bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field Desorption Mass Spectra of Polymer Chemicals
Authors: Lattimer R. P. , Welch K. R. 
Published: February 2011

Abstract
From the results presented here, it is clear that FD-MS is a very effective analytical method for determining molecular weights of polymer chemicals. Molecular ions were the only prominent ions produced in the FD mode of analysis for the series of representative polymer chemicals discussed in this paper. Good molecular ion spectra were obtained even from compounds that are quite unstable, both structurally and thermally. It is also evident, on the other hand, that FD-MS by itself provides only limited chemical structure information. The molecular weight is provided and often nothing else. Fortunately the molecular weight and “chemical intuition” regarding the history of the sample in question are often enough to deduce the structure. If not, then other techniques are available to provide complementary information. Electron impact (EI) mass spectra can be run on the same samples to obtain fragmentation patterns, and other spectro-scopic techniques (infrared and magnetic resonance) can be used to provide detailed structural information. Several application areas can be identified in which FD-MS can play an important role in the characterization of nolymer chemicals in industry. These include chemical identification (molecular weight and structure determination), direct detection of components in mixtures, identification of liquid chromatographic (LC) effluents, characterization of polymer blooms and extracts, identification of vapors from polymer processing, and identification of polymer chemical degradation products. For many of these applications the samples to be analyzed are very complex mixtures of chemical compounds. Electron impact mass spectroscopy is quite limited in its ability to analyze such complex mixtures due to the extensive fragmentation (and perhaps decomposition) that takes place in the ion source. Since molecular ions are normally the only prominent ions formed in the FD mode of analysis, FD-MS can be a very powerful tool for the characterization of polymer chemical mixtures. In summary, field desorption mass spectroscopy can in many cases provide molecular weight and structural data for polymer chemicals heretofore not obtainable by any analytical technique. In addition this information complements well the structural data obtained by magnetic resonance, infrared, and electron impact mass spectroscopy. We therefore feel confident that FD-MS will become increasingly important in the characterization of polymer chemicals in the future.
Finite Deformation Behavior of Elastomers: Dependence of Strain Energy Density on Degree of Crosslinking for SBR
Authors: Tsuge K. , Arenz R. J. , Landel R. F. 
Published: February 2011

Abstract
The non-linear mechanical behavior of styrene-butadiene rubbers (SBR) having five different crosslink densities (νe) has been determined in large deformation biaxial stress-relaxation tests of thin-sheet specimens. A significant experimental development was the use of individual strain gages at the specimen support points to determine directly the stress distribution in the web. The tests indicated the separability of strain and time effects for extension ratios up to 3.0 for the most lightly crosslinked SBR. Long-time data showed the equilibrium shear modulus Ge to be directly proportional to νe. The ratio W/Ge was independent of crosslinking so that the strain energy density W has the same functional strain dependence for all SBR systems.
Ozonolysis of Polyisoprene Popcorn Polymer
Authors: Miller G. H. , Tobias R. H. 
Published: February 2011

Abstract
Ozonolysis of polyisoprene popcorn polymer gave the volatile products: water, formic acid, acetic acid, levulinaldehyde, 2,5-hexanedione, and propionic acid. The rates of formation of levulinaldehyde and 2,5-hexanedione varied during the 96-hour ozonolysis period; more levulinaldehyde was formed during the early stages, and more 2,5-hexanedione during the later stages. The molar yields of formic and acetic acid were approximately 20 and 10 times larger, respectively, than the average hexanedione or levulinaldehyde yield. A chain unzipping mechanism is postulated for the production of most of the formic and acetic acids, and it is believed that most of the 2,5-hexanedione is formed in secondary reactions initiated by alkoxy or peroxy radicals. A large amount of oxygen remained on the polymer which still had a high degree of unsaturation following the ozonolysis. Ozonolysis of bulk PIP is not a satisfactory way for the determination of head-to-head and tail-to-tail structural sequences. The evidence obtained, however, indicates that the polymer is composed primarily of head-to-tail structural units.
The Mechanical Stability of Natural Rubber Latexes
Authors: Pendle T. D. , Gorton A. D. T. 
Published: February 2011

Abstract
From the information presented in this paper and from the cited literature, it is clear that the mechanical stability of natural latex can be influenced by a large number of factors. The arguments presented here suggest that the effects of most of these factors are explicable in terms of classical colloidal stability theory. It is suggested that the ionic strength of the aqueous phase of natural latex is a key feature in determining stability because of its effects on the electrical double layers around the latex particles. Increases in ionic strength reduce stability because of compression of the electrical double layer, such compression permitting closer approach of adjacent particles, and consequently, an increase in the attractive forces between them. Other phenomena are explained by postulating adsorption of anions at the particle surface where they have the effect of increasing the potential of the surface and therefore the repulsive force between adjacent particles—the attractive force being presumed to remain constant. It is believed that not all of the possible factors influencing the mechanical stability of natural latex concentrates have yet been discovered and, more generally, that the specific effects of anions on colloidal stability remain to be evaluated. In this context further investigation of the nonvolatile acid anions present in natural latex could be worthwhile. The way in which the mechanical stability of natural latex concentrates is affected by both internal and external factors and the means which latex producers use to control this characteristic have been shown. The results presented here illustrate the sensitivity of the mechanical stability test as a measure of the stability of the latex particle to mechanical influences and thereby indicate its value both to the producer and consumer of natural latex.
Factors Which Influence Autohesion of Elastomers
Authors: Rhee C. K. , Andries J. C. 
Published: February 2011

Abstract
The following conclusions can be drawn from our studies: (1) An optimum molecular weight (Mn=2095) exists for t-octylphenol-formaldehyde resin to give maximum autohesion to rubber compounds. A critical level of the phenolic resin is required in a given rubber compound to make the tackifying action effective. In addition, the presence of polar groups in a resin molecule is a structural requirement in order for the resin to provide tackiness to rubber compounds. (2) The autohesion of a rubber compound decreases as the loading of processing oil increases from 5 phr to 25 phr. This behavior is independent of the type of oil. (3) The autohesion of a rubber compound decreases with increasing carbon black level, surface area, and structure. (4) Autohesion maximizes at an optimum molecular weight of rubber. (5) Humidity has a pronounced effect on the autohesion of aged SBR compounds, whereas very little effect on that of aged NR compounds. (6) A dual diffusion-adsorption mechanism is operative in autohesion.
Investigation of the Structure-Property Relationships of Improved Low Compression Set Nitrile Rubbers
Authors: Chang D. M. 
Published: February 2011

Abstract
The effect of polymer structures on the rubber processing and physical properties of the improved Hycar 1090 low compression set nitrile rubbers was investigated. The molecular weight and acrylonitrile content of a polymer are important variables in determining the compound processing and vulcanizate physical properties. Within the range of 21 to 88 Mooney, a blend of high and low Mooney polymers has approximately the same properties as those from a single polymer of the same Mooney viscosity. The molecular weight distribution was not significantly broadened to become an important factor affecting the polymer properties. All polymers with Mooney viscosities from 21 to 88 showed good properties. An understanding of the structure and properties of this new type of NBR, will help in choosing the right kind of polymer for particular applications.
Photo-Oxidation of an IR Vulcanizate
Authors: Yano Shoichiro 
Published: February 2011

Abstract
On irradiation with uv light, changes in uv and ir spectra were observed. In the uv spectrum, a minimum at 290 nm due to sulfur, dibenzothiazyl disulfide, and double bonds in the main chains disappeared initially by the consumption of them; but the minimum reappeared on further irradiation reflecting the formation of carbonyl groups. On the other hand, in the ir spectrum two absorption bands appeared at 1720 cm−1 (due to carbonyl groups) and 3450 cm−1 (due to hydroxyl groups). The latter band faded out suggesting the decomposition of hydroperoxides when the vulcanizate was kept in the dark after irradiation. From the findings of the wavelength dependence of photo-oxidation on uv and ir spectra, it was found that the degradation occurred below about 430 nm. However, investigation of the wavelength dependence of photo-oxidation by the measurement of the crosslink density gave the results that crosslinking reactions occurred below about 340 nm, scissions of C-C and polysulfide crosslinks between 340 and about 400 nm, and scissions of polysulfide crosslinks between 400 and 600 nm. These were confirmed by measurements of the dynamic modulus during irradiation. The relative modulus E′(t)/E′(0) increased on irradiation with light at 253.7 nm in a longer time region reflecting a crosslinking reaction. On the other hand, on irradiation with light above 330 nm, E′(t)/E′(0) decreased with time. Change in E′(t)/E′(0) could be represented by the equation of the first order reaction containing an exponential term and the rate constant was determined. The activation energy was calculated as 18.6 kcal/mole from the temperature dependence of the rate constant and agreed with that for scission of polysulfide crosslinks. The photodegradation of the IR vulcanizate occurred also on irradiation with visible light (&gt; 430 nm), and the modulus decreased.
Testing Submergible Power Cables for Oil Well Applications
Authors: Martin Jon W. 
Published: February 2011

Abstract
A downhole simulator can be used to test oil well power cable, providing results more quickly and economically than can be obtained from field testing. Electrical properties of the cable can be monitored durng the test. Thermal limits can be established. Field degradation mechanisms can be reproduced. TRW uses the facility to evaluate oil well cable designs and to test new cable insulation and protection materials. From this experience, submergible cables have been improved to meet the most severe downhole conditions being encountered throughout the world.
Migration and Blooming of Waxes to the Surface of Rubber Vulcanizates
Authors: Nah S. H. , Thomas A. G. 
Published: February 2011

Abstract
The model proposed in this paper appears to give an adequate explanation for the magnitude of the blooming rates observed. The driving force is due to elastic stresses set up around the precipitated wax particles and thus the blooming rate is influenced quite strongly by the modulus of the rubber. On the basis of this mechanism it would be expected that unvulcanized rubber would show little blooming, and this is in accord with general observations on such materials. The solubility of the wax is an important parameter and, because of its sensitivity to temperature, the ambient temperature and the melting point of the wax will be important factors influencing the blooming in practical applications. The precipitation of the wax has been assumed to occur at imperfections in the material. The source of these is not yet clear, although impurities could clearly be important. The values that have to be assumed for the volume fraction of these seeding sites, about 10−3, is not unreasonable in general magnitude for impurity concentrations.
Extrusion-Shaping of Curved Hose Reinforced with Short Cellulose Fibers
Authors: Goettler L. A. , Lambright A. J. , Leib R. I. , DiMauro P. J. 
Published: February 2011

Abstract
A new development in hose technology, the direct shaping of curved hose reinforced with short fibers at the extrusion die, is described. By moving the inner and outer portions of the tube die out of concentricity in a programmed sequence, the extrusion direction can be made to deviate from the machine axis and thus to produce bends in the hose. This process has been demonstrated on planar S-bends of a 38 mm hose. Bend radii as tight as 13 mm to the inside of the bend are feasible. Such a hose might find various industrial applications. Performance characteristics are similar to cord reinforced coolant hoses. The reproducibility of the die motions and timing sequences to produce the hose shapes are maintained by a digitally controlled hydraulic cylinder that is driven through a stepper motor. The driver for the stepper motor could involve hard-wired or microprocessor circuitry. All of the components for this system are commercially available with the exception of a customized extrusion head to accomodate the mounting and connection of the hydraulic cylinder. This unique process for producing curved hose is contingent upon the use of short fiber reinforcement for several reasons: (a) The reinforcement must be present in the stock before it is extruded. (b) The dispersed short fibers give the hot extruded hose structural integrity to minimize shape distortion before cure. (c) The hoop-wise fiber orientation pattern produced in the novel conically expanding die is augmented by additional reinforcement in the thinner hose wall that occurs on the inside of the bend. An important consequence of the third item above is that the curved hose sections display practically the same burst strength as a straight section, despite the wall thinning that occurs as a result of offsetting the die and pin. The production and performance of these short-fiber reinforced curved hoses can be rationalized in terms of the fluid and mechanical behavior of short fiber composites.
Upgrading of Scrap Rubber Powder by Vulcanization without New Rubber
Authors: Acetta A. , Vergnaud J. M. 
Published: February 2011

Abstract
Rubber powder recovered from old tires can be converted to materials with interesting, useful physical properties. Rubber powder is recognized as a valuable raw material which may be processed into several useful products. In the cure cycles described, using only rubber powder and vulcanizing agent without virgin parent-compound, rubber powder can be converted to a plastic or elastomeric material, according to the percentage vulcanizing agent. As in the case of classical rubber vulcanization, the physical properties of the vulcanizates from rubber powder are found to be largely dependent on the conditions of cure. The effect of vulcanizing parameters on the vulcanizate properties were particularly studied.
Laboratory Vulcanization as an Aid to Factory Air Analysis
Authors: Willoughby B. G. , Lawson G. 
Published: February 2011

Abstract
The pollution problems of the rubber industry are complex and the pollutants arise from a variety of sources. Prior knowledge of the nature of these pollutants is invaluable to the successful execution of a factory monitoring program. Such a knowledge enables the most appropriate monitoring equipment to be preselected and provides for cost effective analysis. The collection and analysis of hitherto unidentified compounds requires a degree of control which is most easily achieved with a laboratory vulcanization. The results presented here show that this control enables a wide range of volatile species to be captured and permits yields to be optimized for the purposes of identification. Examples of the control that may be achieved in a laboratory vulcanization include the ability to handle samples without loss and to carry out this work with ready access to the most sophisticated analytical equipment. A knowledge of the chemical nature of the fumes from a vulcanizing rubber is not only of value to the industrial hygienist but also provides an insight into the chemical processes of vulcanization. For example, evidence for the free radical contribution to a sulfenamide cure can be obtained. Of special note is the fact that these data can be obtained from fully compounded rubber stocks.
Tack and Green Strength of NR, SBR and NR/SBR Blends
Authors: Hamed G. R. 
Published: February 2011

Abstract
1. A simple NR compound has superior tack compared to an SBR stock because of its greater ability to flow under compressive load and its higher green strength. The difference becomes greater as surface roughness is increased or test rate decreased. Tack differences between the two stocks can be quantitatively explained without assuming differences in the interdiffusion rate of SBR and NR molecules. NR is an “ideal” material for developing high tack. It can be processed to a low viscosity and still maintain high green strength. Furthermore, the mechanism responsible for the high green strength (strain crystallization) is not active in the bond formation step, hence does not interfere with contact and interdiffusion, but rather develops upon stressing. SBR, on the other hand, depends on entanglements, which tend to inhibit flow, to achieve green strength. Thus, if the molecular weight of the SBR is raised to enhance green strength to the level of NR, the stock will flow very poorly. Likewise, if SBR molecular weight is lowered, flow can be improved substantially, but green strength will decrease rapidly. Either of the above conditions result in poor tack. 2. For smooth, shiny surfaces brought together, contact occurs rapidly and nearly completely for both the NR and SBR stocks. This results in a relative tack near unity and hence, in this case, the tack strength is really a measure of stock green strength, i.e., tack is green strength limited. Obviously, when this condition exists, the addition to the stock of plasticizers, tackifiers, oils or other additives to facilitate stock flow (but decrease green strength) will nontheless reduce tack. Here, tack can only be increased by enhancing stock green strength, preferable without hindering flow ability. 3. The relative tack of SBR and SBR-dominated blends with moderately rough surfaces is less than unity and increases with contact pressure. Thus, tack is contact limited. In this instance, relative tack can be improved by decreasing stock viscosity, however, absolute tack will only be increased if good green strength is maintained. This may be the mechanism for the action of commencal tackifiers. 4. The tack of NR/SBR blends passes through a maximum with composition at about 80% NR. This is readily understood by noting that the green strength also reaches a maximum at this composition. For NR/SBR blends containing 60% or more of NR, green strength plays the dominant role in controlling tack. 5. Uncured adhesion of SBR to NR is less than the tack of either pure component. This suggests that interdiffusion is required to obtain high tack.
Effects of Wax and Substituted p-Phenylenediamine Antiozonants in Rubber
Authors: Lederer D. A. , Fath M. A. 
Published: February 2011

Abstract
Wax was found to reduce fatigue life and dynamic ozone resistance. These losses can be partially compensated for by the addition of a substituted paraphenylenediamine (PPD). An increase in PPD concentration leads to a slight increase in wax bloom. At low levels of wax (1 phr), this effect will lead to a significant increase in static ozone protection. A critical level of wax bloom is required to form a continuous film for optimum static ozone protection. The relative increase in ozone protection provided by a wax/PPD combination was similar for both an NR tread and an NR/BR sidewall formulation. The amount of wax bloom was much higher in the NR/BR compound compared to the NR stock. In both cases, however, the critical level of wax bloom was exceeded; thus, a significant difference in static ozone protection is not expected. At practical levels of antiozonant, no synergism between wax and PPD was observed in static or dynamic ozone exposure tests. Significant synergism was observed under intermittent test conditions. This is due to a combination of the effective static ozone protection of the wax with the dynamic protection of the PPD.
Effects of Carbon Black Types on Treadwear of Radial and Bias Tires at Variable Test Severities
Authors: Wilder C. R. , Haws J. R. , Cooper W. T. 
Published: February 2011

Abstract
Trends observed in testing various types of carbon blacks in radial tires follow those observed in bias tires with some differences, as noted in the following statements. There is less advantage for the use of high structure blacks in radial tires than found in bias tires. The improvement of wear resistance with blacks of increased surface area in radial tires is equal to or greater than that found in bias tires. Good dispersion of carbon black is important for good treadwear in all tires, but adverse effects of poor dispersion appear reduced in radial tires.
Laboratory Simulation of a Factory Extrusion Process by the Die Swell Tester
Authors: Tokita Noboru 
Published: February 2011

Abstract
The simulation principle (scaling) of the tire tubing process was studied by the “Die Swell Tester”. It was found that once the following three conditions were established, the die swells (ratio of extrudate to die cross section) of factory tubed extrudate were identical to lab scale DS results: namely, (1) same operation temperature, (2) same residence time in die, and (3) same ratio of die length to die diameter (L/D). In order to obtain the same L/D values between the complicated die shape of a factory tuber and the circular die of the DST, it is shown that the hydraulic radii (area/perimeters) must be kept the same. The correlation coefficient between factory extrudate properties and DST values was 99.6%. On the contrary, the Mooney torque ML1 + 4 values did not correlate with the die swell properties of the factory extrudates. Cold shrinkage of cut lengths of factory extrudates was simulated by the use of an extension control attachment to the DST. The theoretical analysis of potential recovery was established using die swell values and the stretch ratios. A good correlation between potential recovery (or total stretch) and cold shrinkage was obtained in both factory and laboratory samples.