Mechanical and morphological properties of cellulose nanocrystal‐polypropylene composites

Abstract

In this work, the rheological, mechanical, morphological, and thermal properties of cellulose nanocrystal (CNC)‐polypropylene (PP) composites prepared in the molten state were investigated. All samples contained a maleated PP used as combatibilizer. Degradation of the PP in the presence of CNCs at high processing temperature was shown to have a significant effect on the rheological behavior. For PPs with two different molecular weights and prepared at different temperatures, the tensile modulus of composites containing 2 wt% CNC was improved by about 30% and the tensile strength was increased up to 16%, in comparison with the unfilled matrices. The tensile strain at break of composites decreased by 17% up to 75% with respect to the matrix, depending on the processing conditions and PP used. Preparing the low molecular weight PP composites via twin‐screw extrusion was shown to be more efficient than using an internal batch mixer. The tensile modulus of the PP/CNC composites could be fairly well described by a model proposed by Nielsen based on the Halpin‐Tsai equation. Finally, properties of the PP/CNC composites have been compared to those of a PP reinforced with flax fibers and a PP filled with nanoclay. POLYM. COMPOS., 39:3605–3617, 2018. © 2017 Society of Plastics Engineers