Thermoplastic adhesives removal methods

Fusion or heated-tool welding is an excellent method of joining many thermoplastics. In this method, the surfaces to be fused are heated by holding them against a hot surface. When the plastic becomes molten and a flash about half the thickness of the substrate is visible, the parts are removed from the hot surface. They are then immediately joined under slight pressure (5 to 15 Ib/in ) and allowed to cool and harden. The molten polymer acts as a hot-melt adhesive, providing a bond between the substrates. 

Heat reactivation In this method, a thermoplastic adhesive is applied to one or both surfaces and is allowed to dry. To bond, the part is heated until the adhesive becomes soft and tacky. The bond is made under pressure while hot. After cooling, a strong bond is obtained. This method is common for nonporous heat-resistant materials. It can also be used in a continuous in-line operation. The adhesive is applied in liquid form to a film or sheet, force-dried with heat to remove the water and then laminated to a second surface while still hot. Temperatures are usually in the range of 121—177 °C... 

Many plastics and plastic composites can be treated prior to adhesive bonding by simple mechanical abrasion or alkaline cleaning to remove surface contaminants. In some cases it is necessary that the polymeric surface be physically or chemically modified to achieve acceptable bonding. This applies particularly to crystalline thermoplastics such as the polyolefins, linear polyesters, and fluorocarbons. Methods used to improve the bonding characteristics of these surfaces include ... 

Thermoplastics, thermosets, and elastomers require surface treatment to remove contamination and prepare their surfaces for adhesion bonding. Both initial bond strength and bond durability are affected by the surface preparation technique. Most materials require unique methods of treatment for optimal bond strength formation. Most surface preparation treatment methods use or generate chemicals that have various serious health effects and must be used with extreme caution. 

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