Compounding of plastic is a process that includes melt-blending of plastics with specific additives that are used to change the thermal, physical, aesthetic and electrical characteristics of the material.
Plastics compounding involves an intricate process with multiple stages. These may include determining additives ratio, high-speed mixing via twin-screw extruders, melt mixing, and cooling, all before final pellet cutting and packaging. A range of materials can be used. Those materials include polypropylene, polyethylene, polyvinyl chloride, polystyrene and expanded polystyrene, polyethylene terephthalate, polyurethane, acrylonitrile butadiene styrene (ABS), nylon and other polymers.
Through compounding processes, a base resin is converted into a desired plastic form with properties that make it more effective, efficient and uniform. The introduction of additives and agents as well as other products, including anti-abrasion additives, can enhance the product of the finished resin.
The pelletized material is then processed into a plastic part, through processes including molding or extrusion.
Typically, compounding is done on twin-screw extruders. This can be a co-rotating or counter-rotating design. Other options include single-screw extruders, kneaders and mixers.
There is a diverse range of products available, depending on the additives and fillers integrated while processing the polymers. These include antioxidants, processing aids, colorants, wear-resistant, blowing agents, lubricants, fillers and reinforcements, antistatic agents, slip/anti-slip agents, anti-block agents, flame retardants, light stabilizers, impact modifiers, and cross linking agents.
Trends also include an increased use of bioplastics that offer improved surface finish for automotive interior and exterior applications. This will further augment the industry share.
For more information on compounding, visit these links on colors and custom compounds, laboratories, recycling content and glass and other fillers.