The fly ash from Pha Lai power plant was modified by three types of silane coupling agent (SCA). The thermal oxidation stability of the composites was determined by thermal gravimetric analysis (TGA). The morphology of modified fly ash and LDPE/EVA/FA composites was analyzed by scanning electron microscopy (SEM). Besides, the mechanical properties of LDPE/EVA/FA composites were also studied.

The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with vinyltrimetoxysilane (VTMS) modification were prepared by melt mixing in a Haake Rheomixer. The FT-IR spectra indicated the bonds between LDPE/EVA and FA modified by vinyltrimethoxysilane were dipole - dipole interaction and hydrogen bonding. Both dynamic storage modulus (G’) and loss modulus (G’’) of the LDPE/EVA/FA-VTMS composites were higher than those of the LDPE/EVA/FA composites.

Here we repor t on the modification of fly ash (FA) with vinyltr iethoxysilane (VTES) in order to enhance the dispersibility and avoid the agglomeration. FA was treated with nitr ic acid before the modification with VTES. The str ucture of fly ash par ticles before and after the modification was character ized by several sophisticated techniques including Four ier transfor m infra-red spectrum (FT-IR), ther mogravimetr ic analysis (TGA), field emission scanning electron microscopy (FE-SEM)and size distr ibution analysis.

The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with organic modification were prepared by melt mixing in a Haake Rheomixer. The dielectric strength of LDPE/EVA/FA and LDPE/EVA/modified FA (MFA) composites was lower than that of LDPE/EVA blend. The LDPE/EVA/MFA composites have the dielectric strength higher than the LDPE/EVA/FA composites at the same content of FA.

The polymer composites of low-density polyethylene (LDPE) and poly(ethylene-co-vinyl acetate) (EVA) blends filled by fly ash (FA) with different content were prepared by melt mixing in a Haake Rheomixer. The relative melt viscosity of the composites is increased and tensile property of the composites is decreased with increasing the FA content. When the fly ash modified with VTMS silane (FA-VTMS), the relative melt viscosity of the LDPE/EVA/FA-VTMS composites is lower the LDPE/EVA/FAs composites.