Showing papers in "Rubber Chemistry and Technology in 1971"
TL;DR: In this article, the authors show that the decrease in shear modulus of filled rubber vulcanizates with strain is due almost certainly to these secondary forces, such as attrition of the carbon black, increased time of mixing, or the addition of chemical promoters which aim at dispersing the carbon-black within the mix better.
Abstract: Carbon black does not exist as single spherical particles but forms itself into a rodlike primary structure. These rodlike structures then form into an aggregated secondary network. This secondary network is believed to be held together by Van der Waals-London attraction forces. The decrease in shear modulus of filled rubber vulcanizates with strain is due almost certainly to these secondary forces. Special mixing techniques such as attrition of the carbon black, increased time of mixing, or the addition of chemical promoters which aim at dispersing the carbon black within the mix better are shown to decrease the value of G′0−G′∞. The absence of any modulus change with strain for unfilled vulcanizates and secondly the little change observed in values of G′0−G′∞ with increasing vulcanization of the rubber when containing the same amount of carbon black confirms that the decrease in modulus with strain amplitude is in no way associated with the gum phase of the filled vulcanizate. The similarity in...
490 citations
TL;DR: In this paper, the carbon-13 chemical shifts of ethylene propylene copolymers were found to be very sensitive to monomer sequence distribution, and a formula was derived for calculating r1·r2, which is independent of monomer feed, and which is based on measuring contiguous and isolated propylene sequences in the copolymer.
Abstract: The carbon-13 chemical shifts of ethylene propylene copolymers were found to be very sensitive to monomer sequence distribution. Methylene resonances were interpreted in terms of methylene sequence length and tertiary carbon resonances were interpreted in terms of propylene centered pentad sequences. Propylene inversion was detected and measured quantitatively in the spectra. A formula was derived for calculating r1·r2, which is independent of monomer feed, and which is based on measuring contiguous and isolated propylene sequences in the copolymer. The interpretations are shown to be consistent for copolymers containing 26, 34, and 62 mole% propylene. The r1·r2 products were determined for each of these polymers. Calculation of copolymer composition based on the 13C chemical shift assignments gave excellent agreement with the compositions as determined by infrared and 1H NMR. A formula was derived, based on copolymerization theory, for calculating the reactivity ratio product, r1·r2, directly fr...
113 citations
TL;DR: Carbon surface chemistry is relatively new as an independent subject of inquiry, and, judging by the volume of publications, is receiving increasing attention throughout the world as discussed by the authors, and its functional behavior has changed significantly since the pioneering publication by Studebaker in 1957.
Abstract: Carbon surface chemistry is relatively new as an independent subject of inquiry, and, judging by the volume of publications, is receiving increasing attention throughout the world. Our conception of carbon black and its functional behavior has changed significantly since the pioneering publication by Studebaker in 1957. Within the last few years there have been a number of excellent reviews covering various aspects of carbon chemistry by authors who are presently active in this field. Donnet, Puri, and Boehm discuss reactions of carbon and the characterization of surface functional groups while van der Plas is particularly thorough on the subject of adsorption properties and porosity. Deviney explores the relationship between surface chemistry and carbon-elastomer interactions, as does Studebaker from the point of view of the practical application of carbon black in rubber. Current monographs containing useful background information are collected in “Les Carbones” and in Walker's continuing serie...
108 citations
TL;DR: In this paper, the relative compatibility of eight commercially available elastomers, blended in two-way combinations in three different proportions, was measured as a function of zone size on phase contrast optical micrographs using the Quantimet Image Analyzing Computer.
Abstract: The relative compatibility of eight different commercially available elastomers, blended in two-way combinations in three different proportions, was measured as a function of zone size on phase contrast optical micrographs using the Quantimet Image Analyzing Computer. Average cross sectional areas of the disperse phase in different blends were measured utilizing micrographs of the relatively noise-free QTM meter images which were characterized by greatly enhanced contrast. A study of the commercially important blends of polybutadiene with SBR was completed using both Differential Thermal Analysis and Electron Microscopy. Blends of several types of polybutadiene with SBR ordinarily exhibited only one glass transition temperature when examined in the vulcanized state. However, the same blends, uncured, showed the Tg's typical of each individual polymer. Moreover, electron micrographs of SBR blends with three different polybutadienes (Butyllithium, Ziegler, and Emulsion types) showed the existence o...
100 citations
TL;DR: In this paper, visual observations of contact areas between soft rubber sliders and hard tracks, and between hard and soft rubber tracks, show that relative motion between the two frictional members is often only due to "waves of detachment" crossing the contact area at high speed from front to rear.
Abstract: Visual observations of contact areas between soft rubber sliders and hard tracks, and between hard sliders and soft rubber tracks, show that relative motion between the two frictional members is often only due to “waves of detachment” crossing the contact area at high speed from front to rear. Adhesion appears to be complete between these waves which are moving folds in the rubber surface, almost certainly produced by buckling. Buckling is attributed to tangential compressive stresses, predicted by a simple theory and qualitatively confirmed by experiment. The driving force for the waves of detachment is a tangential stress gradient, also theoretically predicted.
73 citations
TL;DR: Several different schools of workers have dominated research in the field of polymer mechanochemistry, including the Russian school with Baramboim, Berlin, Butyagin; Watson, Ceresa and others of the Natural Rubber Producers' Research Association; and a host of other European workers.
Abstract: Several different schools of workers have dominated research in the field of polymer mechanochemistry. These include the Russian school with Baramboim, Berlin, Butyagin; Watson, Ceresa and others of the Natural Rubber Producers' Research Association; and a host of other European workers. Also active are the Japanese and Rumanian groups. In the U. S. the activity has centered at the National Bureau of Standards and in a number of labs including our own. The tables for the review summarize mechanochemical studies on individual polymers, multicomponent polymer systems, and on polymer solutions. For a field so important, it is surprising so few summaries have been prepared. An early review (1960), emphasizing the mechanical degradation of rubber, was prepared by Watson. The classic book on Mechanochemistry of Polymers by Baraboim was published in English in 1964. In the same year Watson also published an excellent book chapter on mechanochemical reactions. Other general volumes and reviews on polymer...
69 citations
TL;DR: In this article, it was shown that to obtain optimum performance, the organofunctional group in the silane monomer must be generally reactive with the cure system being used, and have the ability to interact with the elastomer through co-polymerization or addition.
Abstract: The special performance properties noted for silane coupling agents in mineral filled EPDM compounds result from the interfacial effects related to the dual function reaction of the organofunctional silane. When common alkoxy substituted vinyl silanes are used, the nature of the hydrolyzable groups on the silicon atom is generally not a critical factor with adequate silane-filler bonding occurring under a variety of silane application techniques. It has been shown that to obtain optimum performance, the organofunctional group in the silane monomer must be generally reactive with the cure system being used, and have the ability to interact with the elastomer through co-polymerization or addition. It has been further shown that in the case of the copolymerizable vinyl silane (A-172) only a relatively low level of peroxide-induced vinyl silane-rubber bonding is obtained using standard levels of peroxide. Increasing the peroxide level in these vinyl silane-containing formulations results in a conside...
43 citations
TL;DR: In this paper, various methods for estimating specific areas of carbon blacks are compared, including the electron microscope count, methods based on adsorption of nitrogen, iodine and surfactants, and optical reflectance tests.
Abstract: Various methods for estimating specific areas of carbon blacks are compared. These include the electron microscope count, methods based on adsorption of nitrogen, iodine and surfactants, and optical reflectance tests.
42 citations
TL;DR: In this paper, the use of accelerators containing higher alkyl substitution has been used to attain improved properties of EPDM diene rubber blends, such as ozone resistant, easy processing, and safe.
Abstract: Through the use of accelerators containing higher alkyl substitution, we have been able to attain improved properties of EPDM diene rubber blends. EPDM/NBR blends vulcanized with sulfur cure systems employing these accelerators compete favorably with CR compounds in heat aging; have essentially the same oil resistance level, and exhibit better low temperature properties. These blends are highly ozone resistant, easy processing, and safe. Because of the versatility of meeting a desired combination of properties by variations both in the ratios of NBR to EPDM and in the selection of the particular grade of each elastomer, these blends will fulfill many sophisticated elastomer applications. These accelerators can also be used to provide non-blooming cure systems for EPDM compounds and safer ultrafast cure systems for diene rubber compounds. We feel that this advance in property improvement in diene rubber EPDM blends through the use of these new accelerators is only the beginning of a whole new comp...
36 citations
TL;DR: In this paper, it was shown that various modulus values of carbon black reinforced rubber are functions of the product of actual black loading and a structure dependent factor, and that the structure factor appears to be a linear function of the so-called 24M4 value of the dibutylphthalate absorption and is independent of elongation, temperature and degree of cross-linking over the ranges covered by the data reported.
Abstract: It is shown that various modulus values of carbon black reinforced rubber are functions of the product of the actual black loading and a structure dependent factor. The structure factor appears to be a linear function of the so-called 24M4 value of the dibutylphthalate absorption and is independent of elongation, temperature, and degree of cross-linking over the ranges covered by the data reported. An interpretation of the results is offered based on the idea of polymer occluded in the interstices of primary structure aggregates and thereby shielded from deformation. Structure-concentration equivalence can only be demonstrated with carbon blacks differing in (primary) structure alone. Deviations are observed whenever the carbon blacks compared vary significantly in specific surface area and surface chemical activity.
32 citations
TL;DR: In this article, the authors measured the relaxation of stress and electrical resistivity of carbon black-loaded vulcanizates subjected to shear deformation varying between 0.5 and 20%.
Abstract: Measurements have been made of the relaxation of stress and electrical resistivity of carbon black-loaded vulcanizates subjected to shear deformation varying between 0.5 and 20%. Samples were initially brought into an equilibrium state by the application of a sinusoidal shear strain for a period of time long enough to ensure equilibrium condition, established by constancy in the dynamic stress- and resistivity-time cycles at each selected strain amplitude. It could be shown that at the small strains employed all phenomena were completely reversible, indicating the absence of rupture of elastomer chains or crosslinks and of strong bonds between carbon and elastomer, as well as of chemical aging. The shear stress relaxation rates show a small initial decrease with deformation and are fairly constant over the rest of the deformation range. Carbon black loading increases the rate—the more, the smaller the particles and the higher, the higher the loading—but the rate is independent of the carbon struc...
TL;DR: In this paper, a high temperature transition was discovered for binary mixtures of polybutadienes with differing molecular weights, with the temperature-frequency position of the transition showing up as a function of the molecular weight of the low molecular weight constituents, and yet the transition does not depend on the concentration of these constituents.
Abstract: 1. For binary mixtures of polybutadienes with differing molecular weights, a high temperature (or low frequency) transition was discovered, with the temperature-frequency position of the transition showing up as a function of the molecular weight of the low molecular weight constituents, and yet the transition does not depend on the concentration of these constituents. The value of the maximum for the mechanical loss tangent is determined by the concentration of low molecular weight components. 2. With regard to the viscoelastic behavior of the mixes at reduced temperatures, the transition reflects mainly the presence of the low molecular weight components, but at high temperatures the transition is indicative of the presence of the high molecular weight constituents. 3. The observed transition is associated with the manifestation of mobility of the molecules of the low molecular weight components, as a whole.
TL;DR: The halogenated EPDM can be covulcanized with the highly unsaturated elastomers such as natural rubber, cis polybutadiene, and the SBR rubbers as discussed by the authors.
Abstract: The ethylene propylene diene rubbers (EPDM) have been modified by halogenation. The reaction has been considered as one mainly of addition to the double bonds of the diene portion of the rubber. Dehydrohalogenation may occur to varying degrees, depending on the conditions of the reaction and the diene present in the rubber. Part of the halogen is believed to be in the allylic position. The halogenated EPDM may be vulcanized by sulfur as well as many of the curing agents used for other halogen-containing polymers. Both types of curing systems can function in the same compound. Therefore, the halogenated EPDM rubbers can be covulcanized with the highly unsaturated elastomers such as natural rubber, cis polybutadiene, and the SBR rubbers. The excellent properties, resistance to ozone, and flexing, of the halogenated EPDM can be imparted to these elastomers using standard curing systems. Also, the uncured tack of halogenated EPDM can be improved by increasing amounts of natural rubber. In addition, o...
TL;DR: In this article, NMR-linewidth measurements are used to obtain information about the crosslinkage density and the average distance between the cross-links in vulcanized rubber.
Abstract: It is shown that NMR-linewidth measurements are useful to obtain information about the cross-linkage density and the average distance between the cross-links in vulcanized rubber. Inhomogeneous structure of the rubber phase in carbon-filled rubber is evidenced and the thickness of the rubber layer on carbon is evaluated at 50 A.
TL;DR: In this article, a good quality Raman spectra can be obtained from vulcanizates prepared from cis-l,4-polybutadiene and significant differences are seen in the spectra of extracted vulcanizers prepared from various recipes.
Abstract: We have demonstrated that good quality Raman spectra can be obtained from vulcanizates prepared from cis-l,4-polybutadiene. Furthermore, significant differences are seen in the spectra of extracted vulcanizates prepared from various recipes. Tentative assignments have been made for many of the following Raman lines observed in the spectra. 1. The 1633, 1187, 734, and 720 cm−1 lines are thought to be associated with dialkenyl sulfide crosslinks. 2. Lines occurring at 440 and 505 cm−1 are assigned to polysulfidic and disulfidic structures respectively. 3. The 635, 690, and 708 cm−1 lines are thought to be associated with cyclic sulfides. In particular, the 635 cm−1 line with six membered thioalkenes, the 690 cm−1 line with five membered thioalkanes and the 708 cm−1 line with five membered thioalkenes. 4. Pendent side groups derived from TMTD are thought to have lines occurring at 1142 and 577 cm−1. Other lines occurring in the Raman spectra of the vulcanizates examined cannot be assigned with the s...
TL;DR: In this paper, two types of fluorosilicone polymers are described, the poly(fluoroalkyl)-siloxanes and the hybrid fluorocarbon silicones, represented by the structure (CF3CH2CH2SiMeO)n exhibits good solvent resistance, thermal and oxidative stability and is commercially available in the form or rubber, sealants and fluids.
Abstract: Two types of fluorosilicone polymers are described, the poly(fluoroalkyl)-siloxanes and the hybrid fluorocarbon silicones. The first type, represented by the structure (CF3CH2CH2SiMeO)n exhibits good solvent resistance, thermal and oxidative stability and is commercially available in the form or rubber, sealants and fluids. The second type, is in the research stage and has demonstrated much improved stability especially under confined heating conditions.
TL;DR: In this article, the relaxation of stress and electrical resistivity of stretched carbon black-loaded vulcanizates throughout the elongation range up to break was investigated and the influence of the degree of loading as well as of the type of elastomer was investigated.
Abstract: Measurements have been made of the relaxation of stress and electrical resistivity of stretched carbon black-loaded vulcanizates throughout the elongation range up to break. Data were obtained for vulcanizates with a number of carbon blacks, varying in particle size and in structure. The influence of the degree of loading as well as of the type of elastomer was investigated. In a gum vulcanizate there is initially a decline in rate of stress relaxation at increasing elongation as a result of the limited extensibility of the elastomer chains, followed by a constant rate at higher extensions. The level for a carbon-loaded vulcanizate is always higher than for the gum. At lower elongations this is due to an additional relaxation mechanism, the reformation of broken weak bonds between elastomer and filler particles upon standing. At medium and higher elongations, the stress relaxation rate for the carbon-filled vuleanizates increases sharply with increasing extension, due to persistent carbon chain a...
TL;DR: In this article, the authors found that wear loss is dominated by viscoelastic properties of tire treads and the combined effect of the cis, trans, vinyl, and styrene content.
Abstract: 1. Car, wheel position, driver, inflation pressure, and shoulder drop have a statistically significant effect upon wear loss and need to bo taken into consideration before material factors affecting wear can be studied. 2. Variations in macrostructure of the polymers are not found to have a significant effect on wear as compared to microstructure variations. 3. At least two material factors control wear loss of tire treads. 4. When polymers are tested near their glass transition temperature (within 80° C), wear loss is dominated by viscoelastic properties. Viscoelastic properties can be related to wear loss through Tg or the combined effect of the cis, trans, vinyl, and styrene content. 5. At higher test temperatures (over 100° C above Tg) wear loss is dominated by a material factor that has a positive correlation with temperature. This is particularly noticeable when treads are worn under mild conditions. However, there is evidence that this wear factor is present at the testing nearer to Tg but...
TL;DR: In this paper, an empirical method is described which enables the energy to be estimated for a tire groove from measurement of the amount by which a crack opens under stress, and the method also enables the strain to be determined and can be applied to any stressed article.
Abstract: The work described has aimed at clarifying the mechanism of groove cracking in tires. Basic studies of the fracture mechanics of rubber have shown that the rate of growth of a crack is independent of sample shape and type of deformation when it is expressed in terms of the available elastic energy. An empirical method is described which enables the energy to be estimated for a tire groove from measurement of the amount by which a crack opens under stress. The method also enables the strain to be determined and can, in principle, be applied to any stressed article. Using this approach and the crack growth characteristics of the tread rubber, the rate of growth of groove cracks in a tire can be predicted. Satisfactory quantitative agreement is found between observed and predicted behavior suggesting that the mechanism has been correctly identified. The work indicates relevant design factors and material properties and enables an appropriate laboratory test for groove cracking resistance to be defined.
TL;DR: In this article, it has been demonstrated that Raman spectroscopy can be used to follow changes that occur in the network of vulcanizates as a function of cure time and that dialkenyl sulfides, cyclic sulfides and conjugated triene structures parallel the cure.
Abstract: It has been demonstrated that Raman spectroscopy can be used to follow changes that occur in the network of vulcanizates as a function of cure time. In the system studied we have found that dialkenyl sulfides, cyclic sulfides and conjugated triene structures parallel the cure. In other words, the Raman lines due to these structures display an asymptotic trend as a function of cure time with the plateau occurring in the region of the optimum cure time. On the other hand those Raman lines assigned to the trans isomer and conjugated dienes do not exhibit the same asymptotic dependence as a function of cure time but show an increase in intensity as the cure time is prolonged up to at least 2 hours at 150° C. This would appear to indicate that these Raman lines are not solely associated with the vulcanization process but that thermal and allied processes may contribute. The Raman line occurring at 440 cm−1 does not show any definitive trend and is unlikely to be associated directly with the network. I...
TL;DR: The literature on acrylic elastomers between 1962 and the present has been reviewed under four topics: New Crosslinking Sites, Property Improvements, Compounding, and Fundamental Studies.
Abstract: The literature on acrylic elastomers between 1962 and the present has been reviewed under four topics: New Crosslinking Sites, Property Improvements, Compounding, and Fundamental Studies.
TL;DR: Microwave curing is a valuable supplement to other continuous vulcanization methods, in comparison with which it offers advantages in some respects.
Abstract: For a number of years the rubber industry has been trying to make its processes as continuous as possible. Techniques which dispense with interruptions are particularly desirable in the production of strip and hose, for extrusion is a continuous process whose interruption for the purpose of enabling the goods to be cured is both illogical and unsatisfactory. Several continuous vulcanization methods, such as the use of hot air and the liquid curing method, are receiving attention. A new development in this field is the use of microwave for vulcanization. Microwave curing is a valuable supplement to other continuous vulcanization methods, in comparison with which it offers advantages in some respects.
TL;DR: Ring-opening polymerization of cycloolefins, employing organoaluminum-tungsten salt catalysts, is a special case of olefin metathesis, a new reaction occurs at the double bond and allows making either large ring macrocyclics or high molecular weight linear chains as mentioned in this paper.
Abstract: Ring-opening polymerization of cycloolefins has led to a variety of new plastics and elastomers with a great range in physical properties. Ring-opening polymerization of cycloolefins, employing organoaluminum-tungsten salt catalysts, is a special case of olefin metathesis, a new reaction. The ring-opening reaction occurs at the double bond and allows making either large ring macro-cyclics or high molecular weight linear chains. Under certain conditions ringchain equilibrium can be established in these systems.
TL;DR: In this paper, a new nomenclature for carbon black morphology is proposed based on actual quantitative electron microscopical measurements, which replaces the earlier imprecise concepts of structure and particle size.
Abstract: A new nomenclature is proposed for carbon black morphology to be based on actual quantitative electron microscopical measurements. Carbon black is now defined in terms of “paracrystalline graphitic units” which are composed of interlocking “domains of rotational graphitic layer orientation”. The measurement of “unit” or “domain” dimensions replaces the earlier imprecise concepts of structure and particle size. Automated measuring procedures have been developed for determining carbon black unit and domain size functions using a Quantimet Image Analyzing Computer. Unit dimensions are expressed in terms of total projected length (L), average width (W), two-dimensional projected area (A), and form factor (L/W). Domain size (d) measurements have been programmed to give comparable results to earlier carbon black “particle” size determinations using a Zeiss Particle Size Analyzer. The new program enables measurement of similar classes of blacks (e.g., tread grades) under identical instrumental condition...
TL;DR: In this paper, a series of copolymers of known composition were synthesized to serve as standards for copolymer analyses and infrared calibration curves were determined on pressed polymer films utilizing several different infrared peaks.
Abstract: Carbon-14 labeled ethylene and propylene were used to synthesize a series of copolymers of known composition to serve as standards for copolymer analyses. Polymers with broad and narrow compositional distributions and differing sequence distributions were produced by varying the catalyst system. Solution and combustion counting techniques were used to determine sample composition and then infrared calibration curves were determined on pressed polymer films utilizing several different infrared peaks. 1. Within the ranges systematically varied neither compositional nor sequence distributions affect the peak ratios studied. 2. No isotope effects exist in the polymerizations. 3. NMR analysis yields the same results as 14C analysis. 4. Use of the 1378 cm−1 methyl band as calibrated with atactic polypropylene yields agreement with the 14C data if the average of polypropylene and copolymer results is used. 5. We amend the results previously published by our laboratory.
TL;DR: In this paper, the fate of amine was traced by extracting the oxidized vulcanizates with acetone and then with dilute hydrochloric acid-ethanol mixture, and by determining free amine or Kjeldahl nitrogen of each of the extracts and of the extracted amines.
Abstract: Thin vulcanizates containing various amines were oxidized at 100° C under 760 mm Hg oxygen pressure. Oxygen absorption and consumption of the amine were plotted as a function of oxidation time. The fate of amine was traced by extracting the oxidized vulcanizates with acetone and then with dilute hydrochloric acid-ethanol mixture, and by determining free amine or Kjeldahl nitrogen of each of the extracts and of the extracted vulcanizates. We observed that the amine combined with the rubber peroxy radical as an intermediate I, from which nitrogen-containing entity was not extracted with acetone but was extracted with the hydrochloric acid-ethanol mixture. The hydrochloric acid-extracts exhibited absorption spectra of Wurster cations of the corresponding amines. Therefore, intermediate I is considered charge transfer complex between the amine and the rubber peroxy radical. We further confirmed that the amine was transformed via the intermediate I into acetone-soluble products II and/or amine-rubber ...
TL;DR: In this paper, a terpolymer of tetrafluoroethylene, perfluoro (methyl vinyl ether) and a small amount of a third perfluoromonomer containing an active cure site is described.
Abstract: Vulcanizate properties of a new high performance elastomer, a terpolymer of tetrafluoroethylene, perfluoro (methyl vinyl ether) and a small amount of a third perfluoromonomer containing an active cure site, are described. The material may be compounded with various reinforcing agents (black exhibits the greatest reinforcing power) or as a gum stock. Perfluorinated oils such as Krytox § may be added as plasticizers. The vulcanizates show outstanding chemical resistance to many alkalies, acids, oxidizing agents and reducing agents; outstanding resistance to air oxidation at temperatures in the 400 ° – 550 ° F range; low volume swell in many organic fluids such as ketones, esters, nitriles, hydrocarbons and halogenated solvents, including the proprietary hydraulic fluids and jet fuels; and good high temperature (to 550 ° F) compression set.
TL;DR: In this paper, wide angle x-ray pictures show the crystals to be highly oriented in the direction of flow and a fibrillar structure changes to a shish-kebab structure about midway down the capillary.
Abstract: Natural rubber is readily crystallized under the pressure and orientation forces existing in a capillary rheometer. The crystallization of natural rubber is readily effected over the temperature range covering commercial processing and fabricating temperatures. The crystalline rubber is stable at atmospheric pressure and room temperature. The observed crystalline melting point increases with increasing crystallization temperatures. Wide angle x-ray pictures show the crystals to be highly oriented in the direction of flow. Electron micrographs of fracture surfaces of the crystalline rubber show the existence of a very complex morphology. Where the degree of orientation is highest, a fibrillar structure is observed parallel to the direction of flow. The fibrillar structure changes to a shish-kebab structure about midway down the capillary. Apparently, a regrouping occurs with chain folded lamellae forming at right angles to the oriented fibrillar type crystals. A rotation of the chain-folded lamell...
TL;DR: The many examples related above should provide the rubber analyst with systems well suited to some of his problems and, if not, certainly with direction for the evolution of custom systems for his specific needs.
Abstract: The many examples related above should provide the rubber analyst with systems well suited to some of his problems and, if not, certainly with direction for the evolution of custom systems for his specific needs. The Rƒ values and colors resulting from the chromatographic conditions employed by the experimenters have generally been well related for the compounds examined. These values and colors are useful as guides to another analyst but cannot be trusted for reliable identifications. Rƒ values are difficult to reproduce from one laboratory to another since the factors influencing Rƒ are not always readily reproduced within the different laboratories. Colors are difficult, if not impossible, to describe accurately or to reproduce faithfully with color photography. In addition, many colors may vary (some quite rapidly) with time after or conditions of indication. An identification is best and most reliably made by comparison to known compounds. An unknown is identified when, after adjusting the s...
TL;DR: A review of the health problems and their control for the rubber industry is presented in this paper, which is restricted to the manufacture of the commonly used synthetic polymers and to the operations incident to the conversion of these polymers, and the natural polymer into marketable products.
Abstract: To present a review of the health problems and their control for the Rubber Industry requires the making of certain choices relative to the breadth of the discussion. It is well known that the Rubber Industry has many facets. These involve not only the conversion of the natural and synthetic polymers into usable articles, but the manufacture of chemicals, plastics, and numerous other materials. For this reason, this review is restricted to the manufacture of the commonly used synthetic polymers and to the operations incident to the conversion of these polymers and the natural polymer into marketable products. Why should there be a concern with respect to the health problems of the Rubber Industry? (1) It is well known that many different chemicals are used, not only in the manufacture of polymers but in the conversion process. The industry is a huge consumer of chemicals, and these run the gamut of highly hazardous to inocuous. Proper environmental controls must be applied in order to handle them...