bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pyrolysis and combustion of cellulose. I. Effects of triphenyl phosphate in the presence of nitrogenous bases
Authors: Hendrix James E. , Bostic James E. , Olson Edward S. , Barker Robert H. 
Published: April 2003

AbstractThe ability of selected phosphorus‐containing compounds and nitrogen‐containing compounds to act as flame retardants for cotton cellulose was investigated using flame tests, thermal gravimetric analysis (TGA), and differential thermal analysis (DTA). The effectiveness of the organophosphorus compounds was found to correlate with the changes which they induced in the pyrolytic degradation of the cellulose as indicated by DTA. Many of the samples containing nitrogen were found to exhibit DTA curves having pronounced exotherms. The presence of nitrogen‐containing compounds in conjunction with the organophosphorus systems enhanced their ability to retard flame propagation but did not produce significant changes in the pyrolytic endotherm as observed by DTA. More conclusive evidence for a chemically based phosphorus‐nitrogen synergism was obtained by the use of TGA. These data can be interpreted in terms of the phosphorus‐nitrogen synergistic effects and flame retardance mechanisms which have been proposed in the literature.
Procedure for calculating the crystallinity of ethylene–vinyl acetate copolymers and low‐density polyethylene as a function of temperature
Authors: Barlow A. , Young M. 
Published: April 2003

AbstractA method is described for determining the x‐ray crystallinity of ethylene–vinyl acetate copolymers at differing temperatures. An equation is derived for the symmetrical curves of crystallinity versus temperature thus obtained, from which the crystallinity at any temperature can be calculated. In order to determine the constants of the equation for a particular polymer, it is only necessary to determine the melting point and per cent crystallinity of the resin at a known temperature. The equation can also be applied to conventional polyethylenes, but not to linear polyethylenes. It is suggested that this is due to the former resins having a broad crystallite size distribution compared with the narrow distribution present in high‐density polyethylene.
Degradation of poly(vinyl chloride). I. Kinetics of thermal and radiation‐induced dehydrochlorination reactions at low temperatures
Authors: Palma G. , Carenza M. 
Published: April 2003

AbstractThe dehydrochlorination reaction arising thermally and from exposure to γ‐radiation has been followed, under vacuum, in the temperature range from 80° to 130°C by measuring the pressure of the evolved volatiles. The catalytic action of HCl, which was recently established, has been observed also at these low temperatures. In agreement with previous data, a free‐radical mechanism has been accepted to be operating in the radiation‐induced reaction, which has been found to be linearly dependent on dose rate and essentially independent of temperature. Assuming the thermal dehydrochlorination to proceed according to the same mechanism, its activation energy, lying within the range of values reported in the literature, represents the activation energy for the thermal process of radical formation by dissociation of normal and anomalous structures in PVC macromolecular chains. Since this value appears to be substantially constant in the temperature range from 90° to 240°C, it can be established whether the dissociation reactions of all the PVC structures are regulated by the same activation energy or, more simply, only one of these structures is concerned.
Thermal analysis of polyacrylonitrile. Part I. The melting of polyacrylonitrile
Authors: Dunn P. , Ennis B. C. 
Published: April 2003

AbstractThe melting point of polyacrylonitrile can be determined directly by differential thermal analysis, provided that a sufficiently fast heating rate is used. The experimental value of 326°C agrees well with predicted values of the melting point. The disparity between oxidative and thermal decomposition of the polymer is noted.
The stress cracking of polyamides by metal salts. Part IV. Metal nitrates
Authors: Dunn P. , Sansom G. F. 
Published: April 2003

AbstractThe stress cracking of polyamide (nylon 6) by a number of metal nitrates in aqueous and nonaqueous solution has been investigated. Copper and zinc nitrates were the most active. Stress cracking parameters were determined and the sorption of the nitrates into nylon 6 film was studied using infrared techniques. Evidence of coordination of some metal nitrates when sorbed into nylon 6 was obtained.
Studies on ion‐exchange membranes. XXXII. Heterogeneity in ion‐exchange membranes
Authors: Mizutani Yukio , Nishimura Masakatsu 
Published: April 2003

AbstractTwelve kinds of cation‐exchange membranes were treated with hydrogen peroxide. Some of them (Selemion CMV, Nepton CR‐61, Scrion C‐100, SAM‐1) were completely destroyed. Heterogeneity is believed to be present in that part of their chemical structures that is decomposable by the treatment. The other membranes were converted into porous membranes by the decomposition of the resinous part. Water permeabilities and electric resistances of the porous membranes were examined to evaluate the pore radius. It was concluded that the “paste method” membranes have a heterogeneity or localized distribution of the resinous part under 50 mμ. The “paste method” membranes seemed to resemble the “graft method” membranes in chemical structure and to be much different from the mosaic‐type membranes such as Permaplex and MC‐3142. These results were also supported by extraction of the membranes with appropriate solvents and observation by electron microscopy.
Studies on dry spinning. II. Numerical solutions for some polymer–solvent systems based on the assumption that drying is controlled by boundary‐layer mass transfer
Authors: Ohzawa Yoshiyuki , Nagano Yutaka 
Published: April 2003

AbstractNumerical solutions of the fundamental equations for dry spinning are obtained by assuming that the rate of the drying of solvent is controlled by the transfer of the solvent vapor at the boundary layer formed outside the filament surface. The polymer–solvent systems for the calculation cover acetate–acetone, poly(vinyl alcohol)–water, polyacrylonitrile–dimethylformamide, and polyurethane–dimethylformamide systems. Quantities necessary for the calculation are summarized. They are material properties (vapor pressures of the solvents, viscosities of the polymer and solvent systems, and so forth) and heat‐ and mass‐transfer coefficients. Mass‐transfer coefficients for acetone and dimethylformamide are evaluated by measuring the ratio of heat‐transfer coefficients to mass‐transfer coefficient based on the method of measuring wet‐ and dry‐bulb temperatures. The variation of the phenomenologic quantities such as solvent content, cross‐sectional area, and temperature of the filament along the spinning path is shown in Figure 4.
The diffusion of gases and water vapor through grafted polyoxymethylene
Authors: Williams J. L. , Stannett V. 
Published: April 2003

AbstractPolyoxymethylene was successfully grafted with styrene, butadiene, and acrylonitrile by the mutual irradiation method in the monomer containing 18% of dimethyl formamide. The CO2 and water vapor permeabilities and diffusivities were determined in the case of the butadiene‐ and acrylonitrile‐grafted products. The former grafts had higher permeabilities than the ungrafted materials. However, the acrylonitrile grafts showed considerably reduced water vapor permeability and diffusivity compared to the ungrafted polyoxymethylene. Films made by grafting to polymer powder and compression molding showed lower permeabilities compared to those made by direct grafting to polyoxymethylene films.
The thermal degradation in vacuo of an amine‐cured epoxide resin
Authors: Leisegang E. C. , Stephen A. M. , Paterson‐Jones J. C. 
Published: April 2003

AbstractThe degradation in vacuo of the cured resin from stoichiometric amounts of the diglycidyl ether of bisphenol A and p,p′‐diaminodiphenylmethane was studied at temperatures of 303.7 and 304.0 ± 0.2°C. The condensible products of the degradation at these temperatures were collected and the major components were isolated as pure compounds. These were identified as water, bisphenol A, 2‐(benzofur‐5‐yl)‐2‐(p‐hydroxyphenyl)propane, N,N,N′,N′‐tetramethyl‐p,p′‐diaminodiphenylmethane, phenol, p‐isopropylphenol, p‐isopropenylphenol, N,N‐dimethylaniline, N‐methylaniline, N,N‐dimethyl‐p‐toluidine, benzofuran, and N‐methyl‐p‐toluidine. The presence of 2,2‐bis(benzofur‐5‐yl)propane was suspected. The gaseous degradation products were identified as acetaldehyde, chloromethane, carbon dioxide, carbon monoxide, methane, ethane, ethene, and nitrogen. Tentative reaction mechanisms are proposed to account for the formation of the products identified. The possible nature of some of the minor degradation products is discussed. The results are related to those of previous studies of the degradation of the same and similar resin–hardener systems.
Thermoplastic elastomers via radical polymerization. I
Authors: Zaganiaris Emmanuel , Tobolsky Arthur 
Published: April 2003

AbstractThermoplastic elastomers were synthesized using a method for preparation of block copolymers introduced by Tobolsky and Rembaum. A hydroxy‐terminated polyester or polyether was chain extended with tolylene diisocyanate and capped with cumene hydroperoxide. The high molecular weight peroxycarbamate was used as initiator for polymerization of styrene, methyl methacrylate, or acrylonitrile monomer. Their physical properties were investigated by modulus–temperature curves. The effect of composition on modulus was also examined.
Studies on tack of pressure–sensitive adhesive tapes
Authors: Toyama M. , Ito T. , Moriguchi H. 
Published: April 2003

AbstractIt has been found that tack values of pressure‐sensitive adhesives are dependent on the surface energies for adherends. The parabolic curves with maxima are obtained from the plots of tack values versus critical surface tensions for the substrates. The maximum occurs at the region where the two surface tensions are almost similar. On the other hand, tack is measured as a dynamic value indicated as the force necessary to deform the adhesive mass. To explain why the tack values is controlled by the surface character of the adherend, a mechanism is proposed for adhesive bond breaking. Primarily, bonding occurs by wetting the surface with adhesive. When the adhesive bond breaks by external force, unbonding proceeds from the viscoelastic deformation of the adhesive mass around the wetted spots on the surface of the adherend. As the total area of wetted spots is determined by surface energy, the tack value is dependent on the critical surface tension of the adherend.
Study of sintering of poly(methyl methacrylate)
Authors: Kuczynski G. C. , Neuville B. , Toner H. P. 
Published: April 2003

AbstractSintering of poly(methyl metacrylate) spheres to the blocks of the same material was studied at temperatures ranging from 127° to 207°C. The analysis of the data based on the empirical Ostwald relation indicates that the predominant mechanism responsible for this process is non‐Newtonian viscous flow. The type of the flow changes with temperature of sintering, being pseudo‐plastic at lower temperatures and tending to dilatancy at higher ones.
Light emission due to peeling of polymer films from various substrates
Authors: Ohara Keiji , Hata Toshio 
Published: April 2003

AbstractThe intensity of the light which is emitted when polymer films are peeled mechanically from various substrates under varying conditions of vacuum was measured by a photomultiplier, amplifier, and pen‐writing oscillograph combination. The wavelength of the emitted light depends upon the sign of static charge generated on the surfaces of the film and the substrate by peeling. In the PVC‐glass sample system, the radiation consists of two bands of light, namely a shorter band (∼4900 Å) and a longer one (5200–5900 Å), but in other sample systems (e.g., PVC–copper, PVAc–glass), only the shorter band was observed. The latter band appeared at the higher degree of vacuum. Comparing these bands with discharge spectra of nitrogen gas and using various substrates, it was proved that the light of the shorter band can be attributed to the light of gas discharge and that of the longer one, to the light of glass luminescence. Generally speaking, the intensity of the light of the longer band is weaker than that of the shorter one. Total intensity of light changes with peeling speed and reaches a saturated value. This type of saturation may be interpretable if the streamer process is taken into consideration as a mechanism of electrostatic discharge. Total intensity of light depends also upon the pressure in the peeling chamber. At pressures of 10−2–10−3 mm Hg, the total intensity of light becomes minimum. This phenomenon is interpreted as a change of discharge potential according to Paschen's law under the condition of constant width of discharge gap.
On the explanation and correlation of turbulent drag reduction in dilute macromolecular solutions
Authors: Gordon R. J. 
Published: April 2003

AbstractA simple mechanistic picture of turbulent drag reduction is proposed, based on the recent work of Corino and Brodkey for Newtonian fluids. Possible explanations are then considered from a phenomenological viewpoint, and the applicability of the well‐known dumbbell model toward this end is discussed. It is seen that the predictions of the “molecular” dumbbell model are surprisingly similar to those of the “continuum” convected Maxwell model utilized by Seyer and Metzner. Furthermore, the significance of the fluid relaxation time θ in characterizing the drag‐reducing effectiveness of a polymer solution is shown to follow from a number of qualitative arguments. A correlation is proposed, closely related to the recent correlations advanced by Rodriguez, Zakin, and Patterson, and Astarita, Greco, and Nicodemo. Some new aspects of this correlation are discussed.
Estimation of crosslinking of diallyl phthalate prepolymer. An investigation by infrared spectroscopy
Authors: Yoshida Katsunari , Kamada Harunori , Kumanotani Ju 
Published: April 2003

AbstractThe cure of the dially phthalate prepolymer was studied by means of infrared spectroscopy. It was found that the CC stretching band of the allyl group, which appears at 1647 cm−1 in diallyl phthalate monomer, splits into two bands at 1645 and 1651 cm−1 in both of the prepolymers and cured resins derived therefrom, the split band being found to be mostly useful to investigate the highly cured resin system of diallyl phthalate. On the basis of the split band, α is defined as a new parameter expressing a degree of residual unsaturation of diallyl phthalate prepolymers as well as highly crosslinked polymers, as revealed experimentally. Further, α proved to correlate closely with other parameters such as the iodine value measured for the prepolymers, and swelling weight ratio or Barcoal hardness (hot) measured for the cured resins, it becoming evidently a convenient parameter to examine the degree of crosslinking of diallyl phthalate resin system. The effect of metal molds employed upon cure of prepolymers was also elucidated from the measured α values.
Rates of crystallization of copolyamides. II. Random copolymers of nylons 66 and 6
Authors: Harvey E. D. , Hybart F. J. 
Published: April 2003

AbstractRates of crystallization of copolyamides of nylons 66 and 6 have been measured by a photometric technique using a hot‐stage microscope. The copolymers all show some crystallinity, but the temperatures of crystallization are reduced as more comonomer is introduced. A close correlation between melting and crystallization behavior is observed. The copolymerized component is acting as a diluent rather than entering the homopolymer crystal.
Shear degradation of polymer solutions
Authors: Ram A. , Kadim A. 
Published: April 2003

AbstractShear degradation of polyisobutylene solutions was studied in laminar flow through capillaries. A special apparatus was designed with a view to a controlled shear history. The various effects of initial molecular weight, concentration, temperature, and shear stress at the wall on the final degradation product are combined in a single parameter representing the minimum force required for degrading a polymer sample to its final state.This work is based on the M.Sc. Thesis of A. Kadim, submitted at the Department of Chemical Engineering, Technion—Israel Institute of Technolog, Haifa, Israel.
The γ‐radiolysis of zeocarb 225 cation‐exchange resins
Authors: Clay P. G. , Hall G. R. , Rahman M. K. , Rashid M. 
Published: April 2003

AbstractIrradiation of Zeocarb 225 cation‐exchange resin leads to a loss of exchange capacity and the formation of SO42− ions. G(SO42−) is dependent upon the relative amount of water associated with the resin and may be reduced by the addition of scavengers, reactive towards hydroxyl radicals. The results suggest that both direct and indirect radiolyses are able to bring about desulphonation and that hydroxyl radicals are responsible for the indirect radiolysis.
Pressure‐induced diffusion of organic liquids through highly swollen polymer membranes
Authors: Paul D. R. , Ebra‐Lima O. M. 
Published: April 2003

AbstractThe transport of twelve organic liquids through a highly swollen rubbery membrane has been studied. The transport was caused by a pressure applied to the liquid above the membrane (reverse osmosis). The flux was found to be a highly nonlinear function of the driving pressure. Detailed thermodynamic and diffusion theories are proposed to describe the transport in terms of the concentration gradient of the swelling liquid within the membrane induced by the applied pressure. The data and the theory appear to be in very good agreement. The diffusion coefficients deduced from the data are explained in terms of a hydrodynamic mechanism of diffusion. Highly swollen membranes can yield very high liquid fluxes at moderate pressure and consequently may have applications for performing certain separations.
The brittle fracture of amorphous thermoplastic polymers
Authors: DiBenedetto A. T. , Trachte K. L. 
Published: April 2003

AbstractThe brittle fracture properties of polyphenylene oxide, polysulfone, polycarbonate, and poly(methyl methacrylate) thermoplastic polymers were investigated over a wide range of temperatures. Fracture energy measurements were made using double edge‐notched tensile samples. Tensile strength, tensile strain, and initial elastic modulus were measured for calculation of the fracture energy and further analysis of the polymer behavior. It was found that mechanical transitions in the tensile properties corresponded reasonably well with transitions in the fracture energy in the temperature range investigated. Fracture surface photographs permitted visual analysis of the fracture process. It was found that the roughest fracture surface corresponded to the maximum in the fracture energy for a given polymer. A theory for prediction of polymer tensile yield strain is presented, based on the volume dilation concept. The implications of this theory are discussed in terms of the crack tip flow process leading to brittle fracture.
The properties of polyethylene crystallized under the orientation and pressure effects of a pressure capillary viscometer
Authors: Southern John H. , Porter Roger S. 
Published: April 2003

AbstractHigh‐density commercial polyethylenes have been crystallized under the combined orientation and pressure effects available in the Instron capillary rheometer. The samples so formed were found to have a high degree of crystal perfection and crystal orientation in combination with the unusual property of transmitting visible light. The procedure for forming the crystal structure is elucidated. X‐Ray and differential scanning calorimetry techniques were utilized to initiate a study of the structure. Evidence is presented that is consistent with the presence of an extended chain component in the crystal structure.
The synthesis of selenium condensation polymers using bis(2‐hydroxyethyl) selenide and bis(2‐aminoethyl) selenide
Authors: Kroll Harry , Bolton Edward F. 
Published: April 2003

AbstractProcedures were developed for the large‐scale synthesis of bis(2‐hydroxyethyl) selenide and bis(2‐aminoethyl) selenide. These bifunctional selenides were converted into a series of polyesters, polyureas, and polyurethanes. Methods of syntheses and properties of these condensation polymers are described.
Network formation in poly(ethylene terephthalate) by thermooxidative degradation
Authors: Yoda Kentaro , Tsuboi Akio , Wada Minoru , Yamadera Reizo 
Published: April 2003

AbstractGelation of poly(ethylene terephthalate) by heating at 263°–300°C was investigated. Under nitrogen flow, crosslinks were scarcely formed. However in air, degradation and crosslinking were common, and these were accelerated by purging gaseous and sublimable degradation products out of the system with a stream of air. The main component of the sublimate was terephthalic acid. Infusible and insoluble gel was treated with methanol at 260°C, and then the methanolysis products were separated into two parts. The methanol‐insoluble part exhibited a polyene structure with ester groups, and the methanol‐soluble part contained dimethyl terephthalate, ethylene glycol, and some 1,2,4‐butanetriol. To clarify the relation between the crosslinking and the formation of vinyl ester groups, the degradation of vinyl methyl terephthalate was studied. Thermoxidative degradation of linear polyesters other than poly(ethylene terephthalate) was also studied. Poly(ethylene isophthalate) and poly(ethylene sebacate) were easily gelated. However, poly(trimethylene terephthalate) and poly(neopentyl terephthalate) were scarcely gelated. The primary reaction leading to crosslinking is assumed as follows. At first, the random scission of polyester chain may take place forming carboxylic acids, vinyl esters, aldehydes, etc. After accumulation of vinyl esters to some extent, vinyl polymerization of the esters takes place and network structures are formed.
Preparation and properties of imide–pyrrone copolymers
Authors: Bell Vernon L. 
Published: April 2003

AbstractTwo series of copolymers containing imidazopyrrolone (pyrrone) and imide groups were prepared by solution polymerization. Thin films of the copolymers showed a general increase in the tangent modulus and a decrease in elongation with increasing pyrrone content. The copolymers were more resistant to degradation by strong acids and bases than the corresponding polyimides. The thermal stabilities of the copolymers in air improved with increasing imide content, while the thermal stabilities in a vacuum improved with increasing pyrrone content. These copolymers represent a way to combine the desirable properties of both classes of homopolymers.