Ice-Templated Cellulose Nanofiber Filaments as a Reinforcement Material in Epoxy Composites

Abstract

Finding renewable alternatives to the commonly used reinforcement materials in composites is attracting a significant amount of research interest. Nanocellulose is a promising candidate owing to its wide availability and favorable properties such as high Young’s modulus. This study addressed the major problems inherent to cellulose nanocomposites, namely, controlling the fiber structure and obtaining a sufficient interfacial adhesion between nanocellulose and a non-hydrophilic matrix. Unidirectionally aligned cellulose nanofiber filament mats were obtained via ice-templating, and chemical vapor deposition was used to cover the filament surfaces with an aminosilane before impregnating the mats with a bio-epoxy resin. The process resulted in cellulose nanocomposites with an oriented structure and a strong fiber–matrix interface. Diffuse reflectance infrared Fourier transform and X-ray photoelectron spectroscopy studies revealed the presence of silane on the filaments. The improved interface, resulting from the surface treatment, was observable in electron microscopy images and was further confirmed by the significant increase in the tan delta peak temperature. The storage modulus of the matrix could be improved up to 2.5-fold with 18 wt% filament content and was significantly higher in the filament direction. Wide-angle X-ray scattering was used to study the orientation of cellulose nanofibers in the filament mats and the composites, and the corresponding orientation indices were 0.6 and 0.53, respectively, indicating a significant level of alignment.

X-ray in-line holography and holotomography at the NanoMAX beamline

“…Among the beamlines that exploit the unique brilliance of MAX IV, NanoMAX (Johansson et al, ISSN 1600-5775 2021) is a hard X-ray beamline with focusing capabilities down to the nanometre scale. Due to its focusing capabilities and high coherent flux, NanoMAX is used for a combination of scanning techniques, such as X-ray fluorescence (Arai et al, 2006;Silva Barreto et al, 2020), X-ray diffraction (Warren, 1969;Bjo ¨rling et al, 2019), and scattering techniques (Birkholz et al, 2005;Nissila ¨et al, 2021). Other techniques implemented at NanoMAX that exploit its unique capabilities are coherent X-ray imaging techniques, such as ptychography (Pfeiffer, 2018) and coherent diffraction imaging (Chapman & Nugent, 2010).…”

NanoMAX: the hard X-ray nanoprobe beamline at the MAX IV Laboratory

“…The main categories of methods regularly used are CDI in forward and Bragg geometries, nano-diffraction in both geometries, and 2D XRF and X-ray absorption near-edge structure spectroscopy (XANES) imaging. Examples of experiments performed are diffraction and strain mapping of nano-wires (Chayanun et al, 2019;Hammarberg et al, 2020;Dzhigaev et al, 2020;Marçal et al, 2020); single nano-particle coherent Bragg imaging (Bjö rling et al, 2019(Bjö rling et al, , 2020bDzhigaev et al, 2021); extreme pressure nano-diffraction (Ji et al, 2020); ptychographic tomography (Kahnt et al, 2020); 2D XRF imaging of plant, animal and human cells (Silva Barreto et al, 2020); nano-diffraction (Nissilä et al, 2021); and X-ray technology development (Akan et al, 2020;Chayanun et al, 2020). The tomography endstation, based on Fresnel zone plate (FZP) optics, is currently under development.…”

Advanced Nanocellulose-Based Materials: Production, Properties, and Applications

“…This Special Issue of Nanomaterials entitled Advanced Nanocellulose-Based Materials: Production, Properties, and Applications, brings together a compilation of original research and review contributions from world-leading scientists working with nanocellulose. Hence, this Special Issue contains a collection of one review paper about the characterization of cellulose nanomaterials [8] and eight research papers focused on the use of BNC [9][10][11], CNFs [12][13][14][15], and CNCs [16] as reinforcements in composites [13][14][15] and to produce ion-exchange membranes for fuel cells [9], patches for tissue engineering and wound healing [10,11], and nanosystems or nanocarriers for cancer treatment [15,16].…”

“…Another original work was reported by Nissilä et al [13], who investigated the use of ice-templated CNF filaments as a reinforcement material in epoxy resin-based composites. The authors successfully manufactured cellulose nanocomposites with an oriented structure and a strong fiber-matrix interface by preparing unidirectionally aligned CNF-filament mats via ice-templating followed by chemical vapor deposition to obtain silane-treated CNF filaments.…”

“…The authors successfully manufactured cellulose nanocomposites with an oriented structure and a strong fiber-matrix interface by preparing unidirectionally aligned CNF-filament mats via ice-templating followed by chemical vapor deposition to obtain silane-treated CNF filaments. The impregnation of these mats with a bio-epoxy resin through vacuum infusion originated composites with 18 wt.% fiber content oriented along the freezing direction of the ice crystals, which translated into composite materials with improved mechanical performance (storage modulus) up to 2.5-fold [13].…”