bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grafting reactions onto poly(organophosphazenes). IV. Light‐induced graft copolymerization of organic polymers containing free acid or basic functionalities onto poly[bis(4‐benzylphenoxy)phosphazene]
Authors: Minto Francesco , Gleria Mario , Bortolus Pietro , Fambri Luca , Pegoretti Alessandro 
Published: April 2003

AbstractThe light‐induced graft copolymerization of acrylic acid, methacrylic acid, and 4‐vinylpyridine onto poly[bis(4‐benzylphenoxy)phosphazene] films to prepare new grafted phosphazene copolymers containing acid and basic functionalities is reported. The process was carried out in monomer/methanol mixtures in the presence of benzophenone or benzoin ethyl ether as photosensitizers by selective excitation of these last species. The yield of the grafting processes was evaluated as a function of the monomer concentration in the reaction medium, type of photoinitiator, and characteristics of the grafted organic monomers. The acid functions inserted in poly[bis(4‐benzylphenoxy)phosphazene]‐g‐poly(meth)acrylic acid grafted copolymers, and the basic groups of the poly[bis(4‐benzylphenoxy)phosphazene]‐g‐poly‐4‐vinylpyridine substrates were allowed to interact with basic and acid dyes, respectively, to form permanently colored polymeric films. The photoactivity of these films as substrates for the photosensitized production of singlet oxygen was tested. © 1995 John Wiley & Sons, Inc.
Diffusion of organic solvents in rubber membranes measured via a new permeation cell
Authors: Guo C. J. , De Kee D. , Harrison B. 
Published: April 2003

AbstractAn experimental method based on a gravimetric permeation cell was designed and successfully used in measuring the diffusivities, permeabilities, and the breakthrough times of several rubber–solvent systems. The experimental results for four organic solvents: benzene, o‐xylene, ethylbenzene, and chloroform in silicone, natural, and bromobutyl rubbers, respectively, are reported along with a description of the experimental method. The relations between the diffusivities measured by a permeation method and a sorption uptake method are discussed. This permeation cell provides a simple and reliable mean to determine the diffusional transport properties of a polymer–solvent system. © 1995 John Wiley & Sons, Inc.
Processing characteristics and structure development in solid‐state extrusion of a new semicrystalline polyimide (BTDA–DMDA)
Authors: Wang Y. D. , Cakmak M. , Harris F. W. 
Published: April 2003

AbstractIn this article, we present detailed processing characteristics and structure development in a thermoplastic polyimide BTDA–DMDA in the solid‐state extrusion process. This fully imidized polyimide polymer is known to crosslink at fast rates when it is brought to a molten phase even for short periods of time. This characteristic makes it difficult to process it in the molten phase and attempts at melt processing result in melt fracture and highly distorted extrudates. However, this polymer can be shaped into high‐quality extrudates when it is processed below its melting temperature directly from its postpolymerization powdered state. The solid‐state extrusion of precompacted BTDA–DMDA powder was studied in the temperature range from 250 to 320°C. At the temperatures from 290 to 320°C, high‐quality extrudates were obtained. Below 290°C, solid‐state extrusion was not possible due to the limitation of the load cell capacity of the capillary rheometer used in this research. Above 320°C, the extrudates were found to be of poor quality as a result of degradation and crosslinking in the molten phase. Structural characteristics of the samples produced by solid‐state extrusion was investigated by the microbeam X‐ray diffraction technique. The thermal behavior of the extrudates was also characterized by differential scanning calorimetry (DSC). The DSC results show that at low extrusion temperatures the samples exhibit dual endothermic peaks and are highly crystalline in an extruded state. The higher melting peak located at about 350°C is due to the melting of the new crystalline phase that has developed partially during the solid‐state extrusion process and partially during the recrystallization process that takes place at temperatures at and slightly above the primary melting process during the DSC heating scan. This has been confirmed by DSC, depolarized light hot‐stage video microscopy, and wide‐angle X‐ray diffraction studies. The long spacing of the higher melting crystals was found to be much larger than that of the lower melting crystals, as evidenced by the small angle X‐ray scattering studies. © 1995 John Wiley & Sons, Inc.
In situ reactive compatibilized noryl/LCP blends
Authors: Chang Dor‐Yaw , Chang Feng‐Chih 
Published: April 2003

AbstractThis article reveals that the already known improved properties of the thermoplastic–liquid crystalline polymer (LCP) blends can be further improved substantially over the corresponding noncompatibilized counterparts by using a reactive in situ type compatibilizer, the styrene–glycidyl methacrylate (SG) copolymer. This SG copolymer has been demonstrated in this article to be an effective reactive compatibilizer to improve the processability, heat deflection temperature, and mechanical properties of Noryl/LCP blends. The epoxy functional groups of the SG copolymer can react with the end groups of PPO (in Noryl) and LCP. The in situ‐formed SG–g–LCP copolymer tends to reside along the interface of Noryl–LCP and reduces the interfacial tension during melt processing. The resultant LCP fibers in the Noryl matrix of the compatibilized blends have a higher aspect ratio because the fibers become finer, longer, and tend to form lamellate domains with a greater interphase contact area than those from the noncompatibilized blends. The compatibilized blends also improve the interphase adhesion between Noryl and LCP. The presence of ethyl triphenylphosphonium bromide catalyst promotes the grafting reaction to improve blend compatibilization. © 1995 John Wiley & Sons, Inc.
Free volume after cure vs. fractional conversion for a high‐Tg epoxy/amine thermosetting system
Authors: Venditti R. A. , Gillham J. K. , Jean Y. C. , Lou Y. 
Published: April 2003

AbstractIsothermal glassy‐state properties of cured thermosetting materials pass through maximum and minimum values with increasing fractional chemical conversion. In this work, a diglycidyl ether of bisphenol A (a diepoxide) and trimethylene glycol di‐p‐aminobenzoate (a tetrafunctional aromatic diamine) system was investigated for the purpose of analyzing the complex behavior after cure of the isothermal properties of the glassy state with increasing conversion. The glass transition temperature (Tg) is used as a direct measure of conversion. Dilatometric, differential scanning calorimetry, torsional braid analysis, and positron annihilation spectroscopy techniques were used to monitor the density, Tg, modulus, and free volume of the material after cure with increasing conversion. The specific volume at 25°C after cure passes through a minimum and the modulus passes through a maximum with increasing conversion. The fractional free volume and the average radius of free volume at 25°C after cure pass through minimum values with respect to conversion. The specific volume, modulus, and fractional free volume at 25°C vs. conversion data qualitatively correlate. The anomaly of the increasing specific volume in the glassy state with increasing conversion is thus considered to arise from changes in free volume on a length scale corresponding to angstroms. The increasing free volume with increasing conversion is related to the phenomenon of antiplasticization. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of biodegradable poly(1,4‐butanediol succinate)
Authors: Song Dae Kyung , Sung Yong Kiel 
Published: April 2003

AbstractBiodegradable poly(1,4‐butanediol succinate) was synthesized from 1,4‐butanediol and succinic anhydride. The synthesized polymer was identified by 1H‐NMR spectrometer and FT‐IR spectrophotometer. The weight average molecular weights were between 4,600 and 29,000, and molecular weight distributions were in the range of 1.7 and 1.9. The glass transition temperature of poly(1,4‐butanediol succinate) was revealed at 73°C. The crystallization and cold crystallization of the polymers were investigated as a function of heating rate, cooling rate, reheating rate, and molecular weight. The biodegradation behavior of poly(1,4‐butanediol succinate) in micro‐organisms such as fungi, actinomycetes, and bacteria was studied by using modified ASTM method. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples. © 1995 John Wiley & Sons, Inc.
Silk fibroin/cellulose blend films: Preparation, structure, and physical properties
Authors: Freddi Giuliano , Romanò Maria , Massafra Maria Rosaria , Tsukada Masuhiro 
Published: April 2003

AbstractThis article deals with the preparation and characterization of silk fibroin (Bombyx mori)/cellulose blend films. Following dissolution with a metal complex solution, the average molecular weight of silk fibroin slightly decreased. While cellulose was almost unaffected. After coagulation and washing, transparent films were obtained by blending fibroin and cellulose in all proportions. The crystalline structures of regenerated fibroin and cellulose were β‐form and cellulose II, respectively, as shown by the characteristic x‐ray diffraction profiles. Density values increased with cellulose content, though less than expected from a pure additive behavior. Moisture regain increased following the addition of a small amount of cellulose to silk fibroin. The mechanical properties showed that both strength and elongation at break of silk fibroin films were improved by blending with cellulose. IR spectra exhibited changes in the skeletal frequences of silk fibroin, suggesting the occurrence of intermolecular interactions between fibroin and cellulose through hydrogen bond formation. © 1995 John Wiley & Sons, Inc.
Polymer‐dispersed liquid crystal materials prepared by electron‐beam‐initiated polymerization
Authors: Maschke Ulrich , Coqueret Xavier , Loucheux Claude 
Published: April 2003

AbstractPolymer‐dispersed liquid crystal (PDLC) films were prepared using electron beam radiation by a polymerization‐induced phase separation process. The composite material was obtained from a blend including a polyester acrylate and the nematic liquid crystal mixture E7. The electro‐optic properties of the PDLC films were investigated as a function of film thickness. The obtained transmission vs. voltage curves exhibit a good reproducibility, low threshold voltages, and a high transmission in the on state. © 1995 John Wiley & Sons, Inc.
Structural characterization of polyester resins by electrospray mass spectrometry
Authors: Hunt S. M. , Binns M. R. , Sheil M. M. 
Published: April 2003

AbstractSixteen different polyester paint resins have been examined by electrospray ionization mass spectrometry (ESI‐MS) in a novel application of the technique for structural analysis of polyesters. Synthetic resins typically contain a range of polymeric structures comprised of various ratios of the monomeric components. When polyesters are analyzed by ESI‐MS, singly and doubly charged ions are produced and oligomeric species of the polyesters can be clearly identified. The addition of alkali metal salts to the polyester samples and modification of the solvent system was also found to dramatically enhance the ESI‐MS efficiency of polyesters. The ESI mass spectra enabled identification of the range and relative abundance of chemical structures present in each sample. Using this information, average molecular weights, polydispersity, the distribution of acid versus alcohol end groups, overall monomer proportions, average functionality per molecule, and average frequency of branching per molecule have been calculated. The identities of peaks in the ESI‐MS spectra have been confirmed by tandem mass spectrometry. © 1995 John Wiley & Sons, Inc.
Influence of molecular weight distribution on the structure and properties of melt‐spun polypropylene filaments
Authors: Misra S. , Lu F.‐M. , Spruiell J. E. , Richeson G. C. 
Published: April 2003

AbstractThe role of molecular weight distribution on the spinnability, structure, and properties of melt‐spun isotactic polypropylene filaments was studied with the aim of clearly distinguishing the effect of the breadth of the distribution from the effect of the average molecular weight and resin melt flow rate (MFR). Nine resins were chosen for this purpose, ranging in MFR from 16 to 78 and in polydispersity from 2.6 to 5.4. It was observed that the spinnability, structure, and properties of the spun filaments were all strong functions of the breadth of the distribution. Spinnability decreased with increasing breadth. At given spinning conditions and polydispersity, an increase in the weight‐average molecular weight (decrease in MFR) produces an increase in crystallinity, birefringence, tensile strength, and tensile modulus. But at given spinning conditions and resin MFR, broadening the molecular weight distribution (increasing the polydispersity) produces an increase in crystallinity, tensile modulus, and elongation‐to‐break while birefringence and tensile strength decrease. The major influence of the polydispersity on the structure and properties developed was attributed to its effect on both the elongational viscosity of the resin and the ability of high molecular weight tails in the distribution to influence the stress‐induced crystallization that occurs in the spinline. © 1995 John Wiley & Sons, Inc.
Soluble aromatic polyimides and polyamides based on 4,4′‐diaminotriphenylmethane
Authors: Likhatchev D. , Alexandrova L. , Tlenkopatchev M. , Vilar R. , Vera‐Graziano R. 
Published: April 2003

AbstractAromatic polyamides and polyimides were synthesized from 4,4′‐diaminotriphenylmethane (DA‐TPM) for studying their solubility, thermal, and mechanical properties. The polymers were found to be soluble in amide solvents and pyridine, and this could be attributed to the practically free rotation of the polymer chain segments around the bridging group within the DA‐TPM and the effect of its pendant phenyl ring. The polyimides and polyamides exhibited well‐distinguished glass transition in the range of temperatures, which is typical for flexible‐chain polymers. For the polyimides, significant differences in solubility and mechanical properties were observed between the samples prepared by chemical and thermal imidization of poly(amic acids). Thermal imidization brought about remarkably less soluble brittle films. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of melt‐polymerizable aminophthalocyanine monomers
Authors: Boyle Michael E. , Adkins James D. , Snow Arthur W. , Cozzens Robert F. , Brady Robert F. 
Published: April 2003

AbstractThe strategy, synthesis, and characterization of a soluble amine‐functionalized phthalocyanine monomer and two examples of its polymerization into optically transparent glasses are reported. A simple, fast, and versatile method for incorporating metal ions into the metal‐free phthalocyanine is demonstrated. Measurements of the nonlinear optical properties associated with a lead‐substituted phthalocyanine/urethane copolymer are also reported. © 1995 John Wiley & Sons, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.
Effect of antioxidant on peroxide modification of LLDPE
Authors: Bremner Tim , Rudin Alfred 
Published: April 2003

AbstractA commercial linear low density polyethylene (1‐hexene comonomer) was reacted with dicumyl peroxide at appropriate levels to initiate chain extension without crosslinking. The peroxide modification was carried out both in the presence and absence of a common hindered phenolic antioxidant. Thermal treatment of the resin was also completed with and without antioxidant present to evaluate the contribution of classical thermooxidative degradation to the peroxide modification process. In terms of pure thermal degradation, the phenolic antioxidant was found to be effective in prevention of reduction of molecular weights at the high end of the molecular weight distribution, as reflected in changes in Mz. At the low end of the distribution, the opposite effect is seen, where the removal of the antioxidant actually allows an increase in the value of Mn, through chain coupling reactions. Processing of the resin with addition of the organic peroxide significantly increases the molecular weights of both antioxidant containing and antioxidant free resins. Increasing the reaction temperature increases the rate of degradative chain scission and nonenlarging disproportionation reactions. At low temperatures, the presence of the antioxidant acts negatively with respect to chain enlargement reactions, and an overall reduction is seen in the efficiency of the peroxide in its role of increasing molecular weights. As the reaction temperature is increased, chain scission reactions become more predominant, and the antioxidant free resin shows very substantial decreases in molecular weight. Retention of the antioxidant at higher reaction temperatures is beneficial to maintaining high molecular weights, both with and without peroxide present. As in the peroxide free case, branching is essentially unchanged by the absence of antioxidant in peroxide modification. © 1995 John Wiley & Sons, Inc.
Correction for interdetector volume in size exclusion chromatography (SEC)
Authors: Pigeon Michael G. , Rudin Alfred 
Published: April 2003

AbstractIn a multidetector SEC system it is necessary to match the outputs of the detectors that sense eluant concentration with that are molecular weight dependent. There are several methods to accomplish this. The most common is to determine the interdetector volume or time difference between detectors. The difficulty with this technique is that with detector systems where the column eluent is split, the interdetector time difference varies with solution viscosity. Two new techniques were implemented on a high temperature SEC/DRI/LALLS/VISC system which take into account changes in solution viscosity due to high molecular weight polymers. Both techniques use calibration curves of hydrodynamic volume versus elution volume for the different detectors to determine the “instantaneous” time difference between the detectors as it varies with solution viscosity. Either method provides the correct interdetector time lag information. We note also that in multidetector systems the configuration of the detectors should be such as to maximize solvent flow rates through each detector and hence to minimize band broadening effects. © 1995 John Wiley & Sons, Inc.
Thermal dehydrochlorination of poly(vinyl chloride) in the presence of Jatropha seed oil
Authors: Okieimen F. E. , Sogbaike Clara E. 
Published: April 2003

AbstractThermal degradation of poly(vinyl chloride) was studied in a nitrogen atmosphere in the presence of Jatropha seed oil, epoxidized Jatropha seed oil, and soaps (barium and cadmium) of Jatropha seed oil at various temperatures. The rate of dehydrochlorination measurement at 1% degradation, RDH, and the time required for dehydrochlorination to attain 1% conversion were used to assess the effect of the additives on the susceptibility of the polymer to dehydrochlorination. It was found from the kinetic studies and the results from viscosity measurements on degraded polymer samples that the Jatropha seed oil derivatives suppressed the initial loss of HCl from the polymer and the extent of polymer chain scission accompanying the dehydrochlorination process. Thermal degradation studies of poly(vinyl chloride) in the presence of mixtures of barium and cadmium soaps of Jatropha seed oil were also carried out. It was found that soap mixtures containing less than 80 wt% cadmium soap exerted a deleterious (antagonistic) effect on the degradation of poly(vinyl chloride) while in the presence of soaps containing more than 80 wt% cadmium soap, considerably lower values of RDH and higher values of tDH were observed. The soap mixture containing 90 wt% cadmium soap was found to exhibit a remarkedly improved stabilizing effect on the dehydrochlorination of poly(vinyl chloride). © 1995 John Wiley & Sons, Inc.
Orientation in uniaxially drawn polystyrene plasticized by CO2 sorption
Authors: Kajitani Takahiro , Uosaki Yasuhiro , Moriyoshi Takashi 
Published: April 2003

AbstractUniaxial drawing experiments of the polystyrene films plasticized by a sorption of compressed CO2 gas at pressures up to about 18 MPa were carried out with strain rates ε of 0.0290 and 0.0079 s−1. The drawing was performed successfully with draw ratio λ up to 4 at the temperatures of 308.15, 318.15, 328.15, and 338.15 K. The Hermans orientation function f of the drawn samples was determined from the dichroic ratio measured by an infrared spectrophotmeter. While f value increases with increasing ε or λ, it decreases with increasing CO2 pressure or temperature. © 1995 John Wiley & Sons, Inc.
Estimation of critical micellar concentration through ultrasonic velocity measurements
Authors: Durackova S. , Apostolo M. , Canegallo S. , Morbidelli M. 
Published: April 2003

AbstractA technique based on ultrasound propagation velocity measurements has been developed to investigate surfactant's behavior in aqueous solutions. Applications to the estimation of the critical micellar concentration of two emulsifiers, sodium dodecyl sulfate and dodecylbenzene sulfonic acid sodium salt, and a mixture of them are discussed. A simple model was developed to interpret the experimental ultrasound propagation velocity measurements. The model provides a theoretical foundation to the experimental results as well as a valuable tool for smoothing out the disturbances affecting the experimental data. © 1995 John Wiley & Sons, Inc.
Mechanical and microstructural properties of pectin/starch films
Authors: Coffin David R. , Fishman Marshall L. , Cooke Peter H. 
Published: April 2003

AbstractFilms were made from blends of high methoxy pectin and high amylose starch gelatinized in a microwave oven in the presence and absence of glycerol at times ranging from 10 to 105 s. Three thermodynamic transitions were observed when storage modulus, loss modulus, and loss tangent were plotted against temperature. All three transitions gave minima when the transition temperature was plotted against time of gelatinization. Overall, there were only modest changes in these moduli over the range of gelatinization times studied, with little difference between films made with the starch gelatinized in either the presence or absence of glycerol. Starch granules were found to disappear at gelatinization times between 20 and 30 s, although much smaller starch particles seemed to recur at gelatinization times of 75 s and above. The minima found in the transition temperature and modulus plots were believed to result from a minimum in the amount of intermolecular interactions between the starch molecules. © 1995 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.