bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of p-Phenylenediamine Antiozonant in Polychloroprene Rubber
Authors: Potter Noel M. , Mehta Ram K. S. , Wyzgoski Michael G. 
Published: February 2011

Abstract
Elastomers susceptible to ozone cracking can be protected by the addition of antiozonants. For polychloroprene (CR) rubber, a mixture of diaryl-p-phenyl-enediamines, Wingstay 100 (WS 100), is one of the most effective antiozonants. Preliminary studies in our laboratory have shown that the effectiveness of WS 100 can be improved even further by the use of an organobentonite clay. To provide more insight into the way in which this antiozonant provides resistance to ozone cracking, a technique for its analysis was required. High performance liquid chromatography (HPLC) is an attractive technique for analyzing WS 100, as well as for a wide variety of additives in polymers. This study describes a newly developed method for the determination of WS 100 in CR. The method is based on acetonitrile extraction of the antiozonant from the rubber, followed by quantitative analysis using HPLC. With this method, subtle differences in concentrations of WS 100 in CR, caused by changes in compounding, mixing sequence, curing conditions, and grease extraction, have been measured.
Processability Testing of Injection Molding Rubber Compounds
Authors: Sezna John A. , DiMauro P. J. 
Published: February 2011

Abstract
A simple model of the injection molding process has been constructed using data from a capillary rheometer (MPT) and the Oscillating Disk Rheometer (ODR). For an NR and an SBR compound, the model had an excellent correlation with injection molding trials. The model successfully predicted the effects of adjusting injection pressure, mold temperature, and barrel temperature on injection times and scorch conditions. Such a model enables an injection molder to predict the effect of adjusting molding conditions, optimize his process for a given mold and compound, and control processability of his compounds batch-to-batch.
Correlation between End Correction and Extrudate Swell for Some Raw Elastomers and Black-Filled Rubber Compounds
Authors: Kannabiran R. 
Published: February 2011

Abstract
A good linear correlation between end pressure and recoverable energy has been shown to exist for some raw elastomers and black-filled rubber compounds. The recoverable energy calculated from extrudate swell is almost a constant fraction of exceess energy given by end pressure for the materials studied in the given entrance geometry with the exception of NR.
Mechanisms of Antiozonant Protection: Antiozonant-Rubber Reactions during Ozone Exposure
Authors: Lattimer R. P. , Layer R. W. , Rhee C. K. 
Published: February 2011

Abstract
Rubber (IR or BR) vulcanizatcs containing DOPPD antiozonant have been aged under ozone, and the soluble constituents have been removed by acetone extraction. Small amounts of nitrogen from the antiozonant remain in the rubber after extraction; this nitrogen is presumed to be chemically attached to the polymer network. Some of this “unextractable nitrogen” may be due to reaction of ozonized rubber with antiozonant, but other explanations are possible. The amount of unextractable nitrogen in the vulcanizate before ozone aging is about the same, within experimental error, as the amount remaining after static ozone aging. Model compound experiments (with cis-9-tricosene or squalene) show that chemical reactions can take place between the ozonized olefins (or unsaturated rubber) and DOPPD. The chemical structure for a model reaction product has been determined. Despite these findings, it seems unlikely that these types of reactions will play a significant role in the overall protection of rubber vulcanizates from ozone attack. That is, these products can form only after the rubber starts to become ozonized, and it has been shown that ozone attack on the rubber does not occur until after the antiozonant is nearly completely consumed. The results of this work are consistent with previous studies in our laboratory that indicate a combined “scavenger-protective film” mechanism is principally responsible for antiozonant protection. There is no definitive evidence to date to show that ozonized rubber reacts with antiozonant during ozone aging of rubber vulcanizates.
Thermal and Age-Resistance Properties of NR Gum Vulcanizates in EV Systems
Authors: Datta Rabindra Nath , Das Mathur Mohan , Basu Dipak Kumar , Chaudhuri Ajit Kumar 
Published: February 2011

Abstract
A comparative study of the cure behavior of thiocarbamyl sulfenamides both in the presence of MBTS and thiazole sulfenamides has been made at 140 and 170°C. It is observed that most of the NR vulcanizates obtained at 170°C are capable of retaining a considerable portion of torque, modulus, and tensile values obtained at 140°C. This provides information regarding the heat resistance of these vulcanizates. It is observed that ZDC's up to a certain concentration increases the thermal resistance of the NR vulcanizates, the maximum effect being produced by ZBD and ZPD. ZOD and ZPD above a critical concentration, impart a deleterious effect to NR gum vulcanizates where a drop in the R∞ value is observed. The age resistance property of the various combinations of thiocarbamyl sulfenamides plus MBTS and thiazole sulfenamides plus thiocarbamyl sulfenamides has been discussed. It is evident from the study that the former combination generally provides higher physical properties of the vulcanizates and better age-resistance than those obtained with the latter combination. Vulcanizates obtained with the CTOS-MBTS combination in the presence of ZDC's provide notable thermal as well as age-resistance.
Mechanisms of Antioxidant Action: The Antifatigue Mechanism of Nitrosamines
Authors: Dweik H. S. , Scott G. 
Published: February 2011

Abstract
1. The present studies have shown that N-nitrosamines derived from the more active diarylamine antifatigue agents are considerably more effective as antifatigue agents than the parent amines when they are predispersed into rubber on an open mill, followed by conventional vulcanization. 2. Some N-nitrosamines are effective retarders of premature vulcanization. 3. All the nitrosamines examined with the exception of nitroso diphenylamine are effective heat stabilizers for rubber in an air oven test. 4. The nitrosamines are partially converted to the parent amine during vulcanization, but other products are also formed which contribute to the antidegradant activity.
Mechanisms of Antioxidant Action: Complementary Chain-Breaking Mechanisms in the Mechanostabilization of Rubbers
Authors: Nethsinghe L. P. , Scott G. 
Published: February 2011

Abstract
It is clear that aliphatic nitroxyls cannot function effectively in the catalytic CB-A/CB-D cycle (Scheme 1) during mechanodegradation in a sulfur vulcanizate, although they have been shown to be effective mechano-chemical inhibitors in rubbers before vulcanization. Aliphatic nitroxyls appear to be more effective when they contain an additional CB-D function.
Elastomers from Polymeric Chelates
Authors: Iwamoto Nancy , Eichinger B. E. , Andersen N. H. 
Published: February 2011

Abstract
In the previous work, we demonstrated that gels may be formed from polymeric acetylacetonate chelates. Now it has been shown that useful elastomers can be prepared from these derivatized polymers as well. Stress-strain measurements have been performed on these Pd(II) crosslinked SIR elastomers, and the results demonstrate that the materials are useful for physical testing. Because of unforeseen complications, we do not yet have a perfectly ideal system to solve fully the problems mentioned in the Introduction. The observations reported here are more than sufficient to encourage us to pursue this research vigorously. The difficult synthesis of ACAC-endcapped PDMS that has been achieved provides a viable route to model networks. What is required now is that we focus attention on the inorganic chemistry in an effort to better understand such things as the kinetics of ligand exchange reactions and the structure of ACAC complexes in low polarity media.
End Group Effects in Polymer Modification of Calcium Carbonate Fillers
Authors: Nakatsuka Takuo , Kawasaki Hitoshi , Yamashita Shinzo 
Published: February 2011

Abstract
Two types of polymer, e.g., polybutadiene and poly(oxy-2-butenyleneoxyfumaroyl), having four different end groups, were prepared and used to treat ground and precipitated calcium carbonate fillers. The coupling effects of the polymer modifiers were evaluated from the physical properties of the filler-loaded vulcanizates of sulfur-cured SBR and peroxide-cured EPDM. The phosphate-terminated polymer was found to be an excellent surface modifier of the ground calcium carbonate filler. For the precipitated calcium carbonate filler of superfine grade, higher coupling effects were attained by the phosphates having relatively small alkyl groups. The modification mechanism is also discussed by taking into account the results of infrared spectroscopy, x-ray analysis, gel permeation chromatography, scanning electron micrography, and BET analysis.
Polymerization of Butadiene and Isoprene with Lanthanide Catalysts; Characterization and Properties of Homopolymers and Copolymers
Authors: Hsieh H. L. , Yeh H. C. 
Published: February 2011

Abstract
The lanthanide polymerization catalysts represent a significant achievement in the synthesis of stereospecific high-cis cis-polybutadiene, high-cis cis-polyisoprene, and high cis random and block copolymers of butadiene with isoprene. In contrast to the conventional 3d transition metal catalysts, changes in lanthanide metals, halogens, and ligands do not significantly affect the cis-1,4 content of the polymer. But, the catalyst activity is greatly dependent on the choice of lanthanide elements, counterions, and donor ligands. Energy efficient processes are possible by performing the polymerizations in low boiling aliphatic hydrocarbon solvents with high solids content and possibly, in the gas phase. In addition, the described lanthanide catalysts are very effective for producing high cis polymers with a broad range of molecular weights.
Model Vulcanization of EPDM Compounds—Part III. Influence of Vulcanization System on the Vulcanization Products from Ethylidene Norbornane
Authors: van den Berg J. H. M. , Duynstee E. F. J. , Maas P. J. D. 
Published: February 2011

Abstract
The vulcanization of ENBH (C9H14), a model for vulcanization of EPDM containing ENB, was studied (140°, 1 h) using four different vulcanization systems (conventional, sulfur free, low-sulfur and high-sulfur). The influence of the system on the total yield of crosslinked products (C9H13—Sn—C9H13) is considerable, low-sulfur giving the lowest and high-sulfur giving the highest yield. The influence of the system on the composition of the crosslinked products as determined by HPLC is surprisingly small. By using 1H-NMR it was shown that formation of monosulfides is almost negligible under our conditions with all four vulcanization systems.
Epoxidized Natural Rubber
Authors: Baker C. S. L. , Gelling I. R. , Newell R. 
Published: February 2011

Abstract
When natural rubber is epoxidized under carefully controlled conditions, it can be converted to a totally new polymer with some properties more akin to speciality rubbers and some properties that appear to be advantageous for tire treads. Three levels of epoxidation have been extensively evaluated. They were 50, 25 and 10 mole% epoxidized NR referred to as ENR-50, ENR-25 and ENR-10 respectively. ENR-50 has been found to undergo strain crystallization like NR, but with oil resistance similar to a medium acrylonitrile NBR and gas permeability similar to butyl rubber. It is a highly damping rubber with a very low room-temperature resilience. ENR-50 and ENR-25 both exhibit good wet grip characteristics and have been examined as tire tread materials. In particular, ENR-25 compounds containing silica or silica/black have been found to give lower rolling resistance than NR and better wet traction than OESBR, so providing an ideal combination of these two properties for tire treads. Unfortunately, wear data is as yet incomplete, but it is anticipated, from truck tire experience, that the black/silica compounds will present no problems. ENR-25 and ENR-50 exhibit this unique feature with silica of reinforcement equivalent to black without the use of a coupling reagent. Thus, these rubbers have potential of providing white or colored vulcanizates with properties previously associated only with black-filled compounds, so extending applicational areas, or even resulting in colored tires or other automotive parts. ENR-10 provides a damping grade of NR when lower resiliences are required. Alternatively, blends of ENR-25 or -50 with NR may be used. Many engineering applications are calling for reduced resilience, and this new form of NR can give precisely this.
Recycled Rubber Crumb as a Toughener of Polystyrene
Authors: Pittolo M. , Burford R. P. 
Published: February 2011

Abstract
Our preliminary investigations indicate that recycled rubber crumb may be used as a toughening agent for brittle thermoplastic such as polystyrene. The toughness of the resultant materials was found to increase with increasing rubber-to-matrix adhesion and decreasing particle size. Although crazing is expected to play some role in the toughening mechanism, the absence of a yield point and the type of fracture morphology indicate it is only a minor factor It is suggested that the main contribution is from a crack bridging mechanism. The increased energy to break results from the rupture of the rubber particles. Further studies in which crumb with known tear strength and tensile properties is used as a filler are currently being carried out. It is hoped that this will lead to a clearer understanding of the toughening mechanism.
Viscoelastic Properties of a Class of Carboxylated Rubbers: The Carboxylato-Telechelic Polydienes
Authors: Jéróme R. , Broze G. 
Published: February 2011

Abstract
Halato telechelic polymers are well-characterized ion-containing polymers the investigation of which gives the scientist a clear insight into the role played by the ions in the modification of the base polymer properties. The end-neutralization of very short length, α,É-dicarboxylic acid polydienes by alkaline earth alcoholates triggers off the crosslinking of the rubber. In a nonpolar environment, the metal carboxylate bonds constitute ion pairs which associate into separate domains responsible for the vulcanization and the reinforcement of the rubber. For the very first time, the relaxation of these ionic domains has been observed and thoroughly investigated. Its mechanism obeys an Arrhenius-type of temperature dependence, whereas the activation energy strongly depends on the ion pair features. When entangled acid-ended polydienes are end-neutralized, an efficient crosslinking is again reported, whereas the relaxation of ionic domains is no longer observed. It means that the ion pair association is extended enough to stabilize a network of entangled chains, but that the size of the aggregates is too small to be accurately detected. In the series of alkaline earth metals, the higher the ionic radius, the less interacting the ion pairs. Nevertheless, the strength of the formed network increases with the ionic radius, which means that the functionality of the crosslinks, i.e., the mean size of the ionic aggregates, increases too. The extent of the ion pair association is therefore largely independent of their anchoring at the ends of macromolecules and is mainly related to the geometry of the metal carboxylates and to their mutual interaction.
Sulfur Vulcanization and Oxidative Aging of Epoxidized Natural Rubber
Authors: Gelling I. R. , Morrison N. J. 
Published: February 2011

Abstract
1. Vulcanization by sulfur alone is faster and more efficient for ENR than for NR because isolated double bonds react more rapidly than contiguous double bonds. This vulcanization may be accelerated by sodium carbonate, which also protects the cured rubber against the subsequent effect of oxidative aging, and the scorch time may be increased by the addition of CTP. 2. The CBS-accelerated sulfur vulcanization of ENR is essentially similar to that of NR, although ENR reacts with MBT formed during the process. 3. The poor aging of sulfur vulcanizates of ENR is due to acid-catalyzed ring-opening reactions of the epoxide groups with the formation of ether crosslinks. The acids are produced by the thermal decomposition of oxidized sulfides. 4. The addition of a suitable base confers excellent resistance to oxidative aging upon conventional, semi-efficient, and efficient vulcanizates of ENR.
A Review of Recent Developments in the Mechanisms of Antifatigue Agents
Authors: Scott Gerald 
Published: February 2011

Abstract
In spite of the remarkable advances that have been made in the engineering design of tires during the past two decades, the basic formulations used in vulcanization and protection during service have essentially remained unchanged. This is to a large extent due to two major factors: 1. The versatility of the traditional accelerated sulfur curing system which provides the necessary combination of resilience and strength with good resistance to cyclical stress. 2. The development of diarylamine antidegradants which confer a high level of thermal-oxidative and mechano-oxidative (fatigue) resistance to the rubber. Both of these developments have occurred slowly with small incremental improvements and, probably because of their success, relatively little fundamental work has been published which addresses the questions of why a polysulfide network is so resistant to fatigue and why N-sec-alkyl-N′-phenyl-p-phenylenediamines are so much more successful as antidegradants than other classes of antioxidant. It is becoming evident, however, that if tires are to withstand the increasingly demanding conditions to which they are subjected in service, much more attention must be paid to the material design as opposed to the structural design of tires. Nowhere is this more evident than in aircraft tires. Recent studies have shown that the tires of heavily laden wide-bodied aircraft reach temperatures in excess of 70°C at the relatively modest speed of 32 km/h (20 mph). Similarly, in heavy duty truck tires, temperatures over 100°C are not abnormal in the shoulder region. This leads to extensive restructurization of the fatigue resistant polysulfide network, particularly in the shoulder of the tire, to give a much weaker mono-disulfide structure. It is no coincidence then that failure normally occurs in this region. The practice of multiple retreading exacerbates the change in chemical decomposition of the rubber. It is well known to the rubber scientist that extending the vulcanization process also leads to restructurization of the rubber network from polysulfide to mono- and disulfide. This is shown typically for a HAF-black tire formulation at 140°C in Figure 1. Antidegradants have virtually no effect on anaerobic restructurization (see Figure 2), and indeed, the established antifatigue agent, IPPD (I), actually accelerates the loss of polysulfide crosslinks from the vulcanizate at 140°C. During fatiguing, on the other hand, IPPD effectively retards restructurization (see Figure 3), whereas a typical bisphenol, nonstaining antidegradant, II, has much less effect.
Vulcanization Chemistry
Authors: Morita E. , Sullivan A. B. , Coran A. Y. 
Published: February 2011

Abstract
Prevulcanization inhibitors based on triazines can be prepared. In each case the triazine ring is amino-substituted such that one or two of the amino hydrogen atoms per amino-group are alkylthio- or arylthio-substituted. The new triazine-derived prevulcanization inhibitors are extremely active in accelerated sulfur vulcanization of diene rubbers (e.g., NR or SBR). Differing accelerators or accelerator systems may require different triazine-derived prevulcanization inhibitors for best results. Provided that the reactivity of the inhibitor is sufficiently near the ideal, its weight-basis activity is greatest when its equivalent weight per S—N bond is least. Overall, hexakis(cyclohexylthio)melamine and especially hexakis(isopropylthio)melamine are the most effective premature vulcanization inhibitors tested, on an equal-weight basis.
Analysis of Rubber, Resin, and Moisture Content of Guayule by Near Infrared Reflectance Spectroscopy
Authors: Black L. T. , Hamerstrand G. E. , Kwolek W. F. 
Published: February 2011

Abstract
Although the overall error associated with the NIR analysis of guayule may be slightly higher than that of some other methods, the trade-off between the increased error and the very rapid aquistion of data by NIR is quite positive.
Carbon Black in NR/BR Blends for Truck Tires
Authors: Hess W. M. , Vegvari P. C. , Swor R. A. 
Published: February 2011

Abstract
A series of ten commercial tread-grade carbon blacks were evaluated in a 60/40 NR/BR truck tire tread formulation. A number of important physical properties and performance criteria were assessed in terms of carbon black surface area and DBPA. Significant response equations were obtained for viscosity, bound rubber, resilience, heat buildup, tear strength, and dynamic properties. Dynamic modulus showed a much greater dependence on DBPA in comparison to previous studies on SBR/BR compounds. In a second designed experiment, a single carbon black (N299) was studied as a function of the NR/BR ratio and the amount of carbon black added to the BR phase. The BR black loading was varied at 30, 60, and 90 phr using separate masterbatches which were blended with NR-black masterbatches to give the same final composition for all of the compounds. Properties such as resilience, heat buildup, fatigue life, and tear strength were all improved in the direction of higher loadings of carbon black in the NR phase. A high loading of black in the BR phase caused low bound-rubber development and poor dispersion. This was found to be related to the viscosity ratio of the separate masterbatches. NR to BR viscosity ratios of about 1 to 3 produced good dispersion and high bound rubber. When the BR masterbatch viscosity was two to three times higher than the NR masterbatch, however, dispersion and bound-rubber development dropped sharply at the same total mixing energy. Low hysteresis properties were found to be most dependent on high bound-rubber development, with polymer phase distribution having a relatively minor influence. In contrast, tear strength and fatigue life reached their maximum levels when the NR was the more continuous polymer phase. High bound rubber also appears to enhance tear strength and fatigue life by improving the microdispersion of the carbon black.
Effect of Pressure and Shear on Compaction of Powdered Rubber with Carbon Black
Authors: Nakajima N. , Kumler P. R. , Harrell E. R. 
Published: February 2011

Abstract
During the incorporation stage of mixing carbon black with elastomer, the mixture becomes one solid mass, i.e., compacted. In this process, the elastomer must be deformed to conform with the topology of carbon black. This work attempts to elucidate the mechanism of compaction. In particular, the effects of static pressure and shear on compaction have been examined. A Sieglaff-McKelvey capillary rheometer was used for the higher pressure range and a Rheometrics mechanical spectrometer for the lower pressure range. A mixture of powdered rubber and carbon black was used. With static pressure alone, the compaction was slow and ineffective because the mixture forms a bridge structure. The compacted material was friable. With the application of shear, the bridge structure was easily broken, the compaction was attained immediately, and the compacted material was “fused” together. However, the application of shear was effective only when there was no slip between the rotor surface and the elastomer compound.