Lipase catalyzed synthesis of epoxidized fatty hydrazides from epoxidized palm oil and its application as a clay modifier for polylactic acid/epoxidized palm oil/organoclaynanocomposites

Poly (lactic acid) (PLA) is a biodegradable polymer that has high potential as an alternative material to replace conventional plastics that create many environmental issues. PLA has high tensile strength, low flexibility and degradation rate which limits the scope of applications. Addition of epoxidized palm oil (EPO) reduces the tensile strength but slightly enhances the degradation rate of PLA. This study aims to improve the mechanical properties and degradability of PLA/EPO blend by addition of epoxidized fatty hydrazides modified montmorillonite (EMT). The EMT was prepared by modifying montmorillonite (MMT) with epoxidized fatty hydrazides (EFHs) through an ion exchange process. The EFHs were obtained from an enzymatic reaction of the EPO with hydrazine monohydrate (using a mol ratio of 1 to 12) in n-hexane at 50 °C and shaking speed of 165 rpm for 24 hours. The enzyme used for the reaction was immobilized native Muchor meihei lipase, (NMML) with the concentration in the reaction mixture of 5 %. Response surface methodology (RSM) was used to determine the optimization conditions. The R2 (multiple correlation coefficients) for the reduced model was 89.68 % and lack of fit value of 0.127 (P>0.05) shows that the model is significant with satisfactory lack of fit and can be used to navigate the experiments. Five grams ( 5. 00 g) of EFHs was adequate to produce modified MMT with the highest basal spacing value of2.41 nm, which was determined by x-ray diffraction. Addition of a small amount of the organoclay (EMT) significantly improved the mechanical properties of PLA/EPO and its flexibility. The presence of2 % EMT improves the PLA/EPO tensile strength and modulus ofup to 72.55 % cpid 28 .69 % respectively, and the flexibility increases to 44.30 % from 26 . 71 % by the addition of 3 % of the organoclay. The EFHs, EMT and PLA nanocomposites were characterized by using Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), nuclear magnetic resonance (NMR) and CHNO elemental analysis. In addition, x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to characterize the EMT and PLA nanocomposites. The biodegradability study of the PLA/EPO/EMT organoclay nanocomposites shows that the materials have good biodegradable characteristics with 17.67 % of weight loss after 6 months of burial test period. Scanning electron microscopic study of the partially degraded sample indicates that the sample surface morphology has many holes and rough parts. As a conclusion, EFHs can produced the organoclay which reinforces the mechanical properties, flexibility and degradability of PLA/EPO composites.