Study On The Preparation Of GIC And Its Flame Retardant PE

Intumescent flame retardants (IFRs) have been one of the most importantfields in flame retardant materials. Thanks to the large volume expansion at hightemperature, graphite intercalation compounds (GICs) are considered as a kind ofpromising flame retardants with the characteristics such as high efficiency andenvironmental friend. GICs as the representative of physical IFRs have attractedmuch attention. This paper aims at intercalating nitrates, organic acids andphosphorous compounds into the interlayers of graphite to prepared GICs by atwo-step method. The structure of GICs was studied by electron microscopy(SEM) and X-ray diffraction (XRD). The expansion properties of GICs wereevaluated in terms of expansion volume. GICs were used in flame retardantpolyethylene (PE), whose flame retardant properties were investigated by meansof limiting oxygen index (LOI).The following results were collected.(1) Multi-components GICs aresuccessfully prepared by the two-step method. By co-intercalated means, GICwith two kinds of phosphorous compounds was prepared.(2) The structure ofGICs depends on the structure and characteristics of intercalants. Duringintercalating process, sulfuric acid was introduced into the interlayers of graphite,then the co-intercalants were introduced. Co-intercalants could be positioned inthe same interlayers with sulfuric acid or the interlayers without sulfuric. Theformer position leads to the same stage structure as sulfuric acid intercalated GICwhile the later leads to the lower stage structure.(3) GICs are characterized ofobvious volume expansion. The expansion volume of GICs has the dependenceon the structure and characteristics of intercalants, as well as temperature. GICswith designed expansion volume can be prepared by selecting intercalants.(4)GICs with different kinds of intercalants exert influences on the flame retardancy of PE. Higher LOI values of flame retardant PE are obtained by using GICs withlarger expansion volume. The flame retardant PE with high LOI values isobtained by using the synergistic effect between GIC and IFR.