Composite is commonly used today attributed to the distinctive characteristics that can be acquired from the mixture of the components in them. However, as time passes on, our globe is heading towards providing green technology for the sector to use environmentally friendly methods. In this study, Fly Ash geopolymer is used as filler, in the production of LDPE / FA composite, to be inserted in a low-density polyethylene matrix. To enhance bonding between the fly ash filler and the LDPE matrix, alkali activator therapy with the use of sodium hydroxide and sodium silicate at the molarity of NaOH is in range of 12M and the ratio for fly ash to alkali activator is about 2.0. In this research properties of these composites are investigate using tensile test, morphology analysis, thermal properties and infrared spectrum analysis, FTIR. The result found that the tensile strength and modulus of elasticity of the composite increased with increasing of filler loading but the percentage of elongation decrease due to filler loading increase while fly ash filler show the interfacial adhesion on LDPE matrix as evidenced by images of scanning electron microscopy (SEM) and this also proved by FTIR spectra explain that LDPE/FA charged with SiO which is fly ash composed with silica. Moreover, thermal properties explain that fly ash interface reaction which can change to amorphous crystallization during the temperature increase.
