After the waste plastics are recycled and processed, their performance will decrease to varying degrees, mainly caused by photo-aging, oxidation and thermal aging. The degree of performance degradation mainly depends on the age and environment. For the scrap edges and waste products produced in the molding processing plant, the performance of the recycled materials is very small, and can almost be used as new materials; indoor use and short-lived products, the performance of recycled materials does not change much; and outdoor use, Products with a long life and poor environment (such as pressure, electric field, chemical media, etc.) have poor performance and cannot even be recycled. Due to thermal aging during the regeneration process, the color of the recycled material changes from light to dark. The following describes the performance changes of several commonly used plastic recycled materials.

Polyvinyl chloride: Discoloration is more obvious after regeneration, it will be light brown after being regenerated once, and it will almost become opaque brown after three times. The specific viscosity does not change at the second time, and tends to decrease after the second time. Regardless of whether it is hard or soft PVC, stabilizers should be added during regeneration. In order to make the re-products shiny, 1% to 3% of ABS for blending can be added during regeneration.

Polyethylene: The performance of polyethylene decreases after regeneration, and the color turns yellow. After multiple extrusions, the viscosity of high-density polyethylene decreases, and the viscosity of low-density polyethylene increases.

Polypropylene: When regenerated once, the color is almost unchanged and the melt index rises. The color increased more than twice and the melt index still increased. After regeneration, the breaking strength and elongation have decreased, but there is no problem in use.

Polystyrene: The color turns yellow after regeneration, so regenerated polystyrene is generally colored. The degradation of the properties of recycled materials is proportional to the number of regenerations. The breaking strength does not change significantly when the blending amount is less than 60%, and the limiting viscosity is not significantly changed when the blending amount is less than 40%.

Other plastics: Discoloration is more pronounced after ABS is recycled, but there is no obvious change in performance when the blending amount does not exceed 20% to 30%.

Nylon regeneration also has problems of discoloration and performance degradation, and the blending amount should be less than 20%. The elongation decreases after regeneration, but the elasticity tends to increase.