Study On Interfacial Compatibility Of Nanocellulose-high Density Polyethylene Composites

Polyethylene is a kind of thermoplastic plastic with excellent comprehensive performance,which has good solvent resistance,electrical insulation,low temperature resistance and other characteristics.It can be used in various industrial products.However,compared with engineering plastics,polyethylene has poor mechanical properties and is easily deformed and aged,which restrict the wider use of polyethylene.Nano-cellulose as a kind of renewable bio-based polymers,has special excellent properties,such as low density,high specific surface area,high strength?about 3 GPa?,high elastic modulus?138 GPa?and lower coefficient of thermal expansion(10^-7 K^-1),which make it possible to make up for the performance defects of polyethylene.In this paper,the esterification hydrophobic modification of nanocellulose was carried out to reduce the surface polarity of nanocellulose,improves the interfacial compatibility with polyethylene matrix,makes its distribution more uniform in the matrix,and improves the comprehensive properties of the prepared polyethylene matrix composites.Using two types of nano-cellulose?NFC and NCC?and different adding quantity of nano cellulose to prepare polyethylene composite,and respectively from the fiber basic features,mechanical properties,thermal properties to analyze the properties of the composite material.NFC was filamentous,NCC was short rod,and the crystallinity and thermal stability of NCC were higher than that of NFC.The mechanical properties,thermal stability and crystallization properties of NCC-HDPE composites were better than those of NFC-HDPE composites after the addition of nanofibers.In addition,the mechanical properties of NCC-HDPE composites were better at 5%addition,with the tensile strength and elastic modulus of 29.2MPa and655.8MPa,respectively.Nanocrystalline whiskers were esterified with alkenyl succinic anhydride,and the morphological and structural changes of modified NCC were investigated from the perspectives of introducing groups with different surface properties and changing degree of hydroxyl substitution.By esterification modification,long and soft hydrophobic long chains were grafted on the surface,forming a bristle-like structure.At the same time,the surface energy and polar component of the modified NCC decreased,and the surface energy and polar component of C12-3-NCC were 36.4 mJ/m² and 2.75 mJ/m² respectively,which were close to the surface energy and polar component of HDPE.The effects of NCC treated with different modifiers?carbon chain length?and NCC with different degree of hydroxyl substitution on the interfacial compatibility,mechanical properties,thermal characteristics and hydrothermal properties of HDPE composites were compared and studied.With the increase of the length of enyl succinic anhydride ester on the surface of NCC and the increase of hydroxyl substitution degree on the surface of C12-NCC,the interfacial compatibility of the composite material was improved,as well as its mechanical properties.When 5%C12-NCC was added,the tensile strength and elastic modulus of the composite material were 33.1 MPa and 745.5 MPa,respectively 24.9%and 38%higher than HDPE,but the elongation at break was reduced.The tensile strength,elastic modulus and elongation at break of C12-3-HDPE were improved by 16.1%,4%and 139%,respectively,compared with5%NCC-HDPE.In summary,compared with NCC,after esterification,the increases in the surface carbon chain length and surface hydroxyl substitution degree of NCC are conducive to the interface interaction between NCC and substrate,and the interface compatibility and mechanical properties of C12-HDPE composites with 5%C12-3-NCC are optimal...