Thermal Degradation and Carbonization Mechanism of Fe-Based Metal-Organic Frameworks onto Flame-Retardant Polyethylene Terephthalate

Abstract

Currently, the metal-organic framework (MOF) is a promising candidate for flame−retardant polymers. In this study, a Fe−based MOF, MIL-88B(Fe), was introduced to polyethylene terephthalate (PET) and 3−hydroxyphenylphosphinyl-propanoic acid copolymer (P−PET) to reduce the fire hazard involved in using PET. The limiting oxygen indexes (LOIs) of MIL−PET and MIL−P−PET improved by 27% and 30%, respectively. The UL−94 level achieved for MIL−P−PET was V−0 rating. The thermal degradation and carbonization mechanisms of MIL−PET and MIL−P−PET were systematically investigated through thermogravimetric analysis coupled with a Fourier transform infrared spectroscopy (TG−IR), pyrolysis-gas chromatography−mass spectrometry (Py−GC−MS), x−ray photoelectron spectroscopy (XPS), and Raman spectrum combined with quantum chemical molecular dynamics simulation. With the addition of MIL−88B(Fe), high graphitization and a hard flammability char residual were generated. Compared with neat PET, the ferric ions efficiently catalyzed the homolytic cleavage and dehydrogenation of PET to produce a large amount of CO2 and terephthalic acid for MIL−PET in gas phase. Rough and hierarchical char residual with ferric oxide was also generated when temperatures exceeded 600 °C. However, the carbonization process was inhibited due to the coordinated complex between phosphorus and ferric ions in MIL−P−PET, invaliding the decarboxylation and generating more benzoic acid and its precursor, which led to heavy smoke.

Сучасне Уявлення Про Перебіг Процесів Деструкції Поліетилентерефталату

“…У відповідності до актуальних досліджень, деструкція ПЕТ поділяється на: гідролітичну [1][2][3][4][5][6][7], термічну [6][7][8][9][10], термоокислювальну [9][10][11], термомеханічну [12][13], фото- [14][15][16] та комбіновану [1]. У свою чергу характер перебігу процесів деструкції значною мірою відрізняється один від одного.…”

Characterization and Flame-Retardant Properties of Cobalt-Coordinated Cyclic Phosphonitrile in Thermoplastic Polyurethane Composites

“…However, the poor compatibility between metal compounds and organic polymer materials results in inadequate dispersion of the former within the polymer matrix, leading to a deterioration in the mechanical properties of the polymer material and hindering the achievement of the desired flame-retardant performance [25][26][27][28][29]. As a result, researchers have recently turned their attention to metal-organic coordination compounds; these compounds, with organic ligands, not only exhibit excellent compatibility with polymers but also provide flame-retardant properties due to the flame-retardant elements present on the organic ligands [30][31][32][33]. Xilei Chen and colleagues utilized a copper metal-organic framework (MOF-Cu) for flame-retardant modification of thermoplastic polyurethane elastomer (TPU) composite materials.…”

PET Functional Upcycling through Surface-Assisted Growth of Ni-BDC MOFs and Laser-Induced Carbonization towards Bend Resistive Sensor

“…This transformation has become the basis for various developments including strategies for the preparation of MOFs powder [36][37][38][39][40][41][42] and composite materials based on PET coated by MOFs (PET@MOF) [27,33,[43][44][45][46], designed for sustainable applications. As a promising upcycling pathway, PET, PET@MOF, and PET-derived MOFs are pyrolyzed to create carbon-based materials for sensors and energy-related applications [38,47,[48][49][50][51][52][53][54][55]56]. However, these approaches typically require significant energy consumption, an inert atmosphere, and postprocessing to obtain the final device [38,50].…”