Surfactant-modified microfibrillated cellulose reinforcement of high-barrier sustainable packaging films

Surfactant-modified microfibrillated cellulose (S-MFC) enhanced the barrier properties of biobased packaging films for food applications. MFC of varying dimensions was mechanically produced from hardwood cellulosic fibers by applying different cumulative energy levels. The MFC was then modified employing a cationic surfactant, viz., cetyltrimethylammonium bromide (CTAB), and a non-ionic surfactant (NS), alcohol ethoxylate, followed by solution casting to develop packaging films. The MFC and S-MFC were characterized by using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The packaging films were evaluated for barrier and mechanical properties, including air permeability, water vapor transmission rate (WVTR), oil and grease resistance, hot oil resistance, water contact angle and surface energy, tensile, and stretch properties. The incorporation of hydrophobic long alkyl chains from the surfactant onto the surface of the MFC through electrostatic and hydrophobic interactions contributed to improved barrier properties of the films. The S-MFC-based films demonstrated a 38 % reduction in WVTR, zero air permeability, the highest oil and grease resistance (kit level 12), and passed the hot oil absorption (<4 %), with increasing fibrillation levels and surfactant modifications. S-MFC films showed the highest contact angle of ~81° and the lowest surface energy (37.2 mN/m).