Table of Contents
Journal of Polymers
Volume 2015, Article ID 821297, 5 pages
http://dx.doi.org/10.1155/2015/821297
Research Article

Preparation and Antiflame Performance of Expandable Graphite Modified with Sodium Hexametaphosphate

1College of Chemistry and Environmental Science, Key Laboratory of Analytical Science and Technology of Hebei Province, Hebei University, Baoding 071002, China
2Department of VIP, Affiliated Hospital of Hebei University, Baoding, Hebei 071000, China

Received 12 May 2015; Accepted 9 July 2015

Academic Editor: Iliya Rashkov

Copyright © 2015 Hongmei Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A kind of polyphosphate modified expandable graphite (EGp) was prepared in graphite oxidation and intercalation reaction with KMnO4 as oxidant, H2SO4 as intercalator, and sodium hexametaphosphate (SHMP) as assistant intercalator. The feasible mass ratio of C : KMnO4 : H2SO4 (98%) : SHMP was determined as 1.0 : 0.3 : 4.5 : 0.6, H2SO4 was diluted to 77 wt% before intercalation reaction, and the reaction lasted for 40 min at 40°C. Expanded volume and initial expansion temperature of the prepared EGp reached 600 mL/g (at 800°C) and 151°C, respectively. X-ray diffraction spectroscopy testified the intercalation and layer structure of EGp, and Fourier transform infrared spectroscopy illuminated the intercalated functional groups. Flame retardance of the prepared EGp and the referenced EG (with only H2SO4 as intercalator) for linear low density polyethylene (LLDPE) was also investigated. Addition of 30 wt% EGp to the polymer improved the limiting oxygen index (LOI) from 17.5 to 27.3%. On the other hand, the LOI of the same amount of the referenced EG was only 24.6%. Assistant intercalation of SHMP improved the dilatability and flame retardancy.