Shape memory polyurethanes reinforced with carbon nanotubes

• Published in: Composite structures 2013-05, Vol.99, p.105-111
• Main Authors: Fonseca, M.A., Abreu, B., Gonçalves, F.A.M.M., Ferreira, A.G.M., Moreira, R.A.S., Oliveira, M.S.A.
• Format: Article
• Language: English
• Subjects: Composites; In situ polymerization; Melt mixing; SMPU/CNT
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2012.11.029

New shape-memory materials (SMMs) for applications in active control and morphing structures have been attracting special attention due to its unique properties. These SMM can be metallic alloys (SMAs), piezoelectric, and polymers such as polyurethanes (SMPUs). The latter detain higher recovery rates but better processability, however, the reaction time is longer when compared with the SMA. The addition of carbon nanotubes (CNTs) to SMPU seems to improve its overall properties with a great deal of potential in what concerns improved shape memory. There are two main techniques to attain SMPU/CNts nanocomposites: in situ polymerization and mechanical melt mixing. The study here presented establishes a comparison between these two techniques. To assess the suitability of the latter a rather extensive characterization was carried out. The homogeneity of the CNTs dispersion into the polymer matrix was established through SEM and the thermal characterization has shown a rise in the glass transition temperature consistent with CNT loading. Furthermore, shape memory seems to improve with the nanoparticle reinforcement. Within the two processing techniques it could be referred that melt processing seems to be simpler to use with better laboratory repeatability, thus detaining a greater potential should nanocomposite tailoring at a larger scale be envisaged.