LDPE:PLA and LDPE:PLA:OMMT polymer composites: Preparation, characterization, and its biodegradation using Bacillus species isolated from dumping yard

Abstract

AbstractThe focus of the present research is on the biodegradation of low density polyethylene (LDPE):polylactic acid (PLA) and LDPE:PLA:organo modified montmorillonite (OMMT) polymer nanocomposites. PLA was synthesized using the polycondensation method. The surface modification of nanomaterials is affected by various factors such as modifying agent, dispersion medium, and the dispersion of nanoparticles. Ultrasound cavitation technique improves the better dispersion of MMT in reaction mixture and enhances the interaction rate of a modifying agent with clay layered structure. A mixture of aminopropyltriethoxysilane and octadecyl amine was used for the surface modification of MMT. Polymer nanocomposite was prepared using the melt mixing method and used further for the biodegradation study. The mesophilic bacterium isolated from the dumping yard, identified by the 16rRNA technique, was capable of biodegradation of LDPE:PLA and LDPE:PLA:OMMT polymer nanocomposites. Isolated bacterial AP1 is 96.05% identical to the current MCCC1A02146 strain of Bacillus albus. After 50 days of incubation, the polymer nanocomposite sheet was characterized using Fourier transform infrared, X‐ray powder diffractometer, UV–Visible spectroscopy, Field Emission Scanning Electron Microscope (FESEM), etc. Further, LDPE:PLA30% (17.5%) and LDPE:PLA30%:OMMT4.5phr (19.20%), shows maximum percentage degradation. It has been observed that the addition of OMMT contributes to an enhancement in the polymer nanocomposite degradation because it has a large d‐spacing gap that is (21 Å) that enables the water to penetrate in the polymer matrix and increases the growth of bacteria within the polymer matrix. The highest change in biomass and change in extracellular protein content was found to be (39.11 mg/L and OD 0.38) LDPE:PLA30%:OMMT4.5phr composites. In addition, the mechanical properties decrease effectively after the incubation period, for LDPE:PLA 30% and LDPE:PLA30%:OMMT4.5phr.