In this study, core-shell carbon microspheres (CMSs-PZS) were synthesized by coating polyphosphazene (PZS) on the surface of carbon microspheres (CMSs) through one-step polymerization, and they were characterized using infrared spectroscopy and electron microscopy tests. CMSs-PZS were added to polyethylene terephthalate (PET) to prepare flame-retardant PET composites. The effects of CMSs-PZS on the flame retardancy, thermal stability, and mechanical properties of the composites were investigated. The results showed that the introduction of CMSs-PZS into PET significantly enhanced the flame-retardant properties. When the content of CMSs-PZS was 3 wt%, the limiting oxygen index (LOI) value of PET/CMSs-PZS increased to 33.4%, achieving a UL-94 V-0 rating. Thermogravimetric (TG) analysis showed that the initial decomposition temperature of PET composites increased, while the decomposition rate decreased, and the amount of residual carbon increased with the addition of CMSs-PZS. Cone calorimeter test data showed that the peak heat release rate (pk-HRR) of PET/3wt%CMSs-PZS decreased to 450.67 kW/m 2 , and the total heat release (THR) decreased to 22.14 MJ/m 2 . It is shown that during the combustion process, CMSs-PZS decomposes to form a charcoal layer covering the surface of PET, which plays the role of heat and oxygen insulation, effectively inhibiting the combustion of PET and its heat release during the combustion process.
Shaopeng Rong,Pengyi Zhang,Jinlong Wang,Fang Liu,Yajie Yang,Guoliang Yang,Song Liu
Ultrathin manganese dioxide (MnO 2 ) nanosheets with the thickness of 1–2 nm were synthesized by chemical oxidation of Mn 2+ ions in the presence of tetramethylammonium cations in an aqueous solution. The composite material MnO 2 /PET (polyethylene terephthalate) was prepared by impregnating PET into MnO 2 nanosheets colloid. The impregnation time has a great influence on HCHO adsorption and removal efficiency. When the PET was impregnated in nanosheets colloid for 1 h at room temperature, the concentration of HCHO decreased quickly within initial 10 min and finally reached about 81% removal efficiency with an initial HCHO concentration of ∼200 ppm. Moreover, the used MnO 2 /PET can be simply regenerated by heating at 105 °C without any rinse treatment. Based on in-situ DRIFTS and TG-MS studies, the mechanism of formaldehyde removal and regeneration was proposed. All the results showed that as-synthesized MnO 2 /PET can be used as an effective, affordable, and recyclable materials to removal and oxide toxic HCHO in indoor air.
Solar-driven nano-semiconductor catalysts have shown great potential in solving environmental pollution and energy issues. They convert solar energy into chemical energy, release strong oxidizing hydroxyl radicals (OH·), and thoroughly degrade organic pollutants. However, these photocatalysts in turn may also damage some organic carriers. Therefore, we have used graphite phase carbon nitride (g-C3N4) as the isolation layer to prevent the carrier polyester fiber (PET) from being oxidized by zinc oxide (ZnO). ZnO-g-C3N4@PET composite has been prepared by hydrothermal method, photoluminescence results indicated that ZnO-g-C3N4@PET has a low photo-generated charge recombination rate, while g-C3N4 improves the visible light response of the composite and exhibits an obvious photocatalytic enhancement effect. In the experiment of degrading methylene blue (MB), the degradation efficiency of ZnO-g-C3N4@PET composite has been significantly improved compared with ZnO@PET and g-C3N4@PET alone. In addition, the prepared photocatalyst also has good reusability and still maintains a high degradation rate after five cycles of tests. In the end, a possible mechanism and a pathway of photocatalytic degradation of MB were proposed. All in all, this is a feasible way to build a highly efficient, environmentally friendly and sustainable supported photocatalyst.
Zihao Zhu,Cong Gao,Yucai Shen,Tingwei Wang,Guangjun Hu
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.
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