PVC resin is a polar non-crystalline polymer, density: […]
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 mixed, and related additives and fillers can be added. However, due to the different types and fractions of the 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 the high performance of general plastics, the conversion of single-component materials to multi-component composite materials (alloys, blends, composites), functionalization of materials, optimization of performance and price, etc. 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. Therefore, the level of PVC formulation technology determines the level of technology and production capacity of a factory.
PVC generally needs to be modified and pelletized first. After being prepared into particles with a screw extruder unit, it will be more fully plasticized and easier to process, especially if the 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. The screw extruder occupies an important position whether it is a plasticizing granulating machine or a forming processing machine. Strictly speaking, PVC products with special requirements and PVC modified formulas are tailor-made according to customer requirements. There is also a copolymerization derivative in the production process of PVC. Such modified varieties include vinyl chloride copolymers, polyvinyl chloride blends and chlorinated polyvinyl chloride.