Sanches, Alex Otavio [UNESP]Siliano Ricco, Luciano Henrique [UNESP]Malmonge, Luiz Francisco [UNESP]Silva, Michael Jones da [UNESP]Sakamoto, Walter Katsumi [UNESP]Malmonge, Jose Antonio [UNESP]2015-03-182015-03-182014-12-01Polymer Testing. Oxford: Elsevier Sci Ltd, v. 40, p. 99-105, 2014.0142-9418http://hdl.handle.net/11449/116716Cellulose nanofibrils (CNFs) were prepared by sulfuric acid hydrolysis from cotton microfibers, and used to prepare polyurethane (PU) nanocomposites by mixing CNFs and PU water suspensions. CNFs as nanofillers improved the tensile strength of PU significantly up to 10 wt% content. With an increase in the CNF content, the glass transition temperature of PU and the temperature onset of the soft segment increased compared with those of neat PU. However, the crystalline phase present in soft domains and its melting temperature decreased. The influences of humidity on the mechanical properties of PU/CNF nanacomposites were also investigated. The tensile strength at different elongations of PU/CNF nanocomposites decreased substantially after being exposed to 60% relative humidity for 24 h; for 10 wt% loading, the tensile strength at 500% dropped from 10.64 to 2.34 MPa. This behavior was attributed to the formation of hydrogen bonds of PU and CNFs with water. (C) 2014 Elsevier Ltd. All rights reserved.99-105engParticle-reinforcementCellulose nanofibrilsNanocompositePolyurethaneArtigo10.1016/j.polymertesting.2014.08.013WOS:000345541800014Acesso restrito10168699749881900896348165708140101686997498819085332954580569550000-0002-2971-1696