annual review
G. ALLIGER F. C. WEISSERT
Elastomers
Progress in pylmer science continues to lead to better organic and inorganic elastomers, and techniquesf o r rubber processing and compounding he technological development of elastomers in 1964
Thas been marked by the continued application of stereospecific polymerization, sophisticated instrumenta-
tion for the elucidation of elastomer structure, the introduction of new compounding ingredients and processing techniques, and especially by the increased understanding of the basic functions of elastomer, filler, vulcanizing agent, and antioxidant as combined to produce a useful vulcanizate. The scientific importance of stereospecific polymer synthesis has been spotlighted by the awarding of the Nobel Prize in Chemistry for 1963 to Ziegler and Natta. T h e present intense activity in relating the response of industrially important products under widely differing environmental conditions of mechanical stresses (both static and dynamic), thermal stresses, and chemical stresses to polymer structure is just beginning to yield unifying fundamental concepts to guide accelerated future developments. This review for 1964, as with the previous report of Alliger and Weissert ( 3 A ) , includes tables which should be useful for the quick selection of the series of references to a specific subject. No attempt is made to discuss each of the references. Special emphasis has been given to articles which relate elastomeric and compounding parameters to product performance. Mark ( 76A) reviewed current accomplishments and problems in elastomer synthesis. Problems were stated to lie in the fields of stability, low temperature performance, and elasticity patterns. The widening scope of High-strength silicone rubber with greatly increased resilience (right) is one of several new elastomer materials developed through strides in understanding of inorganic polymer chemistry and physics. VOL. 5 7
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Stereospecific polvbutadiene and polyisoprene and natural rubber copolymerization was noted. The development of new synthetic elastomers derived from isoprene, butadiene, ethylene-propylene, ethylene-vinyl acetate, propylene oxide monomers, and sulfur-curable polyalkylene oxide rubber was reviewed at the Third International Synthetic Rubber Symposium ( 2 7 4 . The significant contribution to elastomer physics and chemistry made by the Natural Rubber Producer’s Research Association was reviewed at a Silver Jubilee Conference (77A). Allen ( 7 A ) , Atlas ( 5 A ) , and Corradini (17A) have related the structural characteristics of selected polymers to their physical behavior. The newer physical methods for polymer characterization have been reviewed by K e (75A). Specialized techniques which have been used to reveal specific aspects of polymer structure are infrared spectroscopy (34A), high resolution nuclear magnetic resonance (28A), light scattering (25A), solution viscosity (72A), and thermal decomposition analysis ( 8 A ) . The mechanism of stereospecific polymerization has been reviewed by Morton (79A) and Houdret ( 7 4 4 ) . Useful copolymerization equations have been developed by Ham (73A). Natta (27A) has reported a special type of stereospecific polymerization which produces optically active polymers from monomers having no optical activity. A new class of polymers designated as “ionomers” (26A) having intermolecular metal ion bonds introduced into ethylene polymer chains was disclosed. Distribution of aggregates produced in the polymer by these ions is important to physical properties. The high extensibility and recovery of elastomers distinguish them from plastics. Morris (78A) has interpreted the stress-strain behavior of natural rubber and cis-polyisoprene at large extensions in terms of crystallization and finite extensibility effects. The equivalent statistical segment was found to be about 4.3 isoprene units for both natural rubber and cis-polyisoprene. Mullins (ZOA) has stated that recent developments in the understanding of detailed structure of cross-linked networks and the ability to express an increasing number of mechanical properties in terms of basic parameters now provide the possibility of tracing rational relationships between structure and properties. The automobile still accounts for the major use of elastomers. About 200 lb. of rubber, including the 100 lb. in tires, are currently required for each car (24A). Polybutadiene is preferred to polyisoprene because of its better abrasion resistance, low heat buildup, and resistance to cold and repeated deformations. The main shortcomings of polybutadiene are related to its processing, friction, and tear strength properties according to Campbell ( Q A ) . The properties of the commercial elastomers which make them suitable for mechanical goods application are described by Tully (3OA). The consumption of rubber latex continues to increase in such applications as paper coatings and flexible foams. 62
INDUSTRIAL A N D ENGINEERING CHEMISTRY
The recent introduction of carboxylated polymers has resulted in a far wider range of latex applications (23A). The average yield of natural rubber is now about 650 lb./acre, but developments toward greater productivity indicate a potential yield of 3000 lb./acre ( 6 4 ) . All of the natural rubber crop is now being used. Synthetic rubber is required to fill world rubber needs as well as to answer the requirements of the design engineers for special rubbers for specific applications. Allen (ZA) has projected a continued increase in the production and use of rubber. However, a slower rate of increase was indicated unless new major nontire end uses are found. Ashe and Fedor (4A) forecast a considerable expansion in the use of polybutadiene, polyisoprene, and EPR. They project U. S. consumption of rubber in 1970 will be about 2,225,000 tons, of which 82% will be synthetic. Diene Homopolymers and Copolymers
Bruzzone (5B) has compared synthetic polyisoprenes of varying cis-1,4 content with natural rubber. The higher cis-l,4 polymers held their good properties over a wide range of cure levels, which he attributed to crystallization effects. At low states of cure, better properties were obtained with synthetic polyisoprenes containing the smallest amount of low molecular weight materials. Saltman (34B)has described the polymerization variables of the Ziegler-type catalyst system which control the molecular weight, gel, and extractables in synthetic polyisoprene. Todd (39B) has compared the synthetic polyisoprene Natsyn 2200 with natural rubber both in raw compound and cured properties. The natural rubber producers, in addition to their efforts toward securing high yields per acre and uniform quality products, have made modifications of the natural polyisoprene for special uses. Prepeptized natural rubber (36B), rubber stabilized against excessive “hardening,” which was attributed to cross-linking between small amounts of aldehyde groups (21B), and an anticrystallizing (AC) natural rubber prepared by treatment with butadiene-sulfone (ZZB) have been described. Chloral has been reacted with polyisoprene (29B). The tear resistance of natural rubber latex films has been improved by the addition of a carboxylated polymer latex (23B). A synthetic gutta percha has been prepared by polymerizing isoprene to a very high trans-l,4 structure (7B). This stereospecific polymer has a glass temperature less than - 60’ C., but because of its high degree of crystallization in the unstretched state, it is hard at room temperature and softens at 65’ C. AUTHOR Glen Alliger zs Director of the Central Research
Laboratories, The Fzrestone Tire & Rubber Co., Akron, Ohio. F. C. Weissert is Chemist in the Fundamental Polymer Research Group of the same company.
display properties which suit them for particular elastomer applications A
Solution polymerized polybutadiene has found increasing use in applications requiring high abrasion resistance and low temperature usefulness. Engel (74B) has suggested that this material, because of its highly linear structure (with no side groups), can accept very large amounts of oil to give inexpensive but still highly serviceable compounds. Molecular weight jumping techniques give a further advantage in this direction. Blumel (3B)has compared the polymer, compound, and vulcanizate properties of fourteen types of polybutadiene. Berger (2B) has studied the effect of isomerization of the &l,4 structure on the physical properties of the polymer. Several patents have been issued which disclose the effect of small alterations in the linear polybutadienes with narrow molecular weight distribution on the resistance to cold flow of raw polymer and improved processibility o€ factory compounds (76B,25B,26B,28B). New emulsion polybutadienes have been proposed (70B)for use in blends with natural rubber for tire compounds with improved skid resistance. Although the heat buildup with these emulsion polybutadienes is higher than that with natural rubber, these polybutadiene/natural rubber blends are claimed to be more stable toward heat reversion than natural rubber or cis-l,4 polybutadiene. These emulsion polybutadienes have 20y0cis-1,4 structure. Morton (2OB) has described the mechanism of stereopolymerization of butadiene to a high trans-l,4 polymer in aqueous medium with rhodium salts. The active species in some alkyl aluminum-titanium iodide catalysts for czs-l,4 polybutadiene hasal so been postulated by Saltman (33B). Krol (79B)has compared synthetic polybutadienes (PBD) and polyisoprenes (PI) in large tire tread compounds. The PBD has the greater wear resistance at equal black loadings. However, the wear resistance of P I was improved by higher black loadings without excessive heat buildup. Draxler (77B)has shown that cis-1,4 polybutadiene forms less gel than SBR during high temperature processing of factory compounds. He has suggested that the gelation tendency is related to the proportion of 1,2 structure. The skid resistance of polybutadiene tread compounds is measurably increased by the use of higher oil and black loadings. Aromatic oils are preferred to naphthenic oils (4B). Certain copolymers of butadiene and styrene prepared with anionic catalyst gave improved vulcanizate properties when compared with emulsion SBR. The more narrow molecular weight distribution and linearity of these elastomers lead to improved hysteresis and abrasion characteristics ( 15B, 78B). Block copolymers of butadiene and styrene prepared in solution polymerization systems are harder at room temperature and suitable for such uses as shoe soles (32%).
A I
Mono-Ene Elastomers, EPR, EPT, BUTYL
A threefold emphasis has characterized the rapid development of ethylene-propylene elastomeric copolymers. Selected polymer structures, identifiable by modern techniques, have been obtained through the use of stereospecific catalysts. Product evaluation has shown the relationship between fundamental polymer structure and performance. Compounding developments have improved properties and reduced cost in selected applications. Natta (27C)has reviewed the synthesis, evaluation of structure, and uses of ethylene propylene rubber (EPR). Bohn (7C) has measured glass temperatures as functions of co-monomeric ratios of both propylene and vinyl acetate to ethylene, cross-linking, and molecular weight. The crystallization of EPR has been shown to be a function of the monomer sequence length by Jackson (77C). A stereo-block polymer with alternating blocks of amorphous EPR and ethylene has been reported (26C) to crystallize upon stretching. Block ethylenepropylene copolymers have also been described by Puett (23C). Infrared spectra of ethylene-propylene polymers have been interpreted in terms of both block ethylene and propylene plus random monomer sequence
(79C). A study of the mechanism of the peroxide-sulfur cure of ethylene-propylene elastomers by Loan (78C)has demonstrated cross-linking through secondary hydrogens which is competitive with scission at the tertiary hydrogen sites. The presence of sulfur introduces labile cross-links which lead to increased tensile strength. Auda (ZC) has studied the influence of vulcanization systems upon the physical properties of ethylene-propylene terpolymers (EPT). The carbon black reinforcement of ethylene-propylene rubbers has been reviewed by Burgess (9C). A similar study of the use of Hi-Si1 233 was outlined by Bartrug (5C). High oil and black loadings were found to be attractive in EPT compounds (27C). Saturated hydrocarbons were preferred for use as the extending oils in EPT compounds (29C). Improved cracking resistance, low heat buildup at high speeds, and high resilience at low temperatures have been claimed for experimental EPT tires (ZUC). Building tack is a problem in the development of E P T tires (7ZC). Crespi ( 7 7C)has related the potential uses of EPT to the excellent mechanical and dynamic properties of the vulcanizate plus the ability of these polymers to accept large amounts of oil and filler. An “Engineering Profile” comparing the physical properties of EPT vulcanizates to those of NR and SBR was published
(73C). Butyl rubber has been blended with ethylene propylene terpolymer, polybutadiene, and SBR. Butyl/ VOL. 57
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polybutadiene blends have been reported (74C) to increase the traction of tire treads. Chlorobutyl polymer is the most versatile butyl for blending with unsaturated polymers because its rate of cure approximates that of diene rubbers (3C). Gessler (75C)has shown that in the reinforcement of butyl rubber with carbon black there is cationic bonding between and rubber, the SBR-black bond is formed through free radicals. Booth (gc> has related the effects of test load, deflection, frequency, and temperature variations to the performance of butyl rubber in antivibration applications.
TABLE I .
GENERAL REFERENCES 3A, 16A, 17A,27A 73A, 14.4, l Q A , 21A, 22A, 26A 8A, lOA, 12A, 75A, 25A,28A, 29A,34A l A , 5 A , l l A , 18A,2OA 2A, 4 A , 6A, 9A, 24A, 30A 7A, 23A, 31A, 32A, 33A, 34A
Reviews Elastomer synthesis Structure characterization Physical properties General applications Special products
Auda (IC)has described the dynamic behavior of butyl rubber at low temperatures as affected by conipound variations. Polymers
Polyurethane polymers are engineering materials which can bridge the materials range from rubbery to plastic properties (77D). Good tear, abrasion, and oil resistance have accounted for their use in both flexible and rigid foams, elastomeric products, fibers, sealants, and mechanical goods (50, IOD, 720). The published literature for 1964 is rather extensive. This report will deal mostly with reviews concerning polyurethane
TABLE V.
HALOGEN, OXYGEN, NITROGEN, SULFUR CONTAI N I N G ELASTOM ERS
i
H a 1ogen Neoprene Fluorinated elastomers
2E, 6 E , 72E, 75E, 17E
I
Oxygen
IE, 7 E QE, 1 I E , 13E, 14E 4 E , 1QE
Polyalkene oxides Polyacrylate Ethylene-vinyl %Lclate Sulfur Nitroso rubber
TABLE I I .
3 E , 2OE 8E
DIENE POLYMERS AND COPOLYMERS TABLE V I .
Polyisoprene (czs-lr4) Synthesis and use Modification of N R Polyisoprene (irans-l,4)
5 B , 6B, 17B, 34B, 35B, 38B, 3QB ~
21B, 22B. 23B, 2QB, 36B l B , 138, 37B
Polybutadiene
2B, 3B, lOB, 14B, 30B
Structure and properties Synthesis Modifications
INORGANIC ELASTOMERS
Organo-silicone polymers New Polymer Developments Compounding and Applications
Organo-boron polymers
71F
QB, lZB, 15B, 188, 32B 4 8 , 7B, 8B, 1 l B , lQB, 41B
TABLE V I I .
PROCESSING 4G, 8G, 7QG,21G, 25G, 36C 5G, 18G, 22G, ZSG, 30G 6G, 28G, 31G: 33G 1G, 2G, 13G, 27G 3G, IdG, 77G, 26G 7G, SG, 16G, 28G,32G, 34G, 35G lOG, 11G, 12G, 15G, 20G, 23G, 24G
Processing tests General rheology Molecular structure Polymer processing Theory of adhesion Formulation of adhesives Injection molding
MONO-ENE ELASTOMERS, EPR, EPT, AND BUTYL TABLE V I I I .
Synthesis and review Polymer structure Fillers and extenders Applications
21C, 22C, 23C, 26C 2C, 7C, 17C, 18C, lQC, 28C 5C, SC, 24C, 27C,29C 4C, 6C, 17C, 12C, 73C, 20C, 25C
Butyl Rubber Compounding studies Applications
,
3C, lOC, 14C, 75C, 16C lC, 8C
Solution masterbatching Oil extended polymers Carbon black structure Reinforcement theory Xonblack fillers Mixing treatments Sulfur vulcanization Pionsulfur vulcanization Anrioxidants Antiozonants
TABLE I X .
General Structure and properties Applications
64
3F, 4F, 6F, 7 F , 8F, QF IF, ZF, 5R, ?OF
20B, 27B, 33B, 40B 16B, 24B, 25B, 26B, 28B, 318
Copolymers Applications
TABLE I I I.
5E,IOE. 16E, 18E
SD, 8 0 , IOD, 1 2 0 , 170 7 0 , 4 0 , 7 0 , QD, 1 3 0 , 75D 2D, 30. 6D, 1 1 0 , 1 4 0 , 16D
I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
Methods Viscoelastic theory Failure effects Tire compounds General applications
~
1
COMPOUNDING 9H, 34H, 3QH, 41H 8H, 1 l H , 21H, 30H 5H, 12H, 18H, 19H, 31H, 36H 13H, 16H, 22H, 23H, 40H 17H, ZOH, 24H 3H, 25H, 27H 6H, lOH, 28H, 29H. 32H 7H, 14H, 35H, 38H I H , 4 H , 33H, 37H, 42H 2H, 75H, 26H
VULCANIZATE TESTING
I ~
i
71, SI, 121, 131, 181, 241, 281 21, 51, 161, 171, 191, 271 rr, sr, 751, 221. 251, 261 41, 81, 701: 171, 201, 271 31, 741, 231, 291
production and articles which deal with the relationships between polymer structure and physical properties. Whitman (150)has related the properties of urethane foams to polymer structure. Harding (40)reported that highest strength is obtained in rigid foams with the use of highly functional aromatic polyols of low molecular weight. Myuller (9D) has considered the glass temperature of the glycol and ester groups both in the main and side chains relative to the physical properties of polyurethanes. Improved rocket propellants have been prepared by using tetrahydrofuran-alkene oxide copolymers as the di-ol component of polyurethane (70). This same study demonstrated the contributions of nuclear magnetic resonance, vapor phase chromatography, and molecular weight determinations to the elucidation of polymer structure and establishment of the kinetics of the copolymerization reactions. Testroet (730) has investigated the degradation of polyester urethane foams due both to hydrolysis at 158' F. and to the attack by microorganisms at room temperature which also leads to hydrolytic cleavage. The addition of both polycarbodiimide and pentachlorophenol stabilized the polyester foams. Polyether foams were not adversely affected by the same conditions of high humidity. Variations of polyurethane structure were studied with respect to their effect on such specific uses as elastomeric spandex fibers (60),foams with mechanical properties sufficient to serve as "air-drop cushions" (740), and for use as potting compounds to protect electrical equipment ( 760). Refinements in the technology related to the production of flexible urethane foams, especially related to the "one-shot" process have been reported (20, 30, 150). Polyurethane elastomers having improved processing characteristics as well as good chemical and solvent resistance were prepared from dipropylene glycol-toluene diisocyanate adducts ( 7 0 ) .
to petroleum and greases and to air aging at the high temperature of 350' F. A fluorosilicone rubber with good chemical and heat resistance and good tensile strength, retained its flexibility in jet fuel, from -70" to 500' F. (5E). Commercial slippery rubber compounds have been prepared by graft polymerization of reactive ester monomer onto the surface of an elastomer, hydrolysis of the ester to an acid, and finally fluorination of the surface. A new family of tough polymers, which have the processing characteristics of thermoplastics but exhibit the resilience and flex properties of a n elastomer, has been prepared by ethylene-vinyl acetate copolymerization (19E). These EVA polymers are not suitable for high temperature service and are expected to be used in areas served by plasticized polyvinyl chloride. Gruber (7E) has described a new polypropylene oxide elastomer which is sulfur curable through the use of an unsaturated epoxide. The exceptional low temperature flexibility, excellent ozone resistance, and high resistance to fatigue in dynamic applications a t high temperatures recommend its evaluation as a specialty rubber for the automotive industry. Acrylate rubbers have been improved in low temperature flexibility characteristics and vulcanized by means of a peroxide-divinyl benzene system (13E). These elastomers have excellent resistance to heat at 350' F. in air or in petroleum oils and greases (77E). Polysulfide elastomers have been modified by the incorporation of pendant unsaturated groups in the main chain so that they are sulfur curable (2OE). These materials serve as solvent-, heat-, and weathering-resistant sealants. Henry (8E) has described nitroso rubbers which have solvent, ozone, and flame resistant properties. They have a glass temperature of -51' C. and hence have satisfactory low temperature flexibility.
Inorganic Elastomers Elastomers Containing Halogen, Oxygen, Nitrogen, Sulfur
Several new neoprene polymers have been developed for adhesive applications (72E). Neoprene AF is cured a t room temperature by metal oxide with rapid development of bond strength. Neoprene ILA, a copolymer of chloroprene and acrylonitrile, has good oil resistance. Neoprene H C resembles polyisoprene in rate and degree of crystallization and plasticity-temperature relationships. General information on the use of commercial neoprenes was set forth in a book by Murray (75E). The heat resistance of various neoprenes was described by Becker (2E). By the use of organotin compounds, a cis-l,4 polychloroprene has been prepared (6E). Most commercial neoprenes are all trans-l,4 with respect to double bond configuration. The processing and fabrication of high temperature and fluid resistant copolymers of vinylidene fluoride and hexafluoropropylene were described by Stivers (78E). Vulcanizates of these polymers have excellent resistance
Three main classes of organosilicon polymers are used for making silicone elastomers : dimethylpolysiloxanes polymers, copolymers of dimethyl-siloxane, and homopolymers from trifluoropropylmethylsiloxane (6F). Lewis (7F) has reviewed the range of physical properties that can be obtained by modification of chain and side groups, by making random copolymers and block copolymers (which have high tensile strength but suffer in flexibility) and by interaction with silica filler of varying particle size. New silicone rubbers which require no postcuring have been prepared by the incorporation of small amounts of vinyl groups, the use of high purity fillers, and by using improved peroxide accelerators (4F, 9F). Certain grades of fibrous talc have improved the high temperature tensile strength of silicone rubbers (7OF). Heat aging additives have been found to be effective in the retardation of depolymerization of silicone rubbers at 480' to 680' F. ( Z F ) . The mechanical properties of four grades of silicone compounds for use between -75" to 500' F. have been V O L . 57
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tabulated (5F). Silicone elastomers have found special uses in automotive applications ( I F ) . A soft, tough partially elastomeric material of low melting point was produced by the emulsion copolymerization of butadiene and isopreriylcarborane ( I I F ) .
Procossing
Rheological Properties. -4 rubbery polymer displays both viscous and elastic behavior. The viscous response of an elastomer can be described in terms of stress, rate of deformation, and temperature. These rheological properties are of considerable importance in understanding the commercial processing of elastomers and their fully compounded but unvulcanized stocks. Viscoelastic effects also determine the range of usefulness of elastomeric vulcanizates. ( S e e Vulcanizate Testing below.) The processing characteristics of factory compounds are now being evaluated by such methods as observation of the rate of flow, degree of die swell, and surface roughness of compounds extruded through a Garvey Die (?9G), extrusion measurements which are interpreted in terms of competitive degrees of breakdown and cross-linking (TMI-Firestone CEPAR Apparatus) (4G), the time required for incorporation of black in Braebender Plastograph (27G) and rheological results obtained by an oscillating disk rheometer (36G). Einhorn (5G) has shown that laboratory rheological properties of SBR compounds are quite sensitive to the magnitude of the shear rate. He has suggested that laboratory tests should be carried out at shear rates approaching those which are characteristic of factory operations. The rheological behavior of filled elastomeric compounds is decidedly not simple, both because of the large strains involved and especially due to the nonNewtonian nature of their viscous behavior. NonNewtonian systems have the complication of having the viscosity coefficient vary with rate of shear. The presence of a normal shear stress-or M'eissenberg effectin these systems also profoundly affects such important practical considerations as flow rate, die swell, and surface roughness. Rheologists are now developing mathematical models so that these factors may be described and measured (?8G, 29G). The general direction of the effects of molecular weight, molecular weight distribution, chain-branching, chain entanglement, and the presence of gel upon these properties has been described in the field of both plastics and elastomers (5G, 6G, 28G, 30G, 33G). Amorphous polymers have been characterized by their viscoelastic parameters by Tobolsky (37G). Booth (7G) has shown that a high polymer breaks down through shearing stresses at points relatively far from the end of the polymer chain, but not necessarily in the middle. Elastomers form the basis of many adhesives. Reinhart (26G) has surveyed the literature related to the basic aspects of the science of adhesion. Kaelble (77G) has analyzed the peel adhesion of polymers in terms of 66
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
their bulk rheological behavior over a range of strain rates and temperatures. He considered both the adhesive and cohesive properties of the materials. Bussemaker (3G) described a new type of tackmeter for the measurement of adhesion. The use of resins in rubbers has been reviewed by Powers. The adhesiveness of resin-rubber systems was found to peak at about 20 to 40y0 resin, depending upon the softening point of the resin (33'G). Hock ( I4G) through electron microscope studies attributed these peak tack values to the two phase nature of the system. Rosin (34G) and phenolic (32G) plasticizers have been suggested for use in elastomers. There has been increased activity in the use of injection molding techniques for rubber compounds. n'ikolov (24G) stated that most compression molding rubber compounds can be injection molded under certain conditions with equally good and often better physical properties as compounds molded for longer times at lower temperatures. Griffiths ( I I G , I2G) has related the rheological properties obtained with the aid of a M'eissenberg Rheogoniometer to the processibility of natural and synthetic rubber compounds. He has stated that progress in the area of injection molding has been delayed by the lack of study of the theoretical physics of the liquid state. Several other reviews of the potentialities of injection molding of elastomers have appeared in 1964 (IOG, ?5G, 20G, 23G). Compounding
The industrial use of elastomers requires that they be reinforced by the addition of fine particle size fillers, vulcanized to provide the best possible balance of strength and hysteresis loss, and protected against loss of properties due to aging. The particular combination of polymer, filler, vulcanizing agent and antioxidant selected must be readily processible in available factory equipment. Much is known about the function of the many compounding ingredients used in rubber. However, at times the utility of new materials is recognized before they are characterized within a more fundamental framework of understanding. Active development of solution masterbatching with the carbon black incorporated in a hydrocarbon solution of an elastomer under conditions which result in suitable dispersion of the fine particle size carbon blacks has continued ( I 4 H ) . One specification has claimed black dispersion to a particle size of 10 to 20 microns (34H). Voet has announced the production of pelletized black with oil added to make it more readily dispersible in hydrocarbon solvents (39H). The present interest in solution masterbatching is related to the increased production of stereoelastomers which are generally prepared in hydrocarbon solution. Oil extended polybutadiene may be used with normal loading levels of compounding ingredients, with only a small increase in the required amount of accelerator (21H). Bruzzone has developed quantitative relationships between the composition of extender oils, the interaction parameter determined by swelling measurements, and the physical properties of oil-extended SBR com-
pounds (8H). The Natural Rubber Producers Research Association has given details on the compounding, processing, and physical properties of oil-extended natural rubber. They have reported improved laboratory abrasion and flex cracking resistance for the oilextended natural rubber compounds (27H). A very extensive symposium outlined in detail the current knowledge of the physical-chemical characteristics of carbon black, the chemical nature of its surface, and the carbon black-poly mer interactions in reinforced elastomers (76H). Fine carbon blacks continue to be the main class of reinforcing fillers in elastomers. New active low structure (ALS) blacks appear to be particularly suitable for EPT, butyl, and natural rubber and can replace adequately the more costly and obsolescent channel blacks (18H,36H). An excellent review by Figielski (79H) outlines the influence of carbon black structure. The term structure describes the tendency of the fine particle blacks to agglomerate in the form of branched chains of carbon particles. High structure blacks improve the processibility of butadiene and acrylate rubbers and make high oil loadings possible in SBR (73H, 78H). Heat treatment of elastomer-black factory mixes results in improved physical properties, especially in the case of butyl elastomers. Bannister ( 3 H ) has postulated that the beneficial effects of heat treatment of butylblack and unsaturated rubber-black stocks are the result of different mechanisms. There is still no general agreement on the mechanism of carbon black reinforcement. Experimental results have been consistent both with theories that propose a strong chemical bond between rubber and filler and those that postulate weaker adhesion forces (72H, 40H). Payne as the result of dynamic tests upon both elastomerfiller and mineral oil-filler systems, has proposed that the modulus increase apparent in black reinforced systems is related to a network of carbon black agglomerates (37H). The degree of stress softening (Mullin’s effect) was measured for different polymers and fillers at varying levels. Both the degree of stress softening and resultant final modulus were related to the amount of filled volume which includes both filler and bound rubber by Brennan (5H). He also suggested that this stress softening serves as an energy absorbing mechanism which decreases the proportion of energy available for any rupture process. The activity of silica reinforcing fillers has been studied with respect to the reaction which may occur between the silica pigment and zinc oxide (37H). Calcium carbonate reinforcing agents have been prepared in the presence of such materials as sorbic acid (20H). Moore has shown that the efficiency of the utilization of sulfur for cross-linking is very sensitive to the cure system and the time-temperature conditions of vulcanization (29H). This resolution of the structural characteristics of various vulcanizate networks permits an advance in designing the type of vulcanizate best suited to industrial applications (28H). The sulfur, accelerator, and antioxidant systems developed for
natural rubber appeared to Roychaudhuri to be adequate for use in the newly developed rubbers (32H). Vulcanizates obtained with maleiimides are claimed to exhibit relative constant physical properties over a range of curing temperatures (3823). Brown has reviewed the cross-linking reactions of carboxylic elastomers (7H) The nature and use of antioxidants and antiozonants have been reviewed by Ambelang (7H). The degree of volatility of antioxidants has been shown to be a prime factor in the permanence of their activity (37H). The effect of the natural antioxidants in natural rubber has been outlined by Boucher (4H).Stress relaxation (33H) and N M R (42H) techniques have been used to study the aging of elastomeric compounds. The testing and characterization of antiozonant activity has been described by Dibbo (75H) and Andrews ( 2 H ) . The quantitative uptake of ozone by rubber in a closed system has been measured by McCool
-
(26H).
Vulcanizate Testing
Vulcanizates are evaluated in routine and special laboratory tests and by direct observation of the final vulcanizate under in-service conditions. The correlation between laboratory and actual performance tests is not always good. Juve has suggested that there is a tendency to run too many laboratory tests which may be either inadequate or not well understood (731). Dynamic testing over a wide range of frequencies is of considerable importance in establishing the range of usefulness of vulcanizates both with respect to their damping or hysteresis loss and strength properties. Dingle has reviewed the use of the torsional pendulum, vibrating reed, and sinusoidal tester in the measurement of dynamic modulus and damping (91). Similar information has been obtained by means of a rolling ball loss spectrometer (71), an identer hysterimeter (241), and a rebound tester (281). A high speed tester for direct measurement of physical properties at very high strains rates has been develcped (781). The maximum damping as determined by the above methods over a range of test speeds or temperatures for plastics and elastomers bears a direct relationship to the glass transition temperature of the polymer. Boyer has presented a very comprehensive review of the effect of chemical and structural factors on both the glass and crystalline melting points of high polymers (51). Peticolas (771) has presented a molecular viscoelastic theory for polymers and their application, while Roscoe (791) has proposed an empirical constitutive equation to give formal representation of elastoviscous liquids. Mussa has pointed to the possibility of the use of stress-relaxation measurements for determination of the molecular weight, molecular weight distribution, regularity of chain structure, branching, and degree of cross-linking (761). The effect of amount and type of carbon black on the dynamic properties of ethylene propylene terpolymers VOL. 5 7
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was studied by Baseden (31). Stratton has shown that the dynamic properties of natural rubber vulcanizates depend, in part, upon the vulcanization system (231). The stress and elongation at break of elastomers determined over a wide range of temperatures and test speeds have been described by means of a failure envelope by Smith (221). Bueche has shown that propagation of a crack in an elastomer is limited by viscoelastic mechanisms (61). Thomas has proposed that the tear strength of an elastomer be expressed in terms of the energy required to cause tear propagation. The strength of an amorphous rubber has been said to be governed by the internal viscosity in contrast to crystallizable rubbers (261). Bassi has found that a portable skid tester correlates well with tire results. The friction coefficient was related to the hysteretic properties and surface character of the tread compounds (41).Diffusion of zinc salts induced by tire service with resultant formation of highly cross-linked modules was reproduced in a laboratory test by Smith (271). Schallamach has divided tire wear into two patterns. Wear on sharp-pointed abrasives is dominated by tensile failure, while on more blunt surfaces the abrasion losses are related to fatigue mechanisms (201). Ecker has proposed an empirical equation which relates abrasion resistance to tensile strength at high speeds, dynamic modulus and damping, and coefficient of friction of the compound (701). Collins has separated the whole tire energy losses in rolling resistance into the separate contributions of tread, sidewall, body, and textile compounds (81). Yin and Pariser have determined the time-temperature dependent mechanical properties of several elastomers. On the basis of these results, combined with an analysis of the viscoelastic requirements for vibration control devices, the effective temperature-frequency region for each separate polymer has been calculated (291)* It is expected that, in the future, it will become more commonplace to see the direct application of fundamental viscoelastic mechanical spectral analysis to the design of elastomeric products with a widening range of applicability. REFERENCES General (1A) Allen, G., J . Appl. Chem. 14, 1 (1964). (2A) Allen, P. rV,, Rubber J . 146, No. 8, 28 (1964). (3A) Alliger, G., iVeissert, F. C., IND.ENG.CHEM.56, No. 8, 36 (1964). (4A) Ashe, A. J., Fedor, W. S., Chem. E n g . hZw542, No. 8, 30 (1964). (5A) Atlas, S. M., .Mark, H. F., Koutschuk u . Gummi, Kunrtsi. 17, 8, 431 (1964). (6A) Bateman, L. C., Rubber J.146, No. 5, 70 (1964). (7A) Boulonnais, D.: Reu. Gen. Caoutchouc 41, 963 (1964). (EA) Brock, M . J., Rubber Age 96, 285 (1964). (9A) Campbell, G., others, Proc. Inst. Rubber I d . 11, h-0, 3, P62 (1964). (10A) Casasra, E. F., Reu. Cur. Lit. Paint I n d . 37, 658 (1964). (11A) Corradini, P., Rubber Abstracfs 43, ahs. 4118 (1965). (12A) Fixman, M., Peterson, J. M.3 J. Am. Chem. SOC.86, 3524 (1964). (13A) H a m , G. E.,J.Polymer S i , A2, 3633 (1964). (14A) H o u d r e t , C., Rubber Abstracis 42, abs. 3869 (1964). (15A) Ke, B., (Editor), Polymer Remews 6, 722 (1964). (16A) M a r k , H., Rubber Plastics Age 45, No. 5, 540 (1964). (17A) Melville, H., Rubber J . 146, N o . 5, 32 (1964). (18A) Morris, M. C., D i n . A b s . 24, No. 8 , 3118 (1964). (19A) Morton, M., Rubber Age 95, 568 (1964). (20A) Mullins, L., Rubber J . 146, No. 5, 35 (1964).
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(21A) N a t t a , G., Chim. e Ind. 46, 397 (1964). (22A) N a t t a , G., Porri, L., Rubber Age 95, 568 (1964). (2314) h-esbit, J. R., Ibid.,p. 778. (24.4) Olmstead, F., Ibid., p . 879. (2514) Prud’homme, J., Sicotte, Y., Can. J.Chsm. 42, 2078 (1964). (26A) Rees, R . IV., .Mod. Plastics 42 h-0. 1, 209 (I 964). (27A) RubberPlastics Age 45, No. 10, 1166 (1964). (28A) SchuP, F., Reo. Gen. Caoutchouc 41, 261 (1964). (29.4) Terry, B. W., K a n g Yang, Chem. E n g . 2 V e w 42, KO. 6, 47 (1964). (30.4) Tully, P. F., Rubber World 150, No. 2, 83 (1964). (31A) Vajta, L., others, J.Ins!. Petrol. 5 0 , (487), abs. 968 (1964). (32.4) \\’bite, \V. \V., Reynolds, J. A,: Gilbert, R . D., J . A,@/. P o l ~ m e rSei, 8, 2049 (1964). (33A) TVilson, A , , H u n t e r , J.: Rubber J. 146, No. 12. 77 (1964). (34A) Zhinden, R . “Infrared Spectroscopy of High Polymers,” Academic, h’ew York, 1964. Diene Homopolymers a n d Co-polymers (1B) h h b o t t , M., Rubber World 150,No. 1: 81 (1964).
(2B) Berger, M , , Buckley. D . J., J . Pol)merSci. l A , 2945 (1963). (3B) Blumel, H., Rubber Chem. Technol. 37, 408 (1964). (4B) Briggs, J. J., Hutchiron, E. J., Klingender, R . C., Rubber World 150, 41 (1964). (5B) Bruzzone, M., Corradini, G., Amato, F., Rubber Plastics Age 45, No. 10, 1182 (1964). (GB) Chalfant, D. L., Mayor, R. H., Rubber Chem. Technol. 37, 103 (1 964). (7B) Daqel, Y . , Rubber Ahstraclr 42, ahs. 1905 (1964). (8B) De Bittera, J., Reo. Can. Cooirtchouc 41, 617 (1964). (9B) Denecker, H. K., Rubber Aqe 94, 590 (1964). (10B) DeDecker, H. K . , others, Rubber Plustics Age 45, No. 10, 1184 (1964). (11B) Draxler, A,, Koirtschuk u . Gummi, Kunrtst. 17, h-o, 2 , 71 (1964). (12B) Dunlop Rubber Co., Ltd., Brit. Patent 946,056 (Jan. 8, 1964). (138) Dunlop Rubber Co., Ltd., Chem. Process. 10, KO. 12, 57 (1964). (14B) Engel, E. F., ochers,. Rubber Pfnrtics Age 45, N o . 12, 1499 (1964). (l5B) Firestone Synthetic R u b b e r a n d Latex Co.. Duradene, Akron (1964). (16B) Firestone T i r e and Rubber Co., Brit. Paten1 968,756 (Sept. 2, 1964). (17B) Goodyear Tire a n d Rubber Co., Tech. Book Facts NS-S, Akron (1964). (18B) H a n m e i , R. S., Railshack, H. E., Rubber World 149, h-o, 6, 87 (1964). (19B) Krol, L. H., Rubber Plastics Age 45, No. 10, 1183 (1964). (2OB) Morton, M., Piirma, I., Das, B., Ibid.. p . 1180. (21B) Natural Rubber Producers Assoc., Brit. Patent 965,757 (Aug. 6 : 1964). (22B) Ibid,, Tech. Inf. Sheet 67; Welwyn Garden City (1964). (23B) Ibid., Sheet 53. (24B) Phillips Petroleum Co.. Brit. Patent 945,851 (Jan. 8, 1964). (Z5B) Ibid., 952,021 ( M a r c h 11, 1964). (26B) Ibid., 964,303 (July 22, 1964). (27B) Ibid., 972,247 (Oct. 14, 1964). (28B) Ibid., 976,229 (Kov. 25, 1964). (29B) Pinazzi, C., Pautrat, R., Cheritat, R.: Reu. Gen. Caoutchouc 40, 1855 (1964). (30B) Poddubnyi, I. Y., Grechanovskii, V. A , : Rubber Abslractr 42, ahs. 1944 (1964). (31B) Polymer Corp., L t d . . Brit. Patent 958,425 (May 21, 1964). (32B) Railshack, H. E., others, Rubber Age 94, 583 (1964). (33B) Saltman, W. M., Farson, F. S., Schoenherg, E., Rubber Plastics Age 45, 1182 (1964). (34B) Saltman, TV. M . , Link, T. H., IND. END.CHEM.PROD.RFS. DEVELOP.3, No. 3. 199, (1964). (35B) Shell International Research, Brit. Patent 965,203 (July 29, 1964). (36R) Socfin, Co.: Ltd., Ibid., 971,390 (Sept. 30, 1964). 137B) Swinney, F. B., K e n t , E. G., Rubber Aye 95, 571 (1964). (38B) Tkac, A,, Kello, V., Rubber Abstracis 42, ahs. 4541 (1964). (39B) T o d d , R . V., Rubber World 150, No. 1 %84 (1964). (40B) U. S. Rubber Co., Brit. Patent 970,764 (Sept. 23, 1964). (41B) \Veiss, G . H. R., Rubber Deuelop. 17, No. 1, 12 (1964). Mono-ene Elastomers, E P R , E P T , ButyI (1C) Auda, R . S. Cardillo, R . M., Enjay Co.. Publn. Eld-34735. New York (1964). (2C) i l u d a , R . S., Hooton, J. R., Rubber Age 94, 926 (1964). (3C) Banks, S. A , , Dudley, R . H., Onken, D. G., Ibid.: p , 923. ( 4 C ) Barrett, H. K.: Ibid., p. 946. (5C) Bartrug, S. G., Hi-Si! Bull. 29, Pittsburgh Plate Glass, Pittsburgh, Pa., 1964. (6C) Baseden, G. A , , Rubber Age 95, 572 (1964). (7C) Bohn, L., Kolloid-2. 194, No. I , 10 (1964). (8C) Booth, D . A,, Brown, B. P., Mayor, L., Rubber Plastics Age 45, No, 10, 1186 (1964). (9C) Burgess, K..4,, T h u n e , S., Palmesi, E., Rubber World 149, No. 4, 34 (1964). (1OC) Callan, J. E., Ford, F. P., Topcik, B.:R u b b e r A g e 9 4 , 926 (1964). (11C) Crespi, G.: others, Rubber Plastics A g e 45, No. 10, 1181 (1964). (12C) Critides, L., I N D .ENG. CHEM. 56, No. 2: 1 1 (1964). (13C) E. I. d u Pont d e Nemours a n d Co., Publn. A-36228, Wilmington, Del. 1964. Fusco? J. V., Waddell, H. H., Rubber World 149, No. 4, 74 (1964) Gessler, A. M . , Rubber Age 94, 598 (1964). Giller, A,, Knutschuk u . Gummi, Kiinsist. 17, h-0, 4, 174 (1964). Jackson, J. F., J.Polymer Sci. A l , 2119 (1963). Loan, L . D., Ibid., A2, 3053 (1964). Lomonte, J. N., Ibid..B1, 645 (1963). McCahe, R . F., Rubber Plastics Age 45, No. 12, 1492 (1964). Natta, G., others, Chim. Ind. ( i M t l a n ) 45, 651 (1963). Natta, G., others, Rubber Chem. Tech. 36, 1583 (1963). Puett, D., Smith, K. J., Ciferri, .4., J. Chem. Phys. 40, 253 (19643. Scott, C. E., Rubber Age 94, 647 (1964). Spenadel, L., Rubber World 149, No. 6,83 (1964).
(26C) U. S. Rubber Co., Brit Patent 957,070 (May 6, 1964) (27C) U. S. Rubber Co., Rubber J. 146, No. 7, 62 (1964). (28C) Vincent, P. I., Plastics 28, 109 (1963). (29C) White, R . M., Rubber Age 94, 897 (1964). U r e t h a n e Polymers Bylsrna, H. R., IND.END.CHEM.PROD.RES. DEVELOP. 3, No. 3, 204 (1964). D’wyer, F. J., others, Mod. Plastics41, No. 9, 139 (1964). Gemeinhardt, P. G., others, SOL.Plaslics Eng. J . 20, No. 4, 357 (1964). Harding, R. H., Hilado, C. J., J Appl. Polymer Sci. 8, 2245 (1964). (5D) Healy, T. T., ed., “Symp. on Polyurethane Foams,” London, Illiffe (1964). (6D) Kirk, W., Am. Dyestug Replr. 15, No. 19, 725 (1963). (7D) Levesque, R. J., Maine, F. W., Rubber Age 95, 574 (1964). (8D) Matei, I., Cocea, E., Petrus, A., J . Appl. Chem. 14, No. 4, abs. 424 (1964). (9D) Myuller, B. E., others, Rubber Abslracts42, abs. 3453 (1964). (lOD) Pedley, K. A., Ross, J. A., Rubber Plaslics Age 45, No. 4, 417 (1964). (11D) Rausch, K. W., others, IND. ENC. CHEM.PROD.R E S . DEVELOP.3, No. 2, 125 (1964). (12D) Saunders, J. H., Frisch, K. C., “High Polymers,” Vol. 16, Intersciences New York, 1964. (13D) Testroet,F. B., U. S. Gout. Res. Repts. 39, No. 11, S-26 (1964). (14D) Turnbow, J. W., Ibid., 38, No. 22, S-23 (1963). (15D) Whitman, R. D., others, Rubber Abstracts, 42, abs. 2177 (1964). (16D) Woodward, J. L., Adhesiues Age 7, No. 1, 20 (1964). (17D) Wright, P., Automot. Des. Eng. 3, No. 17, 31 (1964).
(1D) (2D) (3D) (4D)
Elastomers Containing Halogen, Oxygen, Nitrogen, Sulfur (1E) Aggarwal, L., others, Rubber Age 95, 570 (1964). (2E) Becker, R . O., Rubber Chem. Technol. 37, 76 (1964). (3E) Churchill Chemical Corp., Rubber Age 94, 956 (1964). (4E) D’Adolf, S., Rubber World 150, No. 3, 80 (1964). (5E) Dow Corning Corp., Ibid., No. 5, 112 (1964). (6E) E. I. d u Pont d e Nemours and Co., Rubber Plastics Age 45, No. 3, 307 (1964). (7E) Gruber, E. E., others, Rubber Age 94, 921 (1964). (8E) Henry, M . C., Griffis, C. B., Rubber Plastics Age 45, No. 10, 1185 (1964). (9E) Holly, H . W., Rubber World 149, No. 6, 82 (1964). (10E) Joclin Mfg. Co., Chem. Eng. h‘ews 42, No. 35, 45 (1964). (11E) Kanavel, G. A., Rubber World 150, No. 1, 84 (1964). (12E) Kelly, D. J., p . 82. (13E) Mendelsohn, M. A., IND.ENC.C H E WPRODUCT RES. DEVELOP. 3, No. 1, 67 (1 964). (14E) Mendelsohn, M . A., Rubber Age 95, 584 (1964). (15E) Murray, R. N., Thompson, D. C., “The Neoprenes,” E. I. du Pont de Nemours and Co., Wilmington, Del., 1963. (16E) Roe, R. J., Krigbaum, W. R., J.PolymerSci. A l , 2049 (1964). (17E) Spektor, E. M., Soviet Rubber Technol. 22, No. 3, 6 (1963). (18E) Stivers, D. A,, Lanin, P. D., IND. END. CHEM.PRODUCTRES. DEVELOP. 3, No. 1, 61 (1964). (19E) U. S. Industrial Chemical Co., Rubber J . 146, No. 7, 30 (1964). (20E) Woodhams, R. T., Adamek, S., Wood, B. J., Rubber Plastics Age 45, No. 10, 634 (1964). Inorganic Elastomers (1F) Bobear, W. J., Rubber Age 95, 71 (1964). (2F) Crockwell, G. W., Ibid., 94, 920 (1964). (3F) Gair, T. J., Rubber World 150, No. 3, 49 (1964). (4F) General Electric Co., Rubber Age 95, 938 (1964). (5F) General Electric Co., Rubber World 161, No. 1, 146 (1964). (6F) Hunter, M. J., Kautschuk u. Gummi, Kunstst. 17,No. 9, 498 (1964). (7F) Lewis, F. M., Rubber Age 94, 647 (1964). (8F) Muller, R., Kautschuk u. Gummi, Kunstst. 17, No. 3, 137 (1964). (9F) Roush, C. W., Kosmider, J., Jr., Benfer, R. L., Rubber Age 94, 744 (1964). (10F) Tsow, K. C., Bodley, R . N., Halpern, B. D., U. S. Gout. Res. Rept. 39, No. 2, 30 (1964). (11F) Wiedenmann, L. G., Ibid., No. 10, 17 (1964) Processing (1G) Booth, C., Polymer4, No. 4, 471 (1963). (2G) Burke, D . W., Brit. Patent 964,185 (July 15, 1964). (3G) Bussemaker, 0. K. F., Van Beek, W. V. C., Rubber Chem. Technol. 37, 28 (1964). (4G) Claxton, W. E., Conant, F. S., Rubber Age 95, 466 (1964). (5G) Einhorn, S. C., Turetzky, S. B., J . Appl. PolymerSci. 8 , 1257 (1964). (6G) Ferguson, J., Wright, G., Howard, R. N., J . AppI. Chem. 14, No. 2 , 53 (1964). (7G) Fisher, F., Rubber Age 95, 778 (1964). (8G) Flynn, R. H., Ibid., p. 468 (1964). (9G) Giller, A., Rubber Plastics Aee 45. 1205 (1964). Gregory, C. H., RubberJ.”l46,No. 8 , 4 6 (1964). Griffiths, J. P., Ibid., No. 2, 30 and 146, 3, 34 (1964). Griffiths, J. P., Ibid., No. 4, 58 (1964). Hagen, R.S., Davis, D. A., J . Polymer Sci. B2, No. 9, 909 (1964). Hock, C. W., Adhesives Age 7 No. 3, 21 (1964). Izod, D. A. W., Morris, W., Rubber Plastics Age 45, No. 10, 1186 (1 964). Johnson and Johnson, Brit. Patent 960,509 (June 6, 1964). Kaelble, D., J . ColloidSci. 19 No. 5, 413 (1964). Lodge, A. S., “Elastic Liquids,” Academic Press, London, 1964. Macey, J. H., Rubber Age 96, 221 (1964). Masson, P. Y., Rubber Chem. Technol. 37, 88 (1964). Meder, A., May, M., Rubber J . 1 4 6 No. 6, 39 (1964). Mooney, M., Rubber Chem. Technol. 37,503 (1964). Muller, R., Kaufschuk u. Gummi, Kunstst. 17,No. 4, 191 (1964). Nikolov, N. S., Reu. Gen. Caoutchouc 41, No. 2, 54 (1964). Powers, P. O., Rubber Chem. Technol. 36, 1542 (1963).
(26G) Reinhart, F. W., Callomon, I. G., U. S. Gout. Res. Rept. 39 No. 1, S-19 (1964). (27G) Reztosova, E. V., others, Souiet Rubber Technol. 22, No. 3, 25 (1963). (28G) Rosen, S. L., Rodriguez, F., Rubber World 149, No. 6, 86 (1964). (29G) Schott, H. J., J . PolymcrSci. A2 No. 8, 3791 (1964). (30G) Sogolova, T. I., others, Rubber Chem. Technol. 37, 627 (1964). (31G) Tobolsky, A. V., Takahashi, M., J . Appl. Polymer Sci. 7, 1341 (1964). (32G) Union Carbide Corp., Rubber World 149, No. 6, 100 (1964). (33G) Van der Hoff, B. M . E., others, Rubber Plastics Age 45, No. 10, 1181 (1964). (34G) Wetzel, F. H., Rubber World 150, No. 1, 82 (1964). (35G) Wetzel, F. H., Alexander, B. B., Adhesiues Age 7, No. 1, 28 (1 964). (36G) Wise, R . W., Decker, G. E., RubberAge 95, 774 (1964). Compounding (1H) Ambelang, J. C., others, Rubber Chem. Technol. 36, 1497 (1963). (2H) Andrews, E. H., Braden, M., J . AppI. PolymerSci. 7, 1003 (1964). (3H) Bannister, E., Rubber J. 146 No. 7, 78 (1964). (4H) Boucher, M., Garlier, G., Reu. Gen. Caoutchouc 41, 1297 (1964). (5H) Brennan, J. J., others, Rubber Age 94, 926 (1964). (6H) Bristow, G. M., J . Appl. PolymerSci. 7, 1023 (1963). (7H) Brown, H. P., RubberChem. Technol. 36, 931 (1963). (8H) Bruzzone, M., Modini, G., Ibid., 37, 451 (1964). (9H) Burgess, K. A,, Hirschfield, S. M., Stokes, C. A., Rubber Age 93, 588 (1363). (10H) Campbell, R. H., others, Chem. Eng. News 42, No. 20, 40 (1964). (11H) Coombs, G., Rubber Age 96, 274 (1964). (12H) D’Adolf, S., Rubber World 150 No. 6, 84 (1964). (13H) Dannenberg, E. M., Rubber J . 146 No. 11, 87 (1964). (14H) Deis, L., Heneghan, F., Rubber World 150, No. 6, 64 (1964). (15H) Dibbo, A., Trans. Inst. Rubber Ind. 40 No. 5, T202 (1964). (16H) Donnet, J. B., others, Rev. Gen. Caoutchouc41, 364 (1964). (17H) Eckelmann, W., Kautschuk u. Gummi. Kunstst. 17 No. 2, 63 (1964). (18H) Emmett R A Coll er, H . J., David, E. L., Studebaker, M . L., Rubber World 149, Nb. 72’(1964r. (19H) Figielski, H. L., Rev. Gen. Caoutchouc41, 491 (1964). (20H) Furukawa, J., others, Ibid., p . 831. (21H) Hallman, R . W., Rubber Age 95, 791 (1964). (22H) Halpin, J. C., Bueche, F., Ibid., 93, 593 (1963). (23H) Kraus, G., Rubber Chem. Technol. 37, 6 (1964). (24H) Linning, F. J., others, Rubber Age 95, 573 (1964). (25H) May, W., Trans. Inst. Rubber Ind. 40 No. 2, T109 (1964). (26H) McCool, J. C., Rubber Age 94, 922 (1964). (27H) Monsanto Chem. Co., Brit. Patent 951,517 (March 4, 1964). (28H) Moore, C. G., Rubber J. 146, No. 5, 34 (1964). (29H) Moore, C. G., Trego, B. R., J . Appl. PolymerSci. 8 , 1957 (1964). (30H) Natural Rubber Producers Research Assn., Tech. Inf. Sheets 60, 61, 62, 75, Welwyn Garden City (1964). (31H) Payne, A. R., Rev. Gin. Caoutchouc 41, 507 (1964). (32H) Roychaudhuri, D. K., Rubber India 16,No. 5, 9 (1964). (33H) Scanlan, J., Rev. Gen. Caoutchouc 41, 1005 (1964). (34H) Shell International Research, Belgian Patent 619,389 (Dec. 27, 1962). (35H) Smith, C. E., U. S. Patent 3,141,867 (July 21, 1964). (36H) Snow, C. ly., Rev. Gen. Caoutchouc 41, 75 (1964). (37H) Spacht, R . B., others, RubberAge 95,573 (1964). (38H) Tawney, P. O., others, J . Appl. Polymer Sci. 8, 2281 (1964). (39H) Voet, A,, Rubber Age 94, 926 (1964). (40H) Voyutskii, S. S., Ibid., 95, 729 (1964). (41H) White, J. W., Ibid., p. 791. (42H) Zalukaev, L. P., Pivnev, V. I., Rubber Abstracts 42, abs. 4993 (1964).
4,
Vulcanizate Testing Akkerman, F. H. D., Rubber Chem. Technol. 37, 186 (1964). Allen, G., others, Trans. Faraday SOL.59, 2493 (1963). Baseden, G., Rubber World 149, 88 (1964). Bassi, A. C., Rubber Age 94, 923 (1964). (51) Boyer, R. F., Rubber Chem. Technol. 36, 1303 (1963). (61) Bueche, F., Halpin, J. C., J . Appl. Physics 35, 36 (1964). (71) Cheetham, I. C., Rubber J . 146,77 (1964). (81) Collins, J. M., Jackson, W. L., Oubridge, P. S., Rubber World 149, No. 6 , 83 (1964). (91) Dingle, A. D., Ibid., p. 91. (101) Ecker, R., Rubber Age 96, 922 (1964). (111) Hallman, R. W., Brunot, C. A., Ibid., 95, 886 (1964). (121) Hotpack Corp., Ibid., 96, 314 (1964). (131) Juve, A. E., Rubber Chem. Technol. 37, X X I V (1964). (141) Kuperman, F. E., Karmin, B. K., Rubber Abstracts 43, abs. 304 (1965). (151) Livingston, D. I., Hildenbrand, L. E., Rubber Chem. Tech. 37, 14 (1964). (161) Mussa, C., PlasficsInst. London Trans. J . 31 (96), 146 (1963). (171) Peticolas, W. L., Rubber Chem. Technol. 36, 1422 (1963). (181) Plas-Tech Equipment Corp., Rubber World 150, No. 4, 120 (1964). (191) Roscoe, R., Brit. J . Appl. Phys. 15, 1095 (1964). (201) Schallamach, A., Rubber J . 145 No. 5, 34 (1964). (211) Smith, R . W., Black, A. L., Rubber Chem. Technol. 37, 338 (1964). (221) Smith, T. L., J . Appl. Phys. 35, 27 (1964). (231) Stratton, R.W., Ferry, J. D., J . Phys. Chem. 67,2781 (1963). (241) Tangorra, G., Rubber Chem. Technol. 36, 1107 (1963). (251) Thomas, A. G., Rubber J. 146, 34 (1964). (261) Thomas, A. G., Rubber Plaslics Age 45, No. 5, 548 (1964). (271) Thomas, D. K., Polymer 5, 463 (1964). (281) Transister Autom. Corp., Rubber Age 95, 798 (1964). (291) Yin, T. P., Pariser, R., J . Appl. PolymerSci. 8, 2427 (1964).
(11) (21) (31) (41)
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