Final answer:
Solvent cements are adhesives specifically designed for bonding plastics by dissolving a thin layer on each surface and creating a strong bond when the solvent evaporates. Different from epoxies and sealants, solvent cements are commonly used in plumbing and construction to join plastic components.
Step-by-step explanation:
Cements composed of solvents combined with a small quantity of the plastics to be joined are called solvent cement. This type of material falls into the category of adhesives because it is used to bond surfaces together, but it has a specific composition that is designed for plastic materials. Solvent cement creates a strong bond by dissolving a thin layer of the plastic on each surface to be joined, effectively welding them together as the solvent evaporates.
An example of this is when PVC pipes are being fitted together; the pipes are coated with a solvent cement that contains solvents and PVC plasticizers. This softens the plastic surfaces and allows the molecules to mix. Once the solvent evaporates, the two pieces of plastic are fused, creating a strong join, which displays elements of elasticity and adapts to slight movements or pressure changes. Solvent cements are a vital tool in certain types of plumbing, construction, and assembly of plastic components.
They are different from other bonding agents such as epoxies, which are usually a two-component system that hardens to form a strong bond, or sealants, which typically provide a flexible barrier to prevent the passage of fluids through surfaces and joints.