Photo‐stabilization mechanisms of High‐Density Polyethylene (HDPE) by a commercial few‐layer graphene

Abstract

AbstractThis work studied few‐layer graphene (FLG) dominant action mechanisms as a photo‐stabilizer. High‐density polyethylene (HDPE) containing 0–0.5 wt% FLG were exposed to UVA radiation in a QUV chamber, according to ASTM G154 for different exposure times, ranging from 0 to 672 h. The chemical, rheological, and mechanical properties were tracked using attenuated total reflection‐Fourier transform infrared (ATR‐FTIR), rheological measurements, and tensile tests. The experimental results showed that the addition of only 0.25 wt% FLG fully stabilized 1‐ to 3‐mm thick HDPE for an exposure time of 672 h. Electron paramagnetic resonance (EPR) test was performed on the UV‐exposed mixture of hydrogen peroxide (H2O2) and the FLG aqueous suspensions (0, 0.2, 1, and 5 mg/mL), to study the FLG performance and mechanisms as a photo‐stabilizer. The results showed that FLG effectively decreased the characteristic EPR signal intensity due to both UV absorption/reflection and free radical scavenging. Fifty‐seven percent of the reduction was found to be due to UV absorption/reflection and 43% due to free radical scavenging. It is demonstrated that UV absorption/reflection and free radical scavenging are the dominant ones among the three FLG photo‐stabilizing mechanisms (UV absorption/reflection, free radical scavenging, and physical barrier to oxygen).Highlights FLG showed potential as a photo‐stabilizer for HDPE. Addition of 0.25 wt% FLG fully stabilized HDPE for 672 h of UVA exposure. FLG demonstrated UV absorption/reflection and free radical scavenging effects.