In this second part of the article, we delve deeper into the research area initiated in the first part, focusing on the critical exploration of polylactide (PLA) modification to enhance thermal and mechanical properties in PLA-based materials, building upon the insights obtained from comprehensive structural and thermal analyses utilizing analytical methods such as infrared spectroscopy (FTIR), diffuse reflectance infrared spectroscopy (DRIFT), and thermoanalytical research (DRIFT, TG-DTG). A series of structural and thermal analysis research (TG-DTG, DSC, DRIFT) were performed for samples of polylactide (PLA), which is commonly used in additive technologies as a structural material. In total, four materials were considered, including two containing dyes with different colors, a material made of PLA recyclate and a graphene-modified PLA material. It was noted that PLA material reinforced with graphene phase (GRAFYLON®) retains the best thermal properties (TG-DTG), which results in its wider potential for processing, including further modification and usability in manufacturing vehicle structural elements. Recycled PLA material (ALFA+W) was characterized by a higher melting point (Tp ) by more than 20°C than other samples (DSC analysis), so it can be more useful in the production of structural elements operating and used at elevated temperatures.
A short literature review was undertaken in terms of the structure, properties and applications of polymers, including those commonly used in 3D printing. The research part included the structural and thermal analysis of polylactide (PLA), which is an example of an extensively used polymer in the developing 3D technology. Special attention was paid to the comparison of structure and thermal stability of two different (from various producers) polylactide samples. The research, involving such analytical methods as infrared spectroscopy (FTIR) and diffuse reflectance infrared spectroscopy (DRIFT), allowed the comparison of the structure of the two PLA samples considered. The determination of the temperature range in which changes related to PLA thermodestruction occur was a result of the performed thermoanalytical research (DRIFT, TG-DTG). Thermal studies also allowed to establish the temperature range in which the material does not yet degrade, which is important in the context of future planned research work on polylactide modification to obtain the improvement of the thermal and mechanical properties of PLA-based materials. This research area will be described in the second part of the publication.
A high energy combustion agent (tetraethylammonium decahydrodecaborate, BHN) was prepared by means of an ion exchange reaction (IER), and the prepared samples were characterized by the advanced diagnostic techniques of Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC) etc. The effects of BHN particles on the hazard and combustion properties of fuel rich solid propellants were investigated. The results showed that the BHN samples and fuel rich propellants containing BHN particles can be prepared successfully and solidified safely. The peak temperature of thermal decomposition and the heat of decomposition of the BHN samples prepared were 305.8 °C and 210.9 J•g-1 at a heating rate of 10 K•min-1, respectively. The burning rate and pressure exponent of fuel rich solid propellants decreases with increases in the fraction of BHN particles in the propellant formulation. Compared with the reference formulation (sample BP-1), the burning rate of the propellant with 10% mass fraction of BHN particles (sample BP-4) had decreased 30% at 3.0 MPa, and the pressure exponent had dropped from 0.44 to 0.41.
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