Towards more homogeneous character in 3D printed photopolymers by the addition of nanofillers

The performance of 3D printed materials differs from that of fully cured polymer materials because of the presence of interfacial areas between consecutively joined layers. These interfaces result in an inhomogeneous character of the printed objects and is frequently reported as their main cause of failures. We noted that the presence of nanosilica particles strengthens the 3D printed layers of the polymer matrix by inducing its additional crosslinking. A model resin composed of poly (ethylene glycol) diacrylate (PEGDA) and nanosilica (Aerosil R972) is used for vat photopolymer 3D printing. Evolution of the interface properties at different nanosilica loadings is tracked by mapping its surface stiffness (Young's modulus mapping) using quantitative Atomic Force Microscopy (AFM). Our research demonstrates that incorporating 6% w/v nanosilica in the polyPEGDA matrix unifies its mechanical properties within the layer, leading to a substantial reduction of microscopic inhomogeneity in the final 3D printed materials.</p

Lignin and Starch Derivatives with Selenium Nanoparticles for the Efficient Reduction of Dyes and as Polymer Fillers

Selenium nanoparticles (SeNPs) were synthesized and stabilized by biopolymers, namely, sodium lignosulfonate (LS) and starch sodium octenyl succinate (OSA). The obtained selenium nanoparticles were studied for their catalytic activity in the reduction of a dye (C.I. Basic Blue 9, methylene blue) by sodium borohydride. The SeNPs-OSA and SeNPs-LS nanoparticles were also dispersed in a photosensitive matrix and studied as polymer composites. The research confirmed the catalytic abilities of the prepared SeNPs in the reduction of the organic dye. Mechanical tests on the polymers and their composites showed an improvement in the composites’ strength in all tested cases. An increase in hardness and Young’s modulus values of the filled materials compared to the pure matrix was found as well.</p

Influence of the Addition of Sialon and Aluminum Nitride Fillers on the Photocuring Process of Polymer Coatings

This article presents the results of a study on polymer coatings containing poly ethoxylated bisphenol A diacrylate (Bis-AEA10) with aluminum silicon nitride oxide (Sialon) and aluminum nitride (AlN). The polymer coatings were obtained by the photopolymerization technique. Investigations were carried out to determine the effect of the AlN and Sialon content on the UV-curing kinetics, as well as on the mechanical (hardness), thermal (Tg, thermal stability), physicochemical (water contact angle), and structural properties of the polymer coatings. Polymerization rates were characterized as functions of double-bond conversion using the photo-Differential Scanning Calorymetry technique (photo-DSC). The results obtained showed that a small addition of sialon filler (3&ndash;5 wt.%) to Bis-AEA10 increases the photopolymerization rate of the varnish, while the addition of more Sialon decreases the rate of photopolymerization. However, for the systems containing AlN filler, the maximum polymerization rate was observed for samples containing 10 wt.% filler. In the case of a varnish composition containing AlN, the maximum polymerization rate is characterized by the system containing 10 wt.% of AlN. This shows that the AlN filler has a good influence on the polymerization process. In either case, the final double bond conversion was high (80%&ndash;95%). Mechanical tests have shown that introducing the filler into the polymer matrix increases its hardness. The content of Sialon and AlN in the coatings causes an increase (up to 4&ndash;5 wt.%) and a decrease (&gt;4&ndash;5 wt.%) in the glass transition temperature. The effect of the addition of fillers on the physicochemical properties of the coating surface has also been investigated and characterized by the water contact angle method. The addition of 20 wt.% Sialon and AlN increased the contact angle of the samples by approximately 40% and 31%, respectively, resulting in coatings with hydrophobic surface properties

Optimization of the Sowing Unit of a Piezoelectrical Sensor Chamber with the Use of Grain Motion Modeling by Means of the Discrete Element Method. Case Study: Rape Seed

Nowadays, in the face of continuous technological progress and environmental requirements, all manufacturing processes and machines need to be optimized in order to achieve the highest possible efficiency. Agricultural machines such as seed drills and cultivation units are no exception. Their efficiency depends on the amount of sowing material to be used and the patency of seed transport tubes or colters. Most available control systems for seed drills are optical ones whose operation is not effective when working close to the ground due to large dusting. Thus, there is still a need to provide seed drills with sensors to be equipped with control systems suitable for use under conditions of massive dusting that would shorten the time of reaction to clogging and be affordable for every farmer. This study presents an analysis of grain motion in the sowing system and an analysis of the operation efficiency of an original piezoelectric sensor with patent application. The novelty of this work is reflected in the new design of a specially designed piezoelectric sensor in the sowing unit, for which an analysis of indication errors was carried out. A seed arrangement of this type has not been described so far. An analysis of the influence of the seed tube tilt angle and the type of its exit hole end on the coordinates of the grain point of collision with the sensor surface and erroneous indications of the amount of sown grains identified by the piezoelectric sensor is presented. Low values of the sensor indication errors (up to 10%), particularly for small tilt angles (0&deg; and 5&deg;) confirm its high grain detection efficiency, comparable with other sensors used in sowing systems, e.g., photoelectric, fiber or infrared sensors and confirm its suitability for commercial application. The results presented in this work broaden the knowledge on the use of sensors in seeding systems and provide the basis for the development of precise systems with piezoelectric sensors

Optimization of the Sowing Unit of a Piezoelectrical Sensor Chamber with the Use of Grain Motion Modeling by Means of the Discrete Element Method. Case Study: Rape Seed

Nowadays, in the face of continuous technological progress and environmental requirements, all manufacturing processes and machines need to be optimized in order to achieve the highest possible efficiency. Agricultural machines such as seed drills and cultivation units are no exception. Their efficiency depends on the amount of sowing material to be used and the patency of seed transport tubes or colters. Most available control systems for seed drills are optical ones whose operation is not effective when working close to the ground due to large dusting. Thus, there is still a need to provide seed drills with sensors to be equipped with control systems suitable for use under conditions of massive dusting that would shorten the time of reaction to clogging and be affordable for every farmer. This study presents an analysis of grain motion in the sowing system and an analysis of the operation efficiency of an original piezoelectric sensor with patent application. The novelty of this work is reflected in the new design of a specially designed piezoelectric sensor in the sowing unit, for which an analysis of indication errors was carried out. A seed arrangement of this type has not been described so far. An analysis of the influence of the seed tube tilt angle and the type of its exit hole end on the coordinates of the grain point of collision with the sensor surface and erroneous indications of the amount of sown grains identified by the piezoelectric sensor is presented. Low values of the sensor indication errors (up to 10%), particularly for small tilt angles (0° and 5°) confirm its high grain detection efficiency, comparable with other sensors used in sowing systems, e.g., photoelectric, fiber or infrared sensors and confirm its suitability for commercial application. The results presented in this work broaden the knowledge on the use of sensors in seeding systems and provide the basis for the development of precise systems with piezoelectric sensors