Effects of Grinding Aids Used in Grinding Calcium Carbonate (CaCO3) Filler on the Properties of Water-Based Interior Paints

Grinding aid chemicals which are used in the grinding of calcium carbonate (CaCO3) to prevent agglomeration are chemisorbed on the surfaces of particles, and the compatibility of them with the solvent, water, or organic resin affects the dispersion of the minerals and ultimately down-stream product properties in consumer industries such as paint, papermaking, and plastic. This study tries to explain the effects of triethanolamine (TEA) and monoethylene glycol (MEG), which are most commonly used as grinding aids, on the behavior of CaCO3 in water-based paints and on the properties of the paints. The powder properties of CaCO3 (grain size, color, surface area, oil absorption capacity, zeta potential, etc.) were characterized, and the changes in the can stability, ease of application, and optical properties (gloss, opacity) of the paints were revealed with rheological and optical analysis. It was observed that amine compounds remained in higher amounts on the CaCO3 surface and created negative results in the paint. On the other hand, glycol compound adhered less on the CaCO3 surface and affected the properties of the final product less than the amine compound. Therefore, CaCO3 ground without using any chemicals gives the best results in terms of long-term stability, ease of application, and visuality of the paint.

Optimizing Solvent Selection and Processing Conditions to Generate High Bulk-Density, Co-Precipitated Amorphous Dispersions of Posaconazole

Co-precipitation is an emerging method to generate amorphous solid dispersions (ASDs), notable for its ability to enable the production of ASDs containing pharmaceuticals with thermal instability and limited solubility. As is true for spray drying and other unit operations to generate amorphous materials, changes in processing conditions during co-precipitation, such as solvent selection, can have a significant impact on the molecular and bulk powder properties of co-precipitated amorphous dispersions (cPAD). Using posaconazole as a model API, this work investigates how solvent selection can be leveraged to mitigate crystallization and maximize bulk density for precipitated amorphous dispersions. A precipitation process is developed to generate high-bulk-density amorphous dispersions. Insights from this system provide a mechanistic rationale to control the solid-state and bulk powder properties of amorphous dispersions.

A Through-Process Experimental Approach to Enable Optimization of Cold Sprayed Al 7075 Consolidation Performance

This work employs an example of a through process experiment systematic approach to study the relationship among powder properties, cold spray (CS) processing parameters, and consolidated specimen behavior through a combined effort of characterization methods and computational models. This process will allow for the systematic isolation of variables that can affect powder and CS deposit properties. In this study, Al 7075 powder was used as feedstock to produce a CS coating using industry-standard processing parameters. Techniques such as SEM, EDS, XRD, nanoindentation, and tensile testing were used to characterize the properties of both the feedstock powder and CS deposits. In addition, computational thermodynamic modeling was used to guide the interpretation of microstructural features of the powder and CS specimen. Finally, an additive yield strength model was employed to quantify the strengthening components introduced through the CS process.

Opposing Effects of Additives in Dry Milling and Tableting of Organic Particles

Applying additives and excipients during the dry processing of fine particles is a common measure to control the particle–particle interactions, to specifically influence the powder properties and to enhance the process efficiency or product quality. In this study, the impacts of a particulate lubricant, a nano-disperse flow additive and liquid grinding aids on the dry fine milling and subsequent tableting of the ground material were investigated for three different organic model compounds. It is presented that the three additive classes cause varying and partly opposing effects during these process steps. Especially the lubricant and the grinding aids were shown to increase the efficiency of the milling process as well as the product fineness of the ground material, and to avoid critical product adhesions on the machine surfaces. Thereby, stable and efficient grinding conditions were partially not possible without the addition of such additives. However, as these positive effects are attributed to a reduction of the adhesive forces between the particles, much lower tablet strengths were achieved for these additives. This propagation of powder, and in turn, final product properties over whole process chains, has not been studied in detail so far. It was further revealed that the material behavior and the microstructure of the product particles is decisive for the processing as well, which is why additive effects may be product-specific and can even be suppressed under certain processing conditions. In comparison to the process performances, the powder properties and surface energies of the product particles were less influenced by the additives. On the contrary, particle-based morphologies or deformation behavior seem to play a major role in comparison to inorganic materials. Thus, it can be stated that global bulk properties and surface energies provide first indications of powder behavior and susceptibility. However, additional specific properties need to be evaluated to more clearly understand the influences of additives.

Optimization of foaming process: drying behaviour, physicochemical, and powder properties of hot air-assisted foam-mat dried nectarine

Nectarine powder is widely used in the industries of baking and confectionery. The production of nectarine powder can be made by several drying techniques such as spray, tray, drum, freeze, and foam mat. This study was aimed to optimize the parameters of the nectarine foaming process. Besides, hot air-assisted foam-mat drying of nectarine was carried out to evaluate the effect of different temperatures (50, 60, and 70 °C) on drying kinetics, physicochemical and powder properties of nectarine powder. Factors studied were egg albumin concentration, carboxymethyl cellulose concentration, and whipping time that varied between 10 and 30% (by weight), 0.2–0.8% (by weight), and 3–5 min, respectively. Optimum conditions were determined as 30% of egg albumin, 0.8% carboxymethyl cellulose, and a whipping time of 5 min to get maximum foam expansion, high foam stability, and minimum foam density. The drying rate and effective moisture diffusivity of nectarine foam powder increased with increasing drying temperature. Carr Index and Hauser Ratio values were in the range of 32.31–47.00 and 1.48–2.00, respectively. Foamed nectarine powder dried at 70 °C had the lowest hygroscopicity value and the highest wettability value. No significant difference was found between the powders’ porosity (p > 0.05). The powders produced at 50 °C resulted in higher total phenolic, vitamin C, and carotenoid content.

Impact of Powder Properties on the Rheological Behavior of Excipients

With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.