Preparation and characterization of sol–gel-modified pineapple leaf fiber/polylactic acid composites

In this study, the fibers generated from agricultural waste-pineapple leaf are obtained through exposure, drying, crushing and sifting. A novel sol–gel method is utilized to modify the pineapple leaf fiber (PALF), which is subsequently treated by a coupling agent. The aim is to improve the compatibility between PALF and the polymer matrix and to enhance the heat resistance and mechanical properties of the composite material. Furthermore, a series of modified PALF/polylactic acid (PLA) composites are prepared. FTIR, high resolution solid-state ¹³C and ²⁹Si NMR experiments show that the PALF was successfully modified by the silane coupling agent and sol–gel method. Polarizing optical microscopy analysis reveals PLA crystal growth of a sufficiently high density along the polymer-fiber interface. Moreover, the storage and loss moduli of PLA are increased by adding the modified PALF. Apart from the enhancement of the mechanical properties, the incorporation of modified PALF reduces the amount of agricultural waste and extends the application of PLA.