Polymer Processing Aids (PPAs) are additives combined with the base polymer to improve the processability and processing characteristics of the material as well as improve the quality of the final product. More specifically, PPAs improve the melt processability and handling of the polymers and improve the appearance of the final product by removing flow marks and die lines.
Internal and external PPAs are very common additives and are often lubricants. Their primary objective is to reduce the friction between the melting, or molten, polymer and the metal production equipment –providing a smooth flow of material by improving flow characteristics such as viscosity. Internal processing aids improve the polymer flow properties by reducing friction within the polymer blend itself. External processing aids migrate to the surface of the polymer to reduce the friction between the plastic and the metal manufacturing equipment, allowing the melt to slip through the die or mold more easily without sticking. Internal and external PPAs can be utilized together to achieve the desired processing characteristics.
Polymer processing aids are used in many applications including blown and cast film processes, pipe and sheet extrusion, blow molding and compounding. Processing aids are very effective for use in the production of high viscosity, high molecular weight polymers such as LDPE, LLDPE, LDPE, HDPE, PP, PS, and others – and are found in a variety of products ranging from plastic bottles to construction pipe to films. PPAs offer significant benefits even at very low addition rates in the Parts Per Million (ppm) range. Additionally, processing aids are typically very stable and able to be used for high temperature operations.
Benefits of Polymer Processing Aids
As the name implies, polymer processing aids provide benefits during the processing of the polymer but they also provide benefits to the final product. In particular, PPAs improve the polymer flow characteristics to reduce the potential for processing issues such as melt fracture, die build up, or gel formation. Melt fracture is a common polymer flow issue caused by the high stress experienced at the die exit; melt fracture causes a roughening of the polymer surface, often referred to as “shark skin” and can also lead to distortion of the final product. Die build-up is the deposition of material when exiting the die, which requires more frequent production stoppages to clean the die and also lowers product quality. Die buildup gets worse with time and can require cleaning in a matter of hours in some cases instead of days or weeks! Gel formation is the result of undesirable linking of the polymer molecules; PPAs improve the polymer flow, reducing the residence time during production and, therefore, reducing the potential for gel formation.
Below is a summary of the benefits of polymer processing aids.
- Reduced melt fracture often referred to as “sharkskin”
- Reduced die lines and die build-up
- Reduced gel formation within the polymer
- Improved product appearance such as surface finish, transparency, gloss, and smoothness
- Higher productivity and lower operating costs due to lower cycle times and longer continuous production runs in between cleaning and maintenance.
- Energy savings due to lower friction between the equipment and the polymer that allows for lower operating pressure and motor torque within the extruder.
Selecting the right polymer processing aid for your application is crucial –especially since a small change in dosage on a ppm level can have a huge impact on your operations! It is not always easy to determine which processing aid is best since there are many options to choose from. This is why it is important to choose a partner like, Amcor, that will guide you through the selection process. Additionally, Amcor provides tech support, assistance with customer’s equipment, and process recommendations to ensure you are set up for success!
About Amcor
Amcor is a manufacturer of polyethylene film and bags, as well as polyolefin compounds, additives, blends, and masterbatches. Amcor has grown from a single product line to hundreds of products and five product divisions. In addition to selling products, we also provide tech support, assistance with your equipment, and process recommendations. Below are some highlights of Amcor’s polymer processing aids (The “Ampro” Product Line):
| · Flow Enhancers | · Surface Enhancers (warpage/roughness) | · Mold Release Agents |
| · Cooling/Cycle Time Reducers | · Purge – “Ampure” | · Web Break Reducer |
Amcor is also a full line distributor of various chemicals, resins, and gases for the plastic industry. With warehousing and distribution facilities across the United States, Mexico, Eastern Europe and China, we service companies of all sizes and locations across multiple industries.
Amcor realizes that quick turnaround, on time delivery, a quality product, and personal service are what it is all about. Contact us today to learn how we can assist with your next project!