bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheology of Adhesion
Authors: Kaelble D. H. 
Published: February 2011

Abstract
This discussion has outlined a series of considerations which begin with engineering definitions of system response of adhesive joints and end with propositions involving molecular interactions at interfaces. Connecting these extreme aspects of the argument is the central subject of the micromechanics of bonding and fracture. Cavitation theory, as simply described by Equations (6a) and (7), illustrates the scale of microresponse in which both the thermodynamic and rheological aspects of adhesion phenomena achieve a parity when applied to cavities of radius r=0.1 to 10 μ. The discussion of the micromechanics of polymer fracture provides ample evidence that pure materials, polymer composites, and adhesive joints, need to be described in terms of their microdefects. The several mathematical models for crack propagation which are imposed upon fracture mechanics data tend to oversimplify the visualization of the true micromechanisms of fracture. The fuller development of micromechanics theory and experimental analysis promises to be an important area of current developments in the better understanding of macroscopic response of filled systems, fiber reinforced composites, and adhesively bonded structures. Recent developments in the several theories of intermolecular forces and the physical chemistry of bonding provide new impetus to the chemist to design optimized polymeric materials with finely adjusted balances of surface and bulk properties. The fuller visualization of adsorption-interdiffusion bonding as a process involving both the two-dimensional interface and the three-dimensional interphase defines bonding as both a thermodynamical and a rheological process. The microstages of bond formation are somewhat the reverse of the stages of microfracture listed earlier. The microdefects that commonly exist in polymeric materials and polymer composites tend to indicate that the viscoelastic constraints typical of polymer chains and networks play an important role in preventing equilibrium bonding in the simple thermodynamic sense as expressed by idealized liquid—liquid or liquid—solid interactions. The current development and application of a refined thermodynamical and rheological argument to both bonding and fracture processes stands as a central issue in directly correlating the molecular criteria of adhesion and performance of bonded systems. Any of the simple mathematical relations introduced in this discussion may be expressed with greater detail and precision by incorporating detailed statements concerning chemical composition, macromolecular structure, and free volume state of the polymeric adhesive.
A Method of Analysis for Compressible Viscoelastic Solids
Authors: Ting E. C. 
Published: February 2011

Abstract
Most of the solutions in the development of methods of viscoelastic stress analysis have dealt with incompressible materials or materials with restrictions in dilatation. It is influenced in part by the increasing complexity due to the additional operator which represents the viscoelastic characteristics in dilatation. A simple procedure of solution is suggested in this paper which shows that a certain class of problems for compressible materials can be solved with the similar simplicity as the analysis of corresponding incompressible solids. Examples are given for problems with spherical boundaries.
Finite Axisymmetric Deformations of Initially Cylindrical Reinforced Membranes
Authors: Kydoniefs A. D. 
Published: February 2011

Abstract
We consider the axisymmetrie deformations of an initially cylindrical membrane composed of an elastic, homogeneous, isotropic and incompressible material reinforced with a two-parameter system of perfectly flexible and inextensible helicoidal cords of variable pitch. The undeformed configuration is determined so that the deformed membrane has a given axial section under specified internal pressure. The corresponding stress field and cord tensions are obtained. The solution given is exact and valid for the general form of the strain—energy function.
Dynamic Properties of a Model Reinforced Elastomer. Styrene-Butadiene Reinforced with Polystyrene
Authors: Kraus Gerard , Rollmann K. W. , Gruver J. T. 
Published: February 2011

Abstract
The dynamic storage and loss moduli of SBR 1503 reinforced with 400 A˚ polystyrene particles were measured at 110 cps over a 200° temperature range. The effect of the polystyrene filler on the rubber was to raise the storage modulus dramatically in the rubbery zone, but only slightly in the glassy region of viscoelastic response. As a result the transition zone appeared broadened and shifted toward higher temperature. Corresponding changes were observed in the loss maximum with a shift of 4° at the highest filler content (46%) investigated. The height of the loss maximum was nearly unaffected. The loss tangent of the filled and unfilled polymers showed no systematic shift with temperature and the dilatometric glass transition was raised only 2° C at the highest filler content. All the essential features of the dynamic behavior could be described in terms of the properties of the component polymers by the phenomenological equivalent mechanical model treatment of Takayanagi. It is concluded that the effects of the polystyrene filler, which resemble those of other fillers as well, need not be caused by restriction of segmental motion in the rubber resulting from elastomer-filler interactions.
Injection Molding with Natural Rubber
Authors: Wheelans M. A. 
Published: February 2011

Abstract
Injection moldings with natural rubber compounds having sections varying between 0.16 and 10 cm thick have been prepared. Almost any natural rubber compound can be satisfactorily injection molded. Cure time, and hence cycle time, is highly dependent on injection temperature and the art of injection molding is to inject at the highest possible temperature consistent with freedom from scorch. The injection temperature of natural rubber depends on the injection molding machine variables such as screw speed, screw back pressure and barrel temperature. Injection and mold filling time are dependent on injection pressure and nozzle orifice diameter. Rubber compounding variables influence injection molding behavior. A curing system with a relatively long, safe Mooney scorch time permits a reduction in the cure time of rubber by allowing a high injection temperature. Conventional curing systems are suitable for a wide range of injection moldings but “Efficient Vulcanization ” systems have special advantages in curing thin sections adjacent to thick ones because of their superior reversion resistance. The effects of compound viscosity are described. Extenders are shown to reduce injection temperatures and thus increase cure times. Black and white fillers are examined in their effect on injection temperature, injection time and cure time. Injection molded vulcanizates are similar in mechanical properties and oven aging resistance to vulcanizates prepared by conventional press methods.
Photo-Oxidation of Polymers without Light: Oxidation of Polybutadiene and an ABS Polyblend with Singlet Oxygen
Authors: Kaplan M. L. , Kelleher P. G. 
Published: February 2011

Abstract
In recent years much evidence has been accumulated to implicate electronically excited oxygen ((1Δg)) molecules as the agent responsible in photo-sensitized oxidations for the formation of allylic hydroperoxides from olefins and of endoperoxides from 1 ,3-dienes. Little regarding the mechanistic aspects of the photo-oxidative degradation of polybutadiene is known, however. To determine if electronically excited oxygen ((1Δg)) molecules can oxidize PBD, the ABS polyblend and standard samples of PBD's containing high trans, high cis, and high vinyl content were treated in homogeneous solution at low temperature with chemically produced singlet oxygen in situ. The source of the singlet oxygen was the triphenylphosphite-ozone adduct. Studies by spectroscopy, elemental analysis, viscosity determinations, and gel measurements showed only the cis- and the trans-PBD were susceptible to oxidation; no chain scission was involved in the attack of cis- and trans-PBD by singlet oxygen; the oxidation of the cis-PBD involved the initial formation of hydroperoxides which on thermal decomposition yielded gel. The trans-PBD was found to oxidize but apparently by a mechanism different from that of cis-PBD. Initial singlet oxygen attack of ABS proceeds by oxidation of the PBD portion of the polyblend. It was also observed that when only a small amount of the double bonds in the cis-PBD polymer had been oxidized to hydroperoxides, subsequent thermal treatment of this sample resulted in gross structural changes in the whole polymer.
Reaction of Radical Acceptors with Polymer Radicals formed by Mechanical Degradation of Vulcanizates
Authors: Razgon D. R. , Drozdovskii V. F. 
Published: February 2011

Abstract
The authors investigated, by the EPR method, the kinetics of the accumulation and subsequent deterioration of polymer radicals, resulting from the mechanical degradation of sulfur and peroxide vulcanizates of SKMS-3 ARKM-15 rubbers at 80 ° K. The reaction of these radicals with a number of acceptors were also studied. The polymer radicals, independently of their nature, will deteriorate at temperatures near the Tg. Polysulfide radicals are completely destroyed at 240–250° K, the hydrocarbon radicals at 220–235° K, and the peroxide ones at 200–210° K. The peroxide radicals will react, at 80° K, with Ionol and alkylphenol disulfides to form phenoxy radicals, and with trichlorothiophenol to produce thiol radicals, but will not react with the stable nitroxide radicals or with di-(trichlorophenyl) disulfides. The carbon free radicals will react, at 150–200 ° K, with trichlorothiophenol and with alkylphenol disulfides, resulting in formation of polysulfide radicals, and, at 80° K, they will react with stable nitroxide radicals to form 2,2,6,6-tetramethyl-4-hydroxypiperidyl. The polysulfide radicals, within a temperature range of 80 to 250° K, do not react to any appreciable degree with any of the radical acceptors investigated.
The Use of a Mechano-Lattice Analogy for Determining the Abrading Stresses in Sliding Rubber
Authors: Yandell W. O. 
Published: February 2011

Abstract
A rigorous mechano-lattice analogy analysis for calculating the hysteretic sliding friction of and stresses in rubber sliding on variously shaped asperities is presented. The analysis allows large strains and any Poisson's Ratio, rigidity or damping factor of the rubber. The analysis was used to calculate the distributions of minor principal stress in rubber sliding over smooth and frictional prisms with different sharpnesses and over a cylinder. The potentially disruptive stress regions were thus revealed and compared. The effect of changes in the Poisson's Ratio and of the damping factor of the rubber were also examined. It was postulated that the fine texture generates more stress-strain hysteretic heat which may lead to the more rapid abrasion observed by some workers.
Monomer Sequence Distribution in Ethylene Propylene Elastomers. I. Measurement by Carbon-13 Nuclear Magnetic Resonance Spectroscopy
Authors: Carman C. J. , Wilkes C. E. 
Published: February 2011

Abstract
The carbon-13 chemical shifts of ethylene propylene copolymers were found to be very sensitive to monomer sequence distribution. Methylene resonances were interpreted in terms of methylene sequence length and tertiary carbon resonances were interpreted in terms of propylene centered pentad sequences. Propylene inversion was detected and measured quantitatively in the spectra. A formula was derived for calculating r1·r2, which is independent of monomer feed, and which is based on measuring contiguous and isolated propylene sequences in the copolymer. The interpretations are shown to be consistent for copolymers containing 26, 34, and 62 mole% propylene. The r1·r2 products were determined for each of these polymers. Calculation of copolymer composition based on the 13C chemical shift assignments gave excellent agreement with the compositions as determined by infrared and 1H NMR. A formula was derived, based on copolymerization theory, for calculating the reactivity ratio product, r1·r2, directly from the copolymer composition (% ethylene) and the ratio of contiguous to isolated propylene sequences. Using this formula an average value for r1·r2=0.42±0.02 was determined for the copolymers made with vanadium acetylacetonate-diethylaluminum chloride catalyst system.
Characterization of Carbon Black Structure by Mercury Penetration
Authors: Moscou L. , Lub S. , Bussemaker O. K. F. 
Published: February 2011

Abstract
The determination of the chain-structure of carbon black by mercury porosimetry is described. It is shown that each type of black has its own porosity curve, depending on specific surface area and degree of structure. An absolute measure for the degree of structure is proposed: The “Structure Index”, calculated from the break point in the porosity curve, the specific surface area and the density of the black. Structure Index for structureless blacks is 1.0 – 1.1, for low structure blacks 1.7 – 1.9, for normal structure blacks 2.3 – 2.4 and for high structure blacks 2.7 – 2.8.
Elastomer Blends. Compatibility and Relative Response to Fillers
Authors: Callan J. E. , Hess W. M. , Scott C. E. 
Published: February 2011

Abstract
The relative compatibility of eight different commercially available elastomers, blended in two-way combinations in three different proportions, was measured as a function of zone size on phase contrast optical micrographs using the Quantimet Image Analyzing Computer. Average cross sectional areas of the disperse phase in different blends were measured utilizing micrographs of the relatively noise-free QTM meter images which were characterized by greatly enhanced contrast. A study of the commercially important blends of polybutadiene with SBR was completed using both Differential Thermal Analysis and Electron Microscopy. Blends of several types of polybutadiene with SBR ordinarily exhibited only one glass transition temperature when examined in the vulcanized state. However, the same blends, uncured, showed the Tg's typical of each individual polymer. Moreover, electron micrographs of SBR blends with three different polybutadienes (Butyllithium, Ziegler, and Emulsion types) showed the existence of discrete polymer zones. Blends of BR/SBR, though more compatible than most polymer systems (e.g., NR/BR), were not homogeneous at the molecular level. A comprehensive study of carbon black distribution between 50/50 blends of several commercially important elastomers was completed. A high structure HAF carbon was added to elastomer preblends to give a 40 phr loading. Filler distribution was then assessed from the frequency of aggregates in the separate polymer zones. The studies indicated that BR and SBR have the highest affinity for a standard type carbon black. Polychlorobutadiene and Nitrile rubbers showed a somewhat lower affinity, though appreciably higher than that of natural rubber. EPDM and Butyl showed the lowest carbon black reactivity. Finally, carbon black transfer was investigated in a variety of polymer systems using Electron Microscopy and Pyrolytic Gas-Chromatography. The extent of carbon black transfer from Butyl to BR, NR and SBR was quite significant. In summary, transfer can occur when the adsorptive capacity of the filler has not been fully utilized. This situation can exist if the masterbatch has minimum heat or mechanical history, or involves low molecular weight or low unsaturation elastomers.
Crosslinking, Filler, or Transition Constraint of Polymer Networks. I
Authors: Blanchard A. F. 
Published: February 2011

Abstract
For a polymer network at equilibrium in solvent, Flory and Rehner related the polymer fraction νr of the swollen volume to the molecular weight Mc of the chains between crosslinks. Their equation is represented below by the function F(νr) with [Mc] denoting the effective mesh weight, i.e., that obtained by physical measurements. Hence the effective crosslinking 1/[Mc]g from swelling measurements νr is given by 1/F(νr).
Polymers from Cycloolefins
Authors: Scott Kenneth W. , Calderon Nissim , Ofstead E. A. , Judy W. A. , Ward J. P. 
Published: February 2011

Abstract
Ring-opening polymerization of cycloolefins has led to a variety of new plastics and elastomers with a great range in physical properties. Ring-opening polymerization of cycloolefins, employing organoaluminum-tungsten salt catalysts, is a special case of olefin metathesis, a new reaction. The ring-opening reaction occurs at the double bond and allows making either large ring macro-cyclics or high molecular weight linear chains. Under certain conditions ringchain equilibrium can be established in these systems.
Inflation and Compression of Rubber Tubes between Parallel Plates
Authors: Charrier J. M. , Gent A. N. 
Published: February 2011

Abstract
When a thin-walled rubber tube containing an incompressible fluid is compressed between two parallel plates the internal pressure rise depends on the restraints in the contact regions. When there is no friction in the contact zone the pressure rise is lower than when slip is prevented, so that the tube, regarded as a spring, has a compression stiffness which depends on the frictional conditions. The same considerations apply to the inflation of a tube between fixed parallel plates. In this case unstable inflation sets in at a critical pressure when the interfaces are frictionless; the tube develops a pronounced bulge when this pressure is approached. Simple theoretical relations are derived for the internal pressure and compressive force for both these deformations, and for both boundary conditions, assuming that the rubber is neo-Hookean in elastic behavior. Experimental measurements on tubes of different dimensions are shown to be in reasonably good quantitative agreement with these theoretical predictions in all cases.
Volume Change Accompanying Rubber Extension
Authors: Goebel J. C. , Tobolsky A. V. 
Published: February 2011

Abstract
A new equation for the volume dilation accompanying rubber extension is obtained from a reinterpretation of the kinetic theory equation for rubber elasticity. This equation is shown to describe published volume-extension data better than either that derived from simple kinetic theory or that derived from the Mooney-Rivlin equation.
Identification and Determination of Polymers in Compounded Cured Rubber Stocks by Pyrolysis and Two-Channel Gas Chromatography
Authors: Cole H. M. , Petterson D. L. , Sljaka V. A. , Smith D. S. 
Published: February 2011

Abstract
Methods for analysis of carbon-black-loaded vulcanizates are of considerable interest to the rubber industry and to those supplying its raw materials. Identification of polymers or copolymers present in such stocks is an important step in this analysis. Often it becomes desirable also to determine the composition of a blend of two or more elastomers. In recent years gas chromatographic analysis of volatile pyrolysis products has been increasingly applied to these intractable materials. A wide variety of polymers and experimental techniques for pyrolysis and subsequent chromatographic analysis have been used. A complete resume of this work is beyond the scope of this report, but recent papers dealing with the use of these methods in elastomer analysis include those of Groten, Hulot and Lebel, Blenkin, Lebel, Fiorenza and Bonomi, and an excellent review of pyrolytic techniques by Brauer. This study was an evaluation of the applicability of simultaneous flame ionization and electron capture (dual-channel) chromatography, with or without temperature programming to polymer identification and to quantitative analysis of elastomer blends.
Relation between Abrasion and Strength of Rubber
Authors: Grosch K. A. , Schallamach A. 
Published: February 2011

Abstract
The temperature dependence of abrasion of various gum and black-filled rubbers on silicon carbide paper is closely similar to the temperature dependence of their energy density at break determined at a high rate of extension. The conclusion is drawn that this type of abrasion is predominantly due to tensile failure, as had been envisaged in earlier work. The effective rate of extension during abrasion at a sliding velocity of 1 cm/sec is about 10,000 per cent/sec. The volume of abraded rubber is approximately proportional to the ratio between frictional energy dissipation and energy density at break. The proportionality constant is greater for black-filled than for gum rubbers. The effects of temperature and velocity on the abrasion of non-crystallizing gums are interrelated by means of the Ferry transform, indicating the viscoelastic nature of the abrasion process operating on these compounds.
Friction of Rubber
Authors: Savkoor A. R. 
Published: February 2011

Abstract
A theory of the adhesional friction of rubber is developed by considering adhesion as a time-dependent process in which a tangential force helps to overcome an energy barrier of the work of adhesion. The frictional phenomenon, as a consequence of such adhesion, would arise primarily from deformation of the rubber aggregates in contact with a smooth, hard surface constituting the “top layer”. The existence and importance of such a highly-deformed layer has been shown by Schallamach in his studies on surface conditions. The true area of contact is considered to increase with time of adhesion as is generally observed in quasi-static behavior of viscoelastic materials. Deformation characteristics describing the time-temperature dependence of mechanical properties would then be reflected in the friction behavior. A simple phenomenological approach is taken here instead of a complicated one with the theory of rate processes applied to basic molecular activity. Variation of the friction force with viscoelastic properties is in fair agreement with the experimentally-obtained results of Grosch. The static coefficient of friction equals the dynamic coefficient at extremely low speeds. The analysis is confined to steady-state conditions and the influence of frictional heating is considered negligible.
A Theory of Dynamic Rubber Friction
Authors: Schallamach A. 
Published: February 2011

Abstract
Assuming dynamic friction to arise from the shearing and subsequent breaking of distinct bonds between the rubbing members, a general equation is derived for the frictional force which involves the number and average life of the bonds as well as the average time lag between breaking and re-making of a bond at a given site. In the case of friction between rubber and smooth, hard surfaces, the bonds are attributed to local molecular adhesion between rubber and track, both formation and breaking of the bonds being thermally activated rate processes. A theory developed on this basis reproduces the experimental results obtained by Grosch in that the coefficient of friction as function of the velocity has a pronounced maximum. The height of the maximum and the velocity at which it occurs are in semi-quantitative agreement with Grosch's findings.
Distribution of Tensile Strength Data
Authors: Heap R. D. 
Published: February 2011

Abstract
The problems of tensile strength estimation are outlined, with particular reference to Ease's work showing that tensile data for rubbers are distributed doubly exponentially. Efficient estimators are given as weighted means for samples of up to six observations, and efficient but simple, easily calculated approximations to these are given. Large or incomplete samples are also considered. A suggested scheme for treatment of experimental data is given, including experimental results comparing the recommended estimators with the mean and median, and showing a doubly exponential distribution of observations.