Permeabilidade ao vapor de água em diferentes temperaturas e matrizes (bio)poliméricas com base na ASTM E96-00: 1ª lei de Fick, princípios de sorção e lei de Henry

Abstract

Food packaging has an important protective barrier function against water vapor. ASTM E-96 is the standard that determines the analysis of water vapor permeability rate, which occurs under specific humidity and temperature conditions. In this work, the present study aimed to study the application of Fick's 1st law, Henry's Law and the Principles of Sorption in the water vapor barrier property of different polymeric and biopolymeric films, according to ASTM E-96-00, applying different temperatures, proposing an adaptation of the methodology. Different biopolymeric films were used, with different polymer matrices, reinforcing agents and blends. The film samples had 30 mm disc formats and values obtained for thickness. The analysis took place using the desiccant method, in which the samples were placed in permeation cells, followed by gravimetric reading in a desiccator with air circulation with a relative humidity of 40%. The water vapor permeability study was carried out under different temperatures, controlled with air conditioning (25 ± 1 °C) and at room temperature (uncontrolled, with an average of 32 ± 1 °C), in two stages: in the 1, the films were analyzed regarding Fick's 1st Law, and in step 2, the films were studied regarding temperature variation in mathematical modeling. All readings were carried out on an analytical balance in quintuplicates with 8 readings until reaching at least 24 hours. The results were analyzed by one-way variance study (ANOVA) and the Tukey method. Films in an uncontrolled environment showed lower permeability values compared to the controlled environment. In the mathematical projection, significant differences were observed in all films in relation to the extremes of 25 °C and 32 °C. The results obtained in the work indicate that studies of the impacts of Fick's 1st Law, Henry's Law and Principles of Sorption presented promising answers in improving the mathematical and chemical understanding of the behavior of films and the temperature condition will depend on their purpose as packaging. foods.