Post‐γ‐irradiation effects in nano‐SiO₂ particle reinforced high‐density polyethylene composite films: Structure–property relationships, thermal stability and degradation

Abstract This paper presents the findings of a study on the effects of gamma radiation on the structural and thermal characteristics of high‐density polyethylene nanocomposite films. These thin films consist of a combination of HDPE and nano‐SiO₂ particles prepared by hydrostatic thermal pressing a mixture of HDPE powder and nano‐SiO₂ in various volume concentrations (ω = 1%, 5%, 10%, and 20%). Fourier transform infrared spectroscopy analysis is used to identify new functional groups on the surface of composite materials that have been irradiated. The effect of the absorbed dose on the physical and chemical changes in the molecular structure of the polymer matrix is investigated. The paper also presents how the absorbed dose affects variations in the melting and crystallization temperatures, thermal stability, and the degradation mechanism of nanocomposites using differential scanning calorimetry and thermogravimetric analysis. Fourier transform infrared spectroscopy analysis shows that gamma radiation enhances the interfacial interactions between the nanoparticles and the polymer matrix. During the repeated heating process within the temperature range of 25–160°C, the melting temperature of the polymer shifted towards a higher temperature, while for the first and second cooling processes, the crystallization peaks for both unirradiated and irradiated samples overlapped. Highlights γ‐irradiation influences the structural and thermal properties of the HDPE/SiO₂. The active surface of nano‐SiO₂ particles acts as a crystallization center. γ‐irradiation reduces the melting and crystallization temperatures. Nano‐SiO₂ particles improve the thermo‐oxidative stability of the HDPE matrix. The degree of oxidation depends on irradiation dose and nano‐SiO₂ concentration.