Authors: Mayara Felix Santana1*, Miriane Maria de Sousa1, Flávia Mitsue Yamashita1, Bárbara Castro Moreira1, José Mauro de Almeida2,

Alvaro Vianna Novais de Carvalho Teixeira1, Deusanilde de Jesus Silva1

1 Universidade Federal de Viçosa (UFV), Viçosa – Minas Gerais, CEP: 36570-900, Brazil.

2 Universidade Federal do Recôncavo da Bahia (UFRB), Cruz das Almas – Bahia, CEP: 44380-000, Brazil.

ABSTRACT

Cellulose nanocrystals have been applied as reinforcing material

in polymer matrices due to their excellent mechanical properties

and the fact that they are derived from natural fibers, which are

biodegradable in the environment and come from renewable sources.

This paper studies the morphological, dimensional, chemical and

surface characteristics of cellulose nanocrystals (CNC) isolated from

cotton fibers pre-treated with sodium hydroxide (NaOH) 2% m/v

focusing on hydrolysis time. Such characterization used transmission

electron microscopy (TEM), X-ray diffractometry (XRD), Fouriertransform

infrared spectroscopy (FTIR), thermogravimetry (TGA),

zeta potential, dynamic light scattering (DLS) and energy-dispersive

X-ray spectroscopy (EDS). The isolated cellulose nanocrystal yield was

evaluated based on hydrolysis of the material with 65% sulfuric acid

(m/m), at a temperature of 50 °C, acid:biomass ratio of 20 mL g-1 and

hydrolysis times of 50, 70, 90, 110 and 130 min. It was found that

treatment with 2% NaOH provided satisfactory accessibility to the

fibers and the effect of hydrolysis time on CNC production showed a

peak yield at 110 min, 33%. The CNC had negative surface charges,

-30.0 to -53.3 mV, giving stability to the suspensions. CNC obtained

under the conditions evaluated can be used in the composition

of composites in various hydrophilic matrices because maximum

degradation temperatures are above 200 °C and because they are

stable and of uniform size.

Keywords: Cellulose nanocrystals, nanomaterials, pre-treatment,

acid hydrolysis, yield.