The intercalation of ammonium sulfamate into kaolinite and its effect on the fire performance of polypropylene.
writer：Tang, Wufei;Li, Hongfei;Zhang, Sheng;Sun, Jun;Gu, Xiaoyu*
keywords：Kaolinite;*X-ray diffraction;*Montmorillonite;*Fireproofing agents;*Layed double hydroxides;*Thermal conductivity
source：期刊
specific source：Journal of Thermoplastic Composite Materials, DOI：10.1177/0892705717738291
Issue time：2018年
Kaolinite has often been intercalated before being introduced into polymers to improve its dispersibility; however, the conventional intercalation usually reduces the flame retardancy of the composite. This work reports our recent efforts on improving both the flame retardant efficiency and dispersibility of kaolinite in polypropylene (PP) by intercalating with ammonium sulfamate (AS). The intercalation had been performed through three steps: dimethyl sulfoxide was firstly introduced into kaolinite layers under supersonic wave, then it was replaced by potassium acetate-aqueous (KAc), and finally the intercalated KAc was replaced by AS to obtain AS-intercalated kaolinite. The structure of intercalated kaolinite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, and thermogravimetric analysis (TGA). The flammability evaluation by limit oxygen index, vertical burning test (UL-94), cone calorimeters test (CONE), and TGA indicated that the fire resistance, thermal stability, and physical properties of PP can be effectively enhanced by the introduction of AS-intercalated kaolinite. The peak heat release rate (pHRR) value of PP composite containing only 1.5 wt% intercalated kaolinite (1169 kW m?2) had been reduced 13.2% compared with that of the sample containing 1.5 wt% raw kaolinite (1346 kW m?2). The morphology analysis from scanning electron microscope images and XRD patterns demonstrated that the compatibility and dispersibility of kaolinite in PP had been significantly improved by intercalation. The flame retardant mechanism of AS-intercalated kaolinite in PP was proposed.