3- If we consider the cold vulcanizing data shown in Figure 9, the control 

 summary sheet, it shows that a stronger bond was created with Goodyear 

 and Uniroyal Royalon belts. Since all the connections were manufactured 

 identically, the differences in strength become a function of the type of 

 rubber covers. Although it is possible to classify rubbers to some extent by 

 the basic rubber (polymer) used in their manufacture, for example the 

 ASTM designation used previously, this is only a general description. Each 

 manufacturer will add other items in the manufacture of the rubber. 



Cold vulcanizing bonds rubber to rubber in a cohesive bond. The compound 

 melts the rubber layer it is applied to, thus creating a stronger connection. 



4- Flexane forms a different type of bond, called sm adhesive bond. This bond 

 is made up of a dissimilar material having an affinity for both sides. The 

 variations in the numbers as one reads across the control specimen table can 

 in part be attributed to the very short pot life of the material. The Flexane 

 was curing in the pot as we were pouring it into the molds. Thus some of the 

 connections were made up of some material that had already cured to some 

 extent. There was approximately a four- month wait to aUow for curing, 

 between completion of fabrication of the first concept, to initial testing of 

 the control samples. Similarly, three and one-half months were allowed 

 before this concept was placed in the water. If one looks at the six-month 

 summary in Figure 10, the failure loads increased for Goodyear and Royalon, 

 In these two cases the water probably helped cure the material. There are 

 urethanes for which a moisture cure system can provide higher loading. 



As you can see, the design of the fastening is complex, and depends on a number of 

 factors. 



38 



