bluuebunny/crossref_metadata_2025_split huggingface dataset:
The relative thermal stability of polymer model compounds
Authors: Sheehan Desmond , Bentz Alan P. , Petropoulos John C. 
Published: April 2003

AbstractThe thermal stability of a variety of derivatives of s‐triazine, benzene, and borazine was determined with an isoteniscope. For the s‐triazines the order of stability was found to be aryl triazines > aryl melamines and benzoguanamines > methyl melamines > higher alkyl melamines > aryl cyanurates and thiocyanurates (with the exception of fluoroalkyl cyanurates). The borazines were poorer than the melamines but better than the cyanurates. Several diand trifunctional linking groups were used to connect biphenyl groups which were known to be stable (from previous studies of p‐quaterphenyl and polyphenyl ethers). The order of stability was found to be phosphate ≅ phosphine oxide ≅ ether > ester > amide > carbonate.
Thermal degradation of epoxide polymers
Authors: Anderson Hugh C. 
Published: April 2003

AbstractThe thermal degradation of five crosslinked epoxide polymers were studied in vacuo by differential thermogravimetry. Three of the polymers were prepared by reacting methyl nadic anhydride, maleic anhydride, and m‐phenylenediamine with diglycidyl ether of bisphenol‐A; the other two were obtained by reacting methyl nadic anhydride and m‐phenylenediamine with resorcinol diglycidyl ether. Tenmilligram powdered samples were heated over the temperature range from 25° to 925°C. at a rate of 5°C./min. Differential thermogravimetric curves showed that the polymers incorporating methyl nadic anhydride decomposed in two distinct stages, whereas those based on m‐phenylenediamine or maleic anhydride degraded in only one stage. This difference in mechanism of decomposition is attributed to decarboxylation of ester groups having the methyl nadicdicarboxylic structure in the polymers. Substitution of a 2,2‐diphenylpropyl group for a phenyl group in resorcinol diglycidyl ether, to give diglycidyl ether of bisphenol‐A, influenced appreciably the maximum rates of decomposition of the corresponding polymers. In the case of the polymer based on m‐phenylenediamine, the rate was increased by this substitution, but for the polymer derived from methylnadic anhydride the rate was decreased.
Nylon 7, a fiber forning polyamide
Authors: Horn C. F. , Freure B. T. , Vineyard H. , Decker H. J. 
Published: April 2003

AbstractEight esters of 7‐aminoheptanoic acid were prepared as monomers for nylon 7 (polyheptanamide). They were made from ε‐caprolactone via the route; 6‐chlorohexanoic acid, alkyl‐6‐chlorohexanoate, alkyl‐6‐cyanohexanoate, alkyl‐7‐aminoheptanoate. The stability of these esters against polymer formation during distillation and at room temperature increased with the number of C atoms in the alcohol. When the esters were heated at 270°C. to form the polyamide, the same trend in stability was observed; the polyamides obtained were of too low molecular weight for melt spinning. Upon heating ethyl‐7‐aminoheptanoate with water (mole ratio 1 to > 3) at 100°C., a mixture of 7‐aminoheptanoic acid with mainly dimeric acid and ester was obtained. This product (“precursor”) was a stable solid at room temperature which could readily be converted at atmospheric pressure within 2 hr. to high molecular weight, spinning grade nylon 7. The melting point, density, moisture regain, and sticking temperature of nylon 7 were compared with those of nylons 6, 8, 9, 10 and 11. Nylon 7 was melt spun into high tenacity yarn and its textile properties were discussed in comparison with those of nylons 6 and 66. The low oligomer content of nylon 7 (1.5%) made extraction of the resin before spinning unnecessary.
Polystyrene modifications. II. Ring‐substituted polystyrenes
Authors: Dunham K. R. , Faber J. W. H. , Vandenberghe J. , Fowler W. F. 
Published: April 2003

AbstractRing‐substituted styrenes were prepared and polymerized. They usually had higher glass transition temperatures than polystyrene. In some disubstituted systems the Tg was an additive function of the individual groups. Crystallinities of methyl‐substituted polymers varied, depending upon the ring positions involved. Crazing tendencies were equivalent to those in polystyrene.
The use of sol‐gel analysis to estimate chain scission during vulcanization. Part I. Peroxide vulcanization of natural rubber
Authors: Bristow G. M. 
Published: April 2003

AbstractSol‐gel analysis, that is, the measurement of the fraction of rubber remaining unconnected to the network as a function of the degree of cure, has been used to estimate the extent of chain scission in the vulcanization of natural rubber with dicumyl peroxide at 130°C. For peroxide concentrations in the range 1–5% and masticated rubbers of M̄n = 0.84–2.67 × 105 there are only 1–3 sites of scission per 100 crosslinked isoprene units.
A study of the oxidative degradation of furfuryl alcohol polycondensates by infrared spectroscopy
Authors: Conley Robert T. , Metil Ignatius 
Published: April 2003

AbstractThe oxidative curing and oxidative degradation of cured furfuryl alcohol polycondensates was examined, with infrared spectroscopy, by following the functional group changes occurring in the solid phase of the resin. It has been found that the oxidative degradation of nitrogen‐cured resins initially proceeds through the oxidation of methylene linkages to bifuryl ketonic species activated by adjacent furan rings. The second stage of oxidation is the scission of the bifuryl ketonic chain positions to produce substituted furoic acids. The process is postulated to proceed in a manner analogous to that observed in phenolic resin systems. The curing of furfuryl alcohol resin in air is shown to be a multistep process in which the initial oxidation of methylol groups to carboxylic acids is competitive with further polymerization through methylol condensation at adjacent furan ring alpha hydrogen positions. In addition, the oxidation of already formed methylene linkages to the bifuryl ketones is a competitive process removing methylene linkages after they are produced during further condensation (curing reactions). These routes of degradation are in good agreement with observed oxidations of furfuryl alcohol resins under more drastic conditions and offer a reasonable mechanism for resin degradation consistent with observations in analogous polymer systems.
The fine structure of fibers and crystalline polymers. I. Fringed fibril structure
Authors: Hearle J. W. S. 
Published: April 2003

AbstractThe inadequacy of the fringed micelle concept of the structure of crystalline polymers has led to the suggestion of a fringed fibril structure. Single crystal, spherulitic forms of bulk polymer, and oriented fibres are considered, and a modified fringed fibril structure, which will account for long periodicities, is proposed. The fringed micelle structure is viewed as a limiting case of fringed fibril structure. The evidence for and against the fringed fibril structure is discussed. The paper concludes with a survey of structures of different types of polymer and fibers.
Dyeing of polyacrylonitrile fibers: I. Rates of diffusion with malachite green and diffusion model
Authors: Rosenbaum S. 
Published: April 2003

AbstractDiffusion of the cationic (basic) dye, Malachite Green, into polyacrylonitrile fibers is shown to take place from a saturated surface layer even with relatively low solution concentrations. This makes possible a simple determination of the integral diffusion coefficient from one sorption‐time curve. In place of the commonly accepted model of dye diffusion, in which the fiber elements play a passive role, it is proposed that the motion in the polymer molecules constituting the fiber is the main factor governing the diffusion process at normal dyeing temperatures. In support, data are shown on the temperature dependence of the diffusion coefficient and its relation to fiber composition and mechanical behavior.
Post extrusion swelling of polyethylene
Authors: Bagley E. B. , Storey S. H. , West D. C. 
Published: April 2003

AbstractWhen polymers are extruded from a reservoir through a capillary the extrudate diameter is generally greater than the capillary diameter. Experiments with polyethylene show that the extent of this extrudate swelling depends, at constant shear stress, on the length‐to‐radius ratio of the capillary even though the viscosity does not. Consideration of this result at various shear stresses indicates that the degree of swelling depends on the total shear strain imposed on the melt. The same factor also governs the amount of extrudate distortion observed when melt fracture occurs.
Diffusibility and solubility of gases in ethylcellulose and nitrocellulose
Authors: Hsieh Paul Y. 
Published: April 2003

AbstractPermeability of ethylcellulose and nitrocellulose films to thirteen different gases and vapors was determined. The solubility of these gases and vapors in ethylcellulose and nitrocellulose was also measured by gravimetric and volumetric methods of equilibrium sorption. From these data for permeability and solubility, diffusion coefficients of the gases and vapors in the polymeric films were calculated by means of the relation, P = DS, in which P and S are the permeability and solubility constants, respectively. It was found that the diffusion coefficient D decreased linearly with an increase of molecular weight; however, the shape factor of the molecules played an important role in the diffusion process. The solubility constants increased linearly with an increase of the Lennard‐Jones force constants ϵ/k when solubility was expressed on a weight basis rather than a volume basis. Both ethylcellulose and nitrocellulose are noncrystalline. Higher solubility, diffusibility, and permeability of ethylcellulose than that of nitrocellulose are considered to be due to the molecular packing in the films.
Moisture and ion sorption in cellulose acetate
Authors: Thomas Charles R. , Barker R. E. 
Published: April 2003

AbstractMeasurements described in this paper show that the effective water permeation coefficients of silver paste electrodes on polymers such as cellulose acetate are of about the same magnitude as those of the polymer itself and, therefore, that such electrodes will have negligible effect on moisture penetration when conditioning periods of several hours or longer are used. X‐ray emission spectrography with Kα radiation from chlorine and potassium was employed to determine the salt content of 0.267‐mm. cellulose acetate films (about 100 acetyl groups per polymer molecule = 40% acetyl), which were soaked for 48 hr. in aqueous solutions ranging up to 1M in concentration of the alkali chlorides or potassium halides. Typically, the salt contents are about 100 ppm or 3 μmole/g. of cellulose acetate. The actual salt contents are discussed in relation to ionic hydration, and Stokes' radii via the differential hydration energy concept of Samoilov and the phenomenological developments of Nightingale. The evidence suggests that ionic motion in moisture‐swollen cellulose acetate is quite similar to that in aqueous solution.
Performance of a versatile variable‐volume permeability cell. Comparison of gas permeability measurements by the variable‐volume and variable‐pressure methods
Authors: Stern S. A. , Gareis P. J. , Sinclair T. F. , Mohr P. H. 
Published: April 2003

AbstractAn improved cell which permits the measurement of permeabilities of membranes to gases over a wide range of temperatures and gas pressures is described. The measurements are made by the variable volume method, under constant pressure differential across the membrane. The cell lends itself particularly well to routine tests, because it does not require calibration or the use of vacuum techniques. The performance of the cell is discussed, and typical experimental results are presented. A modified permeability cell of the same type for high‐pressure studies is also described. Measurements with this apparatus show that the rate of gas permeation obeys, in some cases, a single from of Fick's law, even under pressure differentials across the membrane as high as 800 psi (54 atm.). The paper also compares permeability data obtained by the variable volume and the variable pressure methods. The permeability of 0.002 in.‐thick Alathon 15 polyethylene to oxygen and nitrogen was determined between 0 and 50°C. by the two methods, using the same sample of membrane in situ, and the measurements were found to agree within experimental error. Permeabilites of 0.010 in.‐thick samples of Alathon 15 polyethylene to nitrogen, oxygen, helium, and carbon dioxide obtained in the same temperature range by the variable volume method were 15–30% higher than the corresponding data determined by the variable pressure method. This discrepancy could be due to the fact that the variable pressure measurements with the thicker membrances may not have been made under true steady‐state conditions, although permeabilities were determined from apparently linear sections of permeated gas pressure vs. time curves. A critical re‐examination of the methods used to determine permeability constants is suggested.
Polyhydroxyethers. I. Effect of structure on properties of high molecular weight polymers from dihydric phenols and epichlorohydrin
Authors: Reinking N. H. , Barnabeo A. E. , Hale W. F. 
Published: April 2003

AbstractAn interesting series of high molecular weight thermoplastic polymers, based on dihydric phenols and epichlorohydrin, have been prepared. The polymers have, in common, a structure which can be represented by the general repeating unit
magnified image
where E is a radical residuum from a dihydric phenol. Certain properties appear characteristic of this class of polymers. All contain some chain branching through the secondary hydroxyl group. They are amorphous, noncrystallizable, transparent, tough, and thermally stable. They show two glassy state transitions, a minor transition at about −70°C. and a major transition at a considerably higher temperature. This family of polymers provides an excellent means for studying structure–property correlations. Data are reported showing the effect of the structure of the dihydric phenol moiety (E) on the major glass transition temperature and on certain barrier properties of a series of these polymers. The polymer prepared from 2,2‐bis(4‐hydroxyphenyl) propane, bisphenol A, is considered typical of this series; its mechanical and physical properties are described in somewhat more detail and compared with properties of certain commercial polymers.
Infrared spectra of irradiated polyethylene
Authors: Luongo J. P. , Salovey R. 
Published: April 2003

AbstractThe irradiation of polyethylene causes a number of molecular rearrangements in the chemical structure of polyethylene. In addition to the significant changes in the type and distribution of unsaturated groups, an infrared comparison of the radiation induced chemical changes that occur in air and in a vacuum showed that the presence of oxygen has a marked influence on the structural rearrangements that occur on irradiation. The infrared spectra of irradiated single crystals prepared by two different means indicated the location of vinyl groups in the crystals and their protection from radiation by aromatic structures. From these data, a number of reaction mechanisms are postulated which can contribute to our understanding of irradiation effects on polyethylene.
Detective work with high speed testing: The location of a phase change area
Authors: Goldblum K. B. 
Published: April 2003

AbstractHigh speed tensile tests on Lexan polycarbonate resin were carried out on three grades of material at four test speeds from 200 to 15,000 in./min. and at five temperatures from −30 to +140°C. A consideration of the results of these tests led to a number of interesting conclusions. Among these conclusions was the identification of a plateau in the plots of some of the variables vs temperature in the 125° to 140°C. range. A more complete study of the variation in the tensile yield values of one of the grades of Lexan resin at 2 and 20 in./min. testing speed over the temperature range, and some‐what beyond, has been made to define this unusual effect.
Slip deformation in drawn polyethylene films
Authors: Kurokawa Masataka , Ban Tetuo 
Published: April 2003

AbstractWhen well oriented and crystallized high density polyethylene film was redrawn, slip deformation and twin deformation, the mode of which depends upon the redrawing angle to the original drawn structure, could be observed. When the redrawing angle is very small, single slips, the direction of which is [001] to the original drawn structure, and homogeneous deformation bands attached to them are usually observed. The [001] directions of slipped and unslipped regions are slightly at an angle to each other. As the redrawing angle approaches a right angle, kink bands can be observed. From these results we may conclude that the structure of this drawn polyethylene film is very similar to that of a single crystal or metal.
Mechanism of polyethylene oxidation
Authors: Bevilacqua E. M. , English E. S. , Gall J. S. 
Published: April 2003

AbstractAcetic and formic acids and acetone are products of the oxidation of propylene and ethylene polymers and copolymers. The two‐ and three‐carbon products can be accounted for as the result of intramolecular attack by radicals, leading to β‐oxidation. A high proportion of scissions in polypropylene involves multiple intramolecular attack.
Gelatin coatings and tensile strength of gelatin films
Authors: Norris T. O. , McGraw John 
Published: April 2003

AbstractStrips of gelatin film were prepared from three commercial gelations and tested for tensile strength on an Instron universal tester. Some of the strips were made from plain gelatin and others from gelatin which had been deionized, treated with formaldehyde, chrome alum, or acetic acid. Strips were also prepared at 10 and 55°C. The results showed the greatest deviation for the acetic acid‐ and heat‐treated gelatins. An attempt is made to account for the results.
Generalized model representation relating the degree of mixing to the rheological behavior of a mechanical mixture of two polymer components
Authors: Fujino Kiyohisa , Ogawa Yasuo , Kawai Hiromichi 
Published: April 2003

AbstractOn assuming that the two polymer components are poorly compatible or incompatible and from semimicro heterogeneous systems composed of homogeneous phases of each component, two kinds of generalized models which relate the degree of mixing of the two phases to the mechanical behavior of the systems were proposed. In this phenomenological theory, the chemical interaction between the two polymer components was negelcted, and the stress or strain distribution along the boundaries between the two phases was much simplified. This might give serious error when the mixed phases become small and the surface effect, instead of volume effect, becomes significant. The mechanical mixtures can be classified by the manner of mixing of the two phases of A and B components as follows: A islands in B matrix, B islands in A matrix, A matrix‐B matrix, and A islands‐B islands mixing. The mechanical properties of the mixed systems are affected not only by those of each component and their volume fraction in bulk, but strongly by the manner of mixing. The terminology used here, as the degree of mixing, is one of the representations of the manner of mixing in terms of distribution function of partial volume fractions of each component in the mixed system.The analysis of some mixed systems of two polymer components gave the following results. The mixed systems cast from acetone solution of poly(vinyl acetate) and poly(methyl methacrylate) give mechanical mixtures of the islands‐in‐matrix type mixing. A phase conversion from PMMA islands in PVAc matrix to PVAc islands in PMMA matrix occurs at about 70% volume fraction of PMMA due to the hexagonal close packing of PMMA islands in PVAc matrix with increase of volume fraction of PMMA On the other hand, the systems cast from mixtures of acetone solution of PVAc and lightly crosslinked PMMA fine particles give mechanical mixtures of the matrix‐matrix type mixing. The mixed systems of polystyrene and 30/70 butadiene–styrene copolymer, which have been classified by Tobolsky as polyblends, might also be a type of mechanical mixture classifiable as matrix‐matrix mixing. However, the manner of mixing should be much modified by the chemical interaction between the two components.
Ion‐exchange membranes by sulfonation of poly(vinylidene fluoride) films
Authors: Richards G. N. 
Published: April 2003

AbstractAttempted sulfonation of poly(vinylidene fluoride) film results predominantly in reaction at the surface of the film owing to lack of penetration by the reagents. When the film is pre‐swollen with a wide range of liquids, however, sulfonation with oleum proceeds smoothly through the body of the film, and a flexible membrane of low electrical resistance is produced. The more important variables in the swelling and sulfonation steps have been investigated. Side reactions during the sulfonation lead to the introduction of carbonyl and ethylenic groupings into the polymer molecule. The latter grouping is assumed to be responsible for the lack of stability of the membrane towards oxidants.
Dynamics of viscoelastic fluids, melt fracture, and the rheology of fiber spinning
Authors: White James Lindsay 
Published: April 2003

AbstractThe hydrodynamic theory for the flow of nonlinear viscoelastic fluids is developed. Two new dimensionless groups must be introduced into the complete second‐order correction of viscoelastic flow. These groups are called the Weissenberg and viscoelastic ratio numbers. Applications to industrially important problems are discussed. It is argued that the Weissenberg number determines the onset of melt fracture.