General Plastic and Composite Bonding

Three types of plastics-based materials can be categorised for bonding, i.e., thermoplastics (e.g., polystyrene or polyethylene (PE) thermosets (e.g., phenolics or epoxies) and composites (plastics reinforced with a mineral or metallic filler). Composites can be thermoplastics or thermosets. 

From the viewpoint of the adhesive technologist, plastics are an anomaly bonded joints can be made in which the plastic fails before the adhesive, but certain plastics are very difficult to bond. Although plastics often present difficulties in adhesive bonding (Table 4.2), all can be joined successfully with the correct choice of adhesive, joint design, and surface preparation [28]  

Inherent flexibility of plastics (induces peel and cleavage stresses in bonds) 

High thermal expansion coefficients compared with metals Stress cracking of thermoplastics by liquids Presence of release agents (one release) 

Structural adhesives for plastics typically are epoxies, cyanoacrylates, polyurethanes or reactive acrylics. 

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