On the evaluation of viscoelastic response of aged PLA/bagasse bio-composites

This paper focuses on the re-use of original data of an available study about PLA bio-composites. New focus, regarding the discussion of the viscoelastic curves, in terms of structure vs. property relationships, followed by a correlation on the mechanical, structural and morphological characteristics were made. Response surface methodology (RSM) was carried out to describe the interaction between the storage and loss moduli as a function of bio-composite exposure conditions and thermal cycles. It was proved, using some considerations, that the effective restriction in the molecular motion of the amorphous polymer chains, imposed by the natural fibers, is given mainly at the elastomeric region. Furthermore, the microcavities at the interface minimize the fiber-matrix stress transfer, while the higher chains proximity promotes lower free volume and a higher molecular restriction. The width of relaxation curves seems to be higher for the aged bio-composites, indicating that a more heterogeneous relaxation process occurs in a broader temperature range. Storage modulus curves were predicted by RSM and it enabled the generation of a single prediction equation with high reliability. On the other hand, due to the greater complexity of the loss modulus, the curves were divided into two parts, aiming to ensure reliability and linearity coefficient.