Study Of Preparation And Properties Of A New Type Of HDPE/MMT Flame Retardant Composites

With comparison to traditional flame retardant polymer, Polymer/montmorillonite nanocomposites has unique flame retardant properties, such as little addition, non-halogen, little effect on mechanical properties of polymer. For this reason, the development and research of high flame retardant polymer/montmorillonite nanocomposites is becoming an important research area in the worldwide, but its flame retardant properties can not meet with demand of conventional flame retardant materials. How to improve the performance of this kind flame retardant material is still a key problem for its application. In this paper a new type of HDPE/MMT flame retardant composites were prepared by modification using coal and intumescent flame retardant. The synergism effect of coal and /or intumescent flame retardant with MMT and their flame retardant mechanism were also studied. Firstly HDPE/MMT flame retardant composites and coal modified HDPE/MMT flame retardant composites are prepared through melt intercalation method. Their structures and performances are measured by XRD, SEM, DSC, LOI analysis methods. The results show that HDPE/MMT flame retardant composites are characteristic of exfolicated structure morphology, which is not changed with addition of coal. So the effect of the addition of coal on the dispersion of MMT in the HDPE/MMT composites is very small. The results of flame retardant properties measurement of the composites show that their limited oxygen index (LOI) is increased to 21 from 18 for unmodified HDPE/MMT composites. That is because the addition of coal can improve residual char rate for combustion of HDPE/MMT flame retardant composites. And the char take on layered structure. In order to further improve on flame retardant properties of HDPE/MMT flame retardant composites, a compound flame retardant, composited of coal and ammonium polyphosphate(APP) /pentaerythritol(PER)/ melamine(MEL) mixture (CP/IFR) is used to further modify the performance of HDPE/MMT flame retardant composites.The study of flame retardant properties of CP/IFR modified HDPE/MMT flame retardant composites show that the LOI is increased to 26 from 18, and it has little effect on the mechanical properties of HDPE/MMT flame retardant composites. The individual addition of coal or intumescent flame retardant can not effectly increase on the flame retardant properties of HDPE/MMT flame retardant composites. So coal and intumescent flame retardant has good synergism effect on HDPE/MMT flame retardant composites and then the flame retardant mechanism of CP/IFR modified HDPE/MMT flame retardant composites is discussed .The free radical catching action of functional group in coal and prompting action of CP/IFR on thermal stability and high char residual play an important role in this flame retardant composites.