PVC generally needs to be modified and pelletized first. After being prepared into pellets with a screw extruder unit, it will be more fully plasticized and easier to process, especially for products whose process is injection molding. Screw extruder is one of the most important equipment for plastic molding and processing. It uses external power transmission and heat transfer from external heating elements to carry out plastic solid transportation, compaction, melting, shearing, mixing, and extrusion molding.
PVC resin is a polar non-crystalline polymer, density: 1.38 g/cm3, glass transition temperature: 87°C, so it has poor thermal stability and is difficult to process. It cannot be used directly, it must be modified and compounded, and related additives and fillers can be added before it can be used. However, due to the different types and fractions of related additives and fillers added, this determines that the properties and requirements of the prepared PVC materials are different. We usually call it PVC formula, strictly speaking, it is PVC modified formula, and PVC can only be used after modification. This category is often classified as polymer modified materials. The modification of polymer materials mainly focuses on research on the high performance of general-purpose plastics, the conversion of single-component materials to multi-component composite materials (alloys, blends, and composites), functionalization of materials, and optimization of performance and price. Modification methods are mainly chemical modification, filling modification, reinforcement modification, blending modification and nano-composite modification. The basic principle of modification is to give materials functions or improve certain properties through additives. [2] Therefore, the level of PVC formulation technology determines the level of technology and production capacity of a factory.