Characterization of linear low-density polyethylene and halloysite nanotube (LLDPE/HNT) composites based on two-roll calendering melt fabrication

In preparation of polymer nanocomposites, achieving good mixing and uniform distribution of nanofillers is highly desired for property enhancement. Polyethylene (PE) and its nanocomposite with halloysite nanotubes (HNTs) possesses a myriad of potentials for advanced engineering properties. A high nanoparticle loading is preferred to capitalize the nano-reinforcement, thermal, and barrier properties. The capability of a two-roll calendaring machine to disperse HNT particles into a linear low-density polyethylene (LLDPE) matrix at elevated processing temperatures was assessed. Morphological, thermal, mechanical, and rheological behavior of prepared nanocomposites were characterized. A homogeneous distribution of HNTs in concentrations up to 5 wt.% was evidenced by SEM analysis. TGA showed the 10 wt.% composite exhibited an overall outstanding thermal stability. DSC analysis revealed the 30 wt.% sample has the highest T_m and T_c, and the %crystallinity did not change much due to HNT incorporation for all samples. DMA showed the storage and loss moduli increased with increase in HNT loadings. The effect of loading HNTs into the LLDPE matrix on T_g was minimal, implying that LLDPE and HNTs are quite compatible. The results demonstrated that the two-roll mill fabrication method can efficiently keep HNT particles unagglomerated and disperse them evenly into the LLDPE matrix.