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Nanotechnology applied to cellulosic fibers has quickly become an interdisciplinary field with great interest in the application as reinforcement in polymer composites, mainly due to the abundance of these raw materials, and to their mechanical properties and multifunctionality. However, one of the critical points to obtain individualized cellulose nanofibers is the drying technique (dehydration), since most of the nanofiber processes are performed in the liquid phase. According to the methodology applied to the cellulose water dehydration process, various morphologies and properties can be obtained in the cellulose fibers. This review study aims to discuss the main processes used to obtain nanocellulose (chemical and mechanical) and the drying techniques applied to nanocellulose structures, such as conventional oven drying, freeze drying (lyophilization), supercritical extraction, and spray drying.

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Thermoset resins are widely used for composite applications due to their excellent mechanical properties. To further enhance their performance, nanofillers such as graphite nanoplatelets (GrNP) have been used, and extra improvement may arrive from surface treating these fillers. This study aims to evaluate the influence of GrNP content and treatment with (3‐glycidyloxypropyl)trimethoxysilane and (3‐aminopropyl)triethoxysilane on curing behavior and mechanical and dynamic mechanical properties of GrNP/epoxy composites. Composites reinforced with 0.25 wt % GrNP displayed increased tensile strength by 11.8% compared to the neat resin. Addition of 0.5 wt % GrNP increased the glass transition temperature in 10°C compared to the neat polymer. Silane treated fillers showed an improvement in tensile strength and dynamic‐mechanical properties compared to the neat resin and non‐treated GrNP/epoxy composites at similar filler content. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46724.

Natural fibres have recently attracted interest due to their beneficial characteristics such as low cost and biodegradability. This work aims to characterise in natura, washed and alkali-treated buriti and ramie fibres and to evaluate the influence of the chemical treatments in the mechanical and dynamic mechanical performances of their composites produced by resin transfer moulding (RTM). Fibres were cut to 45 mm in length, washed in distilled water and treated with 2, 5 and 10 wt.% sodium hydroxide solutions. The chemical composition of the washed fibres was not altered. The 2 wt.% NaOH solution increased the flexural strength of polyester/ramie composites by 70%, and improved the impact performance of the alkali-treated polyester/buriti composites. The polyester/ramie composites exhibited superior dynamic mechanical properties and better adhesion at the fibre/matrix interface, and the morphology of buriti limited the fibre wettability during the RTM processing.

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Cellulose nanofibers were produced with waste from the paper industry, in a stone grinder and were used as filler in elastomeric composites in the acrylonitrile-butadiene copolymer (NBR). Two different cellulose mass concentrations (0.5 and 2.0 wt%) were ground in water and incorporated in concentrations of 0, 10 and 20 phr by the coagulation of the NBR, followed by drying. The other components of the formulation were incorporated and vulcanized in an open mixer and molded by compression. Due to the proposed grinding it was possible to obtain nanocellulose, in the range of 20.5 nm to 83.6 nm at an average diameter of 42.8 nm for the solution produced with 2.0 wt% and 18.3 nm at 90.5 nm at an average diameter of 44.3 for the solution with 0.5 wt%. The composites with a 20 phr of nanofiber presented lower vulcanization times and better mechanical properties before and after accelerated aging for 7 days, as well as a superior resistance to gasoline and diesel than the NBR and the samples with 10 phr. A tear strength of 61 N.mm−2 was obtained at the concentration of 20 phr and 0.5 wt% of incorporated nanofibers in line with a shorter vulcanization time.