Phenol functionalized high-density polyethylene as compatibilizer of high-density polyethylene/graphene nanocomposites toward enhanced mechanical and interfacial adhesion

In this work, the methodology to obtain high-density polyethylene (HDPE) and graphene (G) nanocomposites using phenol-modified graphene and phenol-modified HDPE as compatibilizer obtained from the reaction of malleated polyethylene (HDPE-g-MA) with phenol, is described. Six different methods were used to obtain these composites, resulting from the combination of melt and solution mixing with three different procedures to functionalize either graphene or HDPE-g-MA with phenol. Nanocomposites were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD), dynamic mechanic analysis (DMA) and tensile properties. The FTIR results evidenced the occurrence of an esterification reaction between HDPE-g-MA and phenol groups serving as compatibilizer. The SEM and WAXD results showed that the addition of this compatibilizer agent had a positive effect on graphene dispersion, which promoted greater stiffness in these composite materials, presenting higher storage modulus. In addition, a noticeable enhancement in dimensional stability at high temperatures was observed according to Tan Delta measurements. These results indicated a good interfacial adhesion between graphene and the polymer matrix by using this compatibilizer agent. It was observed that the composites obtained by solution mixing method showed better performance and stronger interfacial adhesions than the composites produced by melt mixing methods. The use of this phenol modified HDPE compatibilizer offers a new option to enhance the final performance of HDPE/graphene composites with better mechanical and thermal properties to be used in materials for various applications, such as automotive industry, electrical and electronics, construction, aerospace, and other engineering applications.