bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Properties, Structure, and Morphology of Natural-Rubber/Low-Density Polyethylene Blends Prepared by Different Processing Methods
Authors: Qin Chuan , Yin Jinghua , Huang Baotong 
Published: February 2011

Abstract
Morphological studies with TEM and SEM showed that, in unvulcanized NR/LDPE blends, phase inversion occurred between NR/LDPE = 40/60 to 60/40; for dynamically vulcanized blends, LDPE remained as a continuous phase even at NR/LDPE = 70/30. Change in morphology of dynamically vulcanized blends of specified composition (NR/LDPE = 70/30) with vulcanization time as observed by SEM indicated that phase inversion occurred with the progress of vulcanization followed by fracture of the crosslinked phase into small particles. A model was proposed. For unvulcanized samples, the tensile strength steadily increased with increasing LDPE content, while their elongation at break first decreased and thereafter increased. Tensile strength and elongation at break of the statically vulcanized samples decreased to a minimum and thereafter increased with increasing LDPE content. However, an interesting trend appeared in the change in tensile strength and elongation at. break of the dynamically vulcanized system with increasing LDPE, where they first increased to a maximum and thereafter decreased. From the suggested model and the experimental results, it was shown that the mechanical properties of dynamically vulcanized blends were higher than those of unvulcanized blends but lower than those of statically vulcanized blends. The other physical properties of blends which are mainly dependent on the properties of the plastic phase, such as tear strength, 300% modulus, hardness and permanent set, all increased with increasing LDPE in different processing methods. In addition, changes in the mechanical properties of different compositions with the progress of dynamic vulcanization were also examined.
Oscillating Disk Curemeter Monitoring of Two-Part Polysulfide Sealants
Authors: Hanhela Peter J. , Huang Robert H. E. , Paul D. Brenton , Symes Theodore E. F. 
Published: February 2011

Abstract
By modifications to the dies and rotor of an oscillating-disk curemeter, continuous monitoring of features of the cure of two-part polysulfide sealants has been achieved. The principal innovations included use of a larger rotor and relocation of the parting line of the dies to the top of an enlarged cavity, which itself was altered in shape to a square design. By these means and through the introduction of an O-ring on the lower die, the fluid mixtures produced after introducing the sealant components were retained in the cavity. Reproducible torque-time curves were obtained using an arc of ±3°. The diverse applications of the procedure for studying curing variables have been demonstrated through examination of the influence of different curatives, curing ratios, liquid polymers, accelerators, fillers, dispersants, and the thermal resistance of cured sealants in confined spaces. The procedure has also been shown to provide a meaningful discrimination between sealants of different crosslink density. The value of the technique may be further enhanced through introduction of new instruments capable of providing loss factor (tan δ) measurements.
Quantitative Analysis of Vulcanized SBR/EPDM Diblends. Magic Angle Spinning 13C-NMR Experiments at 80°C
Authors: van der Velden G. P. M. , Kelm J. 
Published: February 2011

Abstract
A new quantitative expression has been derived in order to estimate the styrene-butadiene ratio from the 13C-NMR olefinic resonances. With the help of this expression, the cis-1,4, trans-1,4, vinyl-1,2, butadiene and styrene ratios could be determined. From the aliphatic region, subsequently, the ethylene and propylene contents could be determined and finally the SBR/EPDM blend ratio. From the 13C-solid-state-NMR spectrum, no evidence could be obtained for homo- or co-vulcanization. The 13C-NMR spectra of the blends are simply a co-addition of the 13C-NMR solution spectra of SBR and EPDM rubbers. No evidence has been found for cis-1,4/trans-1,4 ratio changes for SBR (in comparison to the starting material).
Orientation Effects in Rubber Double Networks
Authors: Roland C. M. , Warzel M. L. 
Published: February 2011

Abstract
The utilization of network structure to impart stable orientation to a rubbery material has been largely unexploited to date. It is demonstrated that the presence of a double network will amplify both the modulus and strain crystallizability of an elastomer, presumably without the disadvantages encountered in achieving these through simple increases in crosslink density. The high residual strains obtained via double-network formation are accompanied by surprisingly low levels of birefringence. The extent of molecular orientation necessary to engender high residual strain is evidently quite low, at least in so far as the former is reflected in a bulk macroscopic measurement such as birefringence. This low equilibrium birefringence, along with the absence of any measurable thermal crystallization effects, indicate that double networks are actually not highly oriented. As seen from their higher moduli and higher strain optical coefficients relative to single networks, and from their enhanced strain crystallizability, double networks are evidently very orientable. Investigation of this aspect of the behavior of double networks would likely prove fruitful, not only concerning these materials, but also with regard to obtaining a broader understanding of rubber elasticity. While the enhancement of strain-induced crystallization might suggest that rubbers with double networks will exhibit superior failure properties, this remains to be demonstrated. The crystallization results described herein clearly raise more questions than can presently be answered concerning the behavior of rubbers with double networks.
Rolling Loss of Pneumatic Highway Tires in the Eighties
Authors: Schuring D. J. , Futamura S. 
Published: February 2011

Abstract
Up to and including World War II, not more than a dozen papers had been written on the subject of tire rolling loss. The number quickly increased after the oil embargo in 1976 and reached a peak around 1980 with more than thirty papers published per year. Several symposia were held in these years on the subject, and a comprehensive review of rolling-loss research was written by one of the authors of this article. Other, briefer reviews were published at that time by Barson, who discussed various techniques of measuring tire rolling loss; Moore, who pointed out ways of reducing rolling loss and hence fuel consumption; Clark, who touched upon some physical phenomena of tire rolling loss; and Chang and Shackleton, as well as Levine, who reviewed the effects of tire construction and materials on rolling loss. The main concern at that time was to understand the mechanism of tire rolling loss so that it could be effectively reduced. Hence, accurate laboratory testing procedures were developed to identify the effects of major tire and service factors on rolling loss, such as tire type, geometry, reinforcement, materials, load, inflation pressure, speed, slip angle, temperature, and road texture. Concurrently, predictive models were developed ranging from simple empirical relations to complex finite-element programs, so that besides costly experiments, mathematical simulations could be employed as guidance toward lower tire rolling losses and thus meeting the stringent governmental fuel-economy standards. The efforts of the tire industry to reduce tire rolling loss have been very successful, and further progress is to be expected. Figure 1 gives an indication of the rolling loss improvements achieved over the past 15 years. The average rolling loss coefficient of a sample of radial passenger car tires manufactured in 1975 was 12.6 N/kN; its standard deviation was 1.3 N/kN. A similar sample of radial tires manufactured a few years later indicated an average coefficient of 11.0 N/kN with a standard deviation of again 1.3 N/kN. A check of recently manufactured (1989) radial passenger car tires revealed a further drop to 9.3 N/ kN with a standard deviation of only 0.4 N/kN. Hence, in the first years after the oil embargo, the average rolling loss was reduced by roughly 10%—without change of the rather broad dispersion, however. The following years led to further improvements of an additional 15%, this time with a drastic drop of variability. This indicates the effects not only of material and construction improvements but also of tighter controls in the production process.
Protection of Rubber against Ozone
Authors: Layer Robert W. , Lattimer Robert P. 
Published: February 2011

Abstract
Currently, chemical antiozonants can be considered to function by scavenging ozone and, in the process, forming a protective barrier to prevent further ozone attack. Therefore, antiozonants must do two things: 1. react more rapidly with ozone than the rubber and 2. in the process, form products on the surface which prevent ozone from reaching both the underlying antiozonant and the rubber. Presently, more work is needed to define exactly what characteristics are required for the ozonized products to serve as an effective barrier. However, indications are that they must have a higher molecular weight than the antiozonant.
Cavitation in Rubber: A Cautionary Tale
Authors: Gent A. N. 
Published: February 2011

Abstract
What can we conclude from this brief history of cavitation in rubber-like solids? At first, the condition for internal cracking appeared to be particularly simple. Whenever a stress was set up equal to the maximum possible stress calculated from simple elasticity theory, i.e., 5E/6, then cavitation ensued. But it is now clear that this criterion is only approximately true and then only for a certain narrow range of void sizes. Because cavitation is often found under the originally deduced conditions, voids are obviously present in rubber of an appropriate size, between about 0.1 µm and 1 mm in radius, at least when the volume of rubber is large enough to accommodate them. Thus, even though the original criterion was arrived at on a faulty premise, it has proved to be a useful and broadly applicable fracture criterion. In preparing this brief historical review, I have been led to some elementary conclusions about research itself. First, the fact that a theory appears to work does not mean that it is true. Secondly, even simple, carefully-selected, systems are often difficult to understand. And, finally, contributions from different points of view are essential to scientific progress.
Direct Measurement of Poisson's Ratio in Elastomers
Authors: Kugler H. P. , Stacer R. G. , Steimle C. 
Published: February 2011

Abstract
Poisson's ratio has been measured in a series of filled elastomers using a novel optoelectronic system. Relative precision of this measurement was found to be approximately 0.7% at 1% strain for this family of materials. The largest contributing error source was determined to be the tolerances that could be obtained in machining the surfaces of the test specimens. As a result of these errors, only three significant figures for Poisson's ratio can be achieved using this measurement approach. Material property tests conducted included constant strain rate and stress relaxation. Constant strain-rate results were used for general characterization, while the stress—relaxation data were employed to investigate time-dependent aspects of Poisson's ratio.
Binder/Filler Interaction and the Nonlinear Behavior of Highly-Filled Elastomers
Authors: Stacer R. G. , Hübner C. , Husband D. M. 
Published: February 2011

Abstract
1. The small-deformation-viscoelastic response of elastomers containing nonreinforcing filler has been investigated. Nonlinear viscoelastic behavior was observed as a pronounced strain-amplitude dependence. The degree of this dependence was quantified using a power-law representation as a single nonlinear parameter, m. 2. The magnitude of m was a function of formulation variables. It was found that m increased with the volume fraction and particle size of filler material, as well as the volume fraction of plasticizer. Reduced values of m were observed in the presence of bonding agent and with greater degrees of apparent crosslinking. The latter was controlled in this study through imbalanced urethane cures. 3. Nonlinear behavior of elastomers containing nonreinforcing filler has been compared and contrasted with the data base for carbon-black-reinforced elastomers. The major difference is in the effect of the surface area of filler particles. Nonlinear response in black-filled rubbers increases with surface area, while the opposite is reported in this study. Additionally, the relationship between viscoelastic dissipation and the magnitude of nonlinear response, well established for black-filled rubbers, was not observed. These results indicate that the response of elastomers containing nonreinforcing filler, although nearly identical in appearance to that seen with reinforcing filler, is not driven by the same mechanism. 4. A binder/filler interaction model is proposed for materials containing nonreinforcing filler. This model is based on the ideal adhesive strength of the binder/filler interface. In this model, greater attraction between polymer and particle surfaces reduces molecular slippage during deformation, leading to a decreased dependence of the modulus on strain amplitude, or decreased nonlinearity. It is shown that the model provides reasonable predictions for the observed phenomena.
Crosslink Distribution and Interfacial Adhesion in Vulcanized Blends of NR and NBR
Authors: Tinker Andrew J. 
Published: February 2011

Abstract
In contrast to expectations from rheometer studies of vulcanization behavior, the NMR technique has demonstrated that blends of NR and NBR vulcanized with sulfur/TMTM show a marked distribution of crosslinks in favor of the NR phase. The presence of even a minor proportion of NBR is sufficient to reduce the degree of vulcanization of the NR phase below levels deemed to be technologically necessary. Replacing the sulfur with a bis-alkylphenol disulfide reduces the degree of preferential distribution of crosslinks substantially. Interpretation of differential-swelling data for the blends on the basis of the swelling expected from a single polymer vulcanized with the same level of curatives as added to the blend gives the impression that the blends are lacking in interfacial adhesion. The interpretation enabled by the NMR estimates of degrees of crosslinking for the phases within the blends demonstrates that there is no lack of interfacial adhesion in blends of NR and NBR having a low acrylonitrile content, although blends containing a minor proportion of NR and vulcanized with sulfur/TMTM may show cohesive failure of the NR phase when the NBR phase is highly swollen due to the low degree of crosslinking of the NR.
Processing of EPDM Polymers as Related to Structure and Rheology
Authors: Beardsley Kenneth P. , Tomlinson Richard W. 
Published: February 2011

Abstract
We have shown that the rate of mixing oil and carbon black with EPDM polymers having the same Mooney viscosity is dependent on their molecular-weight distribution and degree of branching. Samples having broad molecular-weight distributions mix more slowly than samples with more narrow distributions, and branched samples mix more slowly than corresponding linear samples. The slower mixing of samples that are branched or broad in molecular-weight distribution is a consequence of their more elastic character. These samples tend to be more non-Newtonian in their flow characteristics and thus have high viscosities at low shear rate and low viscosities at high shear rate. They also drop more in viscosity on mixing with oil. These factors cause these polymers to wet the carbon black more slowly and to have lower shear stresses during the mixing, leading to slower mixing.
Interaggregate Interaction in Filled Rubber
Authors: Roland C. M. , Lee G. F. 
Published: February 2011

Abstract
Measurements of the dynamic properties of carbon-black-filled rubber can be carried out on most instrumentation at strains within the limits of linear behavior; thus, assessments of acoustic performance can readily be made. The equivalence of small-strain dynamic-mechanical testing and acoustic measurements has been demonstrated herein. Blends of NR with a high concentration of 1,2-BR are attractive candidates for damping applications because of the extended frequency range of the glass to rubber transition. One approach to improving the magnitude of the damping is to incorporate high levels of carbon black into the material. Significant interaggregate interaction, promoted for example by a low degree of carbon-black dispersion, will amplify the energy dissipation. The strain dependence of the dynamic properties implicit in such an approach can result in a damping performance sensitive to deformation. The loss tangent rises significantly after such a deformation, while the loss modulus experiences a barely measurable decline. This sensitivity to deformation will thus impact more on constrained layer damping applications than on simple extensional damping. For the materials tested in the present study, complete recovery of the damage to the carbon-black network (which engenders the changes in dynamic mechanical properties) required more than a day at room temperature.
Application of Fatigue Methods Based on Fracture Mechanics for Tire Compound Development
Authors: Young D. G. 
Published: February 2011

Abstract
It is important to develop laboratory fatigue methods which are predictive of tire performance to minimize development time and costs. A basic premise of this paper is that fatigue testing based on fracture mechanics principles has major advantages over traditional methods or those which attempt to simulate the geometry of the composite tire in the laboratory. Basic fracture-mechanics theory will be reviewed, followed by summaries of previously published studies. Three new studies will illustrate the wide applicability of the methodology.
FTIR Spectroscopic Studies of Miscible Polymer Blends
Authors: Yamada Kazuhiro , Funayama Yoshinori 
Published: February 2011

Abstract
The miscibility of IR and V-BRs with various vinyl contents has been investigated by using DSC and temperature-dependent FTIR spectroscopy, from which we conclude: 1. The glass-transition temperatures of the sequences which relate to the microstructures in IR and V-BRs can be detected by using temperature-dependent FTIR spectroscopy. 2. A miscible polymer blend exhibits a single Tg in DSC thermograms. But, judging from the infrared spectroscopic probe, the IR segments and the V-BR segments do not begin to move at the same temperature. When the data of infrared spectroscopy are compared with those of DSC, it would be possible to conclude that Tg− corresponds to the onset of the segmental movement of IR and then V-BR segments begin to move next, resulting in the broadening of the DSC transition region. 3. This broadening of the DSC transition region originates from the disparity of Tgs between IR and V-BR and may not be necessarily related to the onset of phase separation.
Aging of Tire Parts during Service. II. Aging of Belt-Skim Rubbers in Passenger Tires
Authors: Kaidou Hiroyuki , Ahagon A. 
Published: February 2011

Abstract
The belt-skim rubber of a passenger-car tire has changes in its tensile properties, M100 and λb, during service in the field. The changes are larger in higher temperature fields with an equivalent duration. It can be interpreted that the changes are caused simply by oxidative crosslinking similar to that which takes place on aging rubber sheets in an air oven at relatively low temperatures, below 100°C. The belt-skim compound showing better aging resistance in the laboratory also shows better aging resistance when used in a tire. Therefore, the aging characteristics of the rubber part in a tire can be satisfactorily predicted. The Arrhenius equations with the same activation energy can be used for the aging of a rubber in the laboratory and in the tires by introducing a factor to the tire equation. The factor is added to the atmospheric temperature to correct for a difference; however, it was found to be slight in the present case.
Polymerization of Ethylene with Propylene by Soluble Titanium (III) Catalyst
Authors: Makino Kenya , Hattori I. , Watanabe M. 
Published: February 2011

Abstract
Soluble TiCl3 complex catalysts were prepared by reduction of TiCl4 with hydrogen in the presence of Pd-carbon and ether in a halogenated hydrocarbon solvent. When copolymerization of ethylene with propylene was carried out with the soluble TiCl3 catalysts, the catalytic activities were very high, and copolymers obtained showed low crystallinity. When a small amount of a metal chloride was added to the soluble TiCl3 catalysts, it was found that the catalytic activity increased and the crystallinity of copolymers obtained was lower compared with those of the copolymers prepared by the original soluble TiCl3 catalysts. The copolymers obtained by the soluble TiCl3 catalysts showed high tensile strength (TB) and elongation at break (EB). From these results, it is concluded that the large values of TB and EB are caused from the microblock sequences of ethylene.
New Studies on the Surface Properties of Carbon Blacks
Authors: Ayala J. A. , Hess W. M. , Dotson A. O. , Joyce G. A. 
Published: February 2011

Abstract
A series of carbon blacks of widely varying morphology and microstructure were analyzed for surface compositional properties employing SIMS, XPS/ESCA, and GC-MS. These studies were supported by bulk analyses for hydrogen and oxygen content. Surface reactivity was assessed by means of inverse gas chromatography, moisture adsorption, and oxidation in an oxygen plasma. To directly assess carbon-black-polymer interaction, the carbon blacks were evaluated in SBR and IIR compounds for stress-strain and dynamic properties as well as bound rubber. The major findings of these studies are: 1. The combined results of hydrogen content, SIMS, and pyrolysis-GC-MS suggest a complex hydrogen functionality at the carbon-black surface, which governs the level of interaction with elastomers. 2. SIMS analyses have shown that the hydrogen functionality at the carbon-black surface is preserved after an 1173 K heat treatment in an inert atmosphere. 3. Gas-solid chromatography results indicate that this technique may be very useful to determine the degree of heterogeneity of a carbon-black surface. It also provides a tool to characterize the nature of the surface sites which are responsible for such a heterogeneity. 4. Moisture-adsorption rates provides a means to explore the reactivity of carbon-black-surface sites. Initial rates of adsorption can be well explained by a second-order-rate mechanism. 5. Bound-rubber development (SBR) and oxygen content per square meter of carbon-black-surface area were directly proportional to the hydrogen content of the black. The hydrogen content is considered to be the primary compositional factor relating to carbon-black-surface activity, while bound rubber and oxygen levels are specific measures of surface reactivity. 6. The slope of the stress-strain curves (or the modulus value) in the λ=1 to 3 region divided by the black networking factor, η (E′ at 2% ptp ÷ at 25% ptp), is sensitive to changes in black-polymer interaction. This ratio (σ/η or M/η) shows an excellent correlation with black hydrogen content and bound rubber (SBR). 7. The σ/η values for SBR and IIR are highly correlated, although the values for SBR are two to three times higher, and there was no measurable bound rubber for any of the IIR compounds. 8. The σ/η values for IIR (λ=2−3) and the oxygen/m2 values were found to be the best discriminators for black-polymer interaction in explaining within-grade treadwear variations in SBR/BR multisection radial-passenger treads.