Preparation and characterization of the plasticized polylactic acid films produced by the solvent‐casting method for food packaging applications

Abstract

A strategy to overcome the brittleness and rigidity of polylactic acid (PLA)-based materials for food packaging applications is adding a proper plasticizer in the right amount. Here, triacetin (TA) and polyethylene glycol (PEG) were used as plasticizers in different amounts (10, 20, and 30 wt%) to produce the plasticized PLA films by the solvent-casting method. Tensile properties, water vapor permeability (WVP), moisture content (MC), optical properties, Fourier transform infrared absorption (FTIR), and thermogravimetric analysis (TGA) are reported. The results showed that both TA and PEG cause increasing elongation at break (Eab) and decreasing tensile strength (TS), where the plasticized PLA films containing 10 and 30 wt% of TA showed the highest TS (26.6 MPa) and Eab (81.1%), respectively. Light transmission of PLA was decreased by introducing the plasticizers, while WVP, MC, and opacity of the plasticized films were increased compared to the neat PLA. Among the plasticized films, the sample with 10 wt% of TA and PEG showed the lowest WVP (4.9 × 10−10 g/m s−1 Pa−1) and MC (5.5%), respectively. Based on the TGA, an improvement in the thermal stability of TA and PEG plasticized films compared to the neat PLA was obvious. The sample containing 10 wt% of TA (PLA-TA10) showed the best performance for food packaging applications. Practical applications Food product packaging provides retarding deterioration, reducing microbial contamination, preserving safety, protecting quality, and extending the shelf life of packaged foods during transmission, storage, and consumption. Petroleum-based plastic and synthetic polymers have been mainly used in food packaging due to their cheap cost and good mechanical and barrier properties. However, increasing the use of these nonbiodegradable polymers causes serious environmental and health problems. The biopolymers which are extracted from biodegradable and renewable sources are considered as suitable alternatives for petroleum-based plastic materials. However, application of biopolymers as packaging materials has been limited due to their low mechanical properties and thermal stability. Many studies have been conducted to modify the properties of PLA-based packaging materials to create a favorable product for the food industry. Moreover, introducing plasticizer to PLA helps to develop biocomposite materials with unique characteristics for food packaging. This article shows an improvement in the properties of the PLA-based composites for food packaging applications.