Multi-functional effect of alkenyl-succinic-anhydride-modified microfibrillated celluloses as reinforcement and a dispersant of CaCO3 in high-density polyethylene

The use of a combination of calcium carbonate (CaCO3) and alkenyl-succinic-anhydride (ASA)-modified microfibrillated cellulose (AMFC) as a filler for high-density polyethylene (HDPE) has been investigated. AMFC and CaCO3 were mixed with HDPE using a twin-screw extruder, and the resulting composites were injection molded. Observations by X-ray computed tomography, phase-contrast microscopy, and energy dispersive X-ray spectrometry confirm that AMFC is homogenously dispersed in HDPE as a result of the alkenyl chains being incorporated on the surface of the microfibrillated cellulose. CaCO3 is also well dispersed in HDPE when mixed with AMFC. The combination of CaCO3 and AMFC results in high mechanical reinforcement of HDPE, and the composite has a tensile modulus that is almost 120% higher than that of neat HDPE. A melt rheological study revealed formation of a network consisting of AMFC and CaCO3 in HDPE. Microfibrillated cellulose treated with ASA acts not only as reinforcement for HDPE, but also as a dispersant of inorganic fillers, such as CaCO3.