Study on the interfacial properties of bi-material structures manufactured by injection molding after compression.

• The bi-material specimens are fabricated by the IMAC process. • The bi-material interfacial properties are characterized comprehensively. • The influence of surface pretreatment methods on interfacial properties is analyzed. • Mechanisms affecting interface properties are revealed. • The matching design principle of material-process-geometry-property is proposed. Injection molding after compression (IMAC) is used for manufacturing the bi-material structure. However, the bi-material interface may be the weakest region restricting overall structural performance. Various specimens with discontinuous GF30/PA66 or GF30/PA6 over-molded injection on a continuous CF/PA6 sheet are prepared using the IMAC process. The interfacial shear and cross-tension tensile strength, mode-I/II fracture energy, and overall bending strength are then systematically characterized. The influence interlock features derived from sandpaper grinding, sandblasting, and nano-coating have on the properties are then investigated. It is found that decreasing interface roughness can improve interfacial tensile strength and mode-I fracture energy while weakening shear strength and mode-II fracture energy. These surface pretreatments are also effective for the promotion of overall bending strength. A design matching principle between the material, process, geometry, and properties is ultimately proposed. This work provides the fundamental interfacial properties of IMAC structures for engineering applications. [ABSTRACT FROM AUTHOR]