They may be used to blend virgin and post-consumer plastic resins or different types of resins to maintain the quality of the products. These ingredients may include Additives to improve a polymer's physical properties, stability or processability. It allows Additives to be compounded into the recycled material to meet target application requirements. It allows virgin materials to be mixed with recycled materials to meet material specifications for performance and recycled material content targets. It provides a very important homogenization step.
Recycled materials are usually a mix of many different grades of the same basic material.
Even though the materials might be from the same family, differences in molecular weight, copolymer ratios, etc. can lead to a mixed material having poor homogeneity. The intensive physical mixing in a molten polymer that is achieved during extrusion can homogenize different grades of materials and even some types and amounts of foreign material that might not have been removed during the recycling process. A methodology that quantifies energy consumption and environmental emissions at each stage of a product's life cycle, beginning at the point of raw material extraction and proceeding through processing, manufacturing, consumer use, and final recycling, reuse or disposal. A collection process where consumers place designated recyclables at the roadside or curb, usually in a special container or bag, for collection separate from non-recyclable material such as garbage.