1. The Foundation of the Recyclability of PLA Plastic

PLA (Poly Lactic Acid) is a biobased plastic made from renewable resources such as corn starch and sugar cane. Its renewability is reflected in two aspects: 

（1）. Recyclability of raw materials: The plant-based raw materials used to produce PLA can be continuously obtained through agricultural cultivation, which is in line with the principles of circular economy. 

（2）. Product Recyclability: 

- *Industrial Composting*: Under industrial composting conditions of 60-70℃ and humidity of 50%-60%, PLA can be completely degraded within 6-12 months (in accordance with the American ASTM D6400 standard). 

- *Chemical depolymerization*: PLA is decomposed through hydrolysis or alcoholysis to convert it into lactic acid monomers, which can then be polymerized to form new PLA, with a conversion efficiency of over 95% (research in "Green Chemistry" in 2021). 

- *Mechanical Recycling*: The melting regrinding method is commonly used. However, due to the low glass transition temperature (55-60℃) and melting point (150-160℃) of PLA, high temperatures must be avoided to prevent the breakage of molecular chains.

II. Key Points in the Preparation of PLA Recycled Particles

The "PLA recycled particles" that users are concerned about need to overcome three major technical challenges: 

（1）.Sorting purity: PLA must be strictly separated from traditional plastics such as PET and PP. Mixing in impurities will reduce the performance of recycled materials. The 2022 pilot project in Japan showed that when the sorting purity is > 99%, the tensile strength retention rate of recycled PLA exceeds 90%. 

（2）. Processing parameters: 

             Parameters                     Ideal Range                                              Exceeding Risk

     Melt Temperature                   160 - 180℃                                > 190℃ leads to degradation

           Screw Speed                      50 - 100 rpm             Excessive speed causes shear thermal degradation

（3）. Additive Compensation: Recycled PLA often requires the addition of chain extenders (such as epoxy types) to repair the molecular chains. An experiment conducted by NatureWorks in the United States showed that adding 0.5% - 1% of chain extenders can restore the melt index of recycled material to the level of the original material.

III. Challenges and Prospects of PLA Recycling

（1）. Current Limitations: 

Currently, the global infrastructure for PLA recycling is insufficient. Only the European Union has built 12 dedicated PLA chemical recycling plants (according to the 2023 report of the European Bioplastics Association). 

After three cycles of mechanical recycling, the impact resistance of PLA decreased by approximately 30%, which limits its multiple recycling usage (data from "Polymer Degradation and Stability"). 

（2）. Application Breakthrough: 

Reclaimed PLA particles have been used in low-demand packaging (such as egg trays) and 3D printing filaments (the strength of the products from the American company Filabot is 85% of that of the original material). 

Japanese automaker Toyota is testing the use of recycled PLA to manufacture interior components, with the goal of achieving a 40% inclusion rate by 2025. 

Conclusion: PLA is a theoretically renewable plastic, but its practical promotion requires addressing issues such as sorting, processing stability, and the recycling system. In the future, with the optimization of depolymerization technology and the establishment of a closed-loop supply chain, PLA recycled particles may become the core carrier of the bioplastic circular economy.