Effect of hot-pressing temperature on the structure and physico-mechanical properties of kapok fiber nonwoven mats.

Kapok fiber (KF) has gained increasing attention due to its lightweight, hollow structure and lignocellulosic nature, with excellent buoyancy, thermal insulation, and sustainability characteristics. However, it presents significant challenges during the carding process and nonwoven mat formation owing to its short fiber length and poor cohesion. Limited studies have systematically investigated the effect of controlled hot-pressing temperature on binder-free KF nonwoven mats. Therefore, this study examines the influence of hot-pressing temperature (140, 150, 160, and 170 °C) on their physical and mechanical properties. The KF nonwoven mats were fabricated using an Ashford drum carder followed by hydraulic hot pressing. Increasing the hot-pressing temperature from 140 to 170 °C reduced Grammage (GSM) and thickness from 30.08 to 28.16 g m-2 and 0.326 to 0.250 mm, respectively, while increasing density, tensile strength, and tensile modulus to 0.450 g cm-3, 50.76 MPa, and 6622.7 MPa, respectively, due to enhanced fiber consolidation. Among the tested conditions, 170 °C provided the highest mechanical performance and most effective fiber consolidation. Surface morphology was analyzed using a tabletop microscope and the results revealed a progressively more compact and smoother fiber structure at higher hot-pressing temperatures. Fourier transform infrared (FTIR) spectroscopy indicated a change in the intensity of hydroxyl (-OH) absorption bands with increasing temperature, suggesting partial thermal modification of the fiber surface. Moreover, tensile strength and tensile modulus increased with increasing hot-pressing temperature. A one-way analysis of variance (ANOVA) confirmed that hot-pressing temperature had a statistically significant effect on the physical and mechanical properties of the nonwoven mats. This work provides valuable insights into the sustainable utilization of KF and offers practical guidance for the industrial production of high-performance, eco-friendly nonwoven materials.