Biodegradable Poly(Lactic Acid)/Clay Nanocomposites by Melt Intercalation: A Study of Morphological, Thermal, and Mechanical Properties

Abstract

Biodegradable polymer nanocomposites of poly(lactic acid) (PLA) and several organically modified montmorillonites (nanoclays), namely, Cloisite 30B, Cloisite Na + , Cloisite 25A, Cloisite 20A, Cloisite 93A, and Cloisite 15A were prepared by melt compounding using a Brabender twin-screw extruder. An exfoliated morphology was observed using both X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) for the combination of PLA and Cloisite 30B (the montmorillonite modified with a quaternary ammonium salt). The first XRD peaks for all the other nanocomposites were observed to shift to lower angles, indicating that intercalation occurred. The extent of intercalation depended on the type of organic modification on the Cloisite organoclay and was exhibited in the sequence of Cloisite Na + > 25A > 20A > 93A > 15A. Further studies were carried out to compare the properties of the PLA-30B nanocomposites with those of the neat PLA at clay loading levels of 1%, 2%, 3%, 4%, and 5% (w/w). Thermal stability of the nanocomposites was studied using thermogravimetric analysis (TGA). An increase in thermal stability was observed with a high at a loading level of 3% (w/w). Biodegradable Poly(Lactic Acid)/Clay Nanocomposites 337Glass transition data were collected and analyzed using differential scanning calorimeter (DSC). An optimum in the glass transition temperature T g of the nanocomposites was observed at 3% (w/w). Improvement in the mechanical properties of the nanocomposites was also observed.

Oxidized multiwalled carbon nanotubes as effective reinforcement and thermal stability agents of poly(lactic acid) ligaments

“…A similar increase was also reported in PLA/MWCNT nanocomposites because of the existence of rigid MWCNTs incorporated into the PLA matrix 20 or in other nanocomposites, such as those with clay. 33 …”

Biodegradable Polymer/Clay Nanocomposites

“…However, the usual result is to obtain partially or completely intercalated structures (Sinha Ray et al 2002Ray et al , 2003aRay and Okamoto 2003;Sinha Ray et al 2002;Chen and Yoon 2005;Krishnamachari et al 2009;Pluta et al 2006). Different plasticizers and compatibilizers have been used, finding little to no exfoliation when montmorillonite clays are involved (Sinha Ray et al 2002;Shibata et al 2006;Thellen et al 2005;Paul et al 2003).…”

Porous composite structures derived from multiphase polymer blends

“…1). At the same time, many studies have demonstrated the good dispersion of Cl15A in PLA-based copolymers [43,[57][58][59]. In Fig.…”