ABOUT 1905 TO ABOUT 1939

Advances in Motoring

The elitism in motoring gradually collapsed within this period due to the development of mass production, notably by Ford, and the quest for cheaper vehicles in Europe developed from the motorcycle (such as the Morgan three-wheeler). Early tyres were both expensive ($100) and short-lived (750 km), but development was rapid: by 1920 they cost $30 and lasted 20,000 km. Pneumatic tyres were gradually developed for buses and trucks, mainly in about the middle of this period, prior to that such tyres tended to made from solid rubber.

Ghosh has some very interesting contemporary comments on this aspect: About 1910 motor cars and trucks were adopted almost everywhere in the West and since then the expansion of automobilism has been almost phenomenal throughout the world. For instance, at the present time (the mid-1920s) it is estimated that there is 1 automobile to every 6 persons in the United States, 1 to every 51 persons in Denmark, 1 to every 53 in France, 1 to every 55 in Great Britain, 1 to every 75 in Sweden, 1 to every 84 in Belgium and 1 to every 99 in Norway. Workmen in the United States actually drive to the factories in their own motor cars mainly because their country possesses the largest automobile industry and the American operative;helped to some degree by 'prohibition' is deservingly passing through his days of abounding prosperity.

Plantation Agriculture

Ghosh (see above) noted that the initiation of rubber culture in plantations many years before the advent of the automobile was really providential for the success of rapid locomotion. Ghosh, like many commentators, over-states the foresight of the plantation industry as such (that is in comparison with the transfer of rubber seeds from Brazil to Asia): the real spur for the development of plantations in Asia came from the increase in Brazilian rubber prices in the latter part of 1905, which in turn had been a consequence of the new-found market in motor vehicles. In the USA rubber prices rose to $1.50 per pound, as compared with $0.68 in 1903-04. Michelin invested in rubber plantations in "French Indochina" (Vietnam and Cambodia) in 1906. By this time, Dunlop was able to take advantage of its own estates in Malaya (Malaysia).

Advances in Compounding

Many improvements were made to compounding techniques during the 1905-1939 period. Accelerators and antioxidants became widely available. W Ostwald patented the use of aniline as an antioxidant in 1908. Aniline is a powerful softener, and a weak accelerator and antioxidant, but highly toxic. Bayer of Leverkusen patented organic bases as accelerators in 1911 as part of their development of synthetic rubber which lacked the proteinaceous materials in natural rubber which accelerate vulcaniation.

In 1914 F. Hoffman and K. Gottlob of Bayer claimed that all bases having a dissociation constant greater than 1 x 10-8 and which show an alkaline reaction at vulcanization temperatures are accelerators. In 1915 Ostromyslenski patented a non-nitrogenous (xanthate) accelerator. During the 1920s there was a considerable amount of work to elucidate the roles of accelerators and zinc oxide in the vulcanization process. This work led to the discovery of diphenyl guanidine and mercaptobenzthiazole as accelerators. More on vulcanization.

Carbon blacks

In 1904 S.C. Mote of the India Rubber Gutta Percha and Telegraph Works in Silvertown, London, discovered the value of carbon black produced by the incomplete combustion of natural gas. His work showed that this material increased the mechanical strength beyond anything prevusly known. By 1910 carbon black was widely used, especially in tyres. Lamp blacks had been known to Hancock and used as a pigment. Lamp blacks had been produced via the incomplete combustion of organic wastes, but their production from natural gas had been discovered by Wright in 1864.

Channel blacks (where natural gas is burned against reciprocating iron channels) had been discovered by McNutt in 1892. In 1922 Columbian Carbon developed the furnace black process where combustion is through larger flames in an enclosed space. The particle sizes of such blacks can be tailored to meet the requirements o the rubber industry (which is the main market for such materials). Thermal blacks had been invented in 1916: in this process natural gas is injected into very hot chambers: fine thermal blacks offer good reinforcement.

Mixing

The Banbury mixer was developed during this period (from about 1916 on): this enabled large quantities of rubber to be compounded in a relatively short time and was especially significant in the development of compounding for the tyre industry.

Advances in agricultural techniques

Improved agricultural techniques (especially for the breeding and propogation of rubber trees) were developed by the larger plantation companies. New research centres were created in what were then Ceylon, Malaya, French Indochina and the Dutch East Indies (Sri Lanka, Malaysia, Cambodia and Vietnam, and Indonesia). Research through selective breeding led to great increases in yield.

First World War

The First World War provided a huge stimulus to the automotive industry, especially in the provision of motorized trucks. In Germany the blockade by Britain and its allies led to the establishment of a synthetic rubber industry, but the quality of this synthetic was very poor and did not yet present a real threat to natural rubber.

Post World War I Slump

After the War there was a brief boom, but this was followed by a slump in natural rubber prices. The Stevenson Scheme was introduced by the British Government to limit output in its Colonies (Malaya and Ceylon) in an attempt to raise prices. This stimulated output from smallholders who had hitherto been an unacknowledged source of supply and infuriated the major consumers especially those in the USA. The Stevenson scheme ended in 1928.

International Rubber Regulation

Following an even more severe decline in rubber prices due to the Great Depression an International Rubber Regulation Agreement was implemented in 1934 by the United Kingdom, India, the Netherlands, France and Thailand. It laid down quotas for existing plantations and new planting was forbidden. The Agreement led to the formation of the International Rubber Study Group and the inception of consumption research into natural rubber, including the formation of the International Rubber Research Board, the precursor of the IRRDB. The Agreement lacked the involvement of the consumers (other than the UK and France) and led many consumers in the USA to consider that they were being held to ransom. It also totally neglected the existence, and needs, of smallholders.

The Regulations did halt the decline in rubber prices, but at the cost of neglecting the smallholder sector and alienating the major consumers, especially those in the USA. Price stabilization measures were established again in the late 1970s.

American responses during the Inter-War period

The large American tyre and automotive companies were highly unhappy with what they regarded as the dominance of the colonial powers (France, the Netherlands and the United Kingdom) in the supply of natural rubber as exemplified by the Stevenson Scheme and sought to develop the rubber industry elsewhere. This also had a major influence on the post Second World War development of the synthetic rubber industry in the USA.

Ford/Edison/Florida/Firestone Liberia

The first response by the Ford company and the major tyre companies was to investigate the rubber producing plants indigenous to the USA and neighbouring areas and set up experimental plantations in Florida. At about this time Edison attempted to mechanize the harvesting process using the experimental plantations in Florida. Later, Ford invested in plantations in Brazil: the Fordlandia venture, but this failed due to SALB and to a shortage of labour. Goodyear became involved in plantations in the Philippines and Costa Rica and Firestone started its large scale venture in Liberia.

State of scientific knowledge

H. Staudinger (Ber. Dtsch Chem. Ges., 1920, 53, 71) first proposed the macromolecule concept. Nevertheless, as late as 1937 textbook was able to state that "Staudinger's assumption that the ultimate particles in dilute solutions of linear high polymers are chemical molecules rather than micelles has been severely criticized, sometimes justly and sometimes otherwise" (W.F. Busse in The Chemistry and Technology of Rubber; ed. C.C. Davis and J.T. Blake. New York: Reinhold). Testing was developed during this period: L. Schopper developed tensile testing apparatus in 1908; W.C. Geer (1916) and J.M. Bierer and C.C. Davis (1924) provided methods for testing accelerated ageing; and I. Williams (1924) and Mooney (1934) developed machines to measure plasticity.

Downstream research

A full understanding of the basic chemical structure of polymeric materials, and rubbers in particular, had to await the post-1945 period, but many advances were made in the 1919-1939 period. Following the period of extremely low prices in the early 1930s research centres to encourage an increased uptake of natural rubber through the devlopment of new and extended uses werer created in Britain, the Netherlands and France. This activity was to lead to the formation of the IRRDB at the end of this period. Industrial research by companies like Dunlop and Goodyear also developed rapidly in this period. The Research Association of British Rubber Manufacturers (the precursor of RAPRA Technology Ltd) was formed in 1921 as the Rubber Club of Great Britain: it held conferences, arranged education, and instigated the Colwyn Medal in 1928. It became the Institution of the Rubber Industry, a British professional body which later was absorbed into the Institute of Materials. The Rubber Division of the American Chemical Society was formed in 1919 and its key journal (in terms of reporting advances in rubber technology) Rubber Chemistry & Technology began publication in 1928.

IRSG & IRRDB and research in consuming territories

The price stabilization Agreement led to the gathering of statistics and to the eventual formation of the International Rubber Study Group and to the co-ordination of research and development in natural rubber which led to the formation of the International Rubber Research Board - the precursor of the IRRDB. It also led to the establishment of research centres in France, the Netherlands and the United Kingdom: TARRC is a successor to this activity in the immediate pre-1939 period. This activity reflected a quest for new outlets for natural rubber.

Quest for New Products

The prevalent low prices led to a quest to new markets for natural rubber. The Rubber Growers' Association established a prize for the establishment of new uses and some very bizarre ideas were submitted. The arrival of latex concentrate in commercial quantities on the European and American markets was a significant development. Much effort was expended in using rubber in road surface dressings. Initial work was directed at rubber blocks which were used in a similar way to granite setts, but later work was directed at the admixture of rubber (as powder or as latex) with bitumen (asphalt). Much of the scientific effort which began during this period enabled new applicatiions to be introduced, such as the use of waterstops in the vast concrete dams constructed in the USA and in automotive components to reduce noise and vibration.

Latex concentrate

Latex concentrate was marketed on a large scale during the late 1920s and this led to the development of a new industry: there were dipped products, extruded thread and foam rubber. To an extent all competed with existing rubber products: solution dipped products (surgical gloves, condoms, etc); cut thread and sponge rubber, but the new products were either superior (in terms of properties and/or ease of manufacture) or could enter different markets. Latex concentrate also formed a useful safe adhesive which could be safely be used by children without the risk of solvents: the mild aroma of ammonia inhibits glue sniffing!

Foam rubber

Foam rubber found novel markets in furniture and bedding (mattresses and pillows) which could not have been exploited by sponge rubber. One of the great advantages of foam rubber upholstery is that it is far more hygeinic than traditional materials.

Latex dipped goods

Latex gloves were far cheaper to produce than solution dipped gloves and the process was far safer (dangers of fire and health) than the solution process which exploited solvents on a large scale.

Latex thread

Latex thread enabled new forms of underwear and swimwear to be created - ones which polyurethane thread would exploit after the War, but not supplant.

Rubber hydrochloride

Pliofilm, a modified form of natural rubber namley rubber hydrochloride, was marketed by Goodyear in the late 1930s. The transparent film was used as a packaging material and even as a form of waterproof material for clothing. In many respsects Pliofilm anticipated PVC. Two other forms of natural rubber, notably cyclized rubber and chlorinated rubber were developed during this period: the former is used in printing inks and adhesives; the latter is used in the paints for swimming pools. Modified rubbers were developed further in the 1940s and 1950s.

Automotive components

The mass-production automotive industry called for large quantities of rubber components. In 1932 G.H. Lanchester listed some of the problems experienced: engine mountings hardened; shock absorbing bushes deformed; hood cloth fouled, and severe ageing occurred in the tropics. Some of the problems were caused by inferior rubber compounding, many to under-design, and some to a lack of knowledge about rubber in service. Many of these problems were resolved during World War II and the period which followed it.

Waterstops

One major new outlet for natural rubber emerged in the mid-1930s; namely the use of waterstops in massive concrete dams, notably in the Imperial Dam which impounds the Colorado River. These were a significant development as their use marked the entry of rubber into large civil engineering projects as an integral component (rubber had been used in seals for watermains and sewers for far longer, however).

Synthetic rubber development

During, and immediately prior to the First World War, Bayer of Leverkusen had developed a form of synthetic rubber into a form which could be used for tyres: there are pictures of the Kaiser standing alongside an automobile with synthetic rubber tyres. In the 1920s I.G. Farbenindustrie continued the development of what has since come to be known as styrene butadiene rubber (SBR). Similar development was also taking place in the USSR and by 1939 nearly 80,000 tonnes were being produced in the USSR and over 20,000 tonnes in Germany. Clearly both countries wished to be independent of supplies of natural rubber which had to be imported.

New synthetics

Polychloroprene rubber was marketed in 1931 and nitrile rubber in 1936. The latter provided a source of oil-resistant rubber for the first time. Polysulphide rubber (Thiokol) was introduced in 1929.

Tyres

Tyre performance increased rapidly in terms of wear resistance, but other improvements in terms of wet skid resistance, etc had to await developments following the Second World War (although Michelin was innovating the radial ply tyre in the immediate pre-War period and managed to keep this invention hidden from the occupying Germans). Heavy duty commercial vehicles , including buses and trolleybuses, switched to pneumatic tyres from solid tyres during this period and this reflected improvements in tyre construction.

In part these improvements stemmed from motor racing and especially from the tyres developed for vehicles attempting the land speed record, such as Sir Malcolm Campbell's Bluebird. The Michelin company sought to develop pneumatic tyres for railway vehicles, but the real success had to await further development for the Paris Metro in the early 1950s.

Summary

Attempts to control rubber prices without involving the major consumers led to higher prices, but at the "cost" of losing consumer good will. The colonial regimes ignored the smallholder sector and even sought to suppress production from it to improve estate sector incomes. Science was firmly taken on board to replace the former highly empirical developments.

>Part 4