Supermolecular structure and nucleation ability of polylactide-based composites with silica/lignin hybrid fillers

In this paper, amorphous silica Syloid 244 and kraft lignin were mechanically coupled. Four hybrid materials containing silica and lignin in ratios 1:1, 2:1, 5:1 and 20:1 were prepared. As reference samples for hybrid fillers pristine silica and lignin were used. Particle size determination and microscopic observations were applied to determine dispersive and morphological properties of hybrid fillers. Fourier transform infrared spectroscopy confirmed the effective preparation of silica/lignin hybrid materials. The parameters of porous structure of examined hybrid filler were determined using the multipoint Brunauer-Emmett-Teller method and Barrett-Joyner-Halenda algorithm. Composite samples of polylactide (PLA) containing 2.5 % (w/w) of hybrid filler were extruded. Optical microscopy, wide-angle X-ray scattering and differential scanning calorimetry were applied to specify the supermolecular structure of functional PLA/hybrid composites and analyze the crystallization parameters as well as the phase transformation in PLA matrix. Silica/lignin hybrid material was found to be a filler capable of an effective crystal nucleation. The nucleating ability of silica/lignin hybrid filler in PLA matrix is related to porous properties of filler and its composition.