PASCAL Database

Rigid polyurethane (PU) foams were modified with rowanberry/vermiculite fillers. The impact of fillers on selected properties of composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive and flexural strength, toughness), thermal properties (temperature of thermal decomposition stages, char residues at 600°C), flame retardancy (ignition time IT, total heat, and smoke release THR and TSR, maximum average rate of heat emission MARHE) was investigated. The results show that the incorporation of rowanberry/vermiculite fillers improves the properties of polyurethane foams. For instance, compared with the reference foam, modified foams showed increased synthesis times and higher values of apparent density, which then influenced the mechanical properties. Compared to the unmodified foam, modified foams showed an improvement in compressive strength (up to 7.8%, measured parallel to the foam growth direction), flexural strength (up to 5.8%), and toughness (up to 6.8%). Most importantly, the modified foams showed improved thermal stability and flammability parameters such as elongated ignition time, lowered values of THR, TSR, and MARHE parameters.

Management of heavy metal-contaminated soil under drought and other harsh hydrological conditions is critical for protecting soil ecosystem services. In this study, we examined the effect of pig manure digestate-derived biochar as a soil amendment (15 t ha−1) with N fertilizer (180 kg ha−1) on soil and plant heavy metal levels and nutrient availability under various moisture regimes (optimal moisture ~15%, drought condition ≤5%, and flooded condition ≥35% wt.). It was observed that biochar applications significantly decreased heavy metals in the spring wheat plants, lowering Cr by 90%, Ni by 50%, Cd by 9% and Pb by 34% compared to non-biochar (control) treatments. However, the pig digestate-derived biochar increased heavy metals in soil under all moisture regimes, increasing soil Cr by 21%, Ni by 43%, Cu by 55%, Zn by 70%, and Pb by 12%. The availability of macroelements also increased with the biochar applications under the optimum moisture regimes in both soil and plants, increasing Mg2+ by 11%, P by 4%, K+ by 50%, and Ca2+ by 56% in the soil, and Mg2+ by 13%, P by 69%, K+ by 29, and Ca2+ by 39% in plants. Biochar addition also improved chlorophyll fluorescence (CF) levels in the crop for the entire season (12th to 62nd day) and the aboveground crop biomass and dry matter contents both increased. Consequently, the use of pig manure digestate-derived biochar with N fertilizer under normal moisture conditions was able to reduce heavy metal availability to plants and thus could be used in contaminated soils to maintain better crop growth and development.

Water-blown polyurethane foams have some drawbacks such as intensive shrinkage, relatively high density, skin peeling phenomena post blowing, and longer demold time. These drawbacks can be partially or fully eliminated by varying the characteristics of the main components. Therefore, aliphatic polyester rapeseed polyol produced via fermentation was mixed with common modifiers, such as propylene glycol, rapeseed glycerine, and corn starch. The impact of molecular weight and hydroxyl values of their mixtures was evaluated by testing the obtained bio-based polyurethane foams for reaction kinetics, some structural parameters, density, compressive strength, structure morphology, the change in thermal conductivity, dimensional stability, and long-term water absorption by total immersion. Keeping in mind the generation of carbon dioxide during foaming, it was interesting to study the change in the thermal conductivity after 1 day and 30 days after foam production. Propylene-glycol-modified foams had competing dimensional stability, reduced density, faster foam curing capability, lowest water absorption, and shortest demold time due to the obtained open cell structure. Rapeseed-glycerine-modified foams had better cross-linking capability, slower aging of thermal conductivity, and higher compressive strength. Corn starch-filled foams did not change the reaction start time, had lower density, better thermal conductivity, and higher closed cell content.