_____________________________________________________________________________________________________ *Corresponding author: E-mail: marsthebiochemist@gmail.com; International Research Journal of Pure & Applied Chemistry 21(18): 33-42, 2020; Article no.IRJPAC.62169 ISSN: 2231-3443, NLM ID: 101647669 Characterization of Cellulose Nanocrystals Derived from Umbrella Plant (Cyperus alternifolius Linn.) Marcelino R. Tradio Jr. 1* and Brian John Sarno 1 1 Department of Chemistry, University of San Carlos, Talamban, Cebu City, 6000, Philippines. Authors’ contributions This work was carried out in collaboration between both authors. Author MRTJ designed the study, wrote the protocol, managed the literature search, performed the analyses and wrote the first draft of the manuscript. Author BJS supervised the analyses of the study and proof read the first draft of the manuscript. Both authors read and approved the final manuscript. Article Information DOI: 10.9734/IRJPAC/2020/v21i1830269 Editor(s): (1) Dr. Richard Sawadogo, Research Institute for Health Sciences, Burkina Faso. Reviewers: (1) M. Ravichandran, K. Ramakrishnan College of Engineering (Affiliated to Anna University), India. (2) M. V. Praveen Kumar, India. (3) M. Rudresh, Dayananda Sagar College of Engineering, India. Complete Peer review History: http://www.sdiarticle4.com/review-history/62169 Received 04 August 2020 Accepted 10 October 2020 Published 17 October 2020 ABSTRACT Plant–based nanocrystals have gained wide research interest due to its application in nano– reinforcement. Hence, the study investigated the stems of umbrella plant as potentials source of cellulose fibers to synthesize cellulose nanocrystals (CNCs). The synthesis of CNCs were conducted using acid hydrolysis with 10 mL 64% w/w sulfuric acid for each gram of purified cellulose at 45C for 30 min. The surface morphology, structural, physical and thermal properties of CNCs were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR), X–ray diffractometer (XRD), and simultaneous thermal analyzer, respectively. The result showed that the CNCs were mixture of rod–like shape and spherical morphology. The CNC rods were less than 20 nm width and 200–300 nm length when viewed under FESEM. However, the CNC rods were shorter when viewed under TEM and had a width less than 5 nm and length between 20–50 nm. The spherical CNCs that were seen only under TEM were less than 20 nm in diameter. The FTIR spectra showed that the CNCs were composed of crystalline cellulose I wherein the molecular structure of cellulose was preserved after the hydrolysis. The XRD patterns showed that the CNCs were highly crystalline with crystallinity index value of 94.48%. Lastly, the CNCs exhibited a three–stage thermal decomposition behavior. Original Research Article