Akbar Zulkarnain, Heri Wibowo, Willy Artha Wirawan
Natural fiber reinforced composites are attractive sustainable materials, but their use is often limited by poor fiber-matrix adhesion and low thermal stability. This study investigates the effect of alkali treatment on the surface physicochemical characteristics and thermal behavior of Calathea lutea fiber (CLF) for composite reinforcement. CLF was treated with 5 wt% NaOH for 0, 2, 4, and 6 h and characterized by SEM-EDX, AFM, XRF, DTA, and TGA. The results showed that alkali treatment significantly altered the fiber surface and thermal response. Among the tested conditions, 2 h treatment (NT2H) produced the highest O/C ratio (1.53), indicating effective removal of lignin and hemicellulose and improved surface oxygenation. SEM and AFM revealed a cleaner and more homogeneous surface after alkali treatment, while AFM analysis showed that NT2H exhibited lower roughness values (Ra = 2.72 nm and Rq = 4.06 nm) and reduced topographical heterogeneity than the untreated fiber. XRF confirmed treatment-dependent elemental changes, and thermal analysis showed improved stability after alkali treatment, although NT4H exhibited the strongest thermal shift. Overall, NT2H provided the best balance between surface activation and structural preservation, supporting its potential for composite applications. © 2026 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license. http://creativecommons.org/licenses/by/4.0/
Doctoral Program in Engineering Science, Faculty of Engineering, Universitas Negeri Yogyakarta, Daerah Istimewa Yogyakarta, 55281, Indonesia; Railway Mechanical Technology, Politeknik Perkeretaapian Indonesia, Madiun, 63161, Indonesia; Mechanical Engineering Department, Universitas Negeri Yogyakarta, Daerah Istimewa Yogyakarta, 55281, Indonesia; Mechanical Engineering Department, Faculty of Vocational Studies, Universitas Negeri Surabaya, Surabaya, 60231, Indonesia
