Cotton cellulose nanofiber-reinforced high density polyethylene composites prepared with two different pretreatment methods

Abstract

The reinforcing effect of cellulose nanofibers (CNF), individualized from cotton fibers subjected to a chemical process and a grinding process, has been investigated using high density polyethylene (HDPE) as matrix. In order to solve the agglomeration problem of cotton nanofiber in non-polar HDPE, two pre-treatment methods have been used prior to the extrusion process, one method was relative to the physical pretreatment, and the other corresponded to the polyoxyethylene (PEO) dispersion agent method. The dispersion of cotton CNF in HDPE and reinforcing effect of cotton CNF on HDPE with the two preparation methods were made a comparison. From the SEM images observation, a good dispersion effect and an ideal network structure of the cotton CNF/HDPE composites could be achieved via two preparation methods. However, PEO dispersion agent method could improve the CNF dispersion much better than the physical pretreatment method, but unfortunately reducing the aspect ratio of the cotton CNF. Addition of cotton CNF clearly increased the bending strength (MOR) and bending modulus (MOE) of HDPE. The MOR and MOE of cotton CNF/HDPE composites with the physical pretreatment method were much higher than those of the nanocomposites with the PEO dispersion agent method. A comparative study was also made to find out the effect of two cellulose based nanofillers (CNF and nanocrystalline cellulose (NCC)) on the rheological, thermal, and mechanical properties of HDPE. The results demonstrated that cotton CNF had a better reinforcing effect on HDPE than NCC, while NCC could decrease the thermal expansion of the nanocomposites more significantly.