Effect of Cellulose Nanofibrils and TEMPO-mediated Oxidized Cellulose Nanofibrils on the Physical and Mechanical Properties of Poly(vinylidene fluoride)/Cellulose Nanofibril Composites

Abstract

Cellulose nanofibrils (CNFs) are high aspect ratio, natural nanomaterials with high mechanical strength-to-weight ratio and promising reinforcing dopants in polymer nanocomposites. In this study, we used CNFs and oxidized CNFs (TOCNFs), prepared by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation process, as reinforcing agents in poly(vinylidene fluoride) (PVDF). Using high-shear mixing and doctor blade casting, we prepared free-standing composite films loaded with up to 5 wt % cellulose nanofibrils. For our processing conditions, all CNF/PVDF and TOCNF/PVDF films remain in the same crystalline phase as neat PVDF. In the as-prepared composites, the addition of CNFs on average increases crystallinity, whereas TOCNFs reduces it. Further, addition of CNFs and TOCNFs influences properties such as surface wettability, as well as thermal and mechanical behaviors of the composites. When compared to neat PVDF, the thermal stability of the composites is reduced. With regards to bulk mechanical properties, addition of CNFs or TOCNFs, generally reduces the tensile properties of the composites. However, a small increase (~18%) in the tensile modulus was observed for the 1 wt % TOCNF/PVDF composite. Surface mechanical properties, obtained from nanoindentation, show that the composites have enhanced performance. For the 5 wt % CNF/PVDF composite, the reduced modulus and hardness increased by ~52% and ~22%, whereas for the 3 wt % TOCNF/PVDF sample, the increase was ~23% and ~25% respectively.

Surface modified microfibrillated cellulose‐poly(vinylidene fluoride) composites: β‐phase formation, viscoelastic and dielectric performance

“…Pure PVDF reveals a dense and smooth fracture surface with scattered spherulites, 55 whereas the fracture surface of the composites appears to be rougher and is also porous. The porosity could be due to the vapor‐induced phase separation in PVDF in the presence of cellulose‐bound water 56 . It is also clear that aggregates of MFC and F‐MFC formed within the matrix (red circles in (b') and (c')), in contrast to A‐MFC fibers that were well dispersed (yellow circles in (d')).…”

Nanocellulose Based Filtration Membrane in Industrial Waste Water Treatment: A Review

“…CNF is obtained by separating microfibrils (bundles) in animal and plant fibers through mechanical shearing or chemical oxidation. The more mature process is chemical-mechanical combined treatment [ 24 ]. CNC is a nanometer-sized cellulose crystal produced by hydrolysis of cellulose, and an aqueous CNC suspension is usually produced by acid hydrolysis ( Figure 1 ).…”

Liquid crystal behavior of cellulose nanoparticles‐ethyl cellulose composites: Preparation, characterization, and rheology

“…47 The obtained CNPs were characterized by rod-shaped nanoscale entities 5-20 nm in diameter and hundreds or thousands of nm in length. 21,48 Many approaches were reported to extract CNPs, for example, mechanical treatment, 49 acid hydrolysis, [50][51][52] TEMPO-mediated oxidation, [53][54][55] enzymatic hydrolysis, 56,57 sono-chemical assisted hydrolysis, [58][59] and ammonium persulfate (APS) that produce functionalized nanoparticles with carboxylated group. [60][61][62][63] This work was done for assessing the role of approach used to produce CNPs on LC behavior of produced EC-CNPs composite.…”