Improving oxygen barrier properties of PET composites via grafting hydroxy‐terminated polybutadiene with nanosilica

Hydroxy‐terminated polybutadiene (HTPB) was grafted onto nanosilica via two steps, and then melt extruded with PET and transition metal catalyst. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) results showed that HTPB successfully bridged to the surface of nanosilica through toluene‐2,4‐diisocyanate (TDI), and the grafting amount of HTPB accounted for about 11.2% of the total mass of nanosilica. The PET composite samples were also uniaxially stretched into films. Tensile results showed that the tensile strength of composite films was generally higher than that of composite sheets, especially the tensile strength of PET/SiO 2 ‐HTPB composite film reached 139.8 MPa. After uniaxial stretching, the crystallinity of all films were significantly improved, and fillers accelerated the crystallization rate of PET, which greatly improved the crystallinity of composite materials, thereby contributing to the improvement of the oxygen barrier performance of composite materials. After adding the catalyst, the PET/SiO 2 ‐HTPB/Co composite film has the lowest oxygen permeability coefficient of 1.05 × 10 −15 (cm 3 ·cm/cm 2 ·s·pa), which was 87.6% lower than that of pure PET sheet. SEM showed that the compatibility between filler and matrix was improved. This study demonstrated that nanosilica grafted with HTPB played a synergistic role in improving the crystallinity of materials and exerting the active oxygen scavenging of HTPB, and uniaxial stretching was helpful for improving the comprehensive properties of composites.