Investigation of the possibilities of using deep eutectic solvents as plasticizers in polyethylene flexible films

Plastics constitute the most used material group in different sectors, especially packaging materials. It is a technological necessity for plastics, which have many types, to be produced with many additives in order to have the desired properties, depending on the area to be used. These additives are used to gain one or more of many functions. The most commonly used additives are plasticizers, and phthalates are the most used group of them. However, many of the phthalates have negative effects on human health and the environment. The use of many types and amounts of phthalates, especially food packaging materials, has been restricted by legal regulations. This situation has increased the interest in natural-based alternative plasticizers that do not have negative effects on human health and the environment. With this master thesis, it is aimed to investigate the changes in the properties of low density polyethylene (LDPE) food packaging films by using natural and biodegradable plasticizers instead of artificial plasticizers. For this purpose, choline chloride (C) as hydrogen bond acceptor (HBA) and lactic acid (L), urea (U), hexanoic acid (H) and pentanoic acid (P) as hydrogen bond donor (HBD) in 2 different molar ratios (1 :1 and 1:2) were mixed at 80°C and deep eutectic solutions (DES) were prepared. These were characterized by performing some basic analyzes (density, viscosity, pH, volatility, molecular structure and thermal). Afterwards, these prepared DES were added to LDPE in two different ratios (10 and 30%) in the extruder and mixed to produce films. Likewise, films without plasticizer (negative control-NC) and containing di-2-ethylhexylphthalate (DEHP) as artificial plasticizer (positive control-PC) were produced. These films were characterized by performing some physical, mechanical, barrier, migration, thermal and spectroscopic analyzes. Densities of DES's were found to be 0.95-1.18 g/ml, viscosities of 18.6-194.3 mPa.s, pH values of 0.05-9.02 and volatility between 0.7-18.9%. For LDPE films with no additives, DES and DEHP additives, the thickness is 0.09-0.39 mm, tensile strength (TS) 7.0-13.4 MPa, elongation at break (EAB) 99-545%, puncture force (PF) 2, 7-51.1 N, puncture distance (PD) 5.2-10.3 mm, water vapor permeability (WVP) 0.009-0.248 g/m2.h.kPa, moisture 0.07-1.92%, solubility in water (SW) 0-2.3%, water holding capacity 0-2%, color values L* 66-91, a* -2.1- -0.7, b* 3.5-14.9, ∆E 1.4-29.9, transparency 0.4-3.6, thermal adhesion 3.3-13.4 N, overall migration LOD-82.6 mg/dm². According to these results; DES added films with better mechanical, barrier and migration properties compared to PC films were obtained. It has been determined by the study that DES's can be used as a natural and biodegradable option in flexible food packaging with the ability to create an alternative to plasticizers with artificial and negative properties such as phthalates.