Solvent welding

The largest market for elastomer-based adhesives is that of lamination (see Laminates). Modem office furniture having Formica as a surfacing material is made with an elastomer-based adhesive. Tile adhesives for ceramic or carpet tile are also elastomer-based and usually solvent appHed. Paper adhesives and shoe manufacture also use substantial quantities of mbber-based materials. Solvent-weld adhesives are used to join plastic plumbing and to repair vinyl sheeting. 

Thermoplastics. There are five elastomeric membranes that are thermoplastic. Two materials, chlorinated polyethylene (CPE) and polyisobutylene (PIB), are relatively obscure. Thermoplastic materials can be either heat-fused or solvent-welded. In contrast to Hypalon and uncured EPDM, this abiHty to fuse the membranes together remains throughout the life of the material. However, cleaning of the membrane surface after exposure to weather is required. Correct cleaning procedures for specific membranes are available from the individual manufacturer. 

It is less resistant to aliphatic hydrocarbons than polyethylene and polypropylene and in fact pipes may be solvent welded. At the same time the resistance to environmental stress cracking is excellent. 

Solvent-Based Adhesives—In these the adhesive flows because it is dissolved in an appropriate solvent, and solidification occurs on evaporation of the solvent. Good bonds are usually formed if the solvent attacks or actually dissolves some of the plastic adherend to produce a solvent-welded bond. 

The Standard includes a definition too for solvent bonding solvent welding (see Chapter 6). 

When solvent welding or thermal welding is not practical or desired, adhesive systems can be used. Adhesive types such as epoxies, urethanes, thermosetting acrylics, nitrile phe-nolics, and cyanoacrylates permit ABS to be bonded to itself and to other substrates. The best adhesives have shown strength greater than that of ABS however, these adhesives provide very rigid bonds. 

The difficulty with analyses by occupation and industry is that they do not identify specific agents as risk factors. For example, farmers may be exposed to pesticides, but they also have potential for exposures to other agents, including fuels, solvents, welding fumes, wood dust, silica, crop dust, animal danders, zoonoses and endotoxins. In addition, although some farmers use pesticides, many others do not (Blair and Zahm, 1993). An elevated risk in a job can only be suggestive of particular exposure risks. 

They may be extruded or blow molded. Parts may be thermally formed and heat or solvent welded. Some applications are blow-molded containers, pipe, ventilating ducts, and molded parts. 

The use of a perfluorinated ionomer as the SPE electrode binder results in better adhesive bonding with the membrane by virtue of the fact that the binder and the membrane are of identical composition. In addition, the solvent in the electrode paste promotes "solvent welding" by softening the membrane during the application process. 

Solvent-based adhesives like model airplane glue contain a volatile solvent that dissolves part of the plastic and when dry forms a solvent weld. 

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