Shape-memory composites based on linear segmented polyurethanes with cellulose nanocrystals. comparison between films and mats

GATTI, GIANLUCA; ESTENOZ, DIANA; HORMAIZTEGUI, M.E. VICTORIA; FOCARETE, LETIZIA; POLO, MARA ; ARANGUREN, MIRTA I.

Buenos Aires

Simposio; XIII Simposio Argentino de Polímeros; 2019

Linear Segmented Thermoplastic Polyurethanes are multi-block copolymers with typical morphologies consisting of hard microphases dispersed in soft rubber matrixes. (Polo, 2017) The presence of these two separated molecular phases is the basis for considering these polymers as shape memory polyurethanes (SMPUs). SMPUs are able to change their shape through the application of external stimuli, such as temperature or pH. (Nicharat, 2017) The hard segments (composed by sequences of diisocyanate and chain extender) act as physical crosslinks and define the permanent shape. The soft segments (composed of glassy and crystalline macrodiol sequences) act as the switching segments and fix the temporary shape. The formation of nanocomposites by introducing nanoparticles is an interesting approach to modify the final properties of SMPUs. (Nicharat, 2017) Cellulose nanocrystals (CNC) are natural fibres that have been used as bio reinforcement in SMPUs. (Nicharat, 2017) The concentration of CNC influences the properties of these composites. This work presents preliminary studies focused on investigating the effect of two different methodologies of incorporation of CNC on the PU.On the order hand, the second objective of this work is to formulate electrospinned mats from SMPU and composites with CNC, and compare the performance with the films obtained by casting.