Construction of catalyst-free, smoke suppression flame retardant PET fiber via bifunctional metal-organic framework

This work prepared a catalyst-free fire retardant PET fiber by developing a Co-based metal-organic framework (Co-MOF), which synthesized in a facile one-step hydrothermal method. With merely addition of 0.4wt% Co-MOF into PET, the LOI value of PET composites reached to 28.0%, the peak heat release rate (pHRR) and total smoking production (TSP) were decreased by 36.97% and 20.75%, respectively. Compared with traditional antimony trioxide catalyst, Co-MOF could shorten the esterification and polycondensation time by 16% and 12%. The char formation, which increased by 44.6% compared with that of neat PET from thermogravimetric analysis (TGA), played the key role in imparting PET with superior fire safety. The research on the flame retardant mechanism shows that Co-MOF plays a role in both the gas phase and the condensed phase. Besides, the mechanical and spinnability of PET-0.4Co-MOF was improved. After heat-setting the as-spun fiber by 3.5 times of draft, its breaking strength and the breaking elongation reached 3.52 cN/dtex and 29.70%, respectively.