title: Degradability enhancement of poly(lactic acid) by stearate-Zn(3)Al LDH nanolayers.
abstract: Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn(3)Al LDH. A solution casting method was used to prepare PLA/stearate-Zn(3)Al LDH nanocomposites. The anionic clay Zn(3)Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn(3)Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn(3)Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn(3)Al LDH nanocomposites showed that the presence of around 1.0-3.0 wt % of the stearate-Zn(3)Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn(3)Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA.
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia.
authors.forename: Mahboobeh
authors.initials: M
authors.lastname: Eili
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Shameli
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia.
authors.forename: Nor Azowa
authors.initials: NA
authors.lastname: Ibrahim
authors.affiliation: Department of Chemistry, Centre for Defence Foundation Studies, National Defence University of Malaysia, Kuala Lumpur 57000, Malaysia.
authors.forename: Wan Md Zin
authors.initials: WMZ
authors.lastname: Wan Yunus
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D055119:Elastic Modulus; D052918:Environmental Restoration and Remediation; D004800:Enzymes, Immobilized / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry*; D019344:Lactic Acid / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D013228:Stearates / Q000737:chemistry*; D013718:Tensile Strength; D013818:Thermogravimetry; D014961:X-Ray Diffraction; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D004800:Enzymes, Immobilized; D006878:Hydroxides; D009566:Nitrates; D011091:Polyesters; D011108:Polymers; D013228:Stearates; D017967:Zinc Compounds; D019344:Lactic Acid; C033616:poly(lactide); C042103:zinc nitrate; C050609:aluminum nitrate