**2. Materials and Methods**

#### **2. Materials and Methods**  *2.1. Materials and Sample Preparation*

*2.1. Materials and Sample Preparation*  Poly(lactic acid) (PLA) with a commercial grade 2003D was supplied by Nature-Works LLC (Minnetonka, MN, USA). Its density was 1.24 g cm−3, with an approximate molecular weight of 120,000 g·mol−1. The base of the plasticizer was chia oil extracted through cold pressing extraction using a CZR-309 press machine (Changyouxin Trading Co., Zhucheng, China) from edible chia seed (*Salvia hispanica, L.*) supplied by Frutoseco (Bigastro, Alicante, Spain). The oil was characterized by a density of 0.928 g cm−3 at 25 °C and iodine value of 197. Epoxidation process was carried out in situ with hydrogen peroxide (30% *v/v*), acetic acid (99.7%), and sulfuric acid (97%) supplied by Sigma Aldrich (Sigma Aldrich, Madrid, Spain). Epoxidized chia seed oil (ECO) presented an epoxy content of 6.71%, equivalent to 238 EEW (Equivalent Epoxy Weight). This value was obtained Poly(lactic acid) (PLA) with a commercial grade 2003D was supplied by NatureWorks LLC (Minnetonka, MN, USA). Its density was 1.24 g·cm−<sup>3</sup> , with an approximate molecular weight of 120,000 g·mol−<sup>1</sup> . The base of the plasticizer was chia oil extracted through cold pressing extraction using a CZR-309 press machine (Changyouxin Trading Co., Zhucheng, China) from edible chia seed (*Salvia hispanica*, L.) supplied by Frutoseco (Bigastro, Alicante, Spain). The oil was characterized by a density of 0.928 g cm−<sup>3</sup> at 25 ◦C and iodine value of 197. Epoxidation process was carried out in situ with hydrogen peroxide (30% *v/v*), acetic acid (99.7%), and sulfuric acid (97%) supplied by Sigma Aldrich (Sigma Aldrich, Madrid, Spain). Epoxidized chia seed oil (ECO) presented an epoxy content of 6.71%, equivalent to 238 EEW (Equivalent Epoxy Weight). This value was obtained following the guidelines of the ASTM D1652–97. ECO presented an iodine value of 25 and density of 1.026 g·cm−<sup>3</sup> at 25 ◦C, which made it suitable to be used as plasticizer.

following the guidelines of the ASTM D1652–97. ECO presented an iodine value of 25 and density of 1.026 g·cm−3 at 25 °C, which made it suitable to be used as plasticizer. In the first stage, PLA pellets were dried at 60 °C for 24 h to remove moisture. After this, PLA pellets and ECO were weighed according to the compositions indicated in Table 1. Percentages of ECO were selected, taking into account published articles that consider that more than 10% of oil shows signs of plasticizer saturation [35–37]. All the five compositions selected were extruded at constant speed (40 rpm) using a twin-screw co-rotating extruder from DUPRA S.L (Castalla, Alicante, Spain) with the following temperature profiles: 162.5 (feeding zone), 165, 170, and 175 °C (die). After extrusion, samples were aircooled to room temperature, pelletized, and dried again at 60 °C for 24 h for further processing by injection. Each composition was shaped by injected molding using a Meteor 270/75 from Mateu & Solé (Barcelona, Spain) at temperature profiles of 170, 180, 190, and In the first stage, PLA pellets were dried at 60 ◦C for 24 h to remove moisture. After this, PLA pellets and ECO were weighed according to the compositions indicated in Table 1. Percentages of ECO were selected, taking into account published articles that consider that more than 10% of oil shows signs of plasticizer saturation [35–37]. All the five compositions selected were extruded at constant speed (40 rpm) using a twin-screw co-rotating extruder from DUPRA S.L (Castalla, Alicante, Spain) with the following temperature profiles: 162.5 (feeding zone), 165, 170, and 175 ◦C (die). After extrusion, samples were air-cooled to room temperature, pelletized, and dried again at 60 ◦C for 24 h for further processing by injection. Each composition was shaped by injected molding using a Meteor 270/75 from Mateu & Solé (Barcelona, Spain) at temperature profiles of 170, 180, 190, and 200 ◦C from feed section to injection nozzle. Cavity filling time was 1 s and the cooling time was set to 10 s.

200 °C from feed section to injection nozzle. Cavity filling time was 1 s and the cooling

time was set to 10 s.


**Table 1.** Composition of ECO plasticized PLA materials and labelling.
