Polymer preparation consists of a series of processing steps conducted on the incoming polymer to increase its processability range and to satisfy the requirements of the finished product. Since unmodified PVC resins are virtually unprocessable, the need for additive modification is indispensable. Additive modification is also needed to enhance polymer properties and to ensure the service life of the end product, hence increasing its utility. Some additives are used to enhance polymer processability:

Heat stabilizers, both primary and adjuvants or costabilizers

Lubricants (without lubrication, melted PVC sticks to hot metals),

external and internal

Processing aids, mainly used to increase “hot melt strength” while reducing melt fracture, allowing processors to extrude or calender at faster rates