Fig. 5: Nucleation mirroring, shish-kebabs from “quiescent” melt and goblet morphology in PLA nanocomposite.
PLA containing 1.3 wt% of 200 nm NR-labeled silica NPs was crystallized isothermally at Tc = 130 °C; after 10 min spherulite growth was arrested by quenching in ice water. This applies to all panels in this figure. a z-slices (a1) near the bottom and a2 near the top surface, illustrating nucleation mirroring across the sheet thickness; the dashed circles in (a2) show the exact position of the spherulites directly opposite at the bottom surface seen in (a1). b Surface rendering of arrested spherulite growth in a 34 µm film; the morphology resembles a treasure of ancient crockery. See also Supplementary Video 6. c Selection of images reconstructing different stages of formation of a “goblet”, starting with (c1) a single spherulite, (c2) formation of a second spherulite at the opposite (bottom) surface, (c3) close approach of the two growing spherulites and the formation of bridging shish-kebabs, and finally, (c4) formation of the goblet stand by multiplication and radial growth of the shish-kebabs or cylindrites. The inset in (c3) is a section through the center of the goblet with inverted contrast (bright = low fluorescence). Panels (c1–c4) actually show different coexisting regions of the sample. d1–d4 Schematic representation of the four stages of goblet formation, roughly corresponding to (c1–c4), with the arrows indicating the approximate direction of melt flow (see also simulation in Fig. 6).
