causing unexpected surface modifications. In addition Si–F bonds could be readily hydrolyzed to SiOH islands on the surface of the substrate to impart anomalous characteristics. © 1994 John Wiley & Sons, Inc.
Degradation of respirable fibrils of poly(p‐phenylene terephthalamide) by solar ultraviolet radiation
Authors: Knoff Warren F.
Published: April 2003

After ∼ 160 days in the environment, the polymer in a respirable‐size poly(p‐phenylene terephthalamide) fibril (diameter = 0.3 μm) is expected to degrade, due to solar ultraviolet radiation, from an initial molecular weight of ∼ 20,000 to less than 400. This estimate is based on ultraviolet absorption characteristics, photolytic degradation kinetics, and judgments regarding how these translate into actual time in the environment. Degradation to this molecular weight level will cause the fibril tensile strength and modulus to decrease to ∼ 1% of their initial values. Mechanically, such a degraded fibril will be weak and brittle with properties similar to those of uncooked spaghetti. © 1994 John Wiley & Sons, Inc.
Studies on the synthesis and properties of copolyesterimide
Authors: Li Chien‐Hui , Chen Chih‐Chiang , Chen Ker‐Ming
Published: April 2003

A series of copolyesterimides was prepared from bisphenol A, diacid (terephthalic acid [TPA] or isophthalic acid [IPA]), and 4‐carboxy‐N‐(p or m‐hydroxyphenyl) phthalimide (M1 or M2) in the presence of diphenyl chlorophosphate (DPCP) and pyridine as the direct condensation agent. Copolyesterimides derived from M1 showed poorer solubility than that of M2 during polymerization; a lower M1 content should be employed to prevent precipitation of the resulting polymers. The inherent viscosities of copolyesterimides were in the range of 0.33–0.56 dL/g. Some of these copolyesterimides were completely soluble in N‐methyl‐2‐pyrrolidone (NMP), N, N‐dimethylacetamide (DMAC), dimethylformamide (DMF), and m‐cresol. The thermal properties of copolyesterimides were examined by DSC and TGA. These copolyesterimides had glass transition temperatures in the range of 173–220°C and a 5% weight loss was observed in the range of 435–482°C. © 1994 John Wiley & Sons, Inc.
Polymeric thermoresistant blends based on poly‐SAN and imidized PMMA: Thermal and electrical characterization
Authors: Paciello G. , Saccani A. , Sandrolini F. , Frezzotti D. , Callaioli A. , Ravanetti G. P.
Published: April 2003

Blends of styrene/acrylonitrile copolymers (poly‐SAN) with imidized PMMA exhibit increased thermoresistance in comparison with poly‐SAN alone. The miscibility of two modified poly(methyl methacrylate) (PMMA) with poly‐SAN has been evaluated with the aid of different techniques: isothermal calorimetry, through which mixing enthalpy and the Flory–Huggins χ parameter can be determined; dielectrical spectroscopy and thermally stimulated discharging currents (TSDC). The results obtained exhibit great consistency, thus supporting the usefulness of the applied methods for determining the mixing behavior of these polymer blends, which can be considered as model systems for thermoresistant ABS nowadays widely used in the automotive industry. Furthermore, the applied methods allow one to obtain useful data for the electrical application of the investigated blends. © 1994 John Wiley & Sons, Inc.
Precrack hysteresis energy in determining its ductile–brittle transition. III. Effect of temperature
Authors: Chang Feng‐Chih , Hsu Hon‐Chun
Published: April 2003

A temperature variable has been used to correlate the precrack hysteresis energy and the corresponding ductility in terms of ductile–brittle transition behavior for polycarbonate. When the precrack plastic zone exceeds a critical value, crack extension thereafter will be effectively contained within the domain of the plastic zone and result in ductile fracture. Whether a specimen will fail in a ductile mode or a brittle mode is actually already being decided before the onset of crack initiation. The precrack elastic storage energy, total input energy minus hysteresis energy, is the major driving force to strain the crack tip for crack initiation. A higher testing temperature with lower yield stress converts a greater fraction of the input energy into the precrack hysteresis energy and relieves the storage strain energy available for crack initiation. A polycarbonate‐toughening mechanism of incrasing temperature is very similar to the presence of rubber by reducing yield stress and increasing the precrack plasticity. © 1994 John Wiley & Sons, Inc.
Radial distribution function analysis study on alkali and heat‐treated ramie fiber
Authors: Sao K. P. , Samantaray B. K. , Bhattacherjee S.
Published: April 2003

The radial distribution function (RDF) analysis of wide‐angle X‐ray diffraction by ramie fibers in untreated condition and after treatment with alkali of mercerizing strength or heat have been carried out. Interatomic distances, coordination numbers, mean square displacements, and coupling constants for different atom pairs have been calculated. The results have been interpreted in terms of a difference in both the conformation and packing of molecular chains in raw and alkali‐treated ramie. In general, the coupling constant values have been found to be more in alkali‐treated ramie, indicating relatively weak bond strength. Heat‐treated ramie shows a marginal decrease in coupling constant values. © 1994 John Wiley & Sons, Inc.
Toughened polystyrene composites by the concentrated emulsion pathway
Authors: Ruckenstein Eli , Li Hangquan
Published: April 2003

Rubber–styrene solutions of various compositions and containing a suitable initiator have been polymerized starting from concentrated emulsions in which the above solutions constitute the dispersed phase and solutions of sodium dodecylsulfate in water the continuous phase. Latexes of rubber‐modified polystyrene composites have been thus obtained. Solutions of rubber–styrene have been also polymerized by bulk polymerization for comparison purposes. The molecular weights have been determined from intrinsic viscosity measurements, and the mechanical properties of the composites have been studied via tensile testings. Because of the lower mobility of the high‐molecular radicals in the concentrated emulsions, higher molecular weights have been obtained by the concentrated emulsion polymerization than by the bulk polymerization method. The tensile properties and toughness of the composites have been determined. While the two polymerization methods provide high, comparable toughness, the concentrated emulsion method generates latexes that can be easily processed in any desirable shape. © 1994 John Wiley & Sons, Inc.
Synthesis and thermal dissociation of phenol‐ and naphthol‐blocked diisocyanates
Authors: Kothandaraman H. , Nasar A. Sultan , Lakshmi R. Kamal
Published: April 2003

Phenol‐, 2‐naphthol‐, and 1‐nitroso‐2‐naphthol‐blocked toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI) adducts and their polymers with PPG‐1000 were prepared and characterized by nitrogen estimation, IR, and 1H‐NMR spectroscopy. The absence of an IR absorption band at 2270 cm−1 confirmed the completion of the reaction between the isocyanate and the blocking agents, whereas the presence of a band at 1075–1150 cm−1 confirmed the formation of poly(ether urethanes). The deblocking temperatures were determined by the use of DSC and by the carbon dioxide evolution methods. The thermal stabilities of the 2‐naphthol‐blocked diisocyanates were less than the phenol‐blocked diisocyanates. Dissociation temperature was also reduced by the nitroso group in the blocking agent. Mass spectral data confirmed the product analysis. The solubility of the adducts were determined in the different polyols. Adducts based on IPDI showed better solubility than did those based on TDI. © 1994 John Wiley & Sons, Inc.
Poly(ϵ‐caprolactam)–poly(butadiene‐co‐acrylonitrile) block copolymers. I. Synthesis, characterization, mechanical properties, and morphology
Authors: Yn Meng‐Song , Ma Chen‐Chi M.
Published: April 2003

Poly(ϵ‐caprolactam)–poly(butadiene‐co‐acrylonitrile) block copolymers have been synthesized that were suitable for the pultrusion process. The effects of amine‐terminated butadiene acrylonitrile copolymer (ATBN) content on copolymerization rate, conversion, crystallization behaviors, and mechanical properteis and morphology of NY 6–ATBN copolymers were investigated. The conversion was over 90% and the copolymerization was completed within 3 min (up to 20 wt % ATBN) at 145–165°C. The higher the [MgBr—CPL] (ϵ‐caprolactam magnesium bromide) initiator concentration, the lower the molecular weight [or intrinsic viscosity (IV)] of the copolymers and the less the copolymerization time. Relationships among mechanical properties, morphology, and structure of copolymers have been studied. The notched Izod impact strength of the NY 6–ATBN copolymers (< 10.5 wt % ATBN) increased more than 10‐fold, while the flexural modulus only reduced 10%. Transmission electron micrographs showed that ATBN rubber particle size changed slightly with ATBN content, but interparticle distance (T) decreased with increasing ATBN content. As T decreased, the ductility of the copolymers increased. When ATBN content reached 10.5–13 wt % (T = 0.32–0.45 μm), the copolymers showed a very high ductile behavior. © 1994 John Wiley & Sons, Inc.
Squeeze film rheology of polymer melts: Determination of the characteristic flow curve
Authors: Pham Hoang T. , Meinecke Eberhard A.
Published: April 2003

The advantage of the constant‐speed squeeze film flow is that the shear rate is not constant but changes with gap height and position. This allows the rheological characterization of a material to be carried out in a shorter amount of experimentation time. A method for determining the characteristic flow curve is proposed. The characteristic flow curves obtained from squeeze film flow is compared with the curves obtained from capillary rheometry are presented. © 1994 John Wiley & Sons, Inc.
The direct fluorination of a porous functionalized polymer
Authors: Hewes John D. , Curran Sean , Leone Edgar A.
Published: April 2003

Macroporous sulfonated polystyrene ion exchange resin was reacted with elemental fluorine in a liquid‐phase suspension reactor at low temperature. This method gave retention of the bulk structure of the resin bead and resulted in a space‐selective distribution of fluorine across the resin bead cross‐section, as determined using 19F secondary ion mass spectroscopy (LMI‐SIMS). The polymer modification was additionally characterized using x‐ray photoelectron spectroscopy, photoacoustic IR spectrophotometry, 19F, and 13C MAS NMR spectrometry, and mercury porosimetry. © 1994 John Wiley & Sons, Inc.
Effects of water‐soluble polymers and aqueous‐phase viscosity on the interfacial tension behavior of reacting oil–alkaline systems
Authors: Touhami Y. , Neale G. H. , Hornof V.
Published: April 2003

This study presents the results of an experimental study of the effects of water‐soluble polymer additives on the dynamic interfacial tension behavior of reacting oil–aqueous systems as measured by the spinning drop tensiometer. Polymer additives can exert both a direct physico‐chemical effect and an indirect viscosity effect on the measured interfacial tension. This work, which complements an earlier study dealing with the effects of oil‐soluble polymer additives, reveals that the nominal effects of aqueous‐phase viscosity are opposite to those of oil‐phase viscosity. In particular, an increase in aqueous‐phase viscosity produces an increase in the rate of increase of the apparent interfacial tension after attainment of the minimum value. These differences are explained in terms of the dependence of diffusion rates and interfacial adsorption on aqueous‐phase viscosity. The conclusion of principal practical interest is that although aqueous‐phase viscosity exerts only a small effect on the dynamic interfacial tension at small times (i.e., prior to attainment of the minimum value) it exerts a very significant effect thereafter. © 1994 John Wiley & Sons, Inc.
Torsional braid analysis of the aromatic amine cure of epoxy resins
Authors: Zukas Walter X.
Published: April 2003

The cure behavior of diglycidyl ether of bisphenol A (DGEBA) type of epoxy resins with three aromatic diamines, 4,4′‐diaminodiphenyl methane (DDM), 4,4′‐diaminodiphenyl sulfone (44DDS), and 3,3′‐diaminodiphenyl sulfone (33DDS) was studied by torsional braid analysis. For each curing agent the stoichiometry of the resin mixtures was varied from a two to one excess of amino hydrogens per epoxy group to a two to one excess of epoxy groups per amino hydrogen. Isothermal cures of the resin mixtures were carried out from 70 to 210°C (range depending on epoxy—amine mixture), followed by a temperature scan to determine the glass transition temperature (Tg). The times to the isothermal liquid‐to‐rubber transition were shortest for the DDM mixtures and longest for the 44DDS mixtures. The liquid‐to‐rubber transition times were also shortest for the amine excess mixtures when stoichiometry was varied. A relatively rapid reaction to the liquid‐to‐rubber transition was observed for the epoxy excess mixtures, followed by an exceedingly slow reaction process at cure temperatures well above the Tg. This slow process was only observed for epoxy excess mixtures and eventually led to significant increases in Tg. Using time—temperature shifts of the glass transition temperature vs. logarithm of time, activation energies approximately 50% higher were derived for this process compared to those derived from the liquid‐to‐rubber transition. The rate of this reaction was virtually independent of curing agent and was attributed to etherification taking place in the epoxy excess mixtures. © 1994 John Wiley & Sons, Inc.
Glass transition temperature (Tg) versus fractional conversion for a linear thermosetting polyamic acid ester–polyimide system
Authors: Venditti R. A. , Gillham J. K. , Chin E. , Houlihan F. M.
Published: April 2003

The relationship of the glass transition temperature, Tg, to fractional conversion, x, for the conversion of the cyclohexylmethyl ester of the benzophenone tetracarboxylic dianhydride–oxydianiline polyamic acid to polyimide has been investigated using dynamic mechanical analysis (torsion pendulum, TBA). The glass transition temperature and conversion measurements were obtained on a single solvent‐free polyamic acid ester specimen during cooling after heating to successively higher cure temperatures. Conversion was determined from the intensity of a sub‐Tg mechanical relaxation peak that has been assigned to a relaxation of the cyclohexyl group. The resulting Tg versus x relationship is nonlinear. The Tg versus x relationship is adequately modeled using an expression derived by Couchman. © 1994 John Wiley & Sons, Inc.
Molecular and macroscopic NLO properties of organic polymers
Authors: Man H. T. , Shu C. F. , Althoff O. , McCulloch I. A. , Polis D. , Yoon H. N.
Published: April 2003

Two classes of aryltrienes in which the conjugation was incorporated in six‐membered rings have been developed. The microscopic nonlinear susceptibility, μβ, the product of the dipole moment and the second‐order nonlinear susceptibility, of these chromophores were measured using electric field‐induced second harmonic generation (EFISH). The chromophores were then copolymerized as side‐chain pendant groups in a methacrylate backbone copolymer with methyl methacrylate and their macroscopic electrooptic coefficients, r, were experimentally determined using a reflection technique after electric field poling of the polymers. When compared with 4,4′‐N,N‐dimethylaminonitrostibene (DANS), these molecules demonstrated electrooptic activities up to three times of DANS, when measured at 1.3 μm. By using a simple two‐level free‐gas model, the two sets of measurements corresponded closely at low poling fields. At high fields, the simple model breaks down as more detailed poling parameters are required to accurately describe the nonlinear poling effects. The results of the analysis of the high‐field poling data will be published separately. © 1994 John Wiley & Sons, Inc.
Concentration of biological liquids by dialysis with modified acrylonitrile copolymer membranes
Authors: Godjevargova Ts. , Dimov A.
Published: April 2003

Acrylonitrile copolymer membranes were subjected to partial hydrolysis in order to improve their dialysis characteristics. The partial hydrolysis time and temperature, as well as the concentration of the hydrolyzing agent, were the variable parameters. The changes in the chemical and physical characteristics of the membrane were proved by infrared spectroscopy, elemental analysis, differential scanning calorimetry, and Mercury intrusion porometry. After each degree of modification, the permeability of the membrane with respect to a solution of vitamin B12 was determined under static conditions and at temperature of 298 K. The improvement in the permeability at a definite degree of hydrolysis is explained by the conversion of nitrile groups to amide and carboxyl groups, as well as increase of the volume of the pores with average radius. The efficiency of the modified PAN membranes for concentration of biological liquids (diluted serum) was studied. © 1994 John Wiley & Sons, Inc.
Vulcanization of liquid carboxyl‐terminated rubber filled with leather buffing dust
Authors: Klásek A. , Vaněk P.
Published: April 2003

Vulcanization of the system of liquid carboxyl‐terminated rubber–triepoxide–diisocyanate–chromium catalyst–leather buffing dust has been investigated. Using the method of statistical planning of experiments, regression equations were obtained, describing the effects of the components weight ratio on the vulcanization parameters and on the physical properties of the vulcanized rubber. © 1994 John Wiley & Sons, Inc.
Spectroscopic analysis of Fraké treated with periodic acid. I. Electron spectroscopy for chemical analysis (ESCA)
Authors: Noah Joseph N. , Prud'Homme Robert E.
Published: April 2003

Fraké, a tropical wood species from Cameroon, was reacted with 1% periodic acid solution at room temperature for 24 h. Untreated and treated woods were analyzed by ESCA. As expected, O1s and C2s were the predominant species in the spectra. While the O1s peak is featureless, the C1s peak can be decomposed into several components. These contributions were calculated, and it was observed that untreated and treated woods exhibit carbon atoms in classes C1 (carbon atoms bonded by a CC or a CH bond), C2 (carbon atoms bonded by a CO bond), and C3 (carbon atoms bonded by a CO or by a OCO bond). Class C4, which refers to carbon atoms bonded by OCO bonds, is completely absent. The periodic acid treatment produces a reduction in C1, an increase in C2, with C3 remaining relatively small. Accordingly, the expected oxidation of hydroxyl groups to carbonyl groups is not observed. It can be postulated that wood–periodic acid intermediates, which are believed to be cyclic periodic esters, do not decompose to form carbonyl groups but rather remain as stable complexes. © 1994 John Wiley & Sons, Inc.
Thermally reversible polymeric sorbents for acid gases: CO2, SO2, and NOx
Authors: Diaf Abderrahmane , Garcia Jose L. , Beckman Eric J.
Published: April 2003

Weakly acidic gases such as CO2, SO2, NO2, and NO discharged directly into the atmosphere have been suggested to contribute to the formation of acid rain and to global climate changes. In an effort to develop an effective process by which to remove these pollutants from gas streams, we synthesized polymeric sorbents that bind acid gases. In an earlier work, we reported that polymers carrying pendant amine groups are capable of absorbing carbon dioxide to form thermally reversible amine/CO2 addition products. In this study, we investigated the effects of amine structure on acid gas sorption and the thermal reversibility of the sorption–desorption reactions of various acid gases including CO2, SO2, NO, and NO2 with both linear and cross‐linked polymers using thermogravimetric analysis. © 1994 John Wiley & Sons, Inc.
Nonstationary peeling apparatus
Authors: Obori Hiroyoshi , Takenaga Mitsuru , Abdulla Aniwar , Nakamura Akira
Published: April 2003

A piece of apparatus for measuring the peel adhesion behavior of pressure‐sensitive adhesive tapes was developed. The apparatus allows peel rates to be varied as any functions of time or peel distance. In a cycle run of the accelerating and decelerating peel processes, nonstationary peeling was investigated over a wide range of peel rates using relatively short‐length samples. The resultant behavior in nonstationary peeling indicated that in the interfacial failure regime, a good agreement with the normal stationary peeling can be obtained. This nonstationary peeling apparatus is expected to be useful for evaluation of peel adhesion. © 1994 John Wiley & Sons, Inc.
Separation of water–alcohol mixtures by pervaporation through asymmetric nylon 4 membrane
Authors: Lai Juin‐Yih , Chu Yuh‐Hsiu , Huang Shih‐Liang , Yin Yih‐Lang
Published: April 2003

The dehydration of aqueous alcohol solutions through asymmetric nylon 4 membranes were investigated using pervaporation processes. The formation of asymmetric pervaporation membranes are discussed in terms of the content of the nonsolvent in the casting solution, polymer concentration, and compositions of the coagulation medium. The effects of the feed composition, feed temperature, and molar volume of the alcohols on the pervaporation performances of the asymmetric membranes are discussed. A separation factor of 4.72 and a permeation rate of 0.78 kg/m2 h for the asymmetric membrane were obtained. Compared to the conventional homogeneous nylon 4 membrane, the asymmetric membrane can effectively overcome the pervaporation performances of the nylon 4 membrane for separation of water–alcohol mixtures. © 1994 John Wiley & Sons, Inc.
Effect of an oxidative environment on the creep compliance of poly(ether urethane urea)
Authors: Wu Y. K. , Sletten K. R. , Topolkaraev V. , Lodoen G. A. , Anderson J. M. , Baer E. , Hiltner A.
Published: April 2003

Secondary creep of unstabilized poly(ether urethane urea) (PEUU) in an oxidative environment appears as a linear time‐dependent component superimposed on the logarithmic, viscoelastic response. The surfaces of unstabilized PEUU crept in H2O2/CoCl2 have been characterized by scanning electron microscopy and ATR–FTIR. By examining PEUU crept for various periods of time, it is found that surface damage proceeds at gradually increasing size scales, culminating in large voids. It is hypothesized that the initial chain scission creates a flaw that grows in size under the influence of the applied load into a “nano‐pit,” which grows further by coalescence into a pit and, finally, a void. The initial stages of voiding occur during an induction period when there is no measurable effect on the creep response. It is possible to estimate the average compliance of the damaged PEUU by assuming a composite model with an undamaged center layer sandwiched between damaged surface layers. When the contribution of the surface layers to the creep compliance is estimated from the creep curves, the average compliance of the damaged layer is found to be about 1.6 times higher than that of the undamaged PEUU. Independent calculations of the damaged layer compliance from the void fraction indicate that the damaged layer behaves as a flexible foam in the early stages, then as a more rigid foam at longer creep times. © 1994 John Wiley & Sons, Inc.