To enhance the flame retardancy and smoke suppression of thermoplastic polyurethane (TPU), a novel flame retardant ZIF-67@GO was fabricated by hybridization of zeolitic imidazolate framework-67 (ZIF-67) and graphene oxide (GO). The flame retardancy of TPU sample was significantly enhanced by the presence of 6.5 wt% ammonium polyphosphate (APP) and 0.5 wt% ZIF-67@GO: the limit oxygen index (LOI) reached 27.4% and UL-94 grade passed V-0, the peak heat release rate (pHRR) and peak smoke production rate (pSPR) values was dropped by 81.2% and 48.7%, respectively, comparing with that of the control sample. The burning time of the flame-retardant TPU sample was prolonged to more than 600 s from 200 s of the control TPU sample during the cone test. Additionally, the tensile strength and elongation ratio of the flame-retardant TPU reached 18.3 MPa and 1026.3%, respectively, which meet the requirement in most industrial applications. This work provides useful information to produce flame retardant synergists for polymeric composites.
Liwen Mu,Danyang Cao,Wei Zhuang,Qiangliang Yu,Meirong Cai,Yijun Shi
The “block-on-plate” nanocomposite structure material is realized with the zeolitic imidazolate framework (ZIF-67) on graphene oxide (GO) with surface oxygen-rich functional groups. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffractograms, fourier transform infrared spectroscopy, and ZIF-67/GO demonstrate a high capability of promoting the lubricating performance of [Choline][Proline] ([CH][P]) bio-ionic liquid. Specifically, the wear volume of the disc by [CH][P]-0.1 ZIF-67/GO is only 52% of the one lubricated by pure [CH][P]. Moreover, ZIF-67/GO shows a long time, high dispersion stability in [CH][P]. In addition, the combination of GO nanosheets and ZIF-67 can make ZIF-67/GO have better polishing effect between the steels during the friction process, which can effectively form a robust lubrication layer and improves overall lubricating properties. As a result, the interfacial lubrication can be significantly improved by these newly developed [CH][P]-ZIF-67/GO lubricants. This work offers a new promising application for ZIF-67 nanocomposites with GO in advanced lubrication systems. This work also provides a new strategy of producing lubricants containing nanoparticles with high dispersion stability, which may solve the biggest challenge in this field.
Wenkai Pei,Junyang Zhang,Haijian Tong,Mengna Ding,Fengyan Shi,Ruizhe Wang,Yuning Huo,Hexing Li
The serious problem from pollution of metal ions placed great pressure to global water ecosystem and human beings. Herein, a synergistic photocatalytic-photothermal system of integrated membrane for the removal and reutilization of aqueous Ag + ions was designed. The crystal of zeolitic imidazolate frameworks-67 (ZIF-67) stably grew on the graphene oxide (GO) membrane with the uniform distribution. In the ZIF-67/GO membrane, the adsorption and photo-reduction of Ag + ions on ZIF-67 crystals led to the deposition of Ag nanoparticles on the membrane surface, which facilitated the capture of visible light, suppressed the recombination of the electron-hole pairs and promoted the photothermal effect. Meanwhile, the high efficiency of photothermal conversion on GO substrate realized the water evaporation to concentrate the Ag + solution and inhibited the separation of photo-induced charges. The synergistic photocatalytic-photothermal route on ZIF-67/GO membrane provides a new sight for the recycle of metal ions for the future practical applications.
Ping Dai,Yuchao Yao,Enzheng Hu,Dongyan Xu,Zhongcheng Li,Chuansheng Wang
In this work, a composite consisting of ZIF-67 and graphene oxide (GO) was successfully synthesized by a facile in-situ synthesis method and applied in hydrogen release from the methanolysis of sodium borohydride (NaBH 4 ). Physicochemical properties of pure ZIF-67 and the ZIF-67@GO composites are well characterized by XRD, BET, SEM and HRTEM. It was observed that the ZIF-67 crystals are intimately anchored on GO sheets. An increase of GO in the composite led to a marked decrease of the BET surface area and an increased average pore size. However, the ZIF-67@GO precursor with high GO doping exhibited much higher activity toward the methanolysis of NaBH 4 , which suggests that the good conductivity of GO is beneficial to improve the catalytic performance. The ZIF-67@GO precursor experienced a structure reconstruction during the methanolysis reaction due to the presence of reducible Co 2+ . Moreover, the reduced ZIF-67@GO displayed a slightly higher activity as compared to the pristine composite and retained excellent durability after five cycles. A possible mechanism for the hydrogen generation from the methanolysis of NaBH 4 using a ZIF-67@GO catalyst was proposed.
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