Thermo-Mechanical Characterization of Electrospun Polyurethane /Carbon- Nanotubes Nanofibers: A Comparative Study

Abstract

Abstract Creating ultrathin mountable fibers from a wide range of polymeric functional materials have made electrospinning an adequate approach to produce highly flexible and elastic materials. In this paper, electrospinning was utilized to produce thermoplastic polyurethane (TPU) nanofibrous membranes for the purpose of studying their thermal and mechanical properties. Towards a study of the effects of fiber orientation and multi-walled carbon nanotubes (MWCNTs) as a filler on both mechanical and thermal characteristics of electrospun TPU mats, an experimental comparison was held between a unidirectional and randomly aligned TPU and TPU/CNT nanofibrous structures. Incorporation of MWCNTs into randomly oriented TPU nanofibers resulted in a significant increase in Young's modulus (E), from 3.66 MPa to 5.68 MPa. Conversely, for unidirectionally spun fibers, Young's modulus decreased from 16.68 MPa to 11.63 MPa upon addition of MWCNTs. However, dynamic mechanical analysis (DMA) revealed a different behavior. The randomly oriented specimens exhibited a storage modulus with a significant increase from 180 MPa to 614 MPa for TPU and TPU/CNT mats, respectively, and a slight decrease from 157 MPa to 143 MPa for unidirectional TPU and TPU/CNT mats, respectively. Meanwhile, the loss modulus increased with the addition of MWCNTs from 15.7 MPa to 58.9 MPa and from 6.4 MPa to 12 MPa for the random and aligned fibers, respectively. Thermal degradation of the membranes was not significantly affected by the addition of MWCNTs, indicating that the mixing of the two constituents did not change the TPU’s polymer structure, and the TPU/CNT nanocomposite exhibited stable thermal degradation properties.