Rubber bonding process

Rubber to metal bonding is a generic phrase covering a number of interdependent processes. The rubber bonded units that result from the process are used for the isolation of noise and vibration in automotive, engineering and chemical industry applications, such as in rubber lining of process equipment. 

Fig. 1. Transmission electron micrograph of ABS produced by an emulsion process. Staining of the rubber bonds with osmium tetroxide provides contrast...

Proprietary bonding agents are used almost exclusively in modern manufacturing processes for metal-rubber bonded products. Isocyanates were proved to be of value in the immediate postwar period, but their moisture sensitivity and tendency to be wiped off the metal during processing have proved as disadvantages. The majority of commercially available adhesives in use today are a complex mixture of undisclosed composition, and in many instances are specifically used for particular rubbers and substrates. 

As previously noted, the primary use for this elastomer has been as solvent-based adhesives and sealants. Solvent-based products are losing market share to water-based poly-chloroprenes, to other polymer types such as acrylics and polyurethanes, and to hot melt adhesives. However, where the processing facility is able to contain the vapor emissions, a solvent-based adhesive or sealant is preferred because of better wetting of surfaces, faster drying, and higher performance of the cured or dried product. Many rubber bonding... 

The fibers are supplemented by the reaction product, coated with natural mbber or SBR and vinal pyridine latex. During the subsequent drying procedure at 150-230 °C, the methylol group reacts with both the fiber surface and the active molecule groups of the rubber. The rubber bonded to the fibers is also cross-linked in the subsequent vulcanization process. 

Historically natural polymers, such as wool, leather, silk, and natural rubber, were processed into usable materials. During the past 70 years or so, chemists have learned to form synthetic polymers by polymerizing monomers through controlled chemical reactions. A great many of these synthetic polymers have a backbone of carbon—carbon bonds because carbon atoms have an exceptional ability to form strong stable bonds with one another. 

Very thin wheels can be made by this process, because of the elasticity of the material, and are ideal for cut-off wheels, where they are run at high surface speeds between 3000 and 4800 m/min. Rubber-bond wheels are also used for control wheels in centreless-grinding machines. 

An important example of cross-linking is the vulcanization of natural rubber, a process discovered by Charles Goodyear in 1839. Natural rubber is formed from a liquid resin derived from the inner bark of the Hevea brasiliensis tree. Chemically, it is a polymer of isoprene, CsHg (A Figure 12.41). Because rotation about the carbon-carbon double bond does not readily occur, the orientation of the groups boimd to the carbons is rigid. In natural rubber, the chain extensions are on the same side of the double bond, as shown in Figure 12.41(a). 

Methods for the production of rubber bonded components have to be established and firmly founded within strict limits of the many parameters for the control of quality. It is in the initial stages of the development of the production process that the use of suitable bond tests is vital. The test values will allow the manufacturer to discover the operational limits for all process variables and ensure that the set conditions for production do not allow a knife-edge situation where small changes can produce large variations in the quality of the bond. This is best achieved through the use of factorial experiment design and statistical regression analysis of the results. 

Rubber to metal bonding processing effects J A LINDSAY Importance of good mould design... 

Many of the plastics available today may be bonded to rubber provided that the thermal and mechanical properties of the plastic are compatible with the process conditions required for the bonding process. Fully saturated polymers such as polyethylene and polypropylene are not generally considered to be suitable for the process but can be successfully moulded to cured rubber. Examples of this can be seen on military vehicles where such mouldings work as aerial bases. 

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