Single and hybrid organoclay‐filled PLA nanocomposites: Mechanical properties, viscoelastic behavior and fracture toughening mechanism

Abstract

Poly (lactic acid) (PLA) nanocomposites based on single and hybrid organic‐modified montmorillonites were previously studied in terms of their morphological, thermal and fire performance. As surfactants of the organoclays influenced the compatibility between the nanofillers and PLA with different degrees of clay platelets dispersion, the present work investigated the effect of these features in the mechanical properties of PLA nanocomposites. PLA nanocomposites specimens were analyzed by dynamic‐mechanical‐thermal analysis, which pointed out changes in the viscoelastic behavior of the materials by the incorporation of the organoclays, namely the increase of the storage modulus due to polymer chains movements restriction and reinforcement effects associated with the dispersion of the nanofillers. Flexural and impact testing showed that hybrid organomontmorillonites containing ester ammonium and ethoxylated amine improved PLA's ductility, toughness and impact resistance. This behavior was explained by the high level of compatibility and interaction between the surfactants and PLA chains due to the polar groups in their structures. These organoclays caused a transition on PLA's fracture from brittle to ductile in a way that the toughening mechanism was explained by crazing and multi‐shear banding induced by the plasticized interfacial region around these organoclays.

Impacts of cellulose nanofibers on the morphological behavior and dynamic mechanical thermal properties of extruded polylactic acid/cellulose nanofibril nanocomposite foam

“…This polymer has been considered in biomedical applications such as tissue engineering, implants, drug delivery systems, and orthopedic devices due to its good tensile strength, as well as its reproducibility and biodegradability 11–14 . Nonetheless, the brittleness, slow crystallization, and higher cost of PLA are some of the drawbacks for its wider application compared to petroleum‐derived plastic 15 …”

Mechanical properties, thermal stability, and thermal degradation kinetics of silicone rubber/ethylene‐vinyl acetate copolymer/magnesium sulfate whisker composites compatibilized by ethylene‐acrylic acid copolymer

“…Similar observations were explained. Tensile strength and modulus increased by 16% and 38% separately compared with pristine PLA by incorporating 2 wt% nano‐silica into PLA 24 …”

“…Tensile strength and modulus increased by 16% and 38% separately compared with pristine PLA by incorporating 2 wt% nano-silica into PLA. 24 Figure S4c shows the hardness shore A of the SR/EVM blend, and all types of the composites contained different loading of untreated MS and treated MS whisker. Commonly, the hardness shore A of the composites should be increased by adding an MS whisker because of the higher stiffness of inorganic materials.…”

Investigation of the Effect of Hybrid Nanofiller on the Mechanical Performance and Surface Properties of Bio-Based Polylactic Acid/Polyolefin Elastomer (PLA/POE) Blend

“…In this regard, not only does PLA instinctively suffer from brittleness, hydrolysis, and low melt strength, but also the production of PLA is not that affordable compared to traditional polymers. To cover these shortages, several methods have been suggested such as adding nanofiller [ 14 , 15 , 16 , 17 ], plasticizing [ 18 , 19 ], copolymerizing with flexible monomers [ 20 , 21 ], and blending with tough materials [ 22 ].…”