Why might a joint between different types of plastic made with solvent cement not be reliable?

A joint between different types of plastic made with solvent cement may not be reliable because the chemical composition of the joint will not be homogeneous. When two different types of plastic are joined, their chemical properties can differ significantly. Solvent cement works by softening the surfaces of the plastics, allowing them to fuse together as the solvent evaporates. If the plastics have incompatible chemical structures, the reaction may not create a strong bond, resulting in a joint that is weak or prone to failure.

This issue of homogeneity is crucial because a consistent and uniform bond is necessary for strength and durability. Variations in the chemical makeup at the joint can lead to weak points, reduced adhesion, and ultimately a higher likelihood of the joint failing under stress or environmental factors.

Understanding how different types of plastics interact chemically is essential for ensuring effective bonding and maintaining the integrity of the joint.