Qicpic

Particle size distribution (PSD) and the particle morphology of MCC-A/P and CAPH are determined via dynamic image analysis (QICPIC, Sympatec GmbH, Clausthal-Zellerfeld, Germany) equipped with a vibrating chute to disperse particles into a free-fall funnel (GRADIS, Sympatec GmbH, Clausthal-Zellerfeld, Germany). Due to the cohesive behavior of LAC, its PSD is determined by laser diffraction with dry dispersion via airflow injector with a dispersion pressure of 2 bar (HELOS laser diffraction, RODOS dispersion system, Sympatec GmbH, Clausthal-Zellerfeld, Germany).
In order to get deeper information about the aspect, shape, and morphology of the analyzed materials, scanning electron microscope (SEM) acquisitions are also presented. Materials were sputtered with gold and investigated with a field emission SEM (LEO 1530, Carl Zeiss Microscopy GmbH, Jena, Germany), applying an acceleration voltage of 5 kV and a working distance of 10 mm. Different magnifications between 150× and 3000× were applied.
The true or skeletal density is determined by means of helium pycnometry (ULTRAPYC 1200e, Quantachrome GmbH, Odelzhausen, Germany). Samples were stored at 20 °C and 45% RH during the 24 h prior to the analysis. Measured values are extracted after 10 runs of the same sample and assuring a typical deviation lower than 0.5%.

The particle size distributions of bulk and tracer powders were analyzed using dynamic image analysis (QicPic, Sympatec GmbH, Clausthal, Germany) using the GRADIS dry powder dispersion unit. Particle sizes were obtained by calculating the diameter of a circle with an equal projection area. For each sample, at least 100,000 particles were analyzed.

The particle size of the carriers DCP, LAC and MCC, as well as the corresponding granules, was analyzed via dynamic image analysis with a QICPIC (Sympatec GmbH, Clausthal-Zellerfeld, Germany) equipped with a GRADIS dispersing unit to ensure a gentle dispersion in free fall, and a VIBRI dosing unit to ensure a constant sample mass-flow. The analysis was performed three times, with at least 100,000 particles analyzed each time.

Dynamic image analysis (QICPIC, Sympatec, Etten-Leur, the Netherlands) was performed to evaluate the granule size distribution (GSD) of the dried granules. A representative sample of 80 g of granules was fed by a vibratory feeder towards a gravimetric feed tube where the granules were dispersed in front of the measurement window. Volume size distributions were calculated by the WINDOX 5 software (Sympatec, Etten-Leur, The Netherlands). Measurements were performed in duplicate. The size fraction smaller than 150 µm was defined as the fines fraction. On the other hand, the fraction larger than 1000 µm corresponded to oversized granules.

The particle size was analyzed with a QICPIC (SYMPATEC, Clausthal-Zellerfeld, Germany) connected to a GRADIS dispersion system with a drop height of 50 cm and an outlet width of 4 mm. The images were captured with an M8 lens (measuring range 20–6820 µm) at a frame rate of 75 Hz when an optical concentration of 0.2% was reached for up to 240 s. A VIBRI was used as the feeder and the VIBRI control was set at an optical concentration of 1.00% with an integral of 2.0. The WINDOX 5 software was used to compute the particle size and sphericity. The software calculated the sphericity with Equation (1), where P_EQPC is the perimeter of the equivalent circle in μm, P_real is the real perimeter in μm, and A is the surface area in μm². The particle size was based on the cumulative volume distribution. For the particle size and sphericity, the 50th percentile was given, indicated by the x₅₀ for the particle size and the s₅₀ for the sphericity. The span was used as a measure for the width of the size distribution, see Equation (2) where x₉₀ is the diameter in μm where 90% of the particles are smaller than this diameter, x₁₀ is the diameter in μm where 10% of the particles are smaller, and x₅₀ the diameter in μm where 50% of the particles are smaller.
$$Sphericity=\frac{P_{EQPC}}{P_{real}}=\frac{2 \sqrt{\pi ·A}}{P_{real}}$$
$$Span=\frac{x_{90}-x_{10}}{x_{50}}$$