Influence of alkali treatment in enhancing crystallinity and breaking force of pineapple leaf fiber

The study investigates the effect of alkali treatment on pineapple leaf fiber (PALF) woven mats. The woven mat was chemically treated with varied concentrations (3, 6, and 9% w/v) of sodium hydroxide (NaOH) solutions for different exposure times (30, 60, and 90 min), making a total of 9 experiments. The structural, morphological, and chemical properties of untreated and alkali-treated specimens were investigated by using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) respectively. The mechanical property was assessed through the breaking force analysis. The XRD result indicated that the fiber mat treated with NaOH of 6% w/v concentration exposed to 30 min yields a crystallinity index (CI) of 63.95% and a crystallite size (CS) of 7.05 nm. The FTIR analysis helped to identify chemically active groups involved in PALF and the characteristic absorption peaks associated with partial and complete removal of wax and other impurities. SEM results quantitatively indicated the elimination of amorphous components from the surfaces. The specimen with the highest CI of 63.95% exhibited the maximum breaking force of 356.92 N. The results indicate that the increase in CI and CS not only improves the mechanical properties but also helps in stronger interfacial bonding in polymer composite applications.