Improving the flame retardancy and mechanical properties of high density polyethylene-g-maleic anhydride with an organic metal phosphonate
writer：Cao ZH, Zhang Y, Zhao LP, Peng M, Fang ZP*, Klatt M
keywords：Metal phosphonate; Polyethylene; Flame retardancy; Mechanical properties
source：期刊
specific source：J.Anal. Appl. Pyrol., 2013.6, 102: 154-160
Issue time：2013年
Zinc N,N’-Piperazinebis(methylenephosphonic acid) (PPMPA-Zn) was melt blended with high density polyethylene-g-maleic anhydride (HDPE-MA) to fabricate flame retardant HDPE-MA/PPMPA-Zn composites. The thermal stability and flame retardancy of the composites were investigated by thermogravimetric analysis (TGA) and cone calorimetry. Incorporation of PPMPA-Zn did not obviously increase the thermal stability of HDPE-MA but the residual char increased to 18.7% when the content of PPMPA-Zn reached 25 wt%. The X-ray diffraction and Raman spectroscopy tests showed that the residual char composed mainly of Zn(PO3)2, Zn11(HPO3)8(OH)6 and amorphous graphite. Scanning electron microscopy (SEM) images of samples collected after cone calorimetric testsalso confirmed the char-formation in the sample with the loading 25 wt% PPMPA-Zn in HDPE-MA, and the char layer acted as a compact and intactphysical barrier in condense phase.Even at a low loading such as 5 wt% of PPMPA-Zn, the peak value of heat release rate (PHRR) was reduced by 38% compared with pure HDPE-MA. In contrary to other intumescent flame retardants, the introduction of PPMPA-Zn not only increased the flame retardancy but also increased the mechanical properties of HDPE-MA. For example, the yield strength and Young’s modulus of HDPE-MA with 5wt% PPMPA-Zn were 125% and 128% compared with that of pure HDPE-MA matrix.