bluuebunny/crossref_metadata_2025 huggingface dataset:
Graft copolymerization of vinyl monomers on modified cottons. XVIII. Grafting of methyl methacrylate and acrylonitrile on cotton treated with N‐methylol crosslinking agents using tetravalent cerium as initiator
Authors: Hebeish A. , El‐Rafie M. M. , El‐Kashouti M. A. , El‐Sisi F.
Published: April 2003

CeIV‐induced grafting of methyl methacrylate and acrylonitrile on cotton fibers crosslinked with dimethylol ethylene urea, dimethylol dihydroxyethylene urea, and dimethylol carbamate was investigated. The graft yields obtained with crosslinked cotton were signifcantly lower than the untreated cotton, irrespective of the crosslinking agent and the monomer used. However, the extent and rate of grafting depended upon the degree of crosslinking and the nature of monomer. Based on the magnitude of grafting and CeIV consumption during grafting and oxidation of the untreated and crosslinked cottons, the different reactions occurring during grafting of vinyl monomers on these modified cottons were elucidated.
The accessibility of sulphonic acid groups in basic dyeable polyester fibers. I. The prevention of fiber hydrolysis during dyeing
Authors: Ingamells W. , Lilou S. H. , Peters R. H.
Published: April 2003

The rate of acid hydrolysis of a basic dyeable polyester in water, before and after heat‐setting, has been investigated. Intrinsic viscosity measurements and chemical analysis have been used to establish experimental conditions under which the hydrolysis is inhibited. It is suggested that the critical stage of the hydrolysis mechanism is the exchange of sodium ions from the sulphonate groups in the fiber for hydrogen ions.
Synthesis of phosphorus‐containing wofatit cation exchangers and their affinity toward selected cations
Authors: Bogoczek Romuald , Surowiec Joanna
Published: April 2003

A number of solid Cationits have been prepared derived from Wofatit

Trademark, VEB Chemiekombinat Bitterfield.

gel and canal structures: styrene/DVB, chloromethylated ST/DVB, and acrylic acid/DVB copolymers. To functionalize the copolymers, PCl3/AlCl3 and dialkyl phosphites or trialkyl phosphites were used. The influence of the polymer matrix structure and the chemical structure of the functional groups of obtained Ionits on their affinity toward 23 metallic cations in acidic media has been investigated using the conductivity method. To obtain comparison data, commercial “Wofatit”–sulfonic and–carboxylic Cationits, have been tested under identical conditions.
Viscoelastic properties of the model system: Epoxy resin–glass beads–poly(buthylmethacrylate)
Authors: Lipatov Yu. S. , Rosovizky V. F. , Shifrin V. V.
Published: April 2003

Temperature dependences of viscoelastic characteristics for a model system epoxy resin–glass beads covered with poly(buthylmethacrylate) were studied. The formation of interphase region was established with its own relaxation maximum. The structure of this region is supposed to be a kind of semi‐interpenetrating network formed by crosslinked and linear polymers. Using the Gordon–Taylor equation, the volume fractions of both polymeric components in the interphase region were calculated. An experimental evidence in favor of theoretical calculations has been obtained showing some increase in the glass transition temperature of a two‐phase polymeric system by introducing small amounts of the component with a lower glass temperature as compared with this temperature for the main component.
Relationship between viscoelastic properties and gelation in thermosetting systems
Authors: Tung Chiang‐Ying M. , Dynes Paul J.
Published: April 2003

A method is described for determining from dynamic viscoelastic data the gel time of thermosetting resins. Gelation of nine systems including epoxies, acetylene‐terminated sulfone, and silicones was correlated with the crossover of the dynamic storage G′ and loss G″ moduli measured during isothermal curing. The effect of measurement frequency on gel time is discussed and related to the standard gel test. A lower temperature limit for the valid aplication of this technique was found to be at T > Tgg + 30°C, where Tgg is the glass transition of the system at the gel point.
Interdependence of structure and properties in segmented polyurethanes
Authors: Foks J. , Janik H. , Winiecki S.
Published: April 2003

On the basis of Clough and Schneider's studies, who investigated segmented polyurethanes with the use of DSC, we assumed that warming may lead to morphological changes in these compounds. We warmed polymers for 10 h in argon atmosphere at 130°. Morphological changes occurring in polyurethanes at a modified temperature were confirmed with an electron microscope and were found to affect to a high degree the mechanical properties of the polymer investigated.
Effect of hygrothermal fatigue on dynamic mechanical properties of glass‐reinforced polyesters
Authors: Mijović Jovan
Published: April 2003

Several nonreinforced and reinforced crosslinked polyester formulations were prepared and investigated. Solid glass microspheres, with and without coupling agent, were used as reinforcement. All samples were exposed to various cyclic hygrothermal fatigue patterns, differing from one another by the temperature and duration of a cycle. Dynamic mechanical measurements were used to evaluate the effect of hygrothermal fatigue on the mechanical properties of all formulations. Fatigue induced changes in the glass–matrix interphase led to the appearance of relaxation peaks (β′ and β″) in the temperature range between −50°C and −10°C. Electron microscopic evidence was obtained for the existence of nodular morphology on all fracture surfaces. The character of nodular morphology was described in terms of an inhomogeneous thermoset network.
Characterization of penetrant interactions in Kapton polyimide using a gravimetric sorption technique
Authors: Iler L. R. , Laundon R. C. , Koros W. J.
Published: April 2003

Sorption of pure anhydrous ammonia and pure sulfur dioxide in Kapton polymide has been measured at 30 and 35°C at subatmospheric pressures using a McBain quartz spring balance. The sulfur dioxide sorption and desorption was well described by the Fickian transport model; however, the ammonia sorption exhibited significant deviations from Fickian behavior. A substantial fraction of the initially sorbed ammonia remained in the film after extended periods under vacuum at 35°C. Infrared analysis of the treated film revealed the presence of new carbonyl and nitrogen–hydrogen stretching peaks characteristic of primary and secondary amides. These observations suggest that the ammonia reacts chemically with some of the imide linkages. Based on infrared analysis of the ammonia‐exposed Kapton, heating the sample under vacuum at 120°C caused re‐formation of most of the orginally disturbed imide structures, with attendant evolution of ammonia as a condensation product.
Polyurethane synthesis reactions in asphalts
Authors: Bukowski Andrzej , Grętkiewicz Jacek
Published: April 2003

A series of asphalt–polyurethane composites was prepared by means of polyurethane synthesis in asphalt and carried out in melt. The applied materials were asphalts of differentiated group components content, polyester polyols of chain structure from linear to strongly branched, 2,4‐tolylene diisocyanate, 4,4‐methylenebis(phenyl isocyanate), and tinorganic catalyst. The asphalt components react with isocyanates to a minimal degree. The influence of the applied substrates, temperature, and polyurethane content in the system on the basic kinetic relations characterizing the process is presented. Polyurethane synthesis in asphalts does not differ in a fundamental way from the obtaining of polyurethanes, especially when their content in the composition is significant, 20 wt % and more.
On the factors governing the pressure dependence of the viscosity of moderately concentrated polymer solutions
Authors: Geerissen H. , Schmidt J. R. , Wolf B. A.
Published: April 2003

Viscosity measurements were carried out as a function of pressure and temperature with solutions of polystyrene in eight (endothermal) θ‐solvents at the respective critical composition by means of a Searle‐type apparatus. A rolling‐ball viscometer was used for the investigation of the pure solvents. In all cases the viscosity coefficient increases in a more or less exponential manner when the pressure is raised. For θ‐conditions, the volumes of activation of the solutions exceed that of the pure solvent by typically 10–15%. The exact amount of this extra efffect stemming from the presence of the polymer and its variation with temperature can be qualitatively correlated with the heats of mixing. The ratio of the viscosity of the solution at 1000 and 1 bar, respectively, can be varied for a given solvent power (θ‐temperature) by the choice of the solvent from ca. 2 (cyclopentane) to 4 (trans‐decalin). Within a given system, the maximum effects that can be realized by a change of the solvent power via the variation of temperature ranges from ca. 3 to 6 (tert‐butylacetate).
Gas permeabilities of cellulose nitrate/poly(ethylene glycol) blend membranes
Authors: Kawakami M. , Iwanaga H. , Hara Y. , Iwamoto M. , Kagawa S.
Published: April 2003

The permeability (P) of cellulose nitrate (CN)/poly(ethylene glycol) (PEG) blend membranes for N2, O2, and CO2 has been measured as a function of film composition. The system CN/PEG‐300 showed excellent miscibility, and films of the composition from 100/0 to 50/50 could be used for permeability measurements. P for each gas has been found to be almost constant or rather slightly lowered up to ca. 20 wt % PEG‐300 content and then increased appreciably with increasing fraction of PEG. The increment of permeability was most remarkable for CO2, and hence the permselectivity for CO2 was considerably enhanced. Such a behavior of P has been found to be attributable to the plasticizing effect of PEG molecule lowering the glass transition temperature of the blend polymers. The effect of the molecular weight of PEG and that of closed voids generated in glassy blend membranes fabricated from acetone cast on gas permeabilities have been also discussed.
Modification of the fine structure of cellulose by halogen and heat treatments
Authors: Lewin Menachem , Guttmann Hilda , Derfler David
Published: April 2003

Treatment of various celluloses such as cotton, sulphite, and sulphate pulp with bromine water brings about profound changes in the fine structure of the fiber. Depending on the conditions of the treatment and on the nature of the cellulose, increases or decreases in the accessibility of the cellulose are observed, indicating crystallization and decrystallization processes. In the case of bleached sulphate pulp, similarly to rayon previously studied, an initial decrystallization proceeds the crystallization step. These changes were determined by the IR method, which was correlated previously to the bromine accessibility method. They are accompanied by highly significant changes in moisture absorption. The crystallization proceeds according to first‐order kinetics with respect to the concentration of the less‐ordered regions (LOR) of the cellulose. The rates of crystallization for the various celluloses varied in a range of 4 orders of magnitude. The activation energies of the bromide induced crystallization were found for all celluloses to be in the range of 10–15 kcal/mol, as compared to 30–40 kcal/mol obtained upon crystallizing the same celluloses by heating in the temperature range of 180–200°C. These values correspond to those of solvent and thermal crystallizations of poly(ethylene terephthalate), indicating the similarity between the crystallization mechanisms of the two polymers.
Thermal characteristics of poly(ethylene terephthalate) fiber grafted with poly(vinyl acetate) and poly(vinyl alcohol)
Authors: Faterpeker S. A. , Potnis S. P.
Published: April 2003

Poly(ethylene terephthalate) (PET) fibers were grafted with poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA). The effects of graft copolymers PVAc and PVA on morphological properties of PET were evaluated by differential thermal analysis, differential scanning calorimetry, and thermogravimetric analysis. Melting temperature, heat of fusion, and mass fractional crystallinity of PET was not affected by graft PVAc and PVA. No individual glass transition and melting points corresponding to the graft PVAc and PVA were observed, indicating thereby that graft copolymer mainly exists in the form of free chains inside the PET matrix. Poly(vinyl alcohol) graft copolymer degraded at much lower temperatures than poly(vinyl alcohol) in powder form. Thermal stability of PET fiber was not affected by graft PVAc, where as PET–g–PVA showed an additional degradation point at 360°C.
Temperature dependence of surface crystallization in bimorphic PET fibers
Authors: Durning C. J. , Scott M. G. , Weigmann H.‐D.
Published: April 2003

Open‐bath, organic liquid treatments may be used to produce high surface area PET fibers through the action of liquid solvent‐induced crystallization (SINC). It has been found that as the treatment bath temperature is increased, surface modification suddenly disappears. For a particular treatment method this occurs at a reproducible temperature, well below the liquid boiling point. A qualitative understanding of the mechanism of surface cavitation during liquid SINC is developed based on current descriptions of the component processes involved. These processes are: the glass–rubber transition, diffusion through rubbery and glassy polymer, and polymer–diluent crystallization. Although calculations of the threshold concentration for swelling support this conceptual framework, the absence of surface cavitation at higher treatment bath temperatures is not explained by it and is therefore attributed to an intervening phenomenon. Analysis of penetration depth data together with surface microscopy suggest the formation of a smooth surface layer interfering with normally observed cavitation at elevated temperatures. Manipulation of the extent of vapor precontact shows that vapor SINC prior to liquid exposure is most likely responsible for the smooth layer.
Photo‐induced graft copolymerization. III. Graft copolymerization of methyl methacrylate onto cellulose using peroxydiphosphate as photoinitiator
Authors: Lenka Subasini , Nayak Padma L.
Published: April 2003

Photo‐induced graft copolymerization of methyl methacrylate onto cellulose was investigated using peroxydiphosphate ion as the photoinitiator. The percentage graft yield increases with increasing both the monomer and initiator concentration. The reaction was carried out at three different temperatures, and the overall activation energy was computed. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. A suitable kinetic scheme has been suggested.
Studies on dyeing and mechanical properties of nylon 6 filaments subjected to swelling treatments
Authors: Subramanian D. R. , Venkataraman A. , Bhat N. V.
Published: April 2003

Drawn nylon 6 filaments were subjected to swelling treatment with benzyl alcohol and aqueous solution of phenol and formic acid under slack condition and under tension. The pretreated samples were dyed with a disperse dye Foron Yellow SE‐FL (C.I. Disperse Yellow 42). A considerable increase in the equilibrium dye uptake was observed as a result of swelling treatment. Studies on lateral order by X‐ray methods showed that lateral order has increased considerably as a result of preswelling treatment. This apparent contradiction, viz., increase in lateral order and at the same time increase in dye upstake, is explained as due to increased void volume. Studies on mechanical properties showed that the percentage elongation is increased as a result of swelling treatment under slack condition in spite of increased lateral order. This is explained as due to the slippage of chain‐folded crystallites.
Investigation of cure in epoxy resins: Ultrasonic and thermally stimulated current measurements
Authors: Bunton Lesley G. , Daly John H. , Maxwell Ian D. , Pethrick Richard A.
Published: April 2003

Acoustic and thermally stimulated current measurements are reported as a function of cure for dicyanodiamide cured epoxy resins. It is found that the acoustic propagation is dominated by the generation of voids and does not directly reflect the extent of cure. In contrast, the thermally stimulated data correlate well with conductivity data, the amplitude of the space charge peak decreasing with increasing degree of cure and the dipole peak shifting to high temperatures as predicted from DSC data. Both methods exhibit potential as NDT methods for cure in resins.
Spontaneous adhesion of silicone rubber
Authors: Gent A. N. , Vondráček P.
Published: April 2003

Lightly crosslinked silicone rubber has been found to bond spontaneouly to polar substrates and to itself. The strength of adhesion increases linearly with time, eventually reaching the fracture strength of the rubber. The process is accelerated by raising the temperature (activation energy ⋍ 60 kJ/g. mol), by the presence of moisture, and by ammonia vapor. It is tentatively attributed to hydrolytic decomposition of the polymer leading to the formation of reactive groups which interlink with surface groups, probably hydroxyls, on polar substrates, or with each other in the case of selfadhesion.
Studies on graft polymerization onto glass fibers. II. Graft copolymerization of glass fiber having pendent mercaptan groups and its application
Authors: Fujisawa Takao , Kobayashi Masahiro , Hashimoto Koshiro , Yosomiya Ryutoku
Published: April 2003

Graft polymerization of styrene using a glass fiber having pendent mercaptan groups was carried out under nitrogen in sealed tubes. The percent grafting appeared to increase with monomer concentration, and also to depend to a large extent on the initiator concentration. When CHPO was used as initiator, the percent grafting was maximum at the initiator concentration of 0.02 mol/L. The percent grafting saturation values decreased with increase in the temperature of polymerization. Chain transfer constants and grafting efficiency, both calculated from the equation of Fox et al., were compared with the experimental results. The absorption of Ag ion increased with increase in the percent grafting, and a maximum appeared at a solution pH of 4.0.
Surface protection of poly(vinyl chloride) by photografting of epoxy–acrylate coatings
Authors: Decker Christian
Published: April 2003

UV‐curable epoxy–acrylate coatings were used to protect poly(vinyl chloride) against superficial degradation. With α‐hydroxy–acetophenone photoinitiators, the crosslinking polymerization develops in the ms time scale; 50% degree conversion is reached after irradiation times of 2.5 ms in a nitrogen atmosphere and 17 ms in air. The adhesion of the coating on to the PVC substrate can be greatly improved by inducing a photochemical grafting process. The best results are obtained by incorporating the photoinitiator into the top layer of the PVC sheet. Highly crosslinked epoxy–acrylate coatings are very stable toward UV radiations and chemical agents like organic solvents and strong acids. By their light‐screening effect they provide an excellent protection against photodegradation for light‐sensitive polymeric materials.
Aging and performance of structural film adhesives. II. Comparison of two nitrile–epoxy systems
Authors: Pearce P. J. , Davidson R. G. , Morris C. E. M.
Published: April 2003

The room‐temperature aging of two nitrile rubber–epoxy adhesives has been examined. Both are 121°C curing systems, based on DGEBA‐type epoxy resins, one of which has been available for about 15 years while the other is a more recent development. It has been found that hydrolysis of the epoxide and polymerization both occur slowly, reducing the epoxide content and solubility. A major reduction in honeycomb peel strength of joints made with aged material was evident in the older system and to a lesser extent in the newer adhesive. This is a result of diminished adhesive flow. Tensile strength was less affected by aging.
Immobilization of mortierella vinacea cells by radiation polymerization
Authors: Kumakura Minoru , Kaetsu Isao
Published: April 2003

Immobilization of Mortierella vinacea cells, which contain active α‐galactosidase, by radiation polymerization at low temperatures was studied. The durability of the enzymatic activity of the immobilized cells was examined by repeating the batch enzyme reaction. The enzymatic activities of the immobilized cells obtained with hydrophilic monomers was affected by the concentrations of the cells and monomer in which optimum conditions were observed. The enzymatic activity of the immobilized cells obtained with hydrophilic monomer was compared to that of hydrophobic monomers. Michaelis constants of the immobilized cells varied with monomer concentration. The effect of addition of porous solid substances on the immobilization of the cells was studied.
Melt spinning of poly(ethylene terephthalate)—structural transitions in a range of spinning speeds
Authors: Hamidi A. , Abhiraman A. S. , Asher Pravin
Published: April 2003

The transitions which occur in the structural state of poly(ethylene terephthalate) filaments in the range of spinning speeds, 1600–4500m/min, have been studied. Thermal annealing of as‐spunfilaments has been shown to provide useful indirect evidence for the structural states of these filaments. The results have been explained with a simple model of orientation distributions arising from crystallization in an oriented precursor.
Precipitative polymerization for polycarbonate: A simultaneous reaction–precipitation technique
Authors: Sikdar S. K.
Published: April 2003

A novel phenomenon, termed precipitative polymerization, is described. In it, the BPA—phosgene reaction is conducted with simultaneous precipitation of polycarbonate granules. Very low organic‐to‐aqueous phase ratio and high pH medium are primarily required to cause this in‐situ precipitation.
Structure and properties of polyethylene–polypropylene blend
Authors: Teh J. W.
Published: April 2003

The structure and mechanical properties of blends of low‐density polyethylene and isotactic polypropylene were studied. The blends behaved like a simple composite obeying the rule of mixture for the modulus dependence on composition. Tensile strength of the LDPE was enhanced with the addition of PP but elongation at break was drastically reduced for all blend compositions. Studies with WAXD, hot‐stage microscope, and DSC indicated lack of interaction between the LDPE and the PP. The crystallographic structure of LDPE and PP remained unchanged. However, the spherulite size of the PP was found to be reduced in the presence of LDPE, possibly due to an increase in nucleation density.
Pyrolysis of poly(ethylene terephthalate) fibers: Characterization of involatile residues
Authors: Carlsson D. J. , Day M. , Suprunchuk T. , Wiles D. M.
Published: April 2003

Poly(ethylene terephthalate) fabric was degraded under rapid heating conditions and the solid residue characterized by diffuse reflectance infrared spectroscopy. Fabric samples with and without flame retardant were pyrolyzed in air or nitrogen and spectra‐recorded after various percentage weight changes. Dominant species included carboxylic acid end groups and linear anhydrides, based on infrared absorbances before and after chemical treatments of the residues. Vinyl benzoate end groups were clearly precluded, as were cyclic anhydrides. Diffuse reflectance spectra were also compared with spectra obtained by transmission infrared on conventional KBr discs prepared from the same residue. The former technique was shown to be superior to the pressed disc method for the tough residues obtained by thermolysis.
Gelation and fusion profiles of PVC dispersion resins in plastisols
Authors: Nakajima N. , Ward D. W.
Published: April 2003

Poly(vinyl chloride) (PVC) plastisols are used for coatings, films, sheets, foams, and rotational castings. In order to satisfy the requirements for the different applications, a variety of PVC dispersion resins are manufactured. The requirements for the plastisols are many: for example, good air release, viscosity stability, fine particle size, foamability, and good heat stability. Processability is another important requirement, which emphasizes the rheological behavior at room temperature and the gelation—fusion behavior. This paper documents research to fingerprint the gelation and fusion profiles of various PVC dispersion resins. The viscoelastic measurements were used to continuously monitor the changes of moduli during gelation and fusion under a heating rate which simulates the temperature profile of the processes. The effects of molecular weight, resin type, and copolymer on the gelation–fusion behavior are discussed.
Rheological properties of mixtures of molten polymer and fluorocarbon blowing agent. II. Mixtures of polystyrene and fluorocarbon blowing agent
Authors: Han Chang Dae , Ma Chin‐Yuan
Published: April 2003

The viscosities of mixtures of polystyrene and fluorocarbon blowing agent were determined, using the experimental technique described in Paper I of this series. For the study, three commercial grades of polystyrene were used, together with the following fluorocarbon blowing agents, trichlorofluoromethane (FC‐11), dichlorodifluoromethane (FC‐12), and blends of FC‐11 and FC‐12. For each combination of polystyrene and blowing agent, blowing agent concentration and melt temperature were varied. We have found that, for all three polystyrenes used, a single correlation exists between the viscosity reduction factor (VRF) and the blowing agent concentration, in which VRF is defined as the ratio of the viscosity of polystyrene‐blowing agent mixture to that of polystyrene homopolymer. The correlation was found to be independent of shear rate and temperature, and dependent upon only the type of fluorocarbon blowing agent. It was suggested that such a correlation be used in predicting the bulk viscosity of mixtures of polystyrene and fluorocarbon blowing agent, using information on the viscosity of polystyrene alone.
A study of tensile modulus and molecular orientation in drawn and shrunk poly(ethylene terephthalate) combining refractive index, polarized fluorescence, and X‐ray diffraction measurements
Authors: Bower D. I. , Korybut‐Daszkiewicz K. K. P. , Ward I. M.
Published: April 2003

Earlier studies of the orientation of the crystalline and amorphous regions in drawn and shrunk PET tapes by refractive index, X‐ray, and polarized fluorescence measurements have been extended to include a study of young's modulus of such samples. The results show that for samples of low crystallinity, whether drawn or drawn and shrunk, the modulus correlates well with the overall orientation, as indicated by the birefringence. For such samples the overall orientation and modulus fall with increasing shrinkage. For samples which crystallize substantially, either on drawing or subsequent shrinkage, the behavior is more complicated. In particular, for samples originally drawn at 80°C to λ = 3.44 there is a range of shrinkage temperatures for which greater shrinkage can be accompanied by a smaller loss of overall orientation and modulus because of an increase in crystallinity for the same degree of crystalline and amorphous orientation. The modulus results are discussed in the light of current understanding of the structure of oriented PET. In the case of the samples which crystallize substantially on shrinkage it is shown that changes in modulus primarily related to changes in crystallinity.
Influence of copolymer composition on non‐fickian water transport through glassy copolymers
Authors: Franson Nancy M. , Peppas Nikolaos A.
Published: April 2003

The dynamic swelling behavior of poly(2‐hydroxyethyl methacrylate‐co‐methyl methacrylate) and poly(2‐hydroxyethyl methacrylate‐co‐N‐vinyl‐2‐pyrrolidone) in water was followed at 37°C. The results were analyzed in terms of a simple non‐Fickian transport equation, which expresses the fractional penetrant uptake as an exponential function of the diffusion time. The exponent n, which indicates Fickian or non‐Fickian transport mechanism, was correlated to the content of the more hydrophilic component of the copolymer. Photomicrographs obtained with polarized light offer new information about the position and movement of the penetrant front in glassy, hydrophilic polymers.
Microstructural characterization of injection‐molded articles
Authors: Kamal Musa R. , Moy Francis H.
Published: April 2003

The techniques of density, X‐ray diffraction, and infrared dichroism measurements were employed to study anisotropic behavior, as a result of processing, in injection‐molded parts. Data pertaining to the distributions of crystallinity and orientation indicated that significant changes occur at or near the surface of the molding. Generally, maximum density (crystallinity) is observed in the core of the molding and near the gate, while minimum density (crystallinity) is observed near the surface. X‐ray diffraction suggests a complex pattern of orientation for the three crystallographic axes. The crystallographic a‐axis tends to be oriented in the flow direction as indicated by both X‐ray diffraction and infrared dichroism measurements. Generally, raising the molding temperature has only marginal influence on crystallinity and orientation. However, the two resins included in the study exhibited substantial differences in the distribution of these properties. The distributions of crystallinity and orientation are attributable to the complex interactions between resin properties and process conditions.
Characteristic features of the matrix effect on the stokes shift of fluorescent dye molecules in pure and plasticized polymers
Authors: Eisenbach C. D. , Sah R. E. , Baur G.
Published: April 2003

The influence of the chemical structure, composition, and physical properties of polymers [polyacrylates and ‐methacrylates, poly(vinyl acetate), polystyrene, and polybutadiene] and plasticized polymers [poly(methyl methacrylate) and polystyrene] on the Stokes shift of fluorescent dyes has been investigated. The results indicate that the structure and overall mobility of the polymer matrix as well as the nature of the dopant all together influence the separation of the absorption and emission band of a given fluorescent dye. In general, polar and highly flexible polymers favor the band separation. The effect of both polar and apolar dopants seems to be primarily a plasticization in case of polar polymers, whereas for apolar polymers the plasticizer effect can be neglected and the increased Stokes shift upon addition of polar dopants has to be attributed to particular dopant/dye interactions. These findings open some new routes to improve the efficiency of solar collectors based on fluorescent dyes.
Effects of dry blending on morphogy of PVC powder particles
Authors: Katchy E. M.
Published: April 2003

Mass and suspension PVC were blended on a Fielder mixer and changes in powder morphology and additive distribution investigated. The techniques used to characterize and assess processing behavior have included microscopy, density, size analysis, torque, and capillary rheometry. The particulate structure of PVC remained intact, and there were no pronounced differences in the processability of blends discharged at different temperatures. In the absence of shear PVC particles are largely unchanged in character. Solid additives do not appear to enter into resin particles while liquid stabilizer readily does so.
Dynamic mechanical and vibration damping properties of polyurethane compositions
Authors: Wong Dennis T. H. , Williams H. Leverne
Published: April 2003

A series of polyurethane compositions with varying comonomer ratio and structure, polyblends with epoxy resin, and filled systems with mica and calcium carbonate were prepared. The dynamic mechanical properties of the compositions were measured at 110 Hz using a Rheovibron. The vibration damping properties were measured using a Brüel and Kjaer damping modulus apparatus with steel strips as substrate, the polyurethane compositions as coatings, and, when used, a constraining layer of aluminum or epoxy. The damping curves by the two techniques were similar in shape. Furthermore, the damping properties of the compositions in both extensional and constrained layer configurations could be estimated from the dynamic mechanical properties. The width of the damping region in terms of the temperature range was used as a criterion for effectiveness. Very wide ranges of temperature, and hence frequency, fell within the damping region which was broadened to as much as −40–60°C by the use of bulky backbone chain polymers, by polyblending with epoxy, and by filling with mica. Mica in an extensional mode configuration could be considered as equivalent to a constraining layer for purposes of calculation. The data agree well with the general view that extensional mode damping requires a high loss modulus and constrined mode damping a high loss factor, in both cases being more effective if the storage modulus were also high.
Chemorheology of thermosetting resins. II. Effect of particulates on the chemorheology and curing kinetics of unsaturated polyester resin
Authors: Lem Kwok‐Wai , Han Chang Dae
Published: April 2003

The effect of particulates on both the rheological properties during cure and the curing kinetics of unsaturated resin has been investigated. For the investigation, a general‐purpose unsaturated polyester resin was used, with calcium carbonate and clay as inorganic particulates and high‐density polyethylene powder as organic particulates. It has been found that, as the particulate content increases, the resin/particulate mixture gives rise to shear‐thinning behavior and the rate of cure increases. It has also been found that the CaCO3 particles helped control shrinkage during cure when the material was subjected to steady shear deformation and that the gel time tη∞ is shorter for mixtures of resin and particulates than for the neat resin alone. Differential scanning calorimetry (DSC) is found useful for determining the curing kinetics of resin/particulate mixtures. We have combined rheological and DSC measurements to obtain a correlation between viscosity and the degree of cure during isothermal curing operations.
Permeant saturation and regulation of membrane transport
Authors: Wirbrant Anita , Sundelöf Lars‐Olof
Published: April 2003

Studies have been made on the equilibrium sorption of p ‐toluene sulfonic acid by nylon 66. The sorption was found to vary strongly with concentration of sulfonic acid in aqueous phase, approaching a saturation concentration in nylon for high concentration in aqueous phase, similar to a Langmuir adsorption isotherm. It was also found to vary strongly with pH. These findings have been used to give simple conditions for the establishment of almost constant permeation rates through nylon film over extended periods of time.
Distribution of molecular weights and branching of high‐density polyethylene
Authors: Agarwal Ram Kumar , Horská Jitka , Stejskal Jaroslav , Quadrat Otakar , Kratochvíl Pavel , Hudec Pavel
Published: April 2003

Samples of industrial high‐density polyethylenes (Liten Macro, Liten FB 29, and Hostalen GM 9255 F) were divided into fractions by precipitation fractionation. The original samples and their fractions were characterized by light scattering, GPC, and viscometry. For all samples the molecular weight distribution is of logarithmic‐normal type. High‐density polyethylenes under investigation contain also high‐molecular‐weight fractions of pronouncedly branched structure, the content of branched molecules being, of course, considerably smaller than that in low‐density polyethylenes.
Tire cord adhesion—A TEM study
Authors: Gillberg Gunilla , Sawyer Linda C. , Promislow A. L.
Published: April 2003

Tire cords are commonly bonded to the rubber by means of resorcinol–formaldehyde–latex (RFL) adhesives. Modified systems involving compatible first dip resins or RFL additives are required for standard polyester (PET) cords. The tire composite contains several interfaces at which adhesive failure can be initiated. However, very little is known about the interfaces between the various materials. This paper describes a method which allows ultrathin sectioning and thereby TEM studies of cord sections embedded in rubber. The studies were performed on model samples produced in the laboratory as well as cord sections cut from commercial tires. The TEM micrographs clearly demonstrate the pronounced capillary flow of the RFL solution from outer fiber surfaces to fiber interstices. This flow leads to either no RFL or very thin RFL layers at the outer filament surfaces of the cord even in the case of high RFL levels (6%) and double dipping of the RFL. A qualitative relationship between adhesion and RFL surface coverage has been demonstrated. The RFL interface to rubber, to a second RFL dip, or to predips of other adhesives is generally very distinct and its texture similar to that of the bulk RFL. Also, no evidence for diffusion of either the predip or RFL components into the fiber surface could be found. This indicates that only limited interdiffusion of the polymeric materials of RFL and rubber phases takes place. Texture differences in the RFL and rubber phases between the various tires can be used to characterize the type of system used.
Immobilization of microbial cells on cellulose–polymer surfaces by radiation polymerization
Authors: Kumakura Minoru , Kaetsu Isao
Published: April 2003

Streptomyces phaeochromogenes cells were immobilized on cellulose–polymer surfaces by radiation polymerization using hydrophilic monomers and paper. The enzyme activity of immobilized cell sheets was higher than that of immobilized cell composites obtained by the usual radiation polymerization technique. The enzyme activity of the sheets was affected by monomer concentration, the thickness of paper, and the degree of polymerization of paper. The copolymerization of hydroxyethyl methacrylate and methoxytetraethyleneglycol methacrylate in the sheets led to a further increase of the enzyme activity due to the increase of the hydrophilicity of the polymer matrix. The Michaelis constant of the sheets from low monomer concentration was close to that of intact cells.
Surface photografting of hydrophilic vinyl monomers onto diethyldithiocarbamated polydimethylsiloxane
Authors: Inoue Hiroshi , Kohama Shigemi
Published: April 2003

Photografting of vinyl monomers has been studied to make hydrophilic polydimethylsiloxane (PDMS) surfaces. A chlorine‐containing polydimethylsiloxane (C‐PDMS) prepared by polymerization of chloromethylheptamethylcyclotetrasiloxane was photocured on a glass plate. The crosslinked C‐PDMA was subjected to a reaction with sodium diethyldithiocarbamate. The diethyldithiocarbamated PDMS was then photoirradiated in the presence of hydrophilic vinyl monomers such as 2‐hydroxyethylmethacrylate and acrylamide to afford surface‐grafted PDMS. Several vinyl monomers were found to graft onto the PDMS surface, as revealed by their attenuated total reflectance infrared and ESCA spectra. Hydrophilicity of the grafted PDMS surfaces was confirmed by the decrease in their water contact angle.
The adsorption of dyes onto chitin in fixed bed columns and batch adsorbers
Authors: McKay G. , Blair H. S. , Gardner J. R.
Published: April 2003

Chitin has the ability to adsorb substantial quantities of dyestuffs from aqueous solutions. Consequently, it may be a useful adsorbent for effluent treatment from textile mills. The design procedures for batch and continuous fixed bed adsorption columns have been investigated for four dyestuffs, namely, CI Acid Blue 25 (Telon Blue Anl, Bayer), CI Acid Blue 158 (Neolan Blue 29, Ciba Geigy) CI Mordant Yellow 5 (Eriochrome Flavine A, Ciba Geigy), and CI Dirert Red 84 (Solophenyl Brown 3RL, Ciba Geigy). The main fixed bed system variables studied are bed height, dye flow rate, and chitin particle size, and these effects have been incorporated into a simplified design model.
A kinetic study of the polymerization of aliphatic imides
Authors: Galanti Anthony V.
Published: April 2003

Thermal polymerization of a homologous series of aliphatic poly(methylene) citra‐itaconimides was investigated by differential scanning calorimetry. Enthalpic analysis indicated that, at least to a major extent, the conversion reactions followed pseudo‐first‐order kinetics. A reasonably linear correlation between the number of sequential methylene groups (6, 8, 10, and 12), between the imide ring structures of the monomers, and the activation energy was observed. Reaction rates and initial temperatures of polymerization as well as thermal stability are compared to those of related poly(methylene)–biscitraconimides and –bismaleimides.
Mechanical properties of acid‐cured epoxide resins with different network structures
Authors: Shimbo Masaki , Nishitani Nobuhisa , Takahama Takashi
Published: April 2003

Static and dynamic mechanical properties of cured epoxide resins based on ester bonds, ether bonds, or a mixture of ester and ether bonds were investigated. Their network structures were estimated from the results of gel content before and after saponification, and conversion of functional groups. It was found that cured epoxide resins based on a mixture of ester and ether bonds indicate intermediate properties between the resins based on ester bonds and the resins based on ether bonds. Both dynamic and static mechanical properties were strongly affected by their network density and their segmental structures suggested in this paper.
Fourier transform infrared spectroscopic characterization of aromatic bismaleimide resin cure states
Authors: Di Giulio C. , Gautier M. , Jasse B.
Published: April 2003

Interesting polyimide materials, possessing good mechanical and thermal properties, are obtained by homopolymerization or reaction of 4,′4‐bis(maleimidodiphenylmethane) with a diamine. Fourier transform infrared spectroscopy has been used to characterize the crosslinking of such materials using maleimide and amine absorption bands. Amine group reaction on double bonds is readily achieved and appears to be insensitive to the temperature of curing. On the other hand, the decrease of maleimide double bonds is strongly dependent on the reaction temperature. The residual amount of double bonds present in the cured material is a function of the temperature: a linear relationship holds between residual double bond concentration vs. curing temperature. The general behavior during crosslinking of this kind of polyimide was related to glass transition temperature changes.
Effect of processing conditions on premature gelling, knit line strength, and physical properties for the RIM process
Authors: Castro J. M. , Macosko C. W. , Critchfield F. E.
Published: April 2003

It is shown how using the relevant dimensionless groups for the RIM process, guidelines for premature gelling, and knit line problems can be achieved. The influence of processing conditions on final plaque physical properties is analyzed. It is shown that RIM parts, due to the fact that most of the polymerization reaction occurs after the mold is filled, are fairly isotropic with respect to planar rotations parallel to the mold walls.
Latex interpenetrating polymer networks based on acrylic polymers. I. Predicted and observed compatibilities
Authors: Hourston D. J. , Satgurunathan R.
Published: April 2003

An investigation of the compatibilities of several acrylic latex interpenetrating polymer networks is the subject of this paper. Initially the compatibilities of the various polymer pairs were predicted using the theory of Krause plus some direct measurement of heats of mixing of monomers and of model compounds. The materials were then synthesized using emulsion polymerization, and the extents of mixing of the components were investigated using dynamic mechanical analysis.
Polycarbonate blends with styrene/acrylonitrile copolymers
Authors: Keitz J. D. , Barlow J. W. , Paul D. R.
Published: April 2003

Lap shear adhesion between laminated sheets of polycarbonate and styrene/acrylonitrile copolymers exhibits a sharp maximum when the acrylonitrile content of the copolymers is in the range of 25–27% by weight. Observations of shifts in glass transitions of the two phases in melt‐mixed polycarbonate/SAN blends suggest partial miscibility of one polymer in the other, and this solubility is at a maximum when the SAN copolymer has an acrylonitrile content in the same range causing maximum adhesion. Mechanical properties of injection‐molded blends of polycarbonate with various SAN copolymers were also best when the acrylonitrile content was the same as that giving maximum adhesion. The partial miscibility behavior in blends as a function of acrylonitrile content of the copolymer is explained qualitatively in terms of a simple binary interaction model.
Application of thermal conductivity detection for investigating the diffusion of component X in the system: A mixture of vapors of X and Y substances–polymer membrane–Y substance vapor
Authors: Izydorczyk Jan , Salwinski Janusz
Published: April 2003

Thermal conductivity detection has been applied for determining the mass transport coefficients of vapor through polymer membranes in the presence of another vapor being in equilibrium with polymer. Apparatus and measuring technique have been described. Diffusion, permeability, and solubility coefficients have been determined for systems comprising polyethylene membrane and two‐component vapor mixtures of selected substances. It has been found that the presence of nonpolar substances affected diffusion, permeability, and solubility coefficients of polar penetrants in the systems investigated. Analysis of the results obtained in evaluating the possibility and correctness of the determination of diffusion and permeability coefficients derived from mathematical descriptions of the process of permeating a single substance has been carried out.
Preparation of tri‐O‐substituted cellulose ethers by the use of a nonaqueous cellulose solvent
Authors: Isogai Akira , Ishizu Atsushi , Nakano Junzo
Published: April 2003

The previously reported method for the preparation of tri‐O‐benzylcellulose was applied to the preparation of various tri‐O‐substituted cellulose ethers. By this method, in which a mixture consisting of SO2, diethylamine (DEA), and dimethylsulfoxide (DMSO) and powdered sodium hydroxide were used as a cellulose solvent and a base, respectively, many tri‐O‐arylmethylcelluloses could be prepared from the corresponding chlorides. Cellulose ethers containing double bonds such as tri‐O‐allyl, tri‐O‐methallyl‐, and tri‐O‐2‐butenylcellulose were also prepared from the corresponding chlorides under a milder condition than that used for the preparation of tri‐O‐arylmethylcelluloses. Reaction factors accelerating complete etherification were discussed.
A “chain fold band” in the infrared spectra of nylon 6
Authors: Hallos R. S.
Published: April 2003

An absorption band found at 974 cm−1 in the infrared spectra of “amorphous” nylon 6 films has been assigned to CH2 wagging or twisting vibrations in molecular chain folds. Annealing amorphous films in air at increasing temperatures up to 150°C has been shown to induce a steady increase in the intensity of the absorption band at 974 cm−1. Annealing at higher temperatures resulted in a sharp decrease in intensity up to an annealing temperature of 210°C. This sharp decrease coincided with a sharp increase in the long period determined by low‐angle x‐ray diffraction studies. Drawing amorphous films has been shown to induce a decrease in the intensity of the band at 974 cm−1. Polarized infrared investigations of amorphous drawn films revealed that the band at 974 cm−1 was strongly perpendicular in character. Treatment of amorphous films in water induced no frequency change in the band at 974 cm−1.