Meaning
Mass transfer techniques remove light pollutants from plastic pellets while they remain in a solid form rather than a molten one. By keeping the resin below its melting point, solid state devolatilization avoids additional thermal stress on the polymer chains while still allowing internal volatiles to escape. This process ends if the material reaches its melting temperature where external pressure control changes significantly.
Gas Extraction
Dry air or inert nitrogen flows around the grains to carry away the departing chemicals. When solid state devolatilization is active, it primarily draws out residual monomers and solvents that entered the polymer during the original polymerization. Removing these elements lowers the sensory impact of the plastic.
Chain Protection
Maintaining a lower temperature prevents the yellowing associated with traditional high-heat extrusion cleanup. Because solid state devolatilization is gentler, the plastic retains its original mechanical strength and molecular weight distribution more effectively than during repeated melt filtration. This leads to high quality secondary resin.
Process Efficiency
Long exposure times at warm temperatures allow for deep cleaning of thick resin sections. Success with solid state devolatilization depends on the initial pellet size and the total duration in the treatment tower. Careful scheduling prevents bottle-necks in the overall factory flow.
