bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dilute Solution Properties of Trans-Polypentenamer: [η]—M Relations and Molecular Conformation
Authors: Gianotti G. , Bonicelli U. , Borghi D. 
Published: February 2011

Abstract
The values of the mean-square unperturbed dimensions of trans-polypentenamer, expressed by (r02/M)1/2, agree well with literature data for polymers with similar structure. In particular, the low value of the structure factor, r02/r0f2 is quite interesting. It tends to prove that the short-range interactions exert a negligible effect for the trans double bond structure. However, the value of this ratio is certainly influenced also by the not completely trans structure of the polymer, which certainly affects the experimental value of (r02/M)1/2. On the basis of the relations proposed, reproducible values of KΘ have been obtained by viscosimetric measurements, when at least one of the solvents is rather poor. On the other hand it is well known that the various relations allow less reliable extrapolations on increasing α. The relation proposed by Berry gives a linear extrapolation in the case under examination, which coincides with that in a pseudoideal solvent. However, this does not mean that it is of general validity and that it must always be preferred to the other analogous relationships reported.
Electron-Impact-Induced Fragmentation of N-(Substitutedthio)Phthalimides. A Rationalization for their Pre-Vulcanization Inhibition
Authors: D'Amico J. J. , Potts K. T. , Kane J. , McKeough D. , Moschner K. F. 
Published: February 2011

Abstract
The pre-vulcanization inhibitor activity of a series of N-(substitutedthio)-phthalimides is attributed to thermal cleavage of the N—S bond with formation of phthalimide and the corresponding thiol radical, which subsequently acts as a scavenger for 2-mercaptobenzothiazole giving the unsymmetrical 2-benzothiazolyl disulfide.
The Energetic Contribution to Rubber Elasticity in the Range of Small Uniaxial Compression and Moderate Elongation
Authors: Wolf F. P. , Allen G. 
Published: February 2011

Abstract
The relative energetic contribution to the retractive force of a deformed rubber sample, fe/f, has been evaluated from thermoelastic measurements at constant pressure. Extension ratios λ have been studied in the range 0.88⩽λ⩽1.79 at 20° and 40°C. The results are given for a reference temperature, 30°C. Since data in the transition region from uniaxial elongation to compression were to be evaluated, a new set of equations was derived on the basis of the Gaussian force law, because the usual equation for measurements at constant pressure tends towards infinity when approaching the undeformed state λ=1. Considerable difference between the results obtained by different, though apparently equivalent, equations have their origins in the deviation of the experimental data from ideal Gaussian behavior. The influence of this inaccuracy on the terms of the equations is discussed and the most reliable functions for small deformations 0.88⩽λ⩽1.15 and for moderate elongation λ&gt;1.10 have been identified. With these precautions the Gaussian force law is a satisfactory approximation for the determination of reliable values of fe/f. The evaluation of data at small deformations is extremely sensitive to experimental error. Even smoothed polynomials L(f) were not sufficient to eliminate an apparent maximum in the fe/f vs. λ curve. Therefore the linear thermal expansion coefficient, βlin(λ), which is a major term in all the fe/f equations at small deformations, had to be scrutinized critically. Although experimental data in this range showed that βlin(λ) is a slightly S-shaped function, a linear approximation is adequate at moderate elongations. Using one of the new equations together with the linear approximation for βlin(λ) in the region of small deformations, and two equivalent equations at moderate elongation, the energetic contribution to the total stress was found to be fe/f=0.18±0.02 for lightly crosslinked natural rubber. Little variation in fe/f was observed over the full range of measurements: 0.88⩽λ⩽1.70.
Crosslinking of Polyolefins in the Presence of New s-Triazines
Authors: Ahne H. , Wiedenmann R. , Kleeberg W. 
Published: February 2011

Abstract
In the crosslinking of polyolefins (such as polyethylene, ethylene-propylene copolymers, and ethylene-(vinyl acetate) copolymers), multiply unsaturated s-triazines (such as triallylcyanurate (TAC), 2-alkylamino-4,6-diallyloxy-s-triazines, and the bridged 2-alkylenamino-4,6-diallyloxy-s-triazines) make it possible to decrease the concentration of the peroxide curing agent, or the radiation dosage, necessary to achieve adequate degrees of crosslinking. The multiply unsaturated alkyl(ene)-amino-s-triazines, most of which are novel compounds obtained by aminolysis of TAC, though similar to TAC in their effectiveness, provide better compatibility with the polymers and, accordingly, improved compound shelf life and processability. The 2-alkyl(ene)amino-4,6-diallyloxy-s-triazines or the bridged alkylamino-s-triazines present special advantages in peroxide crosslinking of filler-containing polyolefins. Especially when acidic fillers, such as calcined kaolin, are used in polyolefins, the addition of small amounts of alkylamino-s-triazine can induce an extraordinarily high degree of crosslinking in the polymers. Complete polymerization of the allyl groups under crosslinking conditions is desirable for optimum aging resistance of the crosslinked polyolefins. In the case of a polyethylene stabilized, for example, with an oligomerized trimethyldihydroquinoline, peroxide crosslinking in the presence of 2-alkyl(ene)amino-4,6-diallyloxy-s-triazines will bring about a further significant improvement in the stability to thermal oxidative degradation.
Fracture Energy of Elastomers in Mode I (Cleavage) and Mode III (Lateral Shear)
Authors: Ahagon A. , Gent A. N. , Kim H. J. , Kumagai Y. 
Published: February 2011

Abstract
Attention has been drawn here to three different reasons why measurements of fracture energy by different methods may not agree: (1) When the test involves propagation of a tear by stored strain energy, as in the method shown in Figure 1, the energy available to cause rupture will be less than that supplied, because of dissipation within the elastomer. Calculation of the fracture energy on the basis of input energy would then lead to an overestimate, by about 100 per cent or more for typical filled elastomers. (2) As shown in Figures 4a and 5, the tear path is sometimes wider than the thickness of the test sheet. In consequence, fracture energy calculated from the sheet thickness would be too large, by about 40 per cent in the cases considered here. (3) Even when allowance is made for the true width of the tear path, measurements of fracture energy in shear (Mode III) are about 50 per cent larger than in cleavage (Mode I). This is attributed to frictional work expended in sliding the rough torn surfaces past each other.
Structural Characterization of Vulcanizates. II. Use of Triphenylphosphine to Determine the Structures of Sulfur Linkages in Unaccelerated Natural Rubber-Sulfur Vulcanizates
Authors: Moore C. G. , Trego B. R. 
Published: February 2011

Abstract
In Part I of this series it was shown that reaction of about 40 to 55 sulfur atoms are required to produce one chemical crosslink in networks obtained from unaccelerated natural rubber-sulfur systems at 140°C. The low crosslinking efficiency of sulfur in these systems is ascribed on the basis of the products derived from model olefin sulfurations at 140° C. to the sulfur being wastefully combined in: (a), polysulfidic crosslinks, rubber—Sx—rubber, where x&gt;1; (b), cyclic monosulfides situated along the polyisoprene chains at sites distant from the crosslinks; and (c), nonrandom crosslinks as in structures (I) and (II) where sulfur attachments are on vicinal carbon atoms of the polyisoprene chain. The crosslinking efficiency data given in Part I necessarily
Reactions of Isoparaffins with Sulfur and DI-t-Butyl Peroxide
Authors: Wanless G. G. , Wei Peter E. , Rehner John 
Published: February 2011

Abstract
The role which sulfur plays in the peroxide vulcanization of polyisoparaffins has been investigated. The problem was studied by using a system in which 2,4dimethylpentane is a model for the polyisoparaffin chain. Two alternative reaction mechanisms are proposed. Work with the model system shows that polysulfides formed from the isoparaffin are the dominant products. By analogy it is inferred that polysulfide linkages join the polyisoparaffin chains, preferably at what were formerly tertiary hydrogen sites. Nearly all of the high boiling products are disulfides and, or, polysulfides, and these total at least a 28 mole per cent yield based on peroxide charged. Thus, it is indicated that sulfur plays a major role, and does not simply prevent minor side reactions. Study of the gaseous reaction products indicates that sulfur does not alter the course of the initiation step. A reaction mechanism is proposed which is consistent with literature and with our experimental work.
The Blooming of Sulfur and Other Ingredients from Compounded Stocks
Authors: Kuzminskiĭ A. S. , Feldshteĭn L. S. , Reĭtlinger S. A. 
Published: February 2011

Abstract
“Blooming” is the name given to the crystallization of compounding ingredients usually on the surface of a stock, cured or uncured, accompanied by the migration of the substance from the bulk to the surface. Almost all ingredients which are soluble in rubber possess the capacity to bloom: sulfur, selenium, many accelerators, antioxidants, organic pigments, fatty acids and so on. Blooming reduces the tackiness of the stock, which causes difficulties in forming multi-ply articles (tires, belts, etc.). To restore tackiness the bloomed substances are washed off with a solvent, and in cases of particularly intense blooming the surface is wet with rubber solvents. The need for these operations reduces labor productivity and hinders automation. In the production of molded articles blooming of ingredients causes nonuniform stresses to be set up. Blooming is a cause of rejection in production (stains on overcoat fabric, on the surface of colored rubbers and so on) and greatly harms production. However, in some case blooming proves useful; films formed as a result of blooming protect rubber from the action of light and air. Thus for instance Graffe notes that vulcanized rubber which is coated with bloomed sulfur proved more resistant to aging under service conditions than rubber without this coating. At the present time wide use is made of the capacity of antioxidants and waxes for giving coatings by blooming which protect vulcanized rubber from ozone aging. All this shows how important are the recognition and correct understanding of the causes of blooming.
Theoretical Strength and Critical Rupture Strength of Solids
Authors: Bartenev G. M. , Razumovskaya I. V. 
Published: February 2011

Abstract
We shall distinguish between two recognized properties: theoretical strength and critical stress. The theoretical strength, calculated for rock salt by Born and Zwicky, is the maximum of the quasi-elastic force to rupture an ideal defect-free lattice under conditions of homogeneous (equal) deformation (in Born's treatment this is uniform dilation, in that of Zwicky it is uniaxial strain). The critical stress is the maximum of the quasi-elastic force under the special conditions in the tip of a crack. The first value is a constant of the material, while the second changes not only from crack to crack, but also for any one crack in the process of its growth. The processes considered by Born and Zwicky are dissociative—volumetric in the first case and along planes perpendicular to the strain in the second. Since in an ideal material there are no defects, neither in any one direction nor along any one surface, and no free surface is formed. The potential energy of each particle, increasing smoothly, approximates asymptotically to a certain limit (different in the first and second treatments) as is characteristic of the potential curve of Coulombican interaction between two particles. The quasi-elastic force passes through a maximum (Figure 1, Fm is the theoretical strength calculated for a single linkage).
Stress Relaxation and Creep of Several Vulcanized Elastomers
Authors: Watanabe Kenzo 
Published: February 2011

Abstract
It is well known that polymeric materials in general creep with increasing time under a given constant stress and that stress relaxes with increasing time under a given constant strain. Recently, theoretical studies en these phenomena have been made in detail for polyisobutylene, vulcanized natural rubber and polymethylmethacrylate. Both properties for any vulcanized elastomer depend on the molecular structure of the network, the temperature and the amount of original stress or deformation, but it can be deduced from the Tobolsky and Eyring theory of viscoelasticity for polymers that both properties are linearly related to log time. In fact, however, the polymers begin to deviate rapidly from such a linear relationship if they are placed in air at high temperature for a long time, because thermal degradation by oxidation occurs. For elastomers used in electrical machinery and for other industrial uses, for example rubber packaging, diaphragms, or vibration and shock absorbers, it is required that we understand thoroughly the behavior of both properties at each temperature and each time for individual materials in order to make a proper choice of material suitable in behavior for each purpose. The author has studied these properties experimentally for natural rubber as well as for several synthetic elastomers and then investigated the relation between thermal life and the temperature employed. This paper describes a few results obtained up to the present.
Crack Propagation in a Strain-Crystallizing Elastomer
Authors: Andrews E. H. 
Published: February 2011

Abstract
The dependence of small-scale crack propagation in a strain-crystallizing elastomer (natural rubber) upon the applied strain has been studied under conditions of cyclic deformation over a range of frequencies. During each cycle the crack propagates along a well-defined path, different from the axis of symmetry, which is identified as the locus of maximum stress in a stationary stress distribution (i.e., one which does not move with small advances of the crack). The stationary stress hypothesis also accounts for the quantitative dependence of crack growth upon the external constraint. It is shown that a stationary stress distribution could arise as a result of the severe mechanical hysteresis displayed by strain-crystallizing rubbers.
Rolling Radius of Rubber-Covered Cylinders
Authors: Borchardt H. A. 
Published: February 2011

Abstract
Although the data were not comprehensive, definite trends can be established. They are: 1. A solid-rubber covered cylinder driven by an all-metal roller of the same outside diameter has a lower average surface speed than the driving metal cylinder. 2. A solid-rubber covered cylinder driving an all-metal cylinder of the same outside diameter has a lower average surface speed than the driven metal cylinder. 3. Per cent of speed difference as a function of deformation of rubber surface approximates a straight-line relationship for higher values of deformation. 4. The slope of the straight line approaches zero for increased radial rubber thickness and infinity for decreased thickness. Slope approaches a finite limit for increased axial rubber length and zero for decreased length. Slope remains nearly constant for different rubber hardnesses.
The Analysis of Pigment Dispersion in Rubber by Means of Light Microscopy, Microradiography, and Electron Microscopy
Authors: Hess William M. 
Published: February 2011

Abstract
The significance of these dispersion studies can be summarized as follows: 1) A simple but highly versatile liquid nitrogen freeze technique makes it possible to microtome pigment loaded rubber stocks into thin (0.05–0.1 microns, e.g.) cross sections for examination by means of light microscopy, microradiography or electron microscopy. All of the common elastomers including polybutadiene and silicone rubber have been successfully sectioned for each of these techniques. Thus the state of dispersion can readily be traced from coarse pigment agglomerates, a few hundred microns in size, down to the ultimate particles which can be below 20 millimicrons. 2) Through the use of one of the techniques described or by the coordinated use of all of them (“dispersion in depth”), most dispersion problems can be resolved. A very complete analysis of this type is often necessary to explain pigment effects upon reinforcement. 3) The effects of varied dispersion quality can now be studied directly using special x-ray and electron microscope tensile specimen holders with which small rubber specimens can be examined under strain. Actually these procedures have a greater scope than simply measuring dispersion. The reinforcing capabilities of different pigments in a variety of polymers may be compared by the use of these techniques.
The Applications of Infrared Spectroscopy to Polymers, Particularly 1,3 Diene Polymers
Authors: Binder John L. 
Published: February 2011

Abstract
As a result of the discovery of methods for making stereospecific polymers, the whole field of polymer chemistry has broadened considerably from its state in the early post-war years. Infrared spectroscopy has played an important role in the study and development of such polymers and has been applied to the study of polymer features which were not considered before the advent of stereospecific polymers. The present review is concerned with some of these applications, particularly to 1,3 diene polymers, such as microstructure determinations, polymer spectra and structures, isomerization, degree of crystallinity, vulcanization, and rubber derivatives. The survey covers the literature to the end of 1960. Some of these applications are discussed in a book edited by Clark and applications of infrared spectroscopy to other types of polymers are also discussed there. Krimm has published an excellent paper on the theoretical analyses of some polymer spectra which leads to assignments of many of the bands in the spectra of the polymers. Diene polymers were not discussed by him but the method he developed should be applicable to such polymers.
Mullins Effect and Rubber-Filler Interaction
Authors: Bueche F. 
Published: February 2011

Abstract
A previously-reported theory for the Mullins softening effect has been used to interpret various new data for the behavior of filled SBR, rubber under tensile load. The strength of the filler-rubber bond, the filler surface area per polymer molecule attachment, and the average filler surface separation have been determined for two fillers, HAF black and Hi Sil-233 (a silica). A styrene-butadiene type filler (Pliolite S-6) has also been investigated. The temperature dependence of the filler-rubber bond has been measured; results lead to the conclusion that the bonds to carbon black and silica are high energy bonds, probably chemical in nature. It is shown that the recovery of hardness in prestretched, filled SBR is a rate process having an activation energy of about 22 kcal ./mole. It is inferred from this and from permanent set data that the recovery is the result of the chemical breaking and reforming of the rubber chain network at the higher temperatures where recovery occurs. Silica-filled rubbers are shown to possess a pseudo-yield stress which gives rise to an anomalous shape for the stress-strain curve of this material when it is stretched for the first time. A prestretched, silica-filled rubber recovers its hardness when left at 115° C for 20 hr, but the anomalous portion of the curve is replaced by more normal behavior. Possible interpretations of the observed results are given.
The Swelling of Unfilled and Highly Filled Polymers
Authors: Bills K. W. , Salcedo F. S. 
Published: February 2011

Abstract
The swelling of elastomers in solvents is a useful method for determining the effective crosslinking of the polymeric structure. However, it is now shown that this method may be applied satisfactorily to highly filled polymers. A unique method has been devised for the accurate measurement of the swelling ratio of the gel phase of the filled polymers. The method is based on the observation that the binder-filler bond, for most filler particles, releases on swelling. The binder around the particle swells, leaving a hollow pocket which becomes filled with solvent. Corrections for this “waste” solvent lead to the equations from which the swelling of the polymer can be calculated. Experimental verification is given for several filled systems.
An Electron Microscope Study of Filler-Rubber Mixtures
Authors: Shvetsov V. A. , Pisarenko A. P. , Shtarkh B. V. , Novikov A. S. 
Published: February 2011

Abstract
1. Observations of solutions of reinforced rubbers in the electron microscope revealed the presence of rubber sol and gel fractions and secondary filler structures. 2. Most important factors in rubber reinforcement are high dispersity and low aggregation tendency of the fillers and the ability of aluminate and silicate fillers to form network and chain structures.
Influence of Concentration of Ozone upon Cracking of Vulcanized Rubber
Authors: Zuev Yu S. , Pravednikova S. I. 
Published: February 2011

Abstract
1. The character of the dependence of the time to first cracking (τ0), of the rate of crack growth in the steady-rate portion (v) and of the time to rupture (τ1) upon deformation does not alter on altering the ozone concentration from 0.15 to 0.0002%. 2. The value of the critical deformation does not alter with alteration in the ozone concentration. 3. The process of destruction of deformed rubber in ozone proceeds kinetically, i.e., it does not depend upon the rate of supply of ozone to the surface of the specimen. The character of the dependences τ0 and τ1 and of the rate of crack growth (vgrowth) upon the ozone concentration is determined by equations of the type of the Freundlich adsorption equation. 4. In the determination of the relative resistance of various vulcanized rubbers to ozone cracking it is desirable to select as an index the value of the ozone concentration at which we get a time to rupture equal for all vulcanized rubbers. 5. The relative resistance of the different vulcanized rubbers to ozone cracking (in assessment by the time to rupture) depends upon the ozone concentration at which it is determined. It is advisable to determine the resistance to cracking at the critical deformation of the vulcanized rubber. 6. The order of resistance to ozone of specimens of one rubber deformed by differing amounts does not depend upon their concentration in the range of concentrations under investigation and usually employed. However, if in the range of high concentrations of ozone the times to rupture of the specimens have values close to each other, then in the range of low concentrations of ozone these values may differ markedly.