Surface hydrophobization of microfibrillated cellulose with octadecylamine for toughening of ABS composites

Microfibrillated cellulose (MFC) has attracted increasing attention as a sustainable reinforcement for polymer composites. However, when incorporated into hydrophobic thermoplastics such as acrylonitrile–butadiene–styrene (ABS), MFC often improves tensile strength but significantly reduces elongation at break. To address this challenge, we designed a surface modification strategy for MFC. Leaf bleached kraft pulp (LBKP) was first carboxyethylated and mechanically fibrillated to produce carboxyethylated MFC (C-MFC), which was subsequently amidated with octadecylamine (ODA) to obtain hydrophobized octadecylamine-modified carboxyethyl MFC (OC-MFC). Composite films of OC-MFC/ABS were fabricated by solution casting followed by hot pressing. The structures and properties of MFC, C-MFC, OC-MFC, and OC-MFC/ABS composites were systematically characterized using laser particle size analysis, FTIR, dynamic water contact angle, tensile testing, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results demonstrated that ODA modification effectively increased the hydrophobicity of MFC, leading to improved dispersion and interfacial compatibility with the ABS matrix. Mechanical testing revealed that the incorporation of 0.5–1 wt% OCMFC into ABS composite films preserved the tensile strength, while significantly enhancing. Morphological observations further supported the toughening effect of OC-MFC. These findings highlight a practical strategy for toughening ABS through the incorporation
of surface-modified MFC, providing insights into the design of high-performance bio-based thermoplastic composites.