What are the differences in melt flow behavior between virgin and recycled PVC?

The melt flow behavior of virgin and recycled polyvinyl chloride (PVC) exhibits significant differences that impact processing parameters and final product quality. Virgin PVC demonstrates consistent rheological properties with predictable viscosity and shear response due to its controlled molecular weight distribution and absence of contaminants. In contrast, recycled PVC undergoes molecular degradation during previous processing cycles and service life, leading to chain scission that reduces molecular weight and increases melt flow rates. The presence of impurities, residual additives, and heterogeneous materials in recycled PVC further alters its flow characteristics, often resulting in higher sensitivity to thermal degradation and inconsistent viscosity under shear stress. These variations necessitate adjusted processing temperatures, shear rates, and stabilization protocols when using recycled content, ultimately influencing product performance in extrusion, injection molding, and other manufacturing processes. Understanding these rheological differences is crucial for optimizing material selection and processing conditions in sustainable manufacturing initiatives.