Modified cellulose nanocrystals enhancement to mechanical properties and water resistance of vegetable oil‐based waterborne polyurethane

Abstract

Environmentally friendly and lightweight silylated cellulose nanocrystal (SCNCs)/waterborne polyurethane (WPU) composite films that exhibit excellent mechanical properties and water resistance were prepared. The cellulose nanocrystals (CNCs) of the filamentous structure were surface-modified by γ-aminopropyltriethoxysilane (APTES) and then introduced into a castor oil-based aqueous polyurethane (WPU) matrix by in situ polymerization. The morphology and silylation degree of CNCs were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier infrared transform spectroscopy at different APTES concentrations. The results showed that the surface of the nanocellulose crystal has the best silylation morphology and thermal stability with incorporation of 6 wt % APTES. The thermal stability, mechanical properties, surface morphology, and water resistance of the nanocomposites were investigated by TGA, tensile test, SEM and optical contact angle, water absorption test, and mechanical property test after immersed in water. It was found that the effective introduction of modified CNCs resulted in a significant increase in tensile strength at high levels, and the thermal stability and hydrophobicity of the material were improved simultaneously, reaching the percolation threshold at a 0.50 wt % SCNCs as determined theoretically. This study provided an approach to the design and development of surface-modified CNCs/vegetable oil-based polymer composites by using an appropriate concentration of silane coupling agent to modify CNCs and improve the compatibility between nanocellulose and vegetable oil-based polymer matrices.

Synthesis and chemical modification of crystalline nanocellulose to reinforce natural rubber composites

“…As a result, MCNC particles are obtained with a nanometric dimension, in the range of 60 to 70 nm (Figure 4B). 37‐39 Consequently, the average aspect ratio of MCNC particles is reduced to 1.21 from 1.79 found for unmodified CNC particles.…”

“…Morphology of the CNC and APTES-modified CNC was examined via field emission electron microscopy (FESEM), and presented in Figure 4B). [38][39][40] Consequently, the average aspect ratio of MCNC particles is reduced to 1.21 from 1.79 found for unmodified CNC particles.…”

Preparation and Properties of Self-Healing Waterborne Polyurethane Based on Dynamic Disulfide Bond

“…Figure 3 are FTIR spectra and XPS survey spectra of the linear WPU-SS samples. In Figure 3 a, all curves have no absorption peak at 2270 cm −1 , which indicates that −NCO groups in the system are all involved in the reaction [ 16 , 17 ]. Compared with the three curves, the distribution of all characteristic peaks was essentially the same, indicating that −OH and −NCO on HEDS reacted to form carbamate, and no new chemical bond was formed.…”

Preparation of cellulose triacetate aerogel via non‐solvent impacted thermally induced phase separation for oil absorption

“…[10] To overcome those issues, many porous sorbents were examined to deal with oil spill and chemical leakage, such as electrospun membrane, [6] nonwoven fabric, [7] aerogel [8] and composite. [11] Those sorbents show excellent hydrophobicity, high specific surface area (SSA) and high oil absorption capacity. Among all sorbents, the aerogel, as one of the lightest solid in the world, has attracted increasing attentions due to three-dimensional structure, large SSA, high pore volumes and controllable surface properties.…”