Six liquid branched poly(methylhydrosiloxanes) of new random structures (PMHS-Q), containing quadruple branching units SiO_4/2 (Q), both MeHSiO (D^H) and Me₂SiO (D) chain building units (or only mers MeHSiO), and terminal groups Me₃SiO_0.5 (M) were prepared by a hydrolytic polycondensation method of appropriate organic chlorosilanes and tetraethyl ortosilicate (TEOS), in diethyl ether medium at temperature below 0 °C. Volatile low molecular weight siloxanes were removed by a vacuum distillation at 150–155 °C. Yields of PMHS-Q reached from 55–69 wt%. Their dynamic viscosities were measured in the Brookfield HBDV+IIcP cone-plate viscometer and ranged from 10.7–13.1 cP. Molecular weights (MW) of PMHS-Q (M_n = 2440–6310 g/mol, M_w = 5750–10,350 g/mol) and polydispersities of MW (M_w/M_n = 2.0–2.8) were determined by a size exclusion chromatography (SEC). All polymers were characterized by FTIR, ¹H- and ²⁹Si-NMR, and an elemental analysis. A microstructure of siloxane chains was proposed on a basis of ²⁹Si-NMR results and compared with literature data.

New branched polymethylvinylborosiloxanes (PMVBSs) with random structures were prepared, and their chemical structures were studied by spectroscopic methods (FTIR, ¹H-, ²⁹Si-, and ¹¹B-NMR) and elemental analysis (% C, % H, % Si, and % B). Average molecular weights M _w and M _n were determined by a size exclusion chromatography (SEC), and dynamic viscosities were measured in Brookfield cone–plate reoviscometer HBDV-II+cP. Thermal properties of PMVBSs were studied under air and under nitrogen atmosphere. Thermal curves were interpreted from the point of view of physical and chemical transitions, taking place during the heating process of PMVBSs. Parameters of their thermal stabilities and glass transition temperatures (T _g) were determined. The synthesized PMVBSs are characterized by low glass transition temperatures (T _g: from −122 to −137 °C) which depend on their chemical structures. It was concluded that gaseous products (such as volatile siloxanes, silanes, CO₂, H₂O, CH₂O, methanol, and formic acid), which could be liberated during the heating process of PMVBSs, promote ceramization processes, leading to the formation of the ceramics of a type SiBCO—a borosilicate glass and silica.

Para-aramid materials such as Twaron^® and Kevlar^® are commonly used for ballistic-resistant body armor, which are designed to protect human life and health. For this reason, the materials from which body armor are made should be thoroughly investigated in the area of long-term reliability, particularly with regard to exposure to UV light, humidity and temperature, as these are known causes of degradation in commonly used ballistic materials. This research presents the durability of soft and hard ballistic inserts designed using para-aramid (Twaron^®) materials. Para-aramid ballistic inserts not subjected to accelerated aging processes and also ones subjected to laboratory aging for 63, 129 and 194 days, which corresponded to 2, 4 and 6 years of aging in real conditions, were tested. The selected para-aramid inserts were verified in terms of ballistic and physico-mechanical properties as well as changes in chemical structure of the ballistic materials. Ballistic tests were carried out with the use of a 1.1 g FSP.22 fragment according to STANAG 2920. Changes in the microstructure of the para-aramid materials were evaluated using infrared spectroscopy and scanning electron microscopy. The obtained results indicate that despite the changes which took place at the molecular level in the Twaron^® materials, accelerated aging processes do not affect the fragmentation resistance properties of ballistic inserts made of para-aramid materials.

The objective of this research was to assess the utility of dynamic mechanical thermal analysis (DMTA) in investigation of polymer-based foams for the potential use in anti-impact protection systems. Therefore, three different types of specimens were chosen (polyolefin, polyurethane, rubber) and examined with: i. amplitude (1-100 µm), ii. frequency (0.1–100 Hz), iii. temperature (-60-60°C) sweeps. These DMTA modes enabled to successfully mimic: i. deformation during the impact, ii. foam behaviour while worn (low frequencies) and hit (high frequencies), iii. summer and winter conditions. Among others, investigation of loss angle tangent (tanδ), being a ratio between loss (E’’) and storage (E’) moduli, favourably revealed an inverse relationship between the tanδ at 100 Hz and maximum impact force needed to destroy the specimen. It was also established that a compromise between elastic (E‘) and viscous (E’’) needs to be maintained to preserve shape stability while dissipating energy to achieve the high compressive strength (CS), e.g., more viscous rubber foam – CS of approx. 86 kPa (tanδ = 0.44), rigid polyolefin foam – CS at the level of 36 kPa (tanδ = 0.15). Therefore, DMTA successfully served as a complementary tool, providing mechanistic insight that supported and explained trends observed in conventional compression and impact testing.