Sun W, Tang W, Gu X, et al. Synergistic effect of kaolinite/halloysite on the flammability and thermostability of polypropylene[J]. Journal of Applied Polymer Science, 2018, 135(29): 46507.

https://doi.org/10.1002/app.46507

ABSTRACT

Kaolinite (Kaol) and halloysite nanotubes (HNT) are both aluminosilicate clays with similar chemical formulation and different microshapes. In this article, nanotubular HNT and nanoplate Kaol together were introduced into polypropylene (PP) containing intumescent flame retardant (IFR). The flammability of the PP composites was characterized by limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimeter tests (CCT). The results showed that for the composite with 75 wt % PP and 25 wt % IFR, its LOI was 31.0% and it obtained a UL‐94 grade of V‐2. For the composite of 75 wt % PP, 23.5 wt % IFR, and 1.5 wt % (Kaol/HNT = 9/1), its LOI increased to 36.9 and it obtained a UL‐94 grade of V‐0; at the same time, its peak heat release rate value in CCT decreased by 82.2% compared to neat PP. The thermostability ****ysis indicated that the mixture of Kaol/HNT could improve the thermostability and final char yield. The char residues were comprehensively ****yzed by scanning electron microscopy and Fourier transform infrared spectroscopy. The results illustrated that the Kaol/HNT combination was beneficial to forming a crosslinked network and promoting formation of a compact char with higher strength. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46507.