Epoxy chain extender grafted pyrophyllite/poly(ethylene terephthalate) composites with enhanced crystallinity and mechanical properties

The surface-grafting modification of nano clay has become increasingly important for improving the practical application of clays. In this study, an epoxy chain extender ADR-4468 was used to modify the surface of pyrophyllite (Prl), and the effect of ADR-4468-modified pyrophyllite (A-Prl) on the properties of poly(ethylene terephthalate) (PET) and PET/poly(ethylene glycol-co-1,3/1,4-cyclohexanedimethanol terephthalate) (PETG) composites was investigated. The modified composites were characterized by Fourier transformed infrared spectroscopy, X-ray diffraction and TG, which proved that the A-Prl was successfully synthesized, and the addition of ADR-4468 did not change the crystal structure of pyrophyllite. The grafted ADR-4468 improved the agglomeration of Prl, and some A-Prl reached nano-scale dispersion in PET and PET/PETG composites. The rheological properties, crystallization behavior and mechanical properties of PET and PET/PETG nanocomposites were systematically investigated. The results showed that A-Prl was an effective nucleating agent for PET, which significantly improved the crystallization properties of PET composites. The A-Prl also improved the comprehensive mechanical properties of PET and PET/PETG nanocomposites. In particular, the impact toughness of A-Prl/PET/PETG composite with 1.5 wt % A-Prl was increased by 120% compared with that of pure PET. The functional additive is expected to be used in the preparation of high-performance and recyclable PET composites.