Polycaprolactone (PCL) and polylactide (PLA) are the two most common biodegradable polymers with potential use in oral applications. Both polymers undergo mainly slow hydrolytic degradation in the human body. However, specific conditions of the oral cavity, like elevated temperature, low pH, and presence of saliva affect the rate of hydrolysis. The study examined the properties of solid samples of PCL and PLA subjected to degradation in phosphate buffered saline (PBS) and artificial saliva (AS) at temperatures of 37 or 42 °C, and pH values 2 or 7.4. A number of tests were performed, including measurement of the degree of swelling, weight loss, molecular weight, differential scanning calorimetry, and thermogravimetry of polymers, as well as hardness and tensile strength. Additionally, topography and stiffness of surfaces using atomic force microscopy are presented. It has been noticed that in the artificial saliva, the processes of polymer degradation occur slightly more slowly, and the effects of temperature and pH are less pronounced. We believe that a layer of porcine gastric mucin from artificial saliva that adsorbed on the surface of polymers may have a key role in the observed differences; this layer resembles protective mucin coating tissues in the oral cavity.

In this work, a series of silsesquioxanes (SSQ) and spherosilicates (SS), comprising a group of cage siloxane (CS) compounds, was tested as functional additives for preparation of isotactic polypropylene (iPP)-based nanocomposites and discussed in the aspect of their rationale of applicability as such additives. For this purpose, the compounds were prepared by condensation and olefin hydrosilylation reactions. The effect of these cage siloxane products on properties of obtained CS/iPP nanocomposites was analyzed by means of mechanical, microscopic (scanning electron microscopy-energy dispersive spectroscopy), thermal (differential scanning calorimetry, thermogravimetry), thermomechanical (Vicat softening point) analyses. The results were compared with the previous findings on CS/polyolefin composites. The role of CS compounds was discussed in terms of plastic processing additives.

Polylactide (PLA) composites were prepared and doped with starch (10% by weight), and mineral salts used as mineral fertilisers (MgSO₄, KNO₃, Ca(NO₃)₂ and Ca₃(PO₄)₂) were prepared. The content of the added fertilisers was 2% by mass in the composites. The tensile strength properties of the obtained composites were tested. The effect of the addition of fertilisers on the structure of polylactide was analysed using spectroscopic methods (FTIR and FTRaman). The thermal properties of the obtained composites were tested using thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). PLA composites with fertilisers were tested for biodegradability in two types of soil—field soil and horticultural soil—and in compost. Biodegradability was assessed based on the mass loss of biodegraded composites, spectroscopic tests and visual assessment of changes occurring in the composites. Tests were performed on the respiratory activity of microorganisms in the compost extract in which the tested composites were placed. The addition of mineral salts used in the tested composites significantly influenced the biodegradation rate of the composites. Mineral compounds (MgSO₄, KNO₃ and Ca(NO₃)₂) added to the PLA–starch composite improve its mechanical properties. It should also be noted that the addition of mineral salts to the prepared composites did not affect the chemical structure of polylactide. The addition of mineral salts to PLA also did not significantly affect its thermal properties, as demonstrated by DSC and TG thermal analysis.