Effect of continuous elongational flow on structure and properties of poly(L‐lactic acid)/poly(ethylene glycol) blend and its organo‐modified montmorillonite nanocomposites

Abstract

An innovative eccentric rotor extruder, which can generate continuous elongation flow, was used to fabricate the poly(L‐lactic acid) (PLLA)/poly(ethylene glycol) (PEG) blends and PLLA/PEG/organo‐modified montmorillonite (OMMT) nanocomposites in different PEG and OMMT content. The morphology was characterized by X‐ray diffractometer (XRD) and transmission electron microscope, showing that the OMMT nanoparticles were highly intercalated or/and exfoliated in the polymer matrix. The rheological behavior was investigated by dynamic rheological measurements, showing that the OMMT nanoparticles dispersed well in the matrix to form OMMT percolation network structure. The crystallization behavior and crystalline structures were studied by differential scanning calorimetry and XRD, respectively, showing that the addition of PEG significantly increased the crystallinity of PLLA and the presence of OMMT further speed up the crystallization rate of plasticized PLLA, which was also proved by the increasing spherulite growth rate and the formation of more perfect crystal structure acquired from polarizing optical microscopy test. However, the crystallization rate and crystallinity had a slight downward trend at high OMMT content because of the inhibition effect of OMMT percolation network structure. Moreover, the thermogravimetric analyzer measurement indicated that the presence of OMMT can significantly improve the thermal stability of PLLA/PEG blends. POLYM. COMPOS., 40:E617–E628, 2019. © 2018 Society of Plastics Engineers