Nanocomposites based on polyethylene and Mg-Al layered double hydroxide: characterisation of modified clay, morphological and rheological analysis of nanocomposites

摘要

Magnesium and aluminium based layered double hydroxide (Mg-Al LDH) after modification with anionic surfactant has been used as nanoclay to prepare polyethylene based nanocomposites using the melt mixing technique. The modified Mg-Al LDH has interlayer separation about four times higher than the unmodified clay and also low surface tension. The modified clay also possesses similar platelet type particle morphology like pristine clay. X-ray diffraction and electron microscopic analyses reveal that the nanocomposites are mainly exfoliated/intercalated type characterised by the presence of hierarchy of clay particle morphology in the matrix. The dispersed particle forms aggregates or localised domains of network structure. As a result, response to steady shear is characterised by the presence of stress overshoot at the start-up flows, especially at higher LDH concentrations. The rheological analysis shows that the dispersed LDH particles caused deviation of linear viscoelastic response of the melt from that of the unfilled polyethylene.