bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of carbon black on processability of rubber stocks. V. Extrusion
Authors: Cotten G. R.
Published: April 2003

A study of postextrusion relaxation (shrinkage) rates identified two separate processes, only one of which is influenced by carbon black structure and surface area. One of these processes is thought to be a solidlike fast elastic recovery and was found to be influenced by carbon black and polymer characteristics. The other process reflected slow randomization of oriented molecular chains: it was mainly influenced by polymer nature and carbon black had almost no effect. In the previous paper of this series, work with various carbon blacks in SBR–1500 indicated that both types of polymer deformation originate within the converging flow region at the die entrance, where extensional flow takes place. In the present work the extensional flow behavior of five polymers (filled with various carbon blacks) was examined at elevated temperatures. The magnitude of shrinkage caused by molecular alignment was related to extensional viscosity of the rubbers. This confirms the hypothesis stated above. Extensional viscosity was measured using the previously described instrument, which is inexpensive to construct, easy to operate, and can be attached to any standard stress–strain tester. The characteristics of extensional flow are defined and it is shown that for polymeric materials it differs substantially from shear flow, since a rapid orientation of the molecular chains takes place during the extensional flow. The effect of carbon black on the extensional viscosity at elevated temperatures is illustrated.
Functionalization of polymer supports for polymerization catalysts by graft polymerization method
Authors: Kritskaya D. A. , Pomogailo A. D. , Ponomarev A. N. , Dyaschkovskii F. S.
Published: April 2003

The specific features of the gas‐phase radiation‐induced and plasma‐initiated graft polymerization of certain monomers possessing the functionality needed for immobilization of transition metal compounds were studied. The radiation yields of allyl monomers grafted to polyethylene, polypropylene, and poly(vinyl chloride) (5–25 molecules/100 eV) were found to be close to the radiation yields of the polymerization of these monomers in a liquid state. The kinetics of methyl methacrylate and acrylic acid postgrafting to polyethylene pretreated with helium discharge plasma were also studied. The graft‐initiating effect of PE powder treated with plasma for 5–10 min was found to be comparable with that of γ‐irradiation in a dose 0.5–4 Mrad. The results of immobilization of transition metal compounds [TiCl4, VCI4, VO(OC2H5)3, Ti(OC4H9)4, etc.] on carriers prepared by the method of polymer support functionalization by grafting are described. The extent of completion of the immobilization reaction is found to vary from 0.1 to 0.96 and to depend both on the nature of the transition metal and on the specificity of the grafted fragments.
The influence of poly(styrene sulfonate) addition to cellulosic fibers by wet processing on the physicomechanical properties of paper
Authors: Eroglu H. , Andreolety J. P. , Silvy J. , Cheradame H.
Published: April 2003

The study of the effect of sodium poly(styrene sulfonate) addition to suspensions of fibers, in the presence of aluminum salts as adsorption aids, revealed the retention effect of fine solids during sheet formation. Polyelectrolyte adsorption also causes an increase of bounding energy in the web. It is shown that the improvement observed for the dry strength properties of paper is a consequence of these two effects. (In this paper the words “fine solids” or “fines” indicate the parts of the cellulosic material which filtrates through a 150‐mesh screen, regardless of its nature.)
Influence of moisture on the flame retardance of textile fabrics
Authors: Zeronian S. H. , Ellison M. S. , Alger K.
Published: April 2003

For cotton fabric not treated with a flame retardant (FR), the oxygen index (OI) increases slowly but at a constant rate with moisture content (MC). Above a MC of roughly 33% which roughly equals the water fiber saturation point of the cotton fiber, the increase becomes more rapid but the relation appears to remain linear. The relation between OI and MC is also linear for all the FR cotton fabrics examined up to an OI of at least 40. It is suggested that the moisture in the FR samples is not reducing flammability by entering into solid and/or gaseous phase reactions but by absorbing thermal energy owing to the endothermic process of heating and vaporization. Empirical relations appear to be present between the inherent hydrophilicity of the FR cotton fabrics and the OI of the dry fabric (OI)o and the temperature of the zenith of the first exothermic peak for the FR cotton fabrics as determined by differential thermal analysis. OI–MC relations for wool fabric and wool treated with an FR are similar to those found for the cotton fabrics except that the slopes of the lines found for the wool samples are lower than those of the equivalent cotton samples. The relation reported by Van Krevelen between OI and char residue for polymeric materials is tested for both the cotton and wool samples. Agreement with Van Krevelen's relation is not good when (OI)o values are used. Better agreement can be obtained if OIs are determined on samples with MCs between 2 and 10%.
Synthesis of phenol‐terminated polyisobutylene: Competitive chain transfer reactions
Authors: Rooney J. M.
Published: April 2003

Polymerization of isobutylene initiated by either aluminum trichloride or tin tetrachloride were conducted in the presence of alkyl phenols in both n‐heptane and methylene dichloride solutions at temperatures between −10 and −70°C. The resultant polymers contained both unsaturated and phenolic endgroups in varying proportions dependent upon reaction conditions. Increased phenol concentrations in the polymerization medium resulted in decreased polymer molecular weights and increased phenol endgroup content. Increased reaction temperature reduced polymer molecular weights and phenol endgroup content. Chain lengths governed by ring alkylation were found to be less sensitive to polymerization temperature than those determined by other modes of chain transfer.
A study of the drawing behavior of poly(ethylene terephthalate)
Authors: Perena J. M. , Duckett R. A. , Ward I. M.
Published: April 2003

Cold‐drawn and hot‐drawn samples of poly(ethylene terephthalate) were studied by means of measurements of shrinkage stress, birefringence and differential scanning calorimetry (DSC). The values of shrinkage stress were comparable for both types of sample, implying that the deformation of a molecular network is important for both cold drawing and hot drawing. The DSC results indicate that substantial crystallization occurs in hot drawing for other than the lowest draw ratios, and this crystallization gives rise to an additional peak in the shrinkage stress measurements. In addition to temperature, strain rate is also an important variable, and changes in strain rate caused significant changes in both hot‐drawn and cold‐drawn samples.
Shrinkage and mechanical properties of poly(ethylene terephthalate) filaments treated with various organic solvents
Authors: Venkatesh G. M. , Khan A. H. , Bose P. J. , Madan G. L.
Published: April 2003

The effects of a number of chemically nonreacting organic on shrinkage and stress–strain properties of preoriented semicrystalline poly(ethylene terephthalate) filaments have been studied. The changes in shrinkage and mechanical properties are found to be highly dependent on time and temperature, as well as on tension applied on the yarn during the treatment. The changes brought about by the solvents at lower temperatures (i.e., below 100°C) are either comparable with or more than those produced by thermal treatments in air or silicone oil above 200°C. The possibility of using slovent treatment for setting polyester for dimensional stability at low temperature as an alternative to the normal dry‐heat‐setting method has been discussed.
Morphology and properties of α‐methylstyrene and butadiene diblock copolymers
Authors: Hsiue Gin‐Ho , Yang Chien‐Hua
Published: April 2003

Diblock copolymers of α‐methylstyrene and butadiene were synthesized, using n‐BuLi as initiator, toluene as solvent, and tetrahydrofuran (THF) as accelerator. The addition of a small amount of THF in polymerization solution would greatly increase the 1,2‐addition of polybutadiene. However, this effect leveled off gradually as the amount of THF increased. Electron microscopic texture and viscoelasticity of diblock copolymer samples cast from THF, toluene, benzene and CCl4 were examined. Two peaks were observed in the dynamic mechanical loss (tan δ) curve at −27 and 145°C, corresponding to segmental motions of polybutadiene and poly‐α‐methylstyrene, respectively. This showed the microphase separation of the block copolymers. Different electron microscopic textures were observed for same sample cast from different solvents.
Selective permeation of hydrocarbon gases in poly(tetrafluoroethylene) and poly(fluoroethylene–propylene) copolymer
Authors: Yi‐Yan N. , Felder R. M. , Koros W. J.
Published: April 2003

The permeabilities and diffusivities of methane, ethane, propane, n‐butane, and isobutane in commercially available poly(tetrafluoroethylene) (TFE) and poly(fluoroethylene–propylene) (FEP) Teflon have been measured in a Pasternak‐type permeation cell. Experiments were carried out at upstream hydrocarbon partial pressures up to 50 torr (1000–60,000 ppm gas phase concentration) and temperatures from 40 to 195°C with films of 0.0508 and 0.127 mm thickness using nitrogen as carrier gas on the upstream and downstream sides of the membrane. The transient and steady‐state permeation data are described well by a combination of Henry's law and Fick's law with a concentration‐independent diffusion coefficient. Linear Arrhenius plots of both permeabilities and diffusivities were obtained. Linear correlations were found both between the activation energy for diffusion and the square of the gas molecule diameter, and between the logarithm of solubility at 90°C and the penetrant boiling point. Separation factors for binary mixtures of hydrocarbons were measured for TFE at 140°C and found to be similar to those predicted by individual permeabilities in most cases. Measurements with mixed gases were not made for FEP Teflon, but selectivities of FEP are expected to be similarly well described by the ratios of the pure gas permeabilities at the low partial pressures studied. The effect of annealing FEP Teflon for 24 hr at 200°C was found to produce an average of 20–30% reduction in solubility as well as a 9% increase in the activation energy for diffusion compared to as‐received films. These effects are believed to be due to increased crystallinity in the sample upon annealing.
Biodegradable polymers: Photolysis and fungal degradation of poly(arylene keto esters)
Authors: Huang Samuel J. , Byrne Catherine A.
Published: April 2003

Poly(keto esters) were prepared from 4,4′‐bis(chloroacetyl) diphenyl ether, 4,4′‐bis(bromoacetyl)diphenyl ether, and 4,4′‐bis(2‐bromopropionyl)‐diphenyl ether and aliphatic diacids of 6, 8, 9, 10, and 12 carbon atoms. Low‐molecular‐weight polymers were found to support the growth of Aspergillus niger and Aspergillus flavus. Introduction of methyl group to the polymer chain decreased the susceptibility of the polymers to fungal attack. Although monomeric model compounds were found to undergo photodegradation the poly(keto esters) underwent mostly crosslinking when irradiated with UV light.
Surface characteristics of solvent‐cast polymers
Authors: Schreiber H. P. , Croucher M. D.
Published: April 2003

Films of poly(methyl methacrylate) (PMMA), polystyrene, and a styrene/acrylic terpolymer have been cast from solutions of varying thermodynamic quality and the film properties studied by inverse gas chromatography and by critical surface tension measurements. Surface properties of the non‐polar polystyrene were independent of solvent medium, but significant variations in these properties were observed in the case of PMMA and the terpolymer. Solvent balance also appeared to affect the bulk properties of the latter films, as judged by the penetration rates of interacting liquids. The observations indicate the feasibility of controlling film properties of the solid by the appropriate selection of solution media; a time‐dependent variation in solid properties is to be expected, however, as the film structure attains an equilibrium state.
New crystalline complex chlorides containing transition metal chlorides or oxychlorides as components of coordination catalysts
Authors: Greco Alberto , Bertolini Guglielmo , Cesca Sebastiano
Published: April 2003

Novel complex chlorides have been obtained by reacting TiCl4, VOCl3, MoOCl4, WOCl4, or AlCl3, with Be, Mg, Ca, or Sr chlorides in the presence of electron donors such as POCl3(L) or C6H5POCl2, (L′). The resulting products, obtained with good yield, show defined stoichimetry, ionic character, and crystalline structure, and may be considered reference systems for high‐yield catalysts in the low‐pressure polymerization of ethylene (HDPE). Complexes (TiCl6)MgL6, (TiCl5L′)2MgL′6, and (Ti2Cl10)MgL6associated with (i‐C4H9)3Al were found very active in HDPE synthesis, but completely unable to polymerize propylene. This result and other evidence suggest that part of the catalytic activity of these systems is displayed by soluble species. The role played by the Mg ion in high‐yield catalysts is displayed by soluble species. The role played by the Mg ion in high‐yield catalysts is discussed in the light of the peculiar behavior shown by the complex chlorides containing this earth‐alkali metal.
Effects of absorbed water on physical properties of polyesters
Authors: Ito Eiko , Kobayashi Yasuji
Published: April 2003

In previous articles, we reported the change in physical properties of hydrophobic polymers caused by absorption of a very small amount of water. This article describes the changes in physical properties of three polyesters owing to absorption of water. The tested polymers were poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and polyethylene 2,6‐naphthalate (PEN). PBT has more flexible main chains than that of PET, and PEN has more rigid main chains. The dielectric measurements revealed that water absorption results in shortening the relaxation time for PET, while the relaxation time for moist PBT becomes longer. The larger amount of absorbed water yields the higher density of PET and the lower density of PBT. The water absorption of the polyesters also yields increments in dielectric constants and relaxation strength. Distribution of relaxation time of the polyesters is narrowed by absorption of water.
Dyeing of cellulose by direct dye in aqueous sodium alginate solution
Authors: Nango M. , Maekawa M. , Katayama A. , Kuroki N.
Published: April 2003

Dyeing of cellulose by direct dye in aqueous sodium alginate solutions containing sodium chloride has been studied to interpret thermodynamically the role of sodium alginate on the adsorption equilibrium of dye on cotton. The result has been compared with that of sodium chloride (low‐molecular inorganic electrolyte) by an adsorption model on cellulose. We have inferred, by the membrane‐equilibrium theory, that the dye has been concetrated into the internal solution of cellulose because of the presence of sodium alginate in the bulk solution.
Penetration‐sorption of cotton fibers measured by immersed weight
Authors: Rowland S. P. , Stanonis D. J. , King W. D.
Published: April 2003

Weight of cotton immersed in an aqueous solution (various concentrations of NaOH) was explored as a basis for assessing penetration and sorption of the solute. The overall effects of swelling are indicated. Penetration and sorption phenomena can be identified with supplementary information, but they cannot yet be quantified. This methodology supplements and complements gel filtration as a means of measuring interactions between solutes in aqueous solution and cellulose fibers.
Structure and properties of microporous membranes prepared by applying phase separation during polymerization
Authors: Mizutani Yukio , Nishimura Masakatsu
Published: April 2003

Porous membranes of poly(vinyl chloride) were obtained from cation exchange membranes prepared by the soaking and paste method, by selective decomposition of the cation exchange resin component. The structure and properties of the membranes as filters were investigated by scanning electron microscopy, infrared analysis, water permeability measurement, and determiantion of rejections for some solutes and dispersers with widely differing sizes. They completely rejected two kinds of bacteria and polymer particles with a diameter of about 0.1 μm. The rejection of hemoglobin ranged from 90 to 100%, depending upon the preparative conditions. Heat treatment of the cation exchange membranes increased water permeability of the resulting PVC porous membranes and decreased hemoglobin rejection in varying degrees, depending upon the treatment temperature.
Polymerization of alkyl acrylates and alkyl methacrylates with starch
Authors: Fanta George F. , Burr Robert C. , Doane Wiliam M.
Published: April 2003

A series of C4‐C12 alkyl acrylates and methacrylates was polymerized with starch by irradiating starch–monomer mixtures with 60Co. Homopolymers were extracted with cyclohexane. The amounts of insoluble versus soluble synthetic polymer in polymerization run with alkyl acrylates varied less with the chain length of the alkyl substuent than in the polymerizations run with alkyl acrylates varied less with the chain length of the alkyl substituent than in the polymerizations run with alkyl methacrylates; and the poly(alkyl acrylate) contents of cyclohexane‐insoluble fractions were all in the 38–45% range. Synthetic polymer contents of the products from butyl, hexyl, and decyl methacrylates were also close to this range. Octyl and lauryl methacrylate, however, gave high conversions to cyclohexane‐soluble poly(alkyl methacrylate) along with little or no unextractable synthetic polymer in the starch‐containing fractions. Poly(lauryl methacrylate) could be rendered insoluble by incorporating a small amount of tetramethylene glycol dimethacrylate in the polymerization mixture. In a series of polymerizations run with hexyl acrylate and hexyl methacrylate, lower irradiation doses led to more cyclohexane‐soluble polymer and less synthetic polymer in the starch‐containing fractions. Enzymatic digestion of starch‐soluble polymer and less synthetic polymer in the starch‐containing fractions. Enzymatic digestion of starch‐containing polymers gave synthetic polymer fractions that were largely insoluble in cyclohexane. Crosslinking is, therefore, probably taking place during these polymerizations; however, we could not eliminate the possibility that reduced solubility was caused by small amounts of residual carbohydrate in these polymer fractions. Ceric ammonium nitrate‐initiated polymerizations of butyl acrylate, hexyl acrylate, and butyl methacrylate with starch gave cyclohexane‐insoluble polymers that contained 33–39% synthetic polymer. The higher alkyl acrylates and methacrylates produced little or no polymer under these conditions. Starch‐containing fractions were tested as absorbents for hydrocarbons. Products prepared from decyl acrylate and lauryl acryle acrylate absorbed about 9 g of isooctane per 1 g of polymer, whereas the lowrer alkyl monomers gave polymers with lower absorbency.
Property–composition dependence of polyurethane–poly(vinyl chloride) polyblends
Authors: Kalfoglou Nikos K.
Published: April 2003

The dynamic mechanical properties of polyblends of a polyurethane (PU) elastomer and poly(vinylchloride) (PVC) at five compositions were studied at 110 Hz, between −120 and 120°C. The study also included tensile testing at 25°C, and examination of polyblend morphology and fire‐retardant properties. The results were analyzed using suitable two‐phase mechanics models valid for such systems. This analysis, together with the morphological evidence and the thermomechanical spectra, indicate that these polymer alloys are essentially heterogeneous and their useful mechanical properties are due to good adhesion between the two phases. This conclusion is also corroborated by the tensile properties study. Fire retardancy is significant only above ∼60% by weight of PVC.
Preparation of ion‐containing elastomers by emulsion copolymerization of dienes with olefinic sulfonic acid salts
Authors: Siadat B. , Oster B. , Lenz R. W.
Published: April 2003

Procedures were developed for the emulsion copolymerization of either butadiene or isoprene with several different water‐soluble monomers containing sulfonic acid salt groups, primarily with sodium styrenesulfonate, for the preparation of ionomer elastomers. By the use of a nonionic surfactant and a two‐component redox initiator, which was based on a water‐soluble reducing agent and a hydrophobic peroxide, copolymers with sufficient amounts of the ionic monomer could be prepared. Unusual effects of conversion on rate, copolymer composition, and molecular weight were observed and attributed to special effects caused by the ionic monomers. The copolymers were soluble in mixed hydrocarbon–alcohol solvent systems.
Influence of shearing history on the rheological properties and processability of branched polymers. IV. Capillary flow and die swell of low‐density polyethylene
Authors: Rokudai Minoru , Fujiki Tokio
Published: April 2003

Low‐density polyethylene (LDPE) melts show anomalous rheological behavior; their viscoelastic properties vary with their shearing histories although their molecular structural parameters do not change. Capillary flow and die swell behavior were dependent not only on the experimental conditions such as temperature or shear stress but also on the processing index (PI), which was introduced in a preceding article in order to quantify the anomalous rheological behavior of LDPE melts. In addition, it was found that the flow activation energy at constant shear stress also varied with the shearing histories. The experimental findings are discussed in terms of the rheological flow units of LDPE melts.
Space charge limited currents in pure and iodinated cellulose acetate films
Authors: Kumar Ashok , Nath Rabinder
Published: April 2003

Current as a function of voltage has been studied in pure and iodine doped cellulose acetate in the temperature range 313–373 K. The space charge limited currents (SCLC) have been found to exist in pure and doped samples. The temperature dependence of conductivity is found to correspond to two activation energies. The activation energies calculated from conductivity vs. temperature plots for ohmic and SCLC regions were almost equal showing the extrinsic nature of conduction. The break point at 78°C in conductivity vs temperature plots for pure cellulose acetate may correspond to effective glass transition temperature (T′g). This has been verified from the differential thermal analysis studies. The effect of iodine doping on the electrical conduction in cellulose acetate has been investigated and the results are reported. The infrared studies reveal that iodine stays in the polymer as a neutral molecule and some of which may interact with the polymer molecules.
The effect of heat setting on the structure and mechanical properties of poly(ethylene terephthalate) fiber. III. Anelastic properties and their dependence on structure
Authors: Gupta V. B. , Kumar Satish
Published: April 2003

Viscoelastic parameters for poly(ethylene terephthalate) (PET) fibers heat set under different conditions were determined at 110 Hz between room temperature and about 200°C. The correlation of dynamic mechanical properties with structure and their dependence on the temperature of the measurement are discussed. It was found that in addition to the structural parameters such as degree of crystallinity, crystallite and amorphous orientation, etc., morphological factors such as size and distribution of crystallites also influence the dynamic mechanical properties. The activation energy of the α‐transition is reported, and the effect of the distribution of relaxation times on the activation energy is discussed.
Assessment of the adhesive bond properties of allyl 2‐cyanoacrylate
Authors: Kotzev D. L. , Ward T. C. , Dwight D. W.
Published: April 2003

The adhesive bond of allyl 2‐cyanoacrylate between steel substrates has been analyzed and compared to that of ethyl 2‐cyanoacrylate. Mechanical strength as well as thermomechanical, calorimetric, thermogravimetric, and dynamic mechanical response was observed. It was demonstrated that the allyl 2‐cyanoacrylate bonds exhibit improved temperature resistance owing to the formation of heat‐induced crosslinks in the adhesive layer, resulting in much improved lap‐shear strengths. Scanning electron microscopy of the fracture surfaces showed that plastic deformation occurred in the allyl 2‐cyanoacrylate adhesive after thermal aging, while interfacial and brittle failure dominated all other cases.
Multiple molecular relaxations of hot‐drawn and quenched polymers above their glass transition temperatures
Authors: Kato T. , Yanagihara N.
Published: April 2003

Thermal shrinkage of highly hot‐drawn and quenched poly(methyl methacrylate) and polycarbonate of bisphenol A were measured. PMMA shows three‐step thermal shrinkage under suitable experimental conditions above its glass transition temperature (Tg). Polycarbonate exhibits four kinds of molecular relaxation associated with shrinkage around and above its Tg. The effect of hot‐drawing and quenching conditions on shrinking behavior is discussed. Almost all of the molecular relaxations are observed above Tg. The molecular origins of the relaxations are discussed in relation with the so‐called T11 transitions of polymers.
Polymer gamma dosimeter
Authors: Chung Woon H.
Published: April 2003

A chemical dosimeter has been developed based on the gas evolution of polymers by γ radiation. The polymers used in this dosimetry were polyacrylamide, poly(vinyl alcohol), and polystyrene. The irradiating γ source was a 60Co annular cell calibrated with the Fricke dosimeter, an average dose rate being 630 rad/min. The irradiated samples were aqueous solution, i.e., polyacrylamide oxygen saturated in water, poly(vinyl alcohol) aerated in water, and polystyrene oxygen saturated in carbon tetrachloride. A manometer system was used as the gas‐measuring device. It was found that the dosimeter showed good linearity above 1 Mrad.
Adhesion of glow discharge polymers
Authors: Sharma Ashok K. , Millich Frank , Hellmuth Eckhard W.
Published: April 2003

Various reaction parameters in a propylene glow discharge polymerization were investigated with the objective of synthesizing films having good adhesion to metal and glass substrate. Monomer flow rate (at a constant pumping efficiency) was found to exert a significant effect on the quality of polymer adhesion to substrates. Good adhering polymeric films were obtained only at high flow rates where the deposition rate decreases with an increase in monomer flow rate. This observation applied also to ethylene, propane, allyl bromide, and ϵ‐caprolactam. Transmission electron microscopy of the freshly deposited polymer films indicated a defect‐free structure of the polymer surface obtained at high flow rates. The polymer surface obtained at low flow rates had a bead structure superimposed by uniformly placed circular defects.
Radiation‐induced oxidative degradation of poly(vinyl chloride)
Authors: Hegazy El‐Sayed A. , Seguchi Tadao , Machi Sueo
Published: April 2003

Gas evolution and oxygen consumption in the γ‐irradiation of PVC were studied. The gas evolution and the oxidative degradation are retarded by the presence of plasticizers and stabilizers. TheG(HCI) andG(H2) and 8 and 0.24 for the irradiation of pure PVC under vacuum and 0.02 and 0.14 for that of plasticized PVC, respectively. Gas evolution increases in the presence of oxygen, specially for the pure PVC. TheG(–O2) values for the pure and plasticized PVC are 30 and 12, respectively. The dependence of gas evolution and oxygen consumption on the oxygen pressure is more pronounced for the plasticized PVC than pure PVC because the oxygen diffusion is controlled.
Structural changes in partially oriented polyester yarns subjected to dry and wet heat
Authors: Warwicker J. O. , Graham S. G.
Published: April 2003

An examination by X‐ray, birefringence, and infrared methods was carried out on partially oriented polyester yarns subjected to dry and wet heat under varying tensions that allowed shrinkage and extension processes to occur. The results can be interpreted in terms of a two‐phase morphology in which one phase is a network and the other crystalline. On this basis the evidence suggests that the crystalline phase is composed of extended chains and the network of randomly folded chains with cohesion points randomly distributed between them.
Nylon 6 water‐permeable membranes prepared by electron beam radiation‐induced graft copolymerization
Authors: Haruvy Yair , Rajbenbach Aryeh L.
Published: April 2003

Nylon 6 films, 25 μm thick, were grafted with polar monomers in aqueous solution following preirradiation with a 550‐kV electron beam accelerator. The graft yield rose linearly with grafting period up to 100% graft and leveled off at a graft yield above 150%. At 100 to 200% graft of several acrylic acid derivatives onto the nylon 6 films, water permeation rates comparable to those of PVA and cellophane films were observed. These high water permeation rates of the grafted nylon films were considered as an indication that some of the acrylate copolymers penetrated throughout the matrix of the host polymer. The highest rates of water permeability were observed in nylon acrylamide grafts.
Adhesion of glow discharge polymers to metals and polymers
Authors: Inagaki N. , Yasuda H.
Published: April 2003

Adhesion of glow discharge polymers to metals and polymers in an adhesive joint was measured by lap‐shear test and immersion in hot water of 70°C °C for an extended time. A glow discharge polymer was deposited onto polymers [polyethylene and poly(tetrafluoroethylene)] and metals (aluminum and stainless steel) prior to when the polymer and metal were joined. It is found that the lap‐shear strength is enhanced by coating the surfaces of these substrates with plasma film produced from methane, ethylene, and acetylene, and that deterioration of the adhesive bonding part, when immersed in hot water of 70°C, is strongly dependent on the gas used as well as operational conditions where a polymer film is formed. The adhesion of a polymer produced from methane on the polymer and metal is strong enough to apply for durable, adhesive joints.
Solubility of phenolic antioxidants in polyolefins
Authors: Billingham N. C. , Calvert P. D. , Manke A. S.
Published: April 2003

The solubilities of six phenolic antioxidants in polypropylene and polyethylene were measured between 50°C and 100°C. Measurements were also made of their solubilities in a range of liquid alkanes. The measured solubilities at 70°C were consistent with regular solution theory and could be used to predict values to within one half of an order of magnitude. No simple correlation was found when regular solution theory was applied to predict the dependence of solubility on either temperature or the molar volume of the solvent. Hence, contrary to previous reports, the relative solubilities of antioxidants, measured at high temperatures or in alkane solvents, cannot be used to estimate their relative solubilities in polymers at room temperature.
Aliphatic polyesters. I. The degradation of poly(ϵ‐caprolactone) in vivo
Authors: Pitt C. G. , Chasalow F. I. , Hibionada Y. M. , Klimas D. M. , Schindler A.
Published: April 2003

The degradation of poly(ϵ‐caprolactone) in rabbits, rats, and water was studied by measurement of changes in intrinsic viscosity, molecular weight, crystallinity, Young's modulus, and weight. Degradation proceeds by nonenzymatic random hydrolytic cleavage of ester linkages. The process is autocatalytic, and the kinetic relationship Mn/Mno = exp(–kt) is observed until the Mn has decreased to approximately 5000. Significant weight loss is not observed until this point but, once initiated, the rate of weight loss depends markedly on the particle size. Chain scission is associated with an increase in crystallinity, which partly determines the rate of degradation.
Study on radiation grafting of acrylic acid onto fluorine‐containing polymers. II. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene)
Authors: Hegazy El‐Sayed A. , Ishigaki Isao , Rabie Abdelgawad , Dessouki Ahmed M. , Okamoto Jiro
Published: April 2003

Some properties of the membranes obtained by the preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene) (PTFE) film have been studied. The dimensional change by grafting and swelling, water uptake, electric conductivity, and mechanical properties of the grafted PTFE films were measured and were found to increase as the grafting proceeds. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions except higher monomer concentration (80 wt %). The electric conductivity and mechanical properties of the membranes at 80 wt % monomer concentration is lower than those at a lower monomer concentration. The results suggest that the membranes obtained at 80‐wt % acrylic acid solution have a somewhat heterogeneous distribution of electrolyte groups as compared with those prepared at a monomer concentration less than 60 wt %. X‐ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the center with progressive diffusion of monomer to give finally the homogeneous distribution of electrolyte groups. The membranes show good electrochemical and mechanical properties which make them acceptable for the practical uses as cation exchange membrane.
Copolyester studies. VII. The dyeing behavior of undrawn fibers derived from tetramethylene terephthalate: Poly(tetramethylene oxide) random block copolymers
Authors: Boussias C. M. , Peters R. H. , Still R. H.
Published: April 2003

A series of copolymers based on poly(tetramethylene terephthalate) containing poly(tetramethylene oxide) blocks whose molecular weights ranged from 1000 to 5000 in concentrations from 10 to 30% by weight was prepared. The polymers were melt spun into fibers and the undrawn fibers dyed with a disperse dye at three temperatures. The equibrium adsorption and diffusion coefficient of the dye increased with both the molecular weight and concentration of the polyether. The equilibrium adsorption varied linearly with both the molecular weight and concentration. It has been assumed that the equilibrium dye partition coefficient KM gives a parameter of the accessibility, V, of the fiber for dye. If the diffusion coefficient DM is given by DM = VDo/τ, where Do is the diffusion coefficient of the dye in the amorphous regions and τ is a tortuosity factor, a good correlation can be obtained between KM and DM, suggesting that changes in Do/τ vary in a systematic fashion.
The adhesion of viscoelastic polymers to wool and polyethylene
Authors: Bateup Brett O. , Souren Illa
Published: April 2003

The relative magnitude of the rate‐dependent peel force for different polymers adhering to polyethylene could be qualitatively predicted from the measured hysteresis of polymer films during stress—strain testing. Calculated values of the energy dissipated at the polymer/polyethylene interface during peeling were of the same order of magnitude as hysteresis values measured at a much lower stress than the breaking stress of the weakest polymer. This was consistent with low values of polymer/polyethylene intrinsic bond strengths expected for pure van der Waals bonding across the interface. In the wool/polymer system, fiber/polymer adhesion was an important facor in determining the shrink‐resist effectiveness (sre) of polymers applied to wool fabric. Correlation between polymer shrink‐resist effectiveness and polymer hysteresis was observed for two series of polymers whose intrinsic wool/polymer bond strengths could be assumed constant. In both cases, cohesive failure in the polymer occurred and hysteresis had to be measured just below the breaking stress of each polymer.
Studies of polymer electrets. I. Factors governing the stabilities of homoelectrets obtained from poly(1‐olefin)s
Authors: Mishra Anu
Published: April 2003

Various poly(1‐olefin)s have been studied as homoelectrets and their stabilities under different environmental conditions have been determined. It has been found that the stabilities of the homoelectrets, prepared from these polymers, depend on their volume resistivities, degrees of crystallinity, and the temperatures at which the crystalline domains of these polymers undergo transitional motions. Excellent stabilities have been exhibited by the homoelectrets prepared from poly(3‐methyl‐1‐butene), poly(4‐methyl‐1‐pentene) and other similar isotactic poly(1‐olefin)s with pendant branched side chains. It is postulated that the charged particles are trapped at the crystalline/amorphous interfaces in these polymers and the bulky alkyl substituents stabilize the charged particles by raising the transition temperatures of these polymers as well as by providing some additional chemical interaction sites.
A thermal analysis study of bisphenol‐A‐polycarbonate–dimethylsiloxane block copolymers
Authors: Grubbs Gary R. , Kleppick Mary E. , Magill J. H.
Published: April 2003

The thermogravimetric analysis (TGA) of three block copolymers of poly(dimethylsiloxane)–Bisphenol‐A‐polycarbonate was measured in nitrogen and air from just above room temperature to 1000 K. Measurements were made on a Perkin‐Elmer TGS‐2 system equipped with a System 4 microprocessor controller. Weight loss curves were obtained for heating rates ranging from 1.5 (or lower) to 80°C/min. Results were analyzed according to the method of Flynn and Wall. Two degradation reactions were observed in air and in nitrogen, respectively. In air, the activation energy was found to be 28–35 kcal/mol. In the inert atmosphere, activation energies were 44±3 kcal/mol and 11–27 kcal/mol, respectively. No straightforward relationship was found between the thermal stability of the copolymers and their composition. The morphology of char residues formed at 80°C/min heating rate to 1000 K have been examined in relation to the Si content. The degree of char formation at different heating rates has been established in nitrogen and in air, respectively.
Dynamic mechanial properties of sulfonated cyclized cis‐1,4‐polyisoprene
Authors: Zhou Zheng Long , Eisenberg A.
Published: April 2003

Acetyl sulfate was used as sulfonating agent for the sulfonation of cis‐1,4‐polyisoprene. IR and NMR spectra showed that the sulfonation was accompanied by extensive cyclization. A series of DSC and loss tangent studies of both the sodium salts and the methyl esters was undertaken. It was found that cyclization exerts a profound influence on the micrbrownian segmental motion of the hydrocarbon matrix and is the dominant factor in raising the glass transition temperatures. However, the differences in the mechanical properties between salts and esters suggest that the presence of ions does influence the melt viscosities and shear moduli of the sulfonated cyclized rubbers; this influence can be minimized by esterification or water absorption. It is seen that the ionic effects in these materials are quite typical of those encountered in a wide range of other ionomers.
The preparation and properties of chelates of transition metal ions with the homopolymer and copolymers of p‐vinylbenzoylacetone
Authors: Chapin Earl C. , Twohig Elizabeth Festa , Keys Loren D. , Gorski Kathleen M.
Published: April 2003

p‐Vinylbenzoylacetone (VBA) was prepared by the condensation of p‐vinylacetophenone and ethyl acetate. This monomer was homopolymerized and copolymerized with acrylamide or maleic anhydride to produce polymers which would chelate substantial amounts of transition metal ions such as Cu2+, Ni2+, Co2+, Eu3+, and VO2+. In the case of the Cu2+ and Ni2+ chelates, about 80–90% of the metal ion could be eluted by dilute mineral acids. The resulting eluted products apparently have a somewhat porous structure because they are capable of rechelating these ions from water solution, even though the solid homopolymer which had not been chelated and eluted is too hydrophobic to chelate very much metal ion from water solution. The eluted Cu2+ chelate readily reaccepted Cu2+ ions from water solution and discriminated against Ni2+ almost completely. However, the eluted Ni2+ chelate would reaccept both Cu2+ and Ni2+ ions, but exhibited a strong preference for Cu2+ ions in competitive batch experiments. The VO2+ chelate was an effective heterogeneous phase catalyst for the epoxidation of allyl alcohols such as geraniol with tert‐butylhyroperoxide. The chelate was stable under these oxidative conditions and could be recovered unchanged and reused.
Behavior of chemically modified cellulose towards dyeing. XIV. Behavior of cotton and crosslinked cottons before and after mercerization towards some reactive dyestuffs
Authors: El‐Aref A. T. , Allam E. , Abou‐Amer M. , El‐Hilw Z. , Hebeish A.
Published: April 2003

Cotton fabric was crosslinked with DMDEU by applying the Form D‐Process and Form W‐Process. The cotton and crosslinked cotton were then treated with caustic soda solution of mercerizing strength. The ability of cotton and crosslinked cottons to dyeing with two reactive dyes, viz. Procion Blue MRB and Procion Red HB was examined. It was found that crosslinking reduces significantly the amenability of cotton to reactive dyes particularly when the Form D‐Process was applied. Mercerization enhances dyeability of all substrates, but the enhancement was much greater in the case of noncrosslinked cotton. Based on dyeing and other properties such as tensile strength, elongation at break, and crease recovery, it was shown that crosslinking decreases considerably the affinity of cotton to caustic soda solution. It was further anticipated that different color designs with different patterns and properties can be conferred on a given cotton fabric by making use of local crosslinking and/or mercerizing followed by dyeing.
Investigations of stabilizing additives. IV. PEPQ as a primary radical scavenger
Authors: Williams J. L. , Williams E. E. , Dunn T. S.
Published: April 2003

Studies of PEPQ in a model antioxidant activity system have demonstrated that this material behaves not only as a hydroperoxide decomposer but as a primary radical scavenger. The temperature dependence of the antioxidant activity also indicates the PEPQ is more effective at higher temperatures than at ambient conditions. The relationship between the model antioxidant activity system and melt stability measurements in polypropylene is in good agreement and implies that PEPQ is an effective melt stabilizer even in the absence of conventional phenolic stabilizers such as BHT.
Studies of polymer electrets. II. Factors governing the stabilities of homoelectrets obtained from polystyrene and its derivatives
Authors: Mishra Anu
Published: April 2003

Polystyrene and its various alkyl and halo derivatives have been studied as homoelectrets and their stabilities under different environmental conditions determined. The stabilities of the homoelectrets prepared from these polymers depended on their volume resistivities, glass transition temperatures, and interactions with electron‐acceptor impurities. Excellent stabilities were exhibited by the homoelectrets prepared from polystyrene, poly(vinyltoluene), poly(chlorostyrene), and poly(t‐butylstyrene). It is postulated that the charged particles are trapped by the π‐orbitals of the phenyl rings present in these polymers and that they are adversely affected by the presence of electron‐acceptor compounds that generally from charge‐transfer complexes with the phenyl groups.
Optimization of spinning, drawing, and annealing conditions in the production of highly oriented fibers from the polycaprolactam/3.7% LiCl system
Authors: Acierno D. , Zenna S. Castrovinci , La Mantia F. P.
Published: April 2003

A polycaprolactam/3.7% w/w LiCl system, obtained by anionic polymerization of caprolactam directly in the presence of salt, has been employed for the production of highly oriented fibers. More particularly, an optimization of spinning, drawing, and annealing conditions has been performed, finally obtaining fibers which shows very satisfactory mechanical results. Namely, average moduli values up to 12 GPa and strength values up to 1 GPa when fracture is far from clamps, have been observed.
Ozonization of amides
Authors: Imamura Sei‐Ichiro , Nishii Koji , Teranishi Hiroshi
Published: April 2003

Ozonization of various amides was carried out as a model reaction for the degradation of polyamides with ozone. N‐alkylamides and N,N‐dialkylamides were found to be reactive compared with those amides which have no alkyl group on the nitrogen atom, and it was suggested that ozone attacks preferentially N‐methylene or N‐methyl group of amides in the first step of ozonization.
A study of sulfur bridges in filled natural rubber vulcanizates by pyrolysis gas chromatography with flame‐photometric detection
Authors: Andersson Eva M. , Ericsson Inger , Trojer Lena
Published: April 2003

Natural rubber vulcanizates of two formulations, with sulfur/N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS) and tetramethylthiuram disulfide (TMTD), respectively, were analyzed by pyrolysis gas chromatography. A sulfur‐selective flame‐photometric detector was utilized. The main pyrolysis products were identified as CS2 and some thiophenes. The yields of the pyrolysis products from the two types of rubber were very different. The yields also varied with the curing time of the rubbers.
Structure–property relationships in PVC compression moldings
Authors: Gilbert M. , Ansari K. E.
Published: April 2003

Compression moldings were produced from two rigid PVC compounds at a range of temperatures. The tensile and impact properties of these moldings depended primarily on the level of particle fusion as assessed by extrusion rheometry. Properties were not related to the level of primary crystallization measured by X‐ray diffraction, but the particle fusion process appears to be at least partly due to recrystallization. Fusion occurred more readily in the mass PVC compound than in the suspension PVC compound. Annealing the sheet produced at 200°C caused changes in crystallinity which resulted in small property changes. The maximum annealing effect occurred at 110°C.
Effect of a synthetic tanning agent on the diffusin properties of an acid dye in nylon 6
Authors: Guthrie J.
Published: April 2003

The diffusion coefficients of an acid dye in nylon 6 polymer hav been measured using two different techniques, one based on the rate at which the fiber absorbs the dyestuff and the other employing the rate of transport of dye through a nylon film. Both of these methods yield diffusion coefficients of similar magnitude. The effect of a synthetic tanning treatment on the diffusion coefficients has been studied and it has been shown that a significant reduction in the diffusion coefficient is only obtained from data based on adsorption measurements. It is concluded that the decrease of rate of dye uptake caused by the presence of the syntan is due mainly to the prevention of initial dye adsorption rather than electrical repulsion or steric effects proposed in earlier studies. These results also highlight the dangers in using adsorption studies as a method for determining diffusion parameters.