Differential scanning calorimetry (DSC) is a useful technique for analysing the thermal behaviour of materials by measuring the heat transferred through a sample during temperature fluctuations. For polymers, understanding their thermal characteristics is crucial to determine their process capability, mechanical properties, stability at high temperatures, and suitability for specific applications. In this context, the electrospinning process involves heating polymers and subjecting them to high voltage, leading to changes in their thermal properties. Therefore, it is essential to identify these modifications to determine the thermal conductivity, stability, and temperature management of the nanofiber for specific applications. This study focuses on the analysis of polyamide (PA6) nanofibers produced by electrospinning using DSC and compares them to virgin PA6 to identify significant changes in thermal properties. The PA6 nanofibers were prepared by electrospinning PA6 polymer and collecting on a rotating drum at a needle tip of 20 cm to the collector centre distance. For comparison of thermal properties, the same virgin PA6 was used for DSC testing from which nanofibers were produced. The results show that the nanofiber mat’s glass transition temperature increased by 3.2%, while the melting temperature decreased by 0.7%. Furthermore, the delta Cp (change in specific heat capacity) of the nanofiber mat was enhanced by 96%, and its thermal heat capacity and crystallinity increased by 16%. Therefore, this study provides insights into the alterations in the thermal characteristics of the nanofiber mat created by electrospinning.
The material under study in this paper is a gypsum composite board, which is a sustainable material, and therefore attracts scientists’ attention in the recent years. This material is of a great importance for Latvian economy, since Latvia has gypsum mining sites and has developed a tradition of gypsum manufacturing. The goal of the study was to compare the mechanical properties of gypsum boards from different manufacturers. For comparison of strength one cement board was tested as well. To complete the study a specific experimental setup was developed and is demonstrated in this paper. The results obtained are experimental values, useful for a scientific community because these can be used for CAD modelling in the future. In this paper the experimental results were used to create FEM models in ANSYS program and complete simulation. It was discovered that some gypsum boards have different physical properties in longitudinal and transverse directions, while for other properties do not differ depending on the direction. In this study, the cheapest board had the yield stress of 2.76 MPa in the longitudinal direction, 1.87 MPa in the transverse direction, while the more expensive board was homogeneous, and the physical properties did not change depending on the direction and the average yield stress was 2.19 MPa. The values obtained in the tensile test in other studies of gypsum boards for other manufacturers are even lower - 1.10 MPa in the longitudinal direction and 0.64 MPa in the transverse direction.
Fluid (water) flow translation motion conveyor (transporter) is being reviewed. In this device the actuator blades move in the plane axis parallel cycloidal motion, but the fluid flows away perpendicular to the rotation axis in translation direction. For this purpose the blade two component movement is synthesized by kinematics of the gear box: the first rotation takes place around the central axis of each blade, while the other rotation moves around this centre around the central axis of the transporter. The movement is designed in such a way that the central axis rotates twice as fast as the blades around its axles. The kinematics and dynamics of the transporter movement are analyzed, taking into account the characteristics of the drive motor and the blade interaction forces with fluid. The results of the analysis are shown in the graphs obtained by computer modelling. The possibility of creating a multi-element conveyor is being reviewed on the basis of one rotational element. In this case, it is possible to increase the efficiency of the system in such a way that the individual small conveyors in pairs operate in counter phase (rotates opposite). For transporter experimental investigations a special system is made inside the water tank. The system includes a rotating beam with a possibility to stick the devise in the end of this beam. Measurement sensors and the engine power system cable are connected to the control system via sliding contacts. A direct current electric motor is created in the conveyor drive. It allows to change the blade drive rotation number of a wide range. The design used in the work may also be used for other purposes, for example, for generation of energy from fluid flow. In this case, like before, all formulas can be used as calculation in relative interaction.
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