bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mold-Flow-Induced Anisotropy in Nitrile Rubber
Authors: Chang W. V. , Yang P. H. , Salovey R. 
Published: February 2011

Abstract
1. Data in all the investigated locations showed anisotropic swelling. The anisotropy is believed to be induced by vulcanization of the rubber in a strained state caused by mold flow. 2. Data and theories of composite networks suggest that the swelling of rubber in the strained direction would be less than in other directions. 3. Anisotropic swelling data were consistent with the flow pattern of rubber in the mold. 4. The volumetric swell ratios at different locations varied only slightly, in-dicating that crosslinking was uniform. 5. The shear rate for compression molding is 1–10 s−1, calendering is 10–102 s−1 extrusion is 102–103 s−1, and injection molding is 103–104 s−1. Hence, rubber products processed by other methods are expected to be even more anisotropic. 6. Microswelling is a fast and easy technique to monitor the strain-induced anisotropy and to infer the flow pattern during mold filling. 7. Mechanical data of composite networks formed under different strains should be collected, and theories should be checked, then, mechanical behavior of networks based on microswelling data may be predictable. 8. Engineering design for both end use and molding should take this frozen strain-induced anisotropy into consideration.
Processability Testing
Authors: Norman R. H. , Johnson P. S. 
Published: February 2011

Abstract
There should be no need for processability testing. If one controls adequately all the raw materials and all the processes prior to the tests, then the resultant materials will all have predictable processability. In the real world, one can try, but never achieve, this state of perfection, so that some processability testing may be essential for process control purposes. The progression from (a) dumping a mixed batch at constant cycle time to (b) dumping at a fixed temperature to (c) dumping at a fixed unit work shows a progressive attempt to produce a more consistent material in spite of the imperfections of the raw material and the process. No one processability tester is adequate for all purposes. The choice of processability testers for process control depends upon the polymer and the subsequent process to which the material or mix is to be subjected. Factors which can be significant are times, shear rates, temperatures, and whether the test modifies the relevant properties. Most of the published information relating to process control relates to controlled experiments rather than to processing under normal factory conditions. However, it is probable that much information on factory experience remains unpublished in order to avoid disclosure of commercially valuable information or, on the other hand, to avoid admission of mixing failures. The cost of purchasing and running the processability testing equipment has to be balanced against the costs of not recognizing a bad batch and the cost of delaying further processing while the tests are made. For these reasons no general recommendation can be made except that a single piece of data is insufficient to characterize either a polymer or a mix. Any factory will probably need several types of processability testing if it wants more than a very cursory view of the material being processed. The choice of a processability test for development of mix composition depends upon the degree of information which it is economical to acquire. If an order calls for an isolated 400 kg of material for a noncritical application, it may be worth doing no processability testing at all. On the other hand, if a factory is to produce hundreds of tonnes per week of a single type of mix, it is well worth while discovering considerable detail about the characteristics of that mix. In this case, equipment providing fundamental data over a wide range of shear rates and at small and large strains may avoid carrying processes so near to a critical condition that any slight change in material or process may cause a catastrophe. Many factory activities fall between these examples and thus require individual consideration.
Recent Advances in Gel Permeation Chromatography
Authors: Ouano A. C. 
Published: February 2011

Abstract
Gel permeation chromatography (GPC), sometimes referred to as size-exclusion chromatography (SEC), has progressed at an almost explosive rate since its introduction less than two decades ago. One has only to refer to the open literature or thumb through the list of Chromatographic equipment manufacturers anxious to sell their latest innovation to be fully convinced of this fact. Because of the extensive progress in GPC technique and instrumentation, the author had a very difficult time in deciding the scope of this review. Mindful that he may be criticized of being myopic in his presentation of the most significant and recent contributions and guilty of gross omission of important references, the author has nevertheless decided to narrow the scope to three major areas and a few key references. The three major areas to be covered are: (1) data acquisition and processing, (2) high-pressure chromatography and (3) detectors. Extensive progress has been made in the computerization of both data acquisition and data reduction, the latter allowing molecular weight distribution (MWD) and molecular weight averages to be obtained on the sample in a matter of minutes rather than hours or days. The main beneficiaries of the computerization of data acquisition and processing have been those concerned with polymer quality control, for it has liberated them from the drudgery of the manual digitization, integration, and normalization of the chromatograms required to reduce them to a useful format. The hours of monotonous eye-straining work to obtain MWD and molecular weight averages has been reduced to a few seconds of punching a few keys of the data system console. The development of the high-pressure Chromatograph has added a new dimension to GPC, for, when it is combined with a computerized data system, the MWD can be obtained almost in real time in relation, for example, to a characteristic time of a polymerization reactor. In high-speed Chromatograph y under nearly ideal conditions (low-viscosity mobile phase and molecular weight of no more than a few hundred thousand), the MWD can be obtained in a few minutes. This capability allows the use of GPC as on-line process-control equipment. The Chromatograph can be used as part of a “feed-back” loop to control the polymerization conditions to obtain a product of consistent MWD.
Recent Advances in Anionic Polymerization
Authors: Halasa Adel F. 
Published: February 2011

Abstract
In summary, one can say that the versatility of living polymerization makes it a very useful and unique technique. Synthetic polymer chemists can utilize the lithium at the end of the chain to add polymer-like conjugated monomers, in order to tailor-make the polymer chain, or they can use chelating diamines to change the microstructure of the polymer chain. They can also run hydrogenation on anionically prepared polydienes to produce thermoplastic elastomers. They can transform anionically made polymer chain ends by adding ethylene oxide, carbon dioxide and halogens. This paper has emphasized recent advances in this field.
Time Dependent Nonlinear Viscoelastic Behavior of Polymer Fluids—A Review of Current Understanding
Authors: Soong David S. 
Published: February 2011

Abstract
The behavior of concentrated polymer solutions and melts in transient flows has been under active investigation in recent years. This research interest stems from the realization that a better understanding of these time dependent phenomena has the potential to greatly improve existing industrial processes and to provide new insights to polymer dynamics. In this article, various aspects of the transient viscoelastic properties are discussed. Special emphases are placed on some important considerations in acquiring reliable transient data. Several promising network theories capable of interpreting these experimental results are reviewed. Future research challenges, such as the design of more complicated and stringent rheological tests for the established models, have also been identified.
Guayule
Authors: Eagle F. A. 
Published: February 2011

Abstract
The microstructure of both GR and NR is comprised of cis-polyisoprene units, resulting in a physicochemical similarity between the two rubbers. However, the processing and vulcanizate properties of guayule and NR differ when the former is substituted in standard NR formulations. Since GR and NR do not contain the same nonrubber constituents, equivalent compounding and processing may not work equally well on both. Therefore, guayule's formulations must be modified in order to use its properties to best advantage. This has recently been demonstrated using standard production equipment and modified NR formulations, with very little disruption to the manufacturing process. It can therefore be concluded that guayule is a useful substitute for NR, and once it is commercially available, applications will be readily found.
Elastomeric Diene/Polyhalophenyl Acrylic Copolymers with Intrinsic Flame Retardance
Authors: Weinstein A. H. 
Published: February 2011

Abstract
It is well known that certain aliphatic or aromatic halogen-containing substituents impart flame retardance to compounds containing them. This fact has been applied not only to development of fire retardant additives for organic compositions but also to preparation of various halogen-containing polymers with intrinsic fire retardance. These include resinous or fibrous homopolymers or copolymers of polyhalophenyl methacrylates or acrylates. The monomers used for these contain relatively high concentrations of highly heat stable aromatic halogen groups and may be prepared by various means from available, potentially low-cost polyhalophenols. The present report describes efforts to prepare elastomeric diene-copolymers with intrinsic flame retardance by the use of such monomers. Utilization of these monomers for the preparation of elastomeric terpolymers with fairly good low-temperature properties and oil resistance is also illustrated.
Vulcanization and Vulcanizate Properties of a Fluoroelastomer Containing Epoxy Groups as Cure Sites
Authors: Kojima G. , Kojima H. , Morozumi M. , Wachi H. , Hlsasue M. 
Published: February 2011

Abstract
The vulcanization behavior and vulcanizate properties of tetrafluoroethylene-propylene elastomer containing a small amount of glycidyl vinyl ether as cure site was investigated both at room temperature and at high temperature with different types of the vulcanizing agents. The conclusions are: 1. Glycidyl vinyl ether incorporates into the tetrafluoroethylene-propylene copolymerization system without disturbing the alternating microstructure and works as an efficient cure site. 2. The room-temperature vulcanization of the terpolymer proceeds at an adequate rate when tris(dimethylaminomethyl)phenol is used as the curative together with phenol as the accelerating agent. 3. Coatings of the terpolymer make a tough finish on many substrates such as steel and hydrocarbon rubbers and protect the substrates from hostile environments. 4. The vulcanization behavior of the terpolymer at high temperature is much influenced by the kind of curative. The carboxylate of hexamethylenediamine [e.g., hexamethylenediamine-N,N′-bis(p-isopropylbenzoate)] provides balanced vulcanization behavior and mechanical properties suitable for molding articles of complex shapes. 5. The mechanical and chemical properties of the high-temperature vulcanizate thus obtained are similar to those of the tetrafluoroethylene-propylene binary system vulcanized by peroxide.
Influence of Large Static Deformation on the Dynamic Properties of Polymers Part II. Influence of Carbon Black Loading
Authors: Meinecke E. A. , Maksin S. 
Published: February 2011

Abstract
The influence of carbon black loading on the dynamic properties of statically deformed elastomers has been investigated. The energy loss per cycle was found to increase according to the square of the strain amplification factor as expressed by the Guth-Gold-Einstein equation. The dynamic complex modulus |E*| is approximately equal to the static modulus obtained from the slope of the static stress-strain curve. The influence of carbon black loading on E* can, therefore, be predicted from its influence on the static stress-strain curve which was found to be governed by the first power of the strain amplification factor. The tangent of the loss angle can thus be predicted from |E*| and the energy loss per cycle. It does not only depend upon the dynamic viscosity of the material; it also depends upon the shape of the stress-strain curve as well.
Study of Transport Phenomena in Guayule Deresination
Authors: Budiman S. , McIntyre D. 
Published: February 2011

Abstract
Renewed interest in guayule as an alternative source of natural rubber has brought the processing aspect back into focus as an important determinant in the effort of guayule commercialization. To meet the current technological requirement, the quality of the guayule rubber needs to be standardized like the presently known Technically Specified Natural Rubber. In order to produce good standard quality guayule rubber, the resin constituent must be thoroughly and consistently eliminated. This condition stipulates an effective and efficient extraction process which in consequence demands a thorough understanding of the resin compounds and their behavior during extraction with acetone. The emphasis of this study is to examine the physical state of resin inclusion in the rubber and the mechanism of its removal during solvent extraction. The ultimate objective is to determine the necessary transport parameters in the deresination process of guayule latex coagulum, better known as ‘worms’ in popular terminology. Worm deresination was used in guayule processing in the U. S. during World War II, and it is currently also performed in the CIQA Pilot Plant in Saltillo, Mexico. Previous work on the subject had been carried out by Banigan and Clark of the U. S. Natural Rubber Research Station at Salinas, California in the early 1950's. Banigan had determined that the worm deresination occurred by diffusion and made experiments to determine diffusion coefficients using thin sheets of dried worms with acetone, ethanol and methylethyl ketone as solvents. He also noted the possibility of two different diffusion coefficients due to the mixed nature of guayule resin. Recent investigations at CIQA have confirmed that the resin consists of two major groups, namely the nonvolatiles and the volatiles. The nonvolatile components are mainly fatty acid triglycerides, while the volatiles are terpenoids such as α-pinene, dipentene, etc. The present study attempts to provide more detailed transport data using modem analytical techniques and the current knowledge of transport processes in polymeric materials. Since the available diffusion data are only for dried worms, whereas in reality the worms are deresinated in the wet state, the present work has used wet worms as the study material.
Transport Methods of Determining Particle Size Distributions in Colloidal Systems
Authors: Shuster C. D. , Schroeder J. R. , McIntyre D. 
Published: February 2011

Abstract
The two techniques examined in this work yield information about the particle size distribution of the latexes studied. The ease of measurement is improved over previous methods used on broadly distributed latexes. The TPC curves for both the natural and synthetic latexes correlate with the centrifuge curves. Both techniques show the Hevea to have larger particles than the guayule. The techniques also show SBR latex samples 1 and 2 to have larger particles than samples 3 and 4. The TPC is useful only for particles between 0.3 µm and 20 µm in size. The centrifuge can be used for any size range of particles by altering the rotor speed or eluant density. By employing the proper mathematics, these data could be easily converted from optical density distributions to particle size distributions.
Shearography: A New Optical Method for Nondestructive Evaluation of Tires
Authors: Hung Y. Y. , Grant R. M. 
Published: February 2011

Abstract
Shearography, a new means of nondestructive testing, has been presented. This paper merely gives some preliminary exploration of shearography for non-destructive testing of tires. Nondestructive testing by shearography is based on the comparison of two states of strain in tires. Ideally, it is desirable to impose stresses similar to those found in service and in an actual malfunction. Therefore, methods of stressing more realistic than the present method of stressing by partial vacuum should be explored. It is believed that only the surface of the potential of shearography has been scratched. In fact, shearography can be used to evaluate the integrity of virtually any structural components, built of any materials—plastics, rubber, metals, composite materials, etc. The full capability of shearography still awaits to be explored.
Gelation and Fusion Characteristics of PVC Resins in Plastisols by Determination of Their Viscoelasticity
Authors: Nakajima N. , Ward D. W. 
Published: February 2011

Abstract
A poly(vinyl chloride) (PVC) plastisol is a suspension of fine particles of PVC dispersion resin in a plasticizer. The particle size ranges typically from about 15 to 0.2 µm and smaller. The PVC particles in the plastisol consist of the primary particles, which are products of polymerization, and of the agglomerates of the primary particles, which result from the spray drying and subsequent grinding. The commercial applications of plastisols are coatings, films, sheets, foams and rotational castings, where the plastisol is first spread on substrates, and then heated to gel and fuse. PVC dispersion resins are used to produce a variety of formulations, including those for automotive applications, coated fabrics and resilient flooring. Requirements for the plastisols are many; for example, good air release, viscosity stability, fine particle size, foamability and good heat stability. In general, the processability requirements emphasize the rheological behavior at room temperature and the gelation-fusion behavior, the latter being the subject of this paper. When a PVC plastisol is heated, the resin particles are penetrated by the plasticizer and become swollen. Consequently, the system becomes a dry, coherent mass; at this point the material has not attained its ultimate strength. This stage is called gelation. Upon continued heating to a higher temperature (e.g., 195°C) the microcrystallites of PVC melt and the polymer molecules fuse together more uniformly. Upon cooling, the material exhibits the intrinsic strength of a plasticized PVC. The rates of gelation and fusion are important and are often critical aspects of the processing of the plastisol. For example, the rate of gelation controls the residence time needed to build the wall thickness desired in slush molded boots or hot dip molded pieces. Gel rate also affects the uniformity of rotocast parts and the penetration of plastisol into fabric in cast coating operations. Fusion rate and the rate of decrease in melt viscosity after fusion affect uniformity of cells in chemically blown foams. Therefore, many commercial grades of PVC dispersion resins are offered, each having a different rate of gelation, fusion and ultimate properties.
Ambient Temperature Effects on Tire Rolling Loss
Authors: Schuring D. J. , Hall G. L. 
Published: February 2011

Abstract
The temperature of the ambient air surrounding an operating tire is an important component of the complex thermal system producing rolling loss. Rolling loss is defined as the amount of heat generated by the rolling tire per unit distance. Figure 1 indicates that part of this heat is conducted and stored within the tire body, part is dissipated at the tire surface. The dissipated heat is directly affected by the temperature of the ambient air. Since all heat modes are interactive, the ambient air temperature must therefore influence the heat generated by the tire and, hence, its rolling loss. Presently, relations between ambient air temperature and rolling loss can be established only through measurements; mathematical models of tire heat generation and distribution have not reached a stage where they can be easily applied.
Water-Resistant Release Coating for Uncured Rubber
Authors: Kuan T. H. , Sommer J. G. 
Published: February 2011

Abstract
Rubber is conventionally formed into sheets or slabs on a two-roll mill. These are immersed in a release agent (slab dip), followed by cooling and drying in air. The low rate of cooling associated with air limits the throughput in rubber mixers. The throughput can be significantly increased through the use of water for cooling. However, water cannot be used with conventional slab dips; it washes them from the rubber slabs, causing the slabs to stick together after stacking. A new slab dip now permits cooling rubber slabs rapidly with water. After they are dried and stacked, the slabs do not stick together. The new dip contains a unique combination of a carboxylated SBR latex, a heat sensitizer, fillers and other additives. The heat sensitizer causes the latex to gel rapidly after it contacts the hot surface of the rubber slabs; this provides a water-resistant release coating. Other additives in this slab dip control its wetting and rheological behavior. The new dip does not significantly alter physical properties of rubber compounds after they are coated and reprocessed.
Thioketals as Prevulcanization Inhibitors
Authors: Morita E. , Sullivan A. B. 
Published: February 2011

Abstract
Thioketals prepared from active methylene compounds are introduced as a new class of nonthioimide prevulcanization inhibitors and compared to other inhibitors in various accelerator systems. The chemical nature of the inhibition by these thioketals has been examined from the interrelations of chemical structure of the thioketals, 13C chemical shift of the quaternary carbon, rate of reaction with 2-mercaptobenzothiazole, and scorch delay.
Factors Affecting the Extrudate Swell and Melt Fracture Phenomena of Rubber Compounds
Authors: Leblanc Jean L. 
Published: February 2011

Abstract
Post-extrusion swelling and extrudate distortion phenomena reveal the viscoelastic nature of elastomeric materials and are particularly critical in rubber processing. With the short dies used in the rubber industry, it is clear that extrudate swell depends not only on the rheological properties of the compounds, but also on the particular geometry of the extrusion system. Consequently, it is very difficult to compare laboratory results with the experience of industrial practice, because of the number and variety of extrusion processes. However, it is possible to draw some generally valid conclusions from the data currently available. The main factors affecting post-extrusion swelling and the critical conditions for the onset of extrudate distortion are: (1) the elastomer, its nature and molecular characteristics; (2) the filler, its grade and level; (3) the (cumulative) energy introduced into the rubber during the mixing operations; (4) the mixing procedure (particularly in blend preparation); (5) the temperature and shear conditions of the extrusion process. The use of sophisticated test instruments, such as the MPT enables the processability parameters of a compound to be rapidly obtained, which can often be used as a key to solve practical plant problems.