Fecha de publicación: -- Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Tuning the surface grafting density of an amine-terminated copolymer on cellulose nanofibers controls the fiber–matrix interface in melt-compounded nanocellulose/ABS composites. Increasing grafting density builds a compliant nanoscale interphase that raises tensile toughness up to ~26-fold while preserving stiffness and lowering thermal expansion, establishing grafting density as a simple dial for tailoring composite performance.

ABSTRACT
The interfacial structure between nanofillers and polymer matrices plays a critical role in determining the overall performance of polymer nanocomposites. In this study, we explored how varying the grafting density of flexible poly(oxyethylene/oxypropylene)-2-propylamine (MPOEA) chains on cellulose nanofibers (CNFs) influences the mechanical and thermal properties of CNF-reinforced Acrylonitrile–butadiene–styrene (ABS) composites. The grafted MPOEA chains formed interfacial layers around the CNFs, with higher grafting densities yielding more interactive interphases. As a result, compared with the unmodified CNF/ABS composite, the optimized composite (J-100%) exhibited an approximately 26-fold increase in tensile toughness, from 0.90 ± 0.24 to 23.62 ± 7.47 MJ m−3, while maintaining a Young's modulus of 1.52 ± 0.30 GPa, which remained comparable to that of neat ABS (1.41 ± 0.03 GPa). Thermomechanical analysis indicated that the addition of CNFs reduced the thermal expansion of the composites, and although this effect diminished at higher grafting densities, the coefficient of thermal expansion (CTE) values remained lower than that of neat ABS, ranging from (133.9 ± 0.3) × 10−6 K−1 for J-0% to (157.2 ± 4.4) × 10−6 K−1 for J-100%, compared with (169.5 ± 7.7) × 10−6 K−1 for neat ABS.