title: New nanocomposite materials reinforced with flax cellulose nanocrystals in waterborne polyurethane.
abstract: New nanocomposite films were prepared from a suspension of cellulose nanocrystals as the filler and a polycaprolactone-based waterborne polyurethane (WPU) as the matrix. The cellulose nanocrystals, prepared by acid hydrolysis of flax fiber, consisted of slender rods with an average length of 327 +/- 108 nm and diameter of 21 +/- 7 nm, respectively. After the two aqueous suspensions were mixed homogeneously, the nanocomposite films were obtained by casting and evaporating. The morphology, thermal behavior, and mechanical properties of the films were investigated by means of attenuated total reflection Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and tensile testing. The results indicated that the cellulose nanocrystals could disperse in the WPU uniformly and resulted in an improvement of microphase separation between the soft and hard segments of the WPU matrix. The films showed a significant increase in Young's modulus and tensile strength from 0.51 to 344 MPa and 4.27 to 14.86 MPa, respectively, with increasing filler content from 0 to 30 wt %. Of note is that the Young's modulus increased exponentially with the filler up to a content of 10 wt %. The synergistic interaction between fillers and between the filler and WPU matrix played an important role in reinforcing the nanocomposites. The superior properties of the new nanocomposite materials could have great potential applications.
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Cao
authors.forename: Hua
authors.initials: H
authors.lastname: Dong
authors.forename: Chang Ming
authors.initials: CM
authors.lastname: Li
mesh_terms: D002151:Calorimetry; D002152:Calorimetry, Differential Scanning; D002482:Cellulose / Q000737:chemistry*; D046911:Macromolecular Substances; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D011140:Polyurethanes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D046911:Macromolecular Substances; D011140:Polyurethanes; D014867:Water; D002482:Cellulose