Cross section SEM micrograph of a continuous carbon fiber (CCF) filament is shown in the figure above. This filament consist of multiple continuous carbon fibers embedded in a thermoplastic matrix (polycarbonate). The filament has an average diameter of 1.75mm and has approximately 24,000 carbon fibers with an individual diameter of 7μm. As it can be observed, the carbon fibers are uniformly distributed in the center of the polycarbonate matrix, and a large central fiber-rich region is clearly distinguishable. In areas without matrix where fibers remain unimpregnated, small voids could be seen, resulting in a weaker surface bond between fibers and thermoplastic. These defects can be attributed to the high melt viscosity of the polycarbonate, which complicates the mobility of the polymer chains during fiber fabrication by coextrusion.

The function of this coating is exclusively that of a vehicle to be able to 3D print the reinforcement fibers. Filament extrusion was performed In a Brabender Plasticorder PLE-650 extruder machine with a screw aspect ratio L/D = 25 and with a coaxial extrusion mold, while filament winding was performed by a strand pelletizer adapted for non pelletizing. The procedure of the extrusion starts with the CCF spooled on a winding and fed into the coaxial extrusion mold, while the thermoplastic pellet that will act as the thermoplastic coating is fed into the extruder. The molten thermoplastic is compressed around the fiber in the nozzle. After coating, the CCF filament is cooled in a water bath to solidify. Finally, the strand pelletizer pulls the strand and keeps the processing speed constant.

2D-STEM micrograph of a dry acrylonitrile-butadiene-styrene (ABS) latex is observed in the left image. ABS latex with 36 % of solid content was synthetized by seeded semi-batch emulsion polymerization. For the sample preparation, the ABS latex was first dialyzed to remove adsorbed species on the surface of the particles, mainly to avoid staining of the surfactant used during the grafting reaction. Then, the polymer latex was dried on a Transmission Electron Microscopy (TEM) grid and stained with OsO4 for one hour, which selectively reacted with the vinylic bonds of the PB. In HAADF-STEM, the contrast of the image is opposite to common TEM micrographs, which means that the PB matrix phase stained with OsO4 will correspond to the bright area while the SAN phases (shell and clusters) to the dark. The image presents the 2D-STEM tomographic image at position OZ = 124 of the particle, where the OZ axis coincides with the direction of the electron beam, and the OY axis is the tilting axis. 

Micrografía SEM a 1.467X de magnitud, con un HV de 10.00kV (WD: 10.6 mm). Fractura de una película polimérica compuesta de metacrilatos (MMA/BA/HEMA) en precencia de nanotubos de carbono multipared (0.5%) mediante polimerización en miniemulsión. Los nanotubos previos a la polimerización fueros sometidos a un tratamiento de ultrasonido en agua y en presencia de polyvinilpirrolidona. Después de la polimerización a 70ºC, el látex obtenido fue de color negro y homógeno sin cuágulos y estable.

Pictures presented in the II Edition

First Edition Photographs presented Pdf version