Cellulose Nanocrystals vs. Cellulose Nanofibers: A Comparative Study of Reinforcing Effects in UV-Cured Vegetable Oil Nanocomposites

Abstract

There is an opportunity to use nanocellulose as an efficient renewable reinforcing filler for polymer composites. There have been many investigations to prove the reinforcement concept of different nanocellulose sources for thermoplastic and thermoset polymers. The present comparative study highlighted the beneficial effects of selecting cellulose nanofibers (CNFs) and nanocrystals (CNCs) on the exploitation properties of vegetable oil-based thermoset composite materials—thermal, thermomechanical, and structural characteristics. The proposed UV-light-curable resin consists of an acrylated epoxidized soybean oil polymer matrix and two different nanocellulose reinforcements. High loadings of up to 30 wt% of CNFs and CNCs in irradiation-cured vegetable oil-based thermoset composites were reported. Infrared spectroscopy analysis indicated developed hydrogen-bonding interactions between the nanocellulose and polymer matrix. CNCs yielded a homogeneous nanocrystal dispersion, while CNFs revealed a nanofiber agglomeration in the polymer matrix, as shown by scanning electron microscopy. Thermal degradation showed that nanocellulose reduced the maximum degradation temperature by 5 °C for the 30 wt% CNC and CNF nanocomposites. Above the glass transition temperature at 80 °C, the storage modulus values increased 6-fold and 2-fold for the 30 wt% CNC and CNF nanocomposites, respectively. In addition, the achieved reinforcement efficiency factor r value for CNCs was 8.7, which was significantly higher than that of CNFs of 2.2. The obtained nanocomposites with enhanced properties show great potential for applications such as UV-light-processed coatings, adhesives, and additive manufacturing inks.

Vat Photopolymerization of Nanocellulose-Reinforced Vegetable Oil-Based Resins: Synergy in Morphology and Functionalization

“…In the glassy state, the matrix properties more strongly determine the achieved storage modulus, whereas a transition to a viscoelastic state yields a significant increase in values over the unfilled VO as the reinforcement begins to bear the load. 26,50 Figure 5 Figure 5b shows the changes in loss modulus values after adding nanocellulose fillers. For all composites except VO/ NFA, the loss modulus peak became narrower and weaker as compared to the pure VO.…”

Tunable Hydrophobic Octadienyl-Ether Nanocelluloses by In Situ Ultrasonication for Reinforced Polymers and Water-Resistant Paper

“…The inherent incompatibility of CNC with natural , or synthetic rubber was overcome by surface modification with 11-mercaptroundecanoic acid or oxidization by KMNO 4 or by oxidizing polybutadiene . Soybean oil was modified and crosslinked with CNC at a high loading of 30 wt % to obtain noticeable reinforcement . All of these approaches involve the separate production and chemical functionalization of nanocellulose and/or polymer modification in multiple processes.…”

“…16 Soybean oil was modified and crosslinked with CNC at a high loading of 30 wt % to obtain noticeable reinforcement. 17 All of these approaches involve the separate production and chemical functionalization of nanocellulose and/or polymer modification in multiple processes.…”

Free-Radical Photopolymerization for Curing Products for Refinish Coatings Market

“…In the field of polymer coating [ 9 , 10 , 11 ], there are different strategies that range from vegetable oil-based, environmentally friendly coatings [ 12 , 13 , 14 ] and epoxy acrylate resins of vegetable origin [ 15 ], or biodegradable lignin as a reactive raw material [ 16 ], to engineering the bio-nano interface using multifunctional coordinating polymer coatings [ 17 ]. However, a faster and greener alternative is ultraviolet (UV) curing, which consists of using UV light to initiate photochemical reactions.…”