Triethyl Citrate: Applications in Boosting PLA/Chitin Nanocomposites and its Toxicity Summary

General Description

Triethyl citrate, a colorless oily liquid, is an effective plasticizer utilized in the development of polylactic acid (PLA) and chitin nanocomposites. It enhances the dispersion of chitin within the PLA matrix, improving optical transparency and mechanical properties, particularly at a concentration of 7.5 weight percent. Besides its application in nanocomposites, triethyl citrate is used as a solvent, softener, and food additive, raising safety considerations. While human studies show low irritation potential, animal tests indicate varied toxicity responses, with some signs of sensitivity and irritation, underscoring the need for careful evaluation of its biological effects.

Figure 1. Triethyl citrate

Applications in Boosting PLA/Chitin Nanocomposites

Triethyl Citrate as a Plasticizer in Nanocomposite Processing

Triethyl citrate, an effective plasticizer, has shown significant potential in the development of polylactic acid (PLA) and chitin nanocrystal (ChNC) nanocomposites. In the study of PLA/ChNC nanocomposites prepared through liquid-assisted extrusion, triethyl citrate was used at various concentrations (2.5, 5.0, and 7.5 weight percent) to enhance the dispersion of chitin nanocrystals within the PLA matrix. The addition of triethyl citrate facilitated improved distribution and uniformity of ChNC, as demonstrated by microscopy studies. The optimal concentration of triethyl citrate was found to be 7.5 weight percent, which yielded the most significant enhancement in the optical transparency and overall thermal and mechanical properties of the nanocomposites compared to those without triethyl citrate. ¹

Impact on Nanocomposite Properties

The integration of triethyl citrate into the PLA/ChNC nanocomposites led to notable improvements in various properties. Specifically, the nanocomposites containing 7.5 weight percent of triethyl citrate exhibited superior mechanical, thermal, and thermo-mechanical attributes. Fourier transform infrared spectroscopy revealed that the presence of triethyl citrate enhanced the interaction between PLA and ChNC through hydrogen bonding. This improvement in interaction is crucial for achieving enhanced material properties and functionality. The gel permeation chromatography analysis confirmed that the extrusion process, including the use of water and ethanol, did not adversely affect the molecular weight of PLA, ensuring that the integrity of the polymer was maintained during processing. ¹

Advantages of Triethyl Citrate in Extrusion Processes

Triethyl citrate proves to be a valuable dispersing aid in the production of PLA/ChNC nanocomposites through liquid-assisted extrusion. The study highlights that triethyl citrate not only improves the dispersion and distribution of chitin nanocrystals but also contributes to the overall enhancement of the nanocomposite properties. The facile and effective use of triethyl citrate in the extrusion process paves the way for scalable production of bio-based nanocomposites. Future research could explore the effects of higher triethyl citrate concentrations to further optimize the balance between dispersing efficacy and material properties. Overall, triethyl citrate stands out as a key additive for advancing the development and large-scale production of high-performance bionanocomposites. ¹

Toxicity Summary

Identification and Uses

Triethyl citrate is a colorless, oily liquid characterized by its bitter taste. This compound is primarily used as a solvent and plasticizer for materials such as nitrocellulose and natural resins. Additionally, triethyl citrate serves as a softener, paint remover, agglutinant, and perfume base. It also functions as a food additive, permitted at concentrations not exceeding 0.25%, where it acts as an emulsifier and flavor-preserving agent. Despite its widespread use in various applications, the safety and toxicity of triethyl citrate remain important considerations for both consumers and manufacturers.

Human Exposure and Animal Studies

Research on human exposure to triethyl citrate indicates that a 20% formulation in petrolatum does not act as a primary irritant or sensitizer. However, animal studies reveal varied responses to triethyl citrate. In one guinea pig maximization test, undiluted triethyl citrate demonstrated strong sensitizing effects. Additionally, a concentration of 33.3% caused irritation in rabbit eyes. Intravenous administration of triethyl citrate at a dosage of 100 mg/kg body weight significantly increased motor activity and respiration in rabbits. A study involving mice showed that daily intraperitoneal doses of 350 mg/kg body weight of triethyl citrate over 14 days led to a slight reduction in growth rate, though there were no significant changes in erythrocyte or leukocyte counts. Toxicological evaluations, including an Ames test with Salmonella typhimurium, confirmed that triethyl citrate is negative for mutagenicity in both activated and non-activated conditions. Overall, triethyl citrate demonstrates a complex profile of biological effects requiring careful evaluation in various contexts. ²

1. Herrera N, Singh AA, Salaberria AM, Labidi J, Mathew AP, Oksman K. Triethyl Citrate (TEC) as a Dispersing Aid in Polylactic Acid/Chitin Nanocomposites Prepared via Liquid-Assisted Extrusion. Polymers (Basel). 2017; 9(9): 406.

2. National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 6506, Triethyl citrate.

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