Preparation of Organo-Montmorillonite Modified Poly(lactic acid) and Properties of Its Blends with Wood Flour

Abstract

In this study, poly(lactic acid) (PLA)/wood flour (WF) composites were prepared by first blending PLA with organo-montmorillonite (OMMT) at different contents (0.5, 1, 1.5, and 2 wt %). The physical and mechanical properties of the virgin and OMMT modified PLA and its WF composites were tested. The results showed that: (1) at low OMMT content (<1 wt %), OMMT can uniformly disperse into the PLA matrix with highly exfoliated structures. When the content increased to 1.5 wt %, some aggregations occurred; (2) after a second extruding process, the aggregated OMMT redistributed into PLA and part of OMMT even penetrated into the WF cell wall. However, at the highest OMMT content (2 wt %), aggregates still existed; (3) the highly exfoliated OMMT was beneficial to the physical and mechanical properties of PLA and the WF composites. The optimal group of OMMT-modified PLA was found at an OMMT content of 0.5 wt %, while for the PLA/WF system, the best properties were achieved at an OMMT content of 1.5 wt %.

Natural Compounds as Sustainable Additives for Biopolymers

“…Overall, the adding of micro-or nano-fillers to polymers and biopolymers leads to a significant increase of their rigidity, thermal-resistance, stability, barrier properties, and durability [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], although in some cases, the presence of the fillers can induce a reduction of some properties due to the development of inappropriate morphology. Besides, the introduction of naturally occurring fillers (nFil), such as nano-sized layered alumino-silicates (e.g., halloysite, bentonite, beidellite, sepiolite, montmorillonite, etc.…”

“…Therefore, the preferential location of the nanofillers into the more polar polymer phase and/or at the interface between the two polymer phases, and subsequent morphology variation from droplet to co-continuous, suggests that the nanofillers can be considered as an efficient and suitable physical compatibilizer for some biopolymer blends. Commonly, the adding of layered alumino-silicates, especially organo-modified layered montmorillonite (OMMT), leads to an increase of the system rigidity, i.e., Young's modulus (elastic, E), tensile strength (TS), flexural modulus (FM), flexural strength (FS), and, mostly, the ductility of the complex systems, i.e., the elongation at break (EB), remains almost unchanged, see Table 3, reported below [39]. Farther, the montmorillonite adding to biopolymers leads to an increase of the barrier properties towards gas and humidity because into the polymeric matrix, the way of the oxygen and water molecules becomes more tortuous.…”

“…Farther, the montmorillonite adding to biopolymers leads to an increase of the barrier properties towards gas and humidity because into the polymeric matrix, the way of the oxygen and water molecules becomes more tortuous. Additionally, the complex system crystallinity could increase if the nFil exerts a nucleating effect, or it could decrease if the nFil prevents and/or inhibits the macromolecules organization in regular crystalline structures [39]. Commonly, the adding of layered alumino-silicates, especially organo-modified layered montmorillonite (OMMT), leads to an increase of the system rigidity, i.e., Young's modulus (elastic, E), tensile strength (TS), flexural modulus (FM), flexural strength (FS), and, mostly, the ductility of the complex systems, i.e., the elongation at break (EB), remains almost unchanged, see Table 3, reported below [39].…”

“…Farther, the montmorillonite adding to biopolymers leads to an increase of the barrier properties towards gas and humidity because into the polymeric matrix, the way of the oxygen and water molecules becomes more tortuous. Additionally, the complex system crystallinity could increase if the nFil exerts a nucleating effect, or it could decrease if the nFil prevents and/or inhibits the macromolecules organization in regular crystalline structures [39].…”

Improved mechanical properties and hydrophobicity on wood flour reinforced composites: Incorporation of silica/montmorillonite nanoparticles in polymers

“…Surface modification of the nanoparticles is an effective method to solve this problem and to improve the interactions between particles and polymer matrix . Liu et al used didecyl dimethyl ammonium chloride (DDAC) modified MMT to modify poly(lactic acid) (PLA), and the results showed that organic MMT could uniformly disperse in the PLA with highly exfoliated structures, resulting in improved mechanical properties of the composites. Zhang et al showed that the improved dispersion of silica in polymer matrix contributed to increase the fraction of interphase in presence of the silane, which was interpreted by the much improved accessible surfaces for silanization.…”