Chemical interactions in the injection molded direct joining of polymers and hot water-treated galvanized steel
Jiaxing Ren, Weiyan Chen, Shuohan Wang, F. Kimura, Jing Sang, Hidetoshi Hirahara, Yusuke Kajihara
Abstract
Metal-polymer hybrid joining technologies are attracting increasing attention as an effective structural lightweighting solution. However, the joining mechanisms of the hybrid joint remain incompletely elucidated, particularly chemical interactions, which are difficult to observe directly. This study demonstrated that hot water treatment (HWT), as a metal surface modification technique of metal-polymer hybrid joining, can help enhance chemical interactions in the hybrid joining of galvanized high-strength steel (GHSS) and polymers at their joint interface. Surface characterization results revealed that HWT not only modified the surface morphology but also increased the polar surface free energy and surface hydroxyl group concentration. The results of atomic force microscopy–infrared (AFM-IR) spectroscopy showed characteristic redshifts and blueshifts in the vibrational peaks of the polymer functional groups (C O and N–H), indicating the formation of hydrogen bonds with the –OH groups on the GHSS surface. Our findings provide evidence for the contribution of hydrogen bonding in the formation of GHSS–polymer joints and a better understanding of the reaction mechanisms and phenomena occurring in GHSS during the HWT process.