The addition of a polymer plasticizer can significantly affect the compatibility of a blend of polystyrene PS and polyvinyl chloride PVC . PS and PVC are immiscible polymers, meaning they do not mix well together due to their different chemical structures and polarities. This results in poor compatibility and phase separation in their blends, leading to weak mechanical properties and poor processability.A polymer plasticizer is a substance that is added to a polymer blend to improve its flexibility, workability, and processability. It works by reducing the intermolecular forces between the polymer chains, allowing them to slide past each other more easily. This results in a decrease in the glass transition temperature Tg and an increase in the free volume of the polymer blend.When a suitable plasticizer is added to a blend of PS and PVC, it can improve the compatibility between the two polymers by reducing the interfacial tension and promoting better adhesion between the two phases. This can lead to an improvement in the mechanical properties, such as tensile strength, elongation at break, and impact resistance, as well as better processability, such as melt flow and thermal stability.However, the choice of plasticizer is crucial for achieving the desired compatibility between PS and PVC. Some common plasticizers used for PVC, such as phthalates, may not be effective in improving the compatibility with PS due to their different polarities and solubility parameters. Therefore, it is important to select a plasticizer that is compatible with both PS and PVC and can effectively reduce the interfacial tension between the two polymers.One example of a suitable plasticizer for a blend of PS and PVC is a copolymer of styrene and maleic anhydride SMA . SMA has both polar and non-polar groups in its structure, which allows it to interact with both PS and PVC and improve their compatibility. Other potential plasticizers include certain types of oligomers, block copolymers, or graft copolymers that have both PS and PVC-compatible segments.In summary, the addition of a polymer plasticizer can improve the compatibility of a blend of polystyrene and polyvinyl chloride by reducing the interfacial tension and promoting better adhesion between the two phases. However, the choice of plasticizer is crucial for achieving the desired compatibility and improved mechanical properties and processability.