bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption Modification of Fillers and Structure Formation in Solutions of Polymers
Authors: Taubman A. B. , Tolstaya S. N. , Borodina V. N. , Mikhaĭlova S. S. 
Published: February 2011

Abstract
On addition of a solid disperse phase to a polymer one requisite for its effectiveness as an active filler is close similarity of the molecular properties of the surface of the particles and the polymer. This along with high “dispersity” (specific surface area) is mainly responsible for the high effectiveness of various types of carbon black—a hydrophobic filler of organic origin. For the same reason the majority of mineral fillers, which are usually of hydrophilic character, have relatively low capacity for the active filling of polymers, which is made evident in improvement in the mechanical and other properties of the filled material. As a consequence particular importance attaches to processes of adsorption modification, i.e., the alteration of the molecular properties of the surface of particles of hydrophilic fillers by orientated adsorption of surface-active substances (SAS). The hydrophobicization of the surface of the particles of filler which takes place here increases their “wettability” by the polymer phase and enhances the strength of its bond to the polymer, as has been investigated in detail in the work of P. A. Rebinder et al.. In this case modification leads to activation of the filler; in a number of cases however activation does not take place. As models for filled systems we may take concentrated suspensions of particles of the fillers in solutions of polymers containing additions of surface-active substances, which depending upon the concentration in the solution and proportionally to its increase, at first peptize the particles, lyophilizing them, and then stabilize them as a result of lyophobicization. This causes in sequence coagulation structure-formation in the system and then destruction of the resulting structures. A number of investigations have been devoted to the influence of fillers and pigments on the properties of polymers in the presence of surface active substances —in rubbers, and in lacquers and paints based on drying oils, but the laws of adsorption modification of mineral disperse phases and its influence on the filling effect in connection with the composition and molecular properties of the complex system: polymer-solvent/filler (or pigment)/surface-active substance have not been systematically studied. The present paper aims to investigate this question.
Reinforcement of Rubber in Latex. III. Electron Microscope Investigation
Authors: Pechkovskaya K. A. , Senatorskaya L. G. , Berman B. Z. , Dogadkin B. A. 
Published: February 2011

Abstract
Electron-microscope photographs show that with the addition to the latex of substances bringing about the effect of reinforcement of the rubber by fillers, there is observed a coalescence of the globules with the formation of a continuous rubber phase, as a result of which direct contact of the rubber is brought about with the particles of filler. This confirms the conceptions previously developed1 of the conditions of reinforcement of rubber in latex.
Use of White Pigments in the Rubber Industry
Authors: Vohwinkel K. 
Published: February 2011

Abstract
Anatase is recommended for all pure-white rubber products, on which no particular demands are made with respect to chalking and yellowing. For pure-white compounds with less chalking tendency, either post-treated anatase or zinc sulfide is useful. (These statements are based upon the studies made on the white pigments given in Table 6). White, pale creamy tints, with especially high resistance to chalking and yellowing, and very good resistance to static cracking, may be obtained with post-treated rutile. These rutile types are also recommended for the whitening in color adjustments, when blue tints are undesirable. Untreated rutile (Bayer titanium dioxide Rutile U was tested) is very well suited for increasing the heat stability of silicone rubber vulcanizates. Lithopone is well adapted for whitening cheap compounds. It must be mentioned that anatase, because of its bluish tint, is especially popular in the rubber industry and is at this time more widely used than the post-treated rutile types.
Vulcanization of Elastomers. 38. the Reactivity of Synthetic Rubbers. I
Authors: Scheele W. , Schulze W. , Hillmer K-H. 
Published: February 2011

Abstract
Investigations relating to the development of other than conventional procedures for vulcanizing synthetic rubbers, especially cis-1,4-polybutadiene, are reported. The results were as follows: 1. cis-Polybutadiene and trans-polybutadiene containing 2% and more of 1,2 addition can be crosslinked to a certain extent by means of dibenzothiazolyl- or dibenzimidazolyldisulfide. 2. cis-1,4-Polyisoprene undergoes a much lower degree of crosslinking with the above disulfides. 3. The physical properties of vulcanizates are considerably improved if the molecules of the added disulfides contain groups which react with isocyanates. When diisocyanates are incorporated, supplementary crosslinking sites are formed. 4. The crosslinking of cis- and trans-polybutadiene via DBIS and Desmodur 15, in the absence and presence of black is described in more detail. The usual physical properties are determined and compared with those obtained when sulfur is used as the vulcanizing agent.
Effect of Sulfur during Radiation Curing of Poly(Vinyl Ethyl Ether) and Ethylene-Propylene Rubber
Authors: Lal Joginder , McGrath James E. 
Published: February 2011

Abstract
A study was made of the effect of sulfur, during radiation curing, on the physical properties of poly(vinyl ethyl ether) and an ethylene/propylene copolymer containing HAF carbon black. The presence of sulfur enabled the attainment of higher maximum tensile strength and generally higher crosslink density than when sulfur was omitted. Furthermore, the maximum tensile strength of the sulfur-containing samples was obtained at a lower radiation dose than in the corresponding control experiments. For a given swelling ratio, a higher tensile strength was generally obtained for samples irradiated in the presence of sulfur. For a given dose of radiation, the per cent elongation-at-break values of poly(vinyl ethyl ether) samples decreased as the amount of sulfur in the recipe was increased. In contrast, in the ethylene/propylene rubber the presence of sulfur resulted in an increase in the elongation values. The per cent sol values were also quite high for the ethylene/propylene vulcanizates as compared to the corresponding values in poly(vinyl ethyl ether) samples. In both rubbers, lower sol values were obtained in the presence of sulfur. Chemically bound sulfur was found in poly(vinyl ethyl ether) samples irradiated in the presence of elemental sulfur or dicyclopentamethylene thiuram tetrasulfide. The ability of the network to lose a portion of the combined sulfur by reaction with triphenyl phosphine may indicate that some of the crosslinks contain disulfide and/or polysulfide groups.
Aldehyde-Amine Accelerators. The Structure of Some Substituted Dihydropyridines
Authors: Westfahl J. C. , Craig David 
Published: February 2011

Abstract
This paper reports unequivocally the structures of the main components in “butyraldehyde-aniline” and “heptaldehyde-aniline” which are commercial vulcanization accelerators and “propionaldehyde-aniline” which is not commercial. All three components are dihydropyridines.
New Elastomers Derived from Copolymers of Tetrahydrofuran and Propylene Oxide
Authors: Dickinson L. A. 
Published: February 2011

Abstract
The homopolymers of tetrahydrofuran, polytetramethylene glycols, may be chain-extended to form polyurethane elastomers. These materials, while possessing a low glass point temperature, suffer from cold hardening, and it was decided to investigate copolymers of tetrahydrofuran and propylene oxide as elastomer ingredients. The preparation of these copolymers has been achieved by use of a boron trifluoride etherate polymerization catalyst. Details are given of the properties of both the copolymer and derived elastomers at nominal compositions in the range 50–85 weight per cent of tetrahydrofuran. The copolymers described were synthesized as ingredients for castable elastomers, and in consequence viscosity effects are important. It has been found that no significant increase in viscosity occurs until the tetrahydrofuran content exceeds 75 weight per cent. This indicates that each side methyl group exerts a screening effect over an average of 13 atoms of the polymer backbones. The mechanical testing of the derived elastomers indicates that the copolymerization of tetrahydrofuran and propylene oxide leads to material possessing a low glass point temperature and much better physical properties than the homopolymer of propylene oxide. The elastic properties of a chain-extended diol are dependent on the degree of crosslinking and on the incidence of network deficiencies. Network deficiencies are caused by the presence of monofunctional species in the copolymeric diols, and a novel technique for determining diol monofunctionality based on analysis of physical test data was evolved for these studies.
Relative Contributions of Viscoelasticity and Aging to the Relaxation of Rubber Vulcanizates
Authors: Thirion P. , Chasset R. 
Published: February 2011

Abstract
Relaxation in relatively stable, gum natural rubber vulcanizates has been studied to determine the effects of viscoelasticity and aging, respectively, using a dark, air-oven. A quantitative analysis of experimental results shows that, in the case of a dicumyl peroxide vulcanizate at 100° C, relaxation is caused by aging, except in its initial stages. Stress decreases as a linear function of time, in agreement with theoretical assumptions. Conversely, at 30° C, the effect of aging is negligible. At this temperature the difference between actual stress and stress extrapolated to infinite time, is proportional to a negative power of time. At intermediate temperatures, both phenomena occur simultaneously over a time interval ranging from. 3 minutes to 150 hours.
Law of Deformation of Cured Rubber
Authors: Bartenev G. M. , Vishnitskaya L. A. 
Published: February 2011

Abstract
Consideration is made in this article of the uniaxial stress and compression deformation of vulcanized rubber, for which there exists a sufficient amount of accurate experimental data. One of the present authors established a considerable while back that for lattice polymers (vulcanized rubbers) in the coordinates σ (true stress) and ε (deformation) , the equilibrium curves for stress in the range 100 to 200% are expressed by practically straight lines. Furthermore, this behavior was confirmed in a number of our investigations based on more accurate methods of measurement (cf. Reference 2), and also in a number of foreign papers. (Note 1. The stress is regarded in relation to the actual cross-section of the specimen of deformed rubber, the deformation in relation to the initial length of the specimen. Note 2. For comparison of single-parameter formulas with experience the experimental data are presented each time in coordinates such that a straight line corresponded to the formula in these coordinates. For these coordinates we selected the stress σ and the “generalized coordinate” of deformation ε0, which is a different function of the multiple of stress A in the various single-parameter equations.) Within the limits of scatter of the experimental data the equilibrium curves for uniaxial deformation below the limit of proportionality (100–200% with stress and 20–30% for compression) are expressed by the following single-parameter law:
A Rugged Semiautomatic Extensometer for Rubber
Authors: Donnelly P. I. 
Published: February 2011

Abstract
The evaluation of an elastomer—new or established—inevitably involves a study of tensile properties. ASTM procedure D 412 is generally used as a guide for the tensile testing of vulcanized rubber. In this method, an operator observes bench marks on the sample and records the modulus at every 100% elongation, the ultimate elongation, and the tensile strength at break. An extensometer has been developed to eliminate operator coordination and judgment factors from rubber tensile testing. It is simple and sufficiently rugged for routine testing. Its features are a counterbalanced guide rod with a sliding electrical contactor, and specimen followers which automatically unlatch to avoid being damaged when specimens break. In addition there is a counter for direct digital indication of elongation, and an electrical circuit which controls a short duration spark to mark the autographic chart. Experience in testing up to 5000 specimens per year has shown that the apparatus makes an inexperienced operator as effective as trained operators working under optimum conditions. The instrument has been used successfully on materials ranging from soft rubber to plasticized and filled poly (vinyl chloride).
Thermal Conductivity of High Polymers from −180° C to 90° C
Authors: Eiermann K. , Hellwege K.-H. 
Published: February 2011

Abstract
The thermal conductivity of plastics is relatively small and for this reason not easily measured. That is why the results in the literature vary sharply. Therefore measurements were made in the German Plastics Institute of the thermal conductivity of plastics with different methods and the results checked against each other. As the overall agreement is very good, we shall give the results only from a quasistationary method which works over a large temperature range. A good thermal contact at the surface of the sample is decisive. Therefore we had to abandon high vacuum as thermal insulation in favor of helium gas, which gives a good and exactly evaluated thermal contact. Thermal losses to the outside had to be prevented by guard rings. We deal first with amorphous high polymers. Their thermal conductivity varies only slightly with temperature even if one goes through the second-order transition region. However, a break in the curve of the thermal conductivity, is characteristic that is to say, a jump of the thermal coefficient at the second-order transition temperature. Figures 1–3 show this for natural rubber, Vulkollan (a crosslinked polyester-urethane elastomer), polyisobutylene, and polyvinyl chloride with different contents of plasticizer. The dependence on the concentration of plasticizer is the same for the break in the thermal-conductivity curve as for the second-order transition temperature. The systematic variation of the thermal conductivity with temperature which has been described seems to be valid in general for amorphous substances with molecules which have the form of a chain. For instance, even selenium, when displaced from the melt, Figure 4, passes smoothly through the second-order transition point without the extreme maxima and minima which have been seen by other authors and which are due to peculiarities in the experimental arrangement used.
High Resolution Nuclear Magnetic Resonance Spectra of Various Polyisoprenes
Authors: Golub M. A. , Fuqua S. A. , Bhacca N. S. 
Published: February 2011

Abstract
There has been some controversy recently as to whether hevea and balata (or gutta-percha) macromolecules comprise 100 per cent 1,4 units, or whether they are predominantly cis and trans structures, respectively, with minor amounts of isopropenyl or 3,4 units. Binder contends, on the basis of a small absorption peak at 11.25 µ in the infrared spectrum of each of these polymers, that the hevea and balata macromolecules contain 2.2 and 1.3 per cent 3,4 units, respectively. This has been disputed by Fraga who showed that there was no evidence for isopropenyl groups in the near infrared spectra; he therefore concluded that the natural polyisoprenes are essentially pure 1, 4-type polymers. Another interesting Question which has never been resolved is whether the 1,4 units in hevea (or balata) are exclusively cis (or trans) or whether these polymers contain a small amount of the opposite isomer as an impurity. Recent developments in high resolution n.m.r. work on polymers, and in particular, the application of n.m.r. to an analysis of butadiene—isoprene copolymer compositions, have prompted us to examine these questions with the aid of this tool. The present communication reports the results of an investigation of hevea and balata microstructure using a Varian high resolution 100 Mc. n.m.r. spectrometer as well as a Mnemotron Computer of Average Transients (C.A.T.) attached to a Varian A-60 spectrometer.
Flexibility and Shape of Macromolecules
Authors: Tsvetkov V. N. 
Published: February 2011

Abstract
The main feature of high molecular weight substances is the great size, chain structure and flexibility of the molecules. Investigation of macromolecules flexibility must be regarded as one of the most important tasks in the investigation of the structure of polymers. In the present article we shall deal quite briefly with certain results achieved in this field, which seem to us to be of fundamental importance. The cause of the flexibility of polymeric chains is the existence of a certain freedom of rotation around the valency bonds of the atoms making up the molecule. Nevertheless, this rotation is always more or less hindered by forces which may be either intramolecular (between the atoms of one and the same chain), or else inter-molecular (between atoms of a given chain and their molecules of the surrounding medium). It is possible to a certain extent to separate the influence of these forces from each other, by studying and comparing the properties of macromolecules in solutions (using different solvents) and in the solid phase. Here, nevertheless, we must keep in mind the difference between thermodynamic (equilibrium) and kinetic (nonequilibrium) flexibility of the polymer chain. The deduction of equilibrium flexibility is made on the basis of investigation of configurations (the dimensions and geometrical shape) of macromolecules in solution in the statistically equilibrium state; and of the kinetic, on the basis of investagation of the rate of the processes which convert the macromolecules from one equilibrium configuration to another. The vast majority of experimental work dealing with the determination of kinetic flexibility has been carried out for polymers in bulk (mechanical and dielectric relaxation processes). In this case the influence of the intermolecular reactions is just as great as that of the intramolecular forces, and therefore it is very difficult to separate these two effects. Therefore at the present time we have at our disposal for the determination of equilibrium flexibility of polymer chains considerably more experimental and theoretical possibilities than is the case for kinetic flexibility.
Static Friction and the Law of Rubber Friction
Authors: Lavrentev V. V. 
Published: February 2011

Abstract
a) The true static friction of vulcanized rubber is in practice immeasurably small (equal to zero, according to theory). b) The static friction as usually determined is an initial friction force. c) The initial friction force is equal to the sliding friction force in accelerated movement. It depends on the contact time, the rate of growth of the tangential force and the other conditions of experiment. d) With long contact times, particularly at higher temperatures, strong chemical bonds are formed between the vulcanized rubber and the track, leading to true static friction. e) The theoretical law of friction agrees well with the experimental results over the whole range of normal pressures. f) Good approximations are given in the range of low normal pressures by Coulomb's law (5) and in the rubber of high normal pressures by that of Thirion (7).
Relaxation Processes in Vulcanized Rubber. I. Relations between Stress Relaxation, Creep, Recovery, and Hysteresis
Authors: Gent A. N. 
Published: February 2011

Abstract
An experimental study is described of stress relaxation, creep, recovery, and hysteresis in vulcanized rubbers under moderate deformations. The measurements indicate that the rate of stress relaxation is substantially independent of the amount or type of deformation for moderate deformations, and is simply related to the hysteresis. The rates of creep and recovery are found to be in good agreement with values calculated from the form of the load—deformation relationship and the (constant) value of the relaxation rate.
Relaxation Processes in Vulcanized Rubber. II. Secondary Relaxation Due to Network Breakdown
Authors: Gent A. N. 
Published: February 2011

Abstract
An experimental study is described of a “secondary” relaxation process in stretched vulcanizates, which becomes dominant after long periods at normal temperatures. It is shown to be affected markedly by the temperature, the atmosphere in which the test is conducted, and the presence of oxidation inhibitors. It is therefore attributed to oxidative deterioration of the molecular structure. In some vulcanizates, however, a similar or even greater relaxation is found to occur in vacuo, and this is attributed to the failure of specific crosslink structures. The extent of recovery on releasing the extended testpieces has also been investigated for a number of natural rubber vulcanizates.
Some Chemical Effects in Fatigue Cracking of Vulcanized Rubbers
Authors: Gent A. N. 
Published: February 2011

Abstract
An apparatus is described for studying the fatigue of rubber strips under repeated simple extensions in different atmospheres. The fatigue life is shown to be greatly increased in vacuo for vulcanizates of natural rubber and SBR. The effect of oxidation inhibitors and radical acceptors has been examined; they are found to prolong the life in air, but have little effect in vacuo. The results suggest that a substantial proportion of crack growth in air is due to oxidative deterioration of the rubber at the crack tip, probably initiated by mechanical rupture.
Dynamic Strain Effects in Elastomers
Authors: Warnaka Glenn E. 
Published: February 2011

Abstract
Many common elastomeric materials have two ranges of dynamic-mechanical behavior. Such materials behave as viscoelastomers at very small strains and as plastoelastomers at strains of practical engineering interest. The change from viscoelastic to plastoelastic behavior occurs at dynamic strain amplitudes of 0.001 inches per inch to 0.005 inches per inch. In the plastoelastic range, the dynamic elastic modulus decreases with increasing dynamic strain amplitude. Loss factor reaches a maximum in the plastoelastic range.
Sinusoidal-Strain Dynamic Testing of Rubber Products
Authors: Payne A. R. 
Published: February 2011

Abstract
This paper is concerned with methods for evaluating the dynamic modulus and hysteresis of rubber under a wide range of conditions. The original machine in use at the Rubber and Plastics Research Assn. (RAPRA), and then its commercially available counterpart, the Wallace electronic sinusoidal-strain dynamic tester, are described. Some typical results obtained with the first machine, but obtainable with either, are given.
The Dynamic Properties of Carbon Black-Loaded Natural Rubber Vulcanizates. Part I
Authors: Payne A. R. 
Published: February 2011

Abstract
The dynamic properties of a natural vulcanized rubber containing carbon black were studied for dynamic tensions of amplitude varying greatly. It was shown that both the elastic responses and viscosity change with amplitude of oscillation and with concentration and type of carbon black. The effects of thermal treatment on the dynamic modulus were also studied. Beginning with conditions of equilibrium between the hard and soft regions of the vulcanizate for very weak stresses, the values for the formation of hard regions from soft regions were determined by means of the Van't Hoff isochore.