Rubber Services Laboratories

In 1921, C. W. Bedford, at Rubber Services Laboratories Co., L. B. Sebrell, for Goodyear Tyre Rubber, both in the US, and Bruni and Romani at Pirelli, in Italy, developed mercaptobenzothiazole (MBT) (97) as an organic accelerator. In 1931, Bayer converted mercaptobenzothiazole into sulfenamides, that contain the grouping =CSNR2. These later became the most important class of accelerators. 

Former positions include Manager of Technical Service Laboratory, Ashland Chemical Company. Technical Service Specialist, Malaysian Rubber Bureau, U.S.A. Initiator of testing program for natural-rubber-treaded tires for Canadian Safety Authority and Malaysian Rubber Producers Research Association Laboratories. Author of numerous papers and a book. 

In another laboratory, a vacuum pump was installed on a shelf buUt into a two-foot knee-hole well above the floor level. It was out of the way, off the floor, and easy to service. Noise was substantially reduced by attaching rubber stoppers to the pump s base plate as vibration absorbers. Connection to equipment was through a hole in the work top. 

Occupational exposure to 1,3-DNB and 1,3,5-TNB can occur when workers handle the compounds in explosives plants and other industries, such as dyestuffs, plastics, and rubber, that use these compounds during manufacturing processes. The National Occupational Exposure Survey (NOES), conducted by NIOSH from 1981 to 1983, estimated that 2,489 workers were exposed to 1,3-DNB in 41 businesses and health services (NOES 1991). The workers included in this survey were chemists (except biochemists), geologists, clinical laboratory technologists and technicians, and health aides (except nursing). 

The second class includes tests for ageing, oxygen and ozone attack, adhesion, resistance to wear and tear, fatigue, etc. This class also includes tests under simulated service conditions under laboratory environments and immersion in fluids. These two classes of tests are conducted on vulcanized rubber. 

Generally, in any wear process more than one mechanism is involved although one mechanism may predominate. The mechanism, and hence the rate of wear, can change with change of conditions such as contact pressure, speed and temperature. The most important consideration in practice is that the wear process will be complex and critically dependent on the service conditions. It is, therefore, necessary that any laboratory test must essentially reproduce the service conditions if good correlation is to be obtained. Even a comparison between two rubbers may be invalid if the predominant wear process in the test is different from that in service. It is failure fully to appreciate this which has led to the conclusion that all laboratory abrasion tests are useless except for quality control. 

The test for evaporation (ASTM D-972) gives a measure of oil volatility under controlled conditions and is used frequently for specification purposes. However, because volatility of oil from a rubber compound may be influenced by its compatibility with the rubber, a volatility test of the compound often is made under laboratory test conditions pertinent to the intended service. 

The data of Table IV are results on a shear stress recovery test that was developed at the Firestone Research Laboratory (4) as a low temperature serviceability index for rubbers. Essentially, the test consists of submitting a double sandwich-type specimen to equilibrium deformation at shear stress of 35.6 pounds per square inch, and then determining the temperature at which 50% recovery takes place in 1 minute upon removal of the load. 

Wear is important in applications as diverse as tires, conveyor belting, footwear, and windscreen wiper blades, yet most of us would accept that the rubber industry still awaits a laboratory test or series of tests that can predict service performance with any confidence. Over the years, there certainly has been no shortage of small-scale tests for abrasion resistance and indeed no shortage of claims or reports of satisfactory correlation with the behavior of various products, but strong doubts remain, and some sectors, not least the tire industry, conclude that there is no substitute for a service trial or a simulated product test, for example, a road trial on tires held at a small slip angle to accelerate wear. 

The Polymer industry embraces the total spectrum of activities from petrochemical cracking, monomer preparation, polymer production and the fabrication of all manner of plastics and rubber products. In addition there is an increasing number of technical. service and or research laboratories being established by local and multi-national companies to support their efforts in Singapore and or throughout the Asia Pacific Region. 

Abrasion Resistance. Abrasion is the wearing of material from a rubber surface due to the action of an abrasive surface in contact with and moving with respect to the rubber surface. It is measured under a specified load, at a specified sp d and type of abrasive surface. Laboratory tests may not predict service life, because the many and complex factors affecting abrasion vary greatly from application to application. However, laboratory tests are useful for quality control of rubber products intended for rough service. 

The slow-bend brittle point test does not have the same practical significance as the BeU Telephone Laboratories brittle point test because most rubber articles which are exposed to low temperatures in service are required to withstand fairly rapid flexing. If the slow-bend brittle point test were used as a criterion of the cold resistance of these rubber articles, it might qualify the rubbers for a lower temperature than they could safely withstand in service (Morris et al. 1944). 

AT-Cyclohexyl-2-benzothiazylsulfenamide is a rubber accelerator chemical. The most frequent occupational categories are metal industry, homemakers, health services and laboratories, and building industries. 

Mercaptobenzothiazole is a rubber chemical, an accelerant of vulcanization. It is contained in the mercapto mix . The most frequent occupational categories are metal industry, homemakers, health services and laboratories, building industries, and shoemakers. It is also used as a corrosion inhibitor in cutting fluids or in releasing fluids used in the pottery industry. 

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