Effect of Repetitive Recycling on the Mechanical Properties of Polypropylene Blends Based on Material Value Conservation Paradigm

Abstract

Contaminated plastic waste if undergo a mechanical recycling process will have a low value. This can be overcome by repetitive implementation of Material Value Conservation (MVC) through material purity protection from design stage to the end of the material life cycle. Repetition of recycling up to eight times caused degradation of mechanical properties of plastics by up to 20%. The repetition was done on a laboratory scale with pure polypropylene as raw material. This research was conducted to overcome the degradation of plastic properties by mixing recycled plastic pellets with virgin plastic in the most optimal proportion. Plastic blends with certain compositions were recycled up to 8 times, then its mechanical properties are tested with the American Society for Testing Materials (ASTM) methods. This research revealed the opportunities to utilize the 6th recycled plastic pellets by mixing it with virgin plastic to improve its mechanical properties. Furthermore, this research shows that repetitive recycling of plastic blends with the implementation of material value conservation (MVC) ​​could increase the value of recycled plastic pellets as raw materials and extend the life time of plastic materials.

Recycling of Polypropylene Recovered from a Composting Plant: Mechanical Behavior of Compounds with Virgin Plastic

“…The mechanical recycling of industrial scraps, that is the re-introduction of scraps of a single polymer into the production cycle of plastic pellets, is a well-assessed and widely adopted practice. Pellets, flakes, and powders can also be obtained by processing end-of-life plastic components and then used for producing new plastic goods [4,5,[7][8][9][10]. However, the degradation of plastic components caused by the action of heat, UV radiation, moisture, and contact with other substances worsens the plastic's material characteristics.…”

“…However, the degradation of plastic components caused by the action of heat, UV radiation, moisture, and contact with other substances worsens the plastic's material characteristics. For these reasons, these recovered plastics are generally used by compounding them with virgin materials [4,8,10].…”

“…Near infrared range radiation has proven to be very effective for recovering polyethylene and polypropylene from mixed waste [12]. Some of the literature deals with the recyclability of polyolefins [17] and some reports are focused on the use of recycled polypropylene in plastic compounding [8,10]. However, as far as we know, the recovery and recycling of polyolefins from the waste rejected by MBT plants has not been well investigated until now, even though this waste shows potential for the recycling of its components [18].…”