Effect of alkaline treatment on the thermal stability, degradation kinetics, and thermodynamic parameters of pineapple crown fibres

Pineapple crown is generally discarded as waste but constitutes an important source of lignocellulosic fibres. In this work, the effect of alkaline treatment on the chemical composition, pyrolysis kinetics, and thermodynamic characteristics of pineapple crown fibres (PCF) were investigated by chemical composition, Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), X-rays diffraction (XRD), and thermogravimetry. Chemical composition analysis indicated cellulose content increased from 18.93 to 57.00% after NaOH treatment. PCF fibre diameter was reduced from 6.1 to 4.3 μm after mercerization. The FTIR results confirmed the removal of non-cellulosic compounds. XRD analysis indicated fibre's crystallinity index rose from 53 to 62% in reason of NaOH treatment. Thermogravimetric results confirm that alkaline-treated PCF (ATPCF) presented higher thermal stability than non-treated PCF (NTPCF). The solid-state thermal degradation mechanism for NTPCF and ATPCF occurred by the diffusion process and random nucleation, respectively. The thermodynamic parameters of NTPCF indicated that a small amount of energy is required to obtain the reaction products and thus bioenergy production from NTPCF pyrolysis will be easier, while ATPCF required more energy to initiate a degradation reaction and could be used as filler in polymeric composites.