The joint between different types of plastic made with solvent cement will not be reliable because the chemical composition of the joint will not ____________.

The reliability of a joint between different types of plastic made with solvent cement hinges on the concept of homogeneity, which pertains to the uniformity of the materials at a molecular level. When two dissimilar plastics are bonded using solvent cement, the chemicals involved in the joint may not form a consistent mixture. This lack of homogeneity can lead to differences in the physical and chemical properties of the joint compared to the properties of each individual plastic, which can compromise the strength and integrity of the connection.

If the joint is not homogeneous, it may exhibit weaknesses such as differences in expansion and contraction under temperature changes, leading to potential cracking or failure over time. The joint needs to be consistently formulated throughout to ensure that it performs well under various environmental conditions and operational stresses. Therefore, for a reliable joint, achieving a homogeneous chemical composition is essential.