Effect of surface modification of MWCNTS on crystallization behaviour and mechanica properties of LDPE/POE/MWCNTs composites

Multi-walled carbon nanotubes (MWCNTs) modified by concentrated sulfuric acid/nitric acid (H2SO4/HNO3) and silane coupling agent (ã- aminopropyltriethoxy silane, KH550) was studied by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of modified MWCNTs on crystallization behaviour and mechanical properties of low density polyethylene (LDPE)/polyolefin elastomer (POE)/MWCNTs composites were investigated. The results revealed that the crystallinity of composites increased with the addition of the raw MWCNTs and MWCNTs which were modified by H2SO4/HNO3 and KH550. The MWCNTs treated by H2SO4/HNO3 had a better dispersion in matrix than raw MWCNTs and it was beneficial to tensile strength. Further modification by KH550 on H2SO4/HNO3 treated MWCNTs could improve the dispersion of MWCNTs in matrix and interfacial adhesion between MWCNTs and matrix, leading to the tensile strength increased by 35.5 % compared to LDPE/POE composite with raw MWCNTs, and modulus at 100% of composites also increased.