This section will cover the how the products go from recycling back to the shelf. The importance of getting finished recycling pellets, to products and their full capability. Plastic pellets can be fully reutilized at the manufacturing level to build products of similar caliber as their original recycled counterparts. It is important to note that even though a plastic that is recycled may not be well suited to be reused for remanufacturing its original product, it can be reapplied to another process in creation of an entirely different application; which is called primary recycling.
Plastic, as it may seem obvious, has many uses and applications for a wide variety of plastics, and these applications remain the same for recycled plastic pellets. The pellets resulting from the recycling process vary based upon their base properties and can be converted into finished goods that relate to those properties. Plastic recycled from milk, shampoo, and laundry detergent containers can be used in manufacturing new bottles and containers, plastic lumber, outdoor furniture, and playground equipment to name a few. Recycled plastic bags can be utilized to also manufacture plastic lumber, backyard decks, and fencing. Plastic beverage bottles can be incorporated into clothing, carpeting, jacket insulation, and more plastic bottles. For example, it would take roughly 10 plastic bottles to generate enough fibers for a new t-shirt. As mentioned previously, plastic bottle caps are made of different plastic than the bottles they are placed upon. Those bottle caps can be used to create car batteries, garden rakes, storage containers, yarn, and rope. Plastic foam can be broken down and remanufactured into picture frames, insultation, and building supplies (What Plastics Can Become). All of these plastics can be reused to either make a similar product as the polymer originated from, or a diverse portfolio of product applications. Therefore, it is important to know how exactly recycled plastic is incorporated in the plastic manufacturing process.
After combing through the plastic recycling process, it is apparent that the result of this process is to achieve the creation of plastic pellets which can come in a variety of shapes, properties/types, or colors. This process is widely known as pelletizing. Pelletizing is when the recycled polymers are heated into hard spheres or pellets (nurdles), which is done from within a kiln. From here the pellets can then be taken to a plastic molding machine where they can be inserted. Once the pellets are dumped into the machine, they are melted down into a malleable liquid and injected into the mold which is in the shape of the desired product, or result (Instructables.). Please refer to the image below for a simple example of the process, as presented by instructables.com. This image depicts the basics of an injection molding machine (Hopewell, J., Dvorak, R., & Kosior, E.).
A great example of recycled plastic as a substitute for actual materials is within the manufacturing process, and a depiction of its capability, is with cement. High Density Polyethylene recycled plastic was mixed with Porltand cement to determine if plastic cement was a feasible substitute for using sand. The amount of HDPE that was used in the study varied from 10% to 80% by volume, and the results were highly positive. The results of the experiment depicted that it is highly possible to use HDPE as a substitute for sand in manufacturing cement using anywhere from 40% to 60% HDPE. The cement changed structure as well when using the recycled plastic and developed decreased density, increased ductility, and improved workability (Recycling of Polyethylene Waste to Produce Plastic Cement.).
What Plastics Can Become. (n.d.). Retrieved from https://www.recycleyourplastics.org/consumers/kids-recycling/plastics-can-become/
Instructables. (2017, October 10). Turning Recycled Products Into Raw Material. Retrieved from http://www.instructables.com/id/Turning-Recycled-Products-into-Raw-Material/
Hopewell, J., Dvorak, R., & Kosior, E. (2009, July 27). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2873020/
Recycling of Polyethylene Waste to Produce Plastic Cement. (2017, March 20). Retrieved from https://www.sciencedirect.com/science/article/pii/S2351978917300872