Title
Optimized oxidative-alkaline treatment of AP1 ramie fibers for enhanced cellulose purity and tensile strength
Authors
DAM XUAN THANG, NGO THUY VAN, PHAM THI THU GIANG and NGUYEN NGOC LINH

Received April 10, 2025
Published Volume 59 Issue 9-10 October-December
Keywords AP1 ramie fibers, alkaline–oxidative treatment, Box-Behnken Design (BBD), Response Surface Methodology (RSM), tensile strength, bio-composites

Abstract
In this study, an optimized oxidative–alkaline treatment was developed to improve the structural and mechanical performance of AP1 ramie fibers. A 7% calcium hydroxide [Ca(OH)2] solution was employed in combination with oxidizing agents – hydrogen peroxide (H2O2), calcium hypochlorite (Ca(OCl)2) and sodium hypochlorite (NaOCl) – to enhance delignification and hemicellulose removal. The treated fibers were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), tensile testing, colorimetric analysis and thermogravimetric analysis (TGA) to evaluate their physicochemical transformations. Among the tested conditions, the treatment with 4% H2O2 and 7% Ca(OH)2 for 90 minutes yielded the highest performance enhancements, with tensile strength increasing by approximately 1.5 times – from 687.26 MPa (untreated) to 1061.60 MPa – and cellulose purity reaching 93%. Optimization of processing parameters using the Box–Behnken design and second-order regression modeling confirmed strong statistical significance (R² > 0.99) and model validation showed deviations below 5% between predicted and experimental values. These findings demonstrate the effectiveness of oxidative–alkaline processing for producing high-performance ramie fibers and the enhanced mechanical and structural properties of treated AP1 ramie fibers suggest their strong potential for use in sustainable textile production and high-strength bio composite applications.