Application of Bonding Agents

As for solvent systems, a barrel spraying machine may be used for surfaces that need to be coated on all areas. The Environmental Protection Act has prompted manufacturers to find means of reducing or eliminating the volume of solvent used in cleaning and coating 

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Surface oxidized before application of bonding agent... 

Many bonding failures can be traced back to faulty metal preparation, poor application of bonding agents or careless handling techniques on the factory floor. 

Direct bonding of orthodontic brackets uses the acid-etch technique, with phosphoric acid gel to etch the surface and deliver the initial pretreatment (Kitayama et al. 2007). This is followed by the application of bonding agents or of lightly filled or completely unfilled resins to the surface. These form attachments to the surface mechanically by flowing into the irregularities created in the etching step. 

The application of conpling agents to an inorganic surface provides a powerful way of affecting the bonding properties of the surface. This plays an important part both in filled polymers and (see Fibre composites - introduction). 

Application of coupling agent(s) to textile reinforcements to improve the interfaces and the fibre/resin bond. 

Figure 4.1 Effect of application thickness of bonding agent Chemosil 211 Chemosil 211 (primer solvent-based) 411 Chemosil 411 (topcoat solvent-based) XW7500 Chemosil XW7500 (topcoat waterborne) APIO Thixon APIO (primer waterborne) 5005 Thixon 5005 (topcoat waterborne) XW1190 Chemosil XW1190...

Plastics that are readily bonded with induction methods include aU grades of ABS, nylon, polyester, polyethylene, polypropylene, and polystyrene, as well as those materials often considered more difficult to bond such as acetals, modified polyphenylene oxide, and polycarbonate. Reinforced thermoplastics with filler levels up to 65 percent have been joined successfully. Many combinations of dissimilar materials can be bonded with induction welding processes. Table 8.5 shows compatible plastic combinations for electromagnetic adhesives. Thermoset and other nonmetallic substrates can also be elec-tromagnetically bonded. In these applications the bonding agent acts as a hot-melt adhesive. 

Cold sizing Application of a small amount of bonding agent at room temperature. 

In joining reinforced thermosetting pipe it is particularly important that the pipe be cut without chipping or cracking it. It is also important to sand, file, or grind any mold-release agent from the surfaces to be cemented. Joints are built up layer by layer of adhesive-saturated reinforcement by following the manufacturer s recommended procedure. Application of adhesive to the surfaces to be joined and assembly of these surfaces shall produce a continuous bond and provide an adhesive seal to protect the reinforcement from attack by the contents of the pipe. Unfilled or unbonded areas of the joint are considered defects and must be repaired. 

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