Thermal characterization and lifetime prediction of the PHBV/nanocellulose biocomposites using different kinetic approaches

In the present study, biocomposite films from cellulose nanocrystals (CNCs) were obtained by the solution casting method. CNCs were isolated from pineapple crown using chemical treatments followed by sulfuric acid hydrolysis and added into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrix. The effect of freeze-dried CNC content (1, 3, and 5 wt%) on the structural, crystallization, thermal degradation lifetime prediction, and thermogravimetric simulation was investigated. An irreversible agglomeration observed after freeze-dried provided changes in the morphology and size of CNCs. Addition up to 3 wt% of CNCs increased the thermal stability, crystallization rate, and crystallinity index of PHBV, as showed by thermal and crystallinity analysis, respectively. The kinetic degradation study by thermogravimetric analysis (TGA) was done using the F-test method by statistically comparing degradation mechanisms in the solid-state. The most probable degradation mechanism was the autocatalytic reaction model for all samples (represented by Cn and Bna-types) with a suitable adjustment of the simulated curves. Lifetime prediction showed to be successfully applied based on the kinetic analysis, and PHBV reinforced with 3 wt% of CNCs presents the highest results for the isothermal temperature of 180 °C.