Historical Development of Rubber

Columbus, on his second trip to America, found the American Indians playing a game with rubber balls (11,12) made of natural rubber. These crude materials were un-cross-linked but of high molecular weight and hence were able to hold their shape for significant periods of time. 

The development of rubber and rubber elasticity theory can be traced through several stages. Perhaps the first scientific investigation of rubber was by Gough in 1805 (13). Working with unvulcanized rubber, Gough reached three conclusions of far-reaching thermodynamic impact  

A strip of rubber warms on stretching and cools on being allowed to contract. (This experiment can easily be confirmed by a student using a rubber band. The rubber is brought into contact with the Ups and stretched rapidly, constituting an adiabatic extension. The warming is easily perceived by the temperature-sensitive lips.) 

Under conditions of constant load, the stretched length decreases on heating and increases on cooling. Thus it has more retractive strength at higher temperatures. This is the opposite of that observed for most other materials. 

Using the newly vulcanized materials, Gough s line of research was continued by Kelvin (16). He tested the newly established second law of thermodynamics with rubber and calculated temperature changes for adiabatic stretching. The early history of rubber research has been widely reviewed (17,18). 

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For more on the development history of polyurethanes at I. G. Farben and elsewhere, see (a) O. Bayer, Angew. Chem, A59, 275 (1947) (b) O. Bayer, E. Mueller, S. Peterson, H. Piepenbrink and E. Windemuth, Angew. Chem, 62, 57 (1950) (c) O. Bayer, E. Mueller, S. Peterson, H. Piepenbrink, andE. Windemuth, Rubber Chem. Technol., 23, 812 (1950) (d) Urethanes Technology, Vol. 4, March and June issues (1987), Crain Communications, London (e) K. C. Frisch, Historical Developments of Polyurethanes, in 60 Years of Polyurethanes, International Symposium and Exhibition, January 15-16, 1998, Technomic Publishing, Lancaster, PA, 1998. 

This historical development of the radiation technology of polymers is reviewed in this outline. The important applications of this technology are divided into two classes - large scale processes such as cross-linking of rubbers and plastics and specialized sophisticated processes such as microlithography. The initial fundamental studies that led to these applications are outlined and the slow process of commercialization is emphasized in this review. 

Polymer technology is quite old compared to polymer science. For example, natural rubber was first masticated to render it suitable for dissolution or spreading on cloth in 1820. and the first patents on vulcanization appeared some twenty years later. About another one hundred years were to elapse, however, before it was generally accepted that natural rubber and other polymers are composed of giant covalently bonded molecules that differ from ordinary molecules primarily only in size. (The historical development of modern ideas of polymer constitution is traced by Flory in his classical book on polymer chemistry [ I ], while Brydson [2] reviews the history of polymer technology.) Since some of the terms we are going to review derive from technology, they are less precisely defined than those the... 

Looking at the historical development of the emulsion pol)nnerization, it is seen that the trigger factor in this development was the necessity for synthetic rubber in the wartime. The production of styrene/butadiene rubber (SBR) satisfied this requirement. Today, millions of tons of S)mthetic latexes are produced by the emulsion pol3merization process for use in wide variety of applications. In the S)mthetic latexes, the most important groups are styrene/butadiene copolymers, vinyl acetate homopol)rmers and copol)nners, and polyacrylates. Other synthetic latexes contain copolymers of ethylene, styrene, vinyl esters, vinyl chloride, vinylidene chloride, acrylonitrile, cloroprene and polyurethane. 

These examples illustrate some key features about the historical development of jxilyester elastomers. Based on a rather limited view of what high performance polymeric materials could do, they were originally thought of as a new class of rubber. However, once a broad program of research and development was underway based on a new understanding of the market, it was discovered that the material could be used in unique ways, unanticipated either by us, developers, or our customers and end-users. 

The historical development of SBR including trends in manufacturing methods is outlined. Variables in micro- and macro-structure are analysed and the properties of the polymer are compared with those of natural rubber. The processability of SBR is considered in some detail and attention is given to recent methods of assessing mixability and other processing characteristics. 

The development of high styrene content styrene-butadiene copolymers (SBCs), such as K-Resin SBC, is best thought of as a branch off the history of anionic polymerization and rubber. A number of excellent reviews cover this aspect of the subject in great detail, and should be obtained for detailed examination of the history of rubber and anionically synthesized rubber polymers [1-3]. What follows is a brief overview to fit the high styrene content SBC into a historical context. 

It will be shown in Chapter 11 that the correlations developed in this monograph can be combined with other correlations that are found in the literature (preferably with the equations developed by Seitz in the case of thermoplastics, and with the equations of rubber elasticity theory with finite chain extensibility for elastomers), to predict many of the key mechanical properties of polymers. These properties include the elastic (bulk, shear and tensile) moduli as well as the shear yield stress and the brittle fracture stress. In addition, new correlations in terms of connectivity indices will be developed for the molar Rao function and the molar Hartmann function whose importance in our opinion is more of a historical nature. A large amount of the most reliable literature data on the mechanical properties of polymers will also be listed. The observed trends for the mechanical properties of thermosets will also be discussed. Finally, the important and challenging topic of the durability of polymers under mechanical deformation will be addressed, to review the state-of-the-art in this area where the existing modeling tools are of a correlative (rather than truly predictive) nature at this time. 

Early uses of colloidal silica for catalysis, ceramics, paper and textile applications, strength enhancement in rubber, tobacco treatment, and medicine are discussed. A historical view of the development of applications is highlighted, and future uses are discussed. 

Although we did not publish our domain theory in 1965, it was fairly evident to those acquainted with the historical developments in Table II that the new products were three-block polymers. Researchers in the field very rapidly commenced to use these polymers as models for comparison and as subject for physicochemical studies. Evidence for this may be seen in the work reported by Cooper and Tobolsky (42) in 1966, in which they correlated the behavior of polyester-polyurethane thermoplastic rubbers (Estane products) (37) with those of a Shell S-B-S polymer. They concluded that the presence of segregated hard and soft phases in the Estane... 

Alkali Metals The direct use alkali metals and alkaline-earth metals as initiators for anionic polymerization of diene monomers as first reported in 1910 is primarily of historical interest because these are uncontrolled, heterogeneous processes [4]. One of the most significant developments in anionic vinyl polymerization was the discovery reported in 1956 by Stavely and coworkers at Firestone Tire and Rubber Company that polymerization of neat isoprene with lithium dispersion produced high di-l,4-polyisoprene, similar in structure and properties to Hevea natural rubber [47]. This discovery led to development of commercial anionic solution polymerization processes using alkyllithium initiators. 

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