The influence of multiple modified MMT on the thermal and fire behavior of poly (lactic acid) nanocomposites

Abstract

This work reported the preparation and physical properties of biodegradable nanocomposites fabricated using polylactic acid (PLA) and multiple organic modified montmorillonite (MMT). In order to improve the chemical compatibility between PLA and Na-MMT, the surface of Na-MMT was first organically modified by cetyl trimethyl ammonium bromide (CTAB) and resorcinol bis(diphenyl phosphate) (RDP) using ion-exchange and adsorption technique. Both Fourier transform infrared and X-ray diffraction (XRD) results indicated that CTAB and RDP molecules were intercalated into the galleries of MMT sheets to enlarge the interlayer spacing. Then, the PLA/MMT nanocomposites were prepared by a simple melt-blending method. The XRD and TEM results of the nanocomposites indicated that the PLA polymer chains inserted into the galleries of co-modified MMT (C-MMT) and contained disorderedly intercalated layered silicate layers within a PLA matrix. The C-MMT nanolayers were homogenously dispersed in PLA matrix, resulting in various property enhancement. The fabricated PLA/C-MMT nanocomposites with 5.0 wt% addition showed significant enhancements (176%) in the storage modulus compared to that of neat PLA. The thermal stability and fire resistance were also remarkably improved. These improvements are probably because of both the physical barrier effect of the MMT nanosheets and charring effect of the C-MMT.

Morphology, rheology property, and crystallization behavior of PLLA/OMMT nanocomposites prepared by an innovative eccentric rotor extruder

“…As can be seen in Figure and Table , the primary (001) diffraction peak of neat OMMT is observed at 3.4°, which corresponds to an interlayer spacing of 2.6 nm. In the X‐ray diffraction pattern of PLLA‐1 sample, the (001) characteristic peak of OMMT is smaller than that of neat OMMT and corresponds to an interlayer spacing of 3.6 nm, indicating that OMMT nanoparticles are highly intercalated and exfoliated and the molecular chains of PLLA are successfully inserted and well dispersed in the OMMT galleries . Moreover, with increasing OMMT concentration, the (001) characteristic peak of nanocomposites becomes stronger but the interlayer spacing changes little, which indicates that there is still a finest intercalated and exfoliated structure of OMMT in the high OMMT concentration.…”

“…In the X-ray diffraction pattern of PLLA-1 sample, the (001) characteristic peak of OMMT is smaller than that of neat OMMT and corresponds to an interlayer spacing of 3.6 nm, indicating that OMMT nanoparticles are highly intercalated and exfoliated and the molecular chains of PLLA are successfully inserted and well dispersed in the OMMT galleries. 25 Moreover, with increasing OMMT concentration, the (001) characteristic peak of nanocomposites becomes stronger but the interlayer spacing changes little, which indicates that there is still a finest intercalated and exfoliated structure of OMMT in the high OMMT concentration. The result shows that the ERE has good mixing dispersion effect of promoting the intercalation and exfoliation of OMMT in the preparation of polymer nanocomposites.…”

Enhanced properties of poly(lactic acid) with silica nanoparticles

“…In recent years, polymer/inorganic hybrid nanoparticles are prevail among academic research, which combine the properties of both components and can provide unique and tunable properties. Nano‐sized fillers, such as carbon black and carbon nanotubes were used to modify PLA. Incorporation of nano‐sized particles, especially silica particles, into PLA can improve its melt behavior, mechanical properties, and thermal stability …”

Flame retarded poly(lactic acid): A review

“…This suggested that the migrated NATP on the burning surface was crosslinked by a large amount of char produced via the interaction between RDP and PLA. Liu et al [62] used double modified pristine MMT to improve the fire retardancy of PLA. First the surface of the sodium-MMT was organically modified by cetyl trimethyl ammonium bromide then by resorcinol bis(diphenyl phosphate) via ion-exchange and adsorption, respectively.…”