Use of deep eutectic solvents based on choline chloride, urea, and lactic acid as plasticizers in low-density polyethylene films

Abstract

This study aims to investigate the performance of deep eutectic solvents (DESs) as plasticizers in low-density polyethylene (LDPE) films and to compare them with di(2-ethylhexyl) phthalate (DEHP). DESs were produced by mixing choline chloride with lactic acid and urea in 1:1 and 1:2 molar ratios. The prepared DESs were added to LDPE at two different ratios (10% and 30%), and films with 10 different compositions were produced by the extrusion method. The densities, viscosities, pH, volatility, and thermal values of the produced DESs were determined between 1.14 and 1.18 g/cm3, 22 and 99 mPa.s, 0.05 and 9.02, 0.7% and 18.9%, and <-70 and 63 degrees C, respectively. When the DESs were examined in terms of their bond structure, it was observed that they could be produced successfully. The LDPE films with DES were characterized by thickness, mechanical, barrier, optical, DSC, FTIR, SEM, water behavior properties, heat sealability, and overall migration (OM) properties. According to the results of some basic analyses performed on the films, the first three films with the best properties (CL1:30, CL2:30, and DEHP:30) were determined using TOPSIS from the multi-criteria decision hierarchy techniques. It was determined that the DES films with the most suitable properties had better properties than the control and DEHP films in terms of tensile strength (10-12 MPa), elongation at break (500%-545%), water vapor permeance (0.03-0.04 g/m2/h/kPa), and oxygen transmission rate (13-14 cm3/m2/day), water contact angle (>99 degrees), and UV light barrier analyses. DES did not cause any change in the DSC and OM values of LDPE films. In general, important results were obtained regarding the use of DES as effective plasticizers in LDPE films.