ABSTRACT This study investigated a novel technology for reducing volatile organic compound (VOC) emissions from impact copolymer polypropylene (PP‐ICP) while maintaining its inherent impact strength. The method involves injecting supercritical carbon dioxide (scCO 2 ) into the extruder barrel while simultaneously removing VOC gases from the molten polypropylene resin through a vacuum extraction system. Experimental results revealed that when the extruder barrel temperature reached 280°C, the core‐shell morphological structure within the dispersed rubber phase was disrupted, with the core‐shell structure particle size expanding to 3–4 μm, which would lead to a significant reduction in the impact strength of PP‐ICP. Under the stringent VDA 277/278 testing standards, the total volatile organic compounds (TVOC) of PP‐ICP samples decreased to approximately 20 μgC/g at a processing temperature of 240°C with 3% CO 2 concentration. Consequently, the optimal operating conditions were determined as follows: barrel temperature of 240°C, residence time of 3 min, 3% scCO 2 dosage, and vacuum degree of 30 mbar abs. This technology presents direct applicability to industrial PP production: integrating polymerization‐grade PP powder into an extruder equipped with both vacuum and dynamic scCO 2 extraction systems enables single‐step manufacturing of low VOC PP pellets without compromising impact performance, while preserving particle morphology and eliminating the need for re‐pelletization. Importantly, this process maintains conventional production throughput and cost parameters without requiring additional processing stages.
Xing et al. (Tue,) studied this question.