Once the silicone rubber is vulcanized at high temperature, a highly stable three-dimensional crosslinking network is formed. This “chemical shackle” makes traditional mechanical recovery (crushing-re-melting-forming) almost impractical. The difficulty is mainly reflected in three points.：


1. Cross-linking is irreversible  
   Silicone rubber is not a thermoplastic material, and cannot be heated, softened and then formed like PVC and PP; mechanical crushing can only obtain inert silicon powder, which cannot be restored to a high elastomer, and the tensile strength is usually reduced by more than 50%.


2. Impurities are difficult to remove  
   Waste products are often sticky with mold release agents, metal shavings, dust and other pollutants. If the cleaning is not thorough, the recycled materials will have problems such as excessive heavy metals and large fluctuations in mechanical properties.


3. Performance deterioration  
   Even after fine sorting and surface modification, the plasticity, vulcanization speed and aging resistance of recycled silicone rubber are significantly lower than that of new materials; after multiple cycles, the rebound and compression permanent deformation indicators deteriorate significantly.


Therefore, the industry generally believes that “mechanical recovery” has limited significance for crosslinked silicone rubber. At present, the mainstream research direction has turned to chemical recovery (de-crosslinking to cyclosiloxane or chlorosilane) or dynamic reversible crosslinking system to achieve true closed-loop utilization.