Transcrystallization behavior at the poly(lactic acid)/sisal fibre biocomposite interface

The focus of this work was to evaluate the transcrystalline effects at poly(lactic acid) (PLA) matrix caused by various sisal fibres, which were untreated (U-sisal), or treated with alkali (A-sisal) and silane (S-sisal). Isothermal crystallization was performed at temperatures between 123 and 130 °C using polarized optical microscopy. Results showed that the sisal fibres untreated or treated all had a nucleating ability to transcrystallize in PLA matrix. Based on the theory of heterogeneous nucleation, the interfacial free energy difference functions Δσ were determined to be 0.68, 0.65, and 0.65 erg/cm2 for PLA/U-sisal, PLA/A-sisal and PLA/S-sisal, respectively. This suggests that the fibre surface modification by using alkali or silane has little or no influence to the nucleation ability of sisal fibre in PLA matrix.