Effect of polymer/organoclay composition on morphology and rheological properties of polylactide nanocomposites

Abstract

In this work the relationships between system composition, polymer–organoclay interaction, morphology and rheological response, under shear, and elongational flow, of different melt compounded polylactic acid (PLA)/organoclay nanocomposites are investigated, with the aim to properly select the better organoclay for a well-specified PLA grade and processing technology. Polylactide nanocomposites are prepared using two commercial polylactide grades (PLA 4032D and PLA 2003D) and two different organomodified montmorillonites (Cloisite 30B and Nanofil SE3010). FTIR analysis evidences the occurrence of stronger polymer/organoclay interactions for the system PLA4032D+C30B, resulting in a higher clay dispersion and exfoliation levels. Moreover, rheological tests at low shear rates show that, if PLA 2003D is used as polymer matrix (differing from PLA4032D by the presence of a high molecular weight tail), a better dispersed nanomorphology can be obtained with Nanofil SE3010, characterized by a double d-spacing compared to Cloisite 30B, despite the higher polar character of this latter nanofiller. On the other hand, elongational rheological measurements evidence for NSE3010-based hybrids a marked extensional thickening, whilst the stronger polar interactions between the phases in both the polylactide grades filled with C30B, determine increments in elongational viscosity, but inhibit the strain hardening behavior

Biodegradable nanocomposites based on starch/polycaprolactone/compatibilizer ternary blends reinforced with natural and organo‐modified montmorillonite

“…All the nanocomposites prepared with modified clays showed higher interlaminar space ( ) than those with CNa + reinforcement. This is an indication of higher dispersion of the reinforcement in the matrix, which is a direct result of increased PCL/clay compatibility . On the other hand, C30B and C20A nanocomposites showed similar values, suggesting similar clay dispersion degree.…”

Morphology Development and Mechanical Properties Variation during Cold-Drawing of Polyethylene-Clay Nanocomposite Fibers

“…On the contrary, after drawing, strong reflections appear, at small angles (near the beam stopper) along equatorial lines for the nanocomposite fibers. These reflections, more intense at increasing clay content, suggest the morphology modification related to orientation and to distance reduction of the of silicate layers during the cold drawing process, as also found in other polymer/layered clay nanocomposite fibers [28,42,44,45]. With concern to the matrix morphology, even at the lowest DR = 7.25, XRD patterns show the presence of well oriented crystallites and poorly oriented material, related to the formation of oriented semi-crystalline fibers (Figure 7).…”

The effect of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE nanocomposites

“…The formation of a network structure, that leads to an elastic reinforcement and to the transformation from the liquid-like to the solid-like response at low frequencies, has been previously documented for CNTs composites [6][7][8][9][10][11][12][13][14][15][16][17][18][31][32][33][34][35][36][37][38][39] as well as for nanocomposites containing carbon nanofibers [40][41][42][43][44], layered silicates composites [45][46][47][48], graphene [49,50], carbon black [51], and for thermotropic liquid crystalline polymers [52,53]. Compared to traditional fillers [54], nanofillers reach the rheological percolation threshold at much lower concentrations, due to their high aspect ratio and high surface area that means contacts with polymer chains are much greater.…”