Comparison of the performance of recycled plastics and new materials

After the waste plastics have been reprocessed, the properties have declined to varying degrees, mainly due to photo-aging, oxidation, and thermal aging. The degree of degradation depends on the age of use and the environment. The scraps and wastes produced during the production of the molding processing plant have a very small decline in the properties of the recycled materials and can be used almost as new materials. In products with indoor use and short service life, the properties of the recycled materials do not change much; while they are used outdoors, Long-term limits and poor environmental conditions (such as pressure, electric fields, chemical media, etc.) have poor product performance and cannot even be recycled. Due to the heat aging during the regeneration process, the color of the reclaimed material becomes darker and darker. The following describes the performance changes of several common plastic regrinds.

Polyvinyl chloride (PVC): After rejuvenation, discoloration is obvious. After one regeneration and extrusion, it will have a light brown color, and three times it will almost become opaque brown. The specific viscosity does not change at the second time, and tends to decrease more than twice. Whether it is hard or soft polyvinyl chloride, stabilizers should be added during regeneration. In order to make the remanufactured product glossy, ABS 1 to 3% for blending can be added during regeneration.

Polyethylene: After the regeneration of polyethylene, the properties have declined and the color has turned yellow. After multiple extrusions, the viscosity of high-density polyethylene decreased, and the viscosity of low-density polyethylene rose.

Polypropylene: When it is regenerated, the color is almost constant and the melt index rises. More than twice the color increase, the melt index is still rising. After the regeneration, the breaking strength and elongation decreased, but there was no problem in use.

Polystyrene: After regeneration, the color turns yellow, so the recycled polystyrene is generally colored. The degree of decline in the performance of the recycled material is proportional to the number of regenerations, and the breaking strength does not change significantly when the blended amount is less than 60%. The intrinsic viscosity does not change significantly when the blended amount is less than 40%.

Other plastics: The color change of ABS is significant after regeneration, but no significant change in performance occurs when the blending amount is not more than 20% to 30%.

Nylon regeneration also has the problem of discoloration and degraded performance. It is advisable that the amount of blended is less than 20%. After the regeneration, the elongation decreases, but the elasticity tends to increase.