Poly(lactic acid)–layered silicate nanocomposites: The effects of modifier and compatibilizer on the morphology and mechanical properties

Abstract

Poly(lactic acid) (PLA) based nanocomposites were prepared to investigate the effects of types of nanoclays. Five different organically modified nanoclays (Cloisites V R 15A, 25A, and 30B, and Nanofils V R 5 and 8) were used. Two rubbery compatibilizers, ethylene-glycidyl methacrylate (E-GMA) and ethylene-butyl acrylate-maleic anhydride, were used in the nanocomposites as compatibilizer-impact modifier. The degree of clay dispersion, the chemical compatibility between the polymer matrix and the compatibilizers, and changes in the morphology and mechanical properties of the nanocomposites were investigated. The mechanical properties and the morphological studies showed that the interactions between the different compatibilizers and PLA resulted in different structures and properties; such that the dispersion of clay, droplet size of the compatibilizer, and tensile properties were distinctly dependent on the type of the compatibilizer. Compatibility between C25A, C30B, and E-GMA resulted in the best level of dispersion, leading to the highest tensile modulus and toughness among the compositions studied. In the mentioned nanocomposites, a network structure was formed owing to the high reactivity of the epoxide group of GMA towards the PLA end groups resulting in high impact toughness.

MMT and LDH organo-modification with surfactants tailored for PLA nanocomposites

“…With reference to layered inorganic systems both montmorillonite (MMT) and layered double hydroxides as hydrotalcite (LDH) have been used. In both cases the use of surfactants (ionic salts employed as organomodifiers) is necessary to enlarge the intergallery spacing and to make more lipophilic the filler surface aimed at favouring complete exfoliation and then morphologies suitable to reach the target features (mechanical improvements and/or barrier properties) [7][8][9][10].…”

Poly(lactic acid)‐based nanocomposites

“…Structures of layered silicate–polymer nanocomposites (the concept was redrawn from the following references) …”

“…Epoxy and maleic anhydride‐based polymeric compatibilizers are often used to homogeneously disperse the blends and modify their interfacial properties, thus stabilizing the melt blend. Cumkur et al recently report a detailed study using five modified clays and compatibilizers, ethylene–glycidyl methacrylate (E‐GMA), and ethylene–butyl acrylate–maleic anhydride . They observe that clay types C25A, C30B, and glycidyl methacrylate result in the best level of dispersion, leading to the highest tensile modulus and toughness.…”

“…Cumkur et al recently report a detailed study using five modified clays and compatibilizers, ethylene-glycidyl methacrylate (E-GMA), and ethylene-butyl acrylate-maleic anhydride. [26] They observe that clay types C25A, C30B, and glycidyl methacrylate result in the best level of dispersion, leading to the highest tensile modulus and toughness. C25 and C30 are organomodified clays marketed under the brand Closite.…”

Preparation, dynamic rheological behavior, crystallization, and mechanical properties of inorganic whiskers reinforced polylactic acid/hydroxyapatite nanocomposites

“…Currently, there have been various methods applied to modify PLA. [14][15][16] The incorporation of hydroxyapatite (HA) nanoparticles is one of the effective ways. As is well known, HA, as the main inorganic component of the human bone, is an important inorganic material with excellent bioactivity, biocompatibility, and osteoconductivity.…”