Properties and Application Potential of Mechanically and Chemically Recycled PET Fibers for Tire Cord and Airbag Applications

초록

The influence of poly(ethylene terephthalate) (PET) recycling methods on recycled PET (rPET) fiber properties was evaluated for tire cord and airbag applications. Virgin PET (vPET), mechanically recycled PET (mrPET), methanolysis-based chemically recycled PET (cmPET), and glycolysis-based chemically recycled PET (cgPET) were subjected to solid-state polymerization, followed by melt spinning and application-specific drawing to 1500 denier (tire cord) and 500 denier (airbag). rPET fibers displayed significant differences in molecular weight (MW), IPA and DEG contents, residual catalyst profile, and crystallinity depending on the recycling route, resulting in varied mechanical properties. Compared with vPET, mrPET fibers showed lower tenacity and higher elongation, correlated with reduced crystallinity and molecular orientation associated with IPA and DEG units. cmPET suffered substantial MW loss during melt spinning, attributed to uncomplexed Mn catalysts, and consequently displayed the lowest tenacity and elongation. In contrast, cgPET delivered balanced tenacity and elongation and the smallest RFL dip-induced tenacity loss (12.3%), delivering the best tire cord performance. For airbag applications, cgPET fibers demonstrated mechanical properties, hot rod puncture resistance, and stability under thermal and humidity aging that were comparable to those of vPET fibers. These findings identify cgPET as the most promising candidate for safety-critical automotive fibers, emphasizing the need to control comonomer content, crystallinity, and residual catalysts across recycling routes.

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