Certified Welding Inspector Practice Exam

Which material property allows an adhesive to bond with base materials?

1. Thermal expansion

2. Attractive forces of the polymeric material

3. Electrical conductivity

4. Both chemical and thermal resistivity

The correct answer is: Attractive forces of the polymeric material

The ability of an adhesive to bond with base materials is primarily due to the attractive forces of the polymeric material. These attractive forces include van der Waals forces, hydrogen bonding, and sometimes even covalent bonding depending on the chemistry of the adhesive and the substrate. When applying an adhesive, its molecular structure interacts with the surface of the materials being bonded, leading to these intermolecular forces that create the bond. The stronger the attractive forces between the adhesive and the substrate, the greater the adhesion achieved. While thermal expansion does affect the bond under changing temperature conditions, it does not directly contribute to the adhesive's ability to bond initially. Electrical conductivity is also unrelated to the adhesive properties of bonding materials; it pertains more to how materials conduct electricity rather than how they adhere. As for chemical and thermal resistivity, these properties relate to the adhesive's performance under various conditions rather than the initial bonding capability itself. Thus, the attractive forces inherent in the polymeric material are essential for the bonding process, making it the crucial characteristic for effective adhesion.