Recent studies on modified cellulose/nanocellulose epoxy composites: A systematic review

Abstract

Cellulose and its derivatives are widely explored for films and thickening of pharmaceutical solutions, in paints, as reinforcement in composites, among others. This versatility is due to advantages such as renewability, low cost, and environmental friendliness. When used in polymer composites, due to the hydrophilic character of the cellulose, surface chemical modification is highly recommended to improve its compatibility with the polymeric matrix. Hence, this paper presents a systematic review of chemically modified cellulose/epoxy resin composites focusing on the last five years. The investigation followed the PRISMA protocol that delivers a meticulous summary of all available primary research in response to a research question. After including/excluding steps, thirty-six studies were included in the review. The results were presented focusing on thermal, mechanical and dynamic-mechanical properties of the composites. In brief, this methodology helped identifying the main gaps in knowledge in that field.

Mechanical Properties of Bio-Composites Based on Epoxy Resin and Nanocellulose Fibres

“…Then, a slight decrease in strain value was observed for composite with 1% on NC and rapid drop-down for EP + 1.5% NC. This might be attributed to the larger amount of well-dispersed cellulose nanoparticles within the epoxy matrix, as well as the formation of strong interaction between EP and NC [29,47]. This is also confirmed by the flexural modulus values shown in Figure 9.…”

“…Significant improvement of the composite resistance in comparison to unmodified epoxy resin can be attributed to well-dispersed NC and possible good interaction as well as a chemical reaction between epoxy resin functional group and hydroxyl or acetyl groups from nanocellulose [29]. Suggesting a few tens of percent improvement in strength parameters with a tiny filler addition, we can conclude that it does not act as an ordinary filler, but as a nanofiller.…”

“…Besides, due to its hydrophilic character, cellulose tends to form agglomerates during composite processing. Nanoparticles, particularly, have the natural tendency to agglomerate due to their high specific area and surface energy [29,30].…”

“…Among the reported chemical methods, mercerization, silanization, oxidation, esterification, grafting of branched/hyperbranched polymers stand out. [29][30][31][32][33][34][35] In our work we modified the method to obtain nanocellulose fibers composed of cellulose acetate. The developed preparation method enabled the direct addition of NC dispersion to EP, whereby we have eliminated the problem of incompatibility of raw materials at the production stage.…”

Nano/Micro Hybrid Bamboo Fibrous Preforms for Robust Biodegradable Fiber Reinforced Plastics

“…Biomimetic methods have been tried to overcome this drawback. When bacteria biosynthesized nanocellulose, a water-soluble polymer, such as hydroxyethyl cellulose or polyvinyl alcohol, was introduced to prepare a nanocellulose/polymer composite [ 7 , 14 ]. These biomimetic nanocellulose/polymer composites showed higher tensile properties than composites prepared by simple mixing [ 12 ].…”