Origin of deterioration in mechanical properties of glass fiber reinforced nylon 6,6 composites by aqueous ethylene glycol solution

Abstract

AbstractGlass fiber reinforced nylon 6,6 (GFNY66) composites widely used for automotive applications undergo degradation when repeatedly exposed to aqueous ethylene glycol (EG) solution, resulting in significantly reduced mechanical properties. Hence, it is important to clearly understand the degradation and hydrogen bond breaking mechanism of nylon 6,6 (NY66) and interfacial failure mechanism in GFNY66 (when exposed to aqueous EG solution) in order to improve the mechanical properties of recycled NY66. From ATR‐IR spectra of NY66 immersed in aqueous EG solution at 108°C for varying intervals of time, the shifting of amide‐I band (νCO) at 1640 cm−1 towards lower frequency with increasing immersion time may be attributed to the breakage of intra‐ and intermolecular H‐bonding between amides in NY66 followed by the new formation of H‐bonding between amide group in NY66 and hydroxyl group in the absorbed EG. GPC data revealed the reduction in molecular weight due to the absorption of EG into NY66 matrix leading to chain scission of NY66. GFNY66 samples treated with aqueous EG solution exhibited pronounced deterioration in mechanical properties because of the interfacial failure between glass fiber and NY66 matrix as well as molecular weight reduction caused by the absorbed EG solution. POLYM. COMPOS., 28:778–784, 2007. © 2007 Society of Plastics Engineers