Effect of the ethylene-acrylic acid melt index on the structural characteristics and properties of high-density polyethylene/layered double hydroxide nanocomposites prepared via the master-batch method

摘要

High-density polyethylene/Mg_2Al-layered double hydroxide nanocomposites with different ethylene-acrylic acid random copolymer/Mg_2Al-layered double hydroxide master batches were prepared by melt-mixing. The effect of the ethyleneacrylic acid random copolymer melt index on the exfoliated/intercalated nanocomposite structures was investigated by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The crystallization behavior and thermal property of the nanocomposites were determined via differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis and cone calorimetry. The Mg_2Al-layered double hydroxide layers were well-dispersed at the nanometer level, providing direct evidence of the formation of intercalated/exfoliated nanocomposites, as well as the important effect of ethylene-acrylic acid random copolymer melt index on these structures and their properties. Lower ethylene-acrylic acid random copolymer melt index resulted in higher exfoliation and better dispersion of layered double hydroxide in the high-density polyethylene matrix. Reductions in the heat release rate, total heat release and the carbonic oxide and carbon dioxide production of the nanocomposites were also observed. These phenomena led to higher thermal stability and changes in the storage modulus, tanδ and loss modulus of the nanocomposites, as well as improvement in the heterogeneous nucleation effect of layered double hydroxide on high-density polyethylene.