Exploring the Role of Compatibilizers in Modulating the Interfacial Phenomena and Improving the Properties of Cork-Nylon Composites

The nature and the quality of the interfacial interaction and adhesion play a critical role in determining the physical characteristics and mechanical properties of all blends, composites, and nanocomposites. Herein, we examined the roles of functional compatibilizers of different natures and compositions that influenced the processing, interfacial interaction, bulk morphology, and final properties of Nylon-12/cork composites. In this study, Nylon-12 was melt-mixed with cork at 190 °C in an internal laboratory mixer in various compositions using four different compatibilizers namely, (i) octadecanamide (O), (ii) polyethylene-graft-maleic anhydride (PE-g-MAH), (iii) polypropylene-graft-maleic anhydride (PP-g-MAH), and (iv) 3-aminopropyl triethoxysilane (APTS), to improve the interfacial interaction and thereby their adhesion. To understand the impact of compatibilizers on the mechanical properties, morphological characteristics, and degradation properties, the developed composites were investigated using universal tensile testing (UTS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis. In addition, a high-resolution synchrotron macro-attenuated total reflection Fourier transform infrared (macro-ATR-FTIR) microspectroscopy was employed to explore the interfacial characteristics of the composites at the molecular level. The results indicated that cork was more evenly distributed in the Nylon-12 matrix when a small amount of compatibilizer was added to Nylon-12/cork composites. In particular, the mechanical properties of the Nylon-12 composites with APTS were substantially improved when compared with the composites without compatibilizers or with other types of compatibilizers used in this study. Furthermore, the study demonstrated the power of the high-resolution chemical mapping capability offered by the synchrotron macro-ATR-FTIR technique to acquire the spatial distribution and molecular-level information on the interfacial interactions of different components in composites. This fundamental information is pivotal for developing lightweight engineering products using Nylon-12/cork composites.