This study describes the development of a renewable and biodegradable biopolymer-based hydrogel for application in agriculture and horticulture as a soil conditioning agent and for release of a nutrient or fertilizer. The novel product is based on a combination of cellulose derivatives (carboxymethylcellulose and hydroxyethylcellulose) cross-linked with citric acid, as tested at various concentrations, with acid whey as a medium for hydrogel synthesis in order to utilize the almost unusable by-product of the dairy industry. The water uptake of the hydrogel was evaluated by swelling tests under variations in pH, temperature and ion concentration. Its swelling capacity, water retention and biodegradability were investigated in soil to simulate real-world conditions, the latter being monitored by the production of carbon dioxide during the biodegradation process by gas chromatography. Changes in the chemical structure and morphology of the hydrogels during biodegradation were assessed using Fourier transform infrared spectroscopy and scanning electron microscopy. The ability of the hydrogel to hold and release fertilizers was studied with urea and KNO3 as model substances. The results not only demonstrate the potential of the hydrogel to enhance the quality of soil, but also how acid whey can be employed in the development of a soil conditioning agent and nutrient release products.

Interfacial localization of conductive fillers in a cocontinuous immiscible polymer blend is an efficient way of improving the electrical and thermal conductivities of the composite. Conductive path formation at the interface of a cocontinuous structure is expected to provide high conductivity by a smaller amount of the filler, which can be used for applications as conductive materials. In this study, biobased poly­(lactic acid) (PLA) was blended with poly­(trimethylene terephthalate) (PTT) to make the cocontinuous immiscible polymer blend. Poly­(glycidyl methacrylate) (PGMA) was grafted on reduced graphene oxide (rGO) to make a PGMA-grafted rGO (rGO-PGMA). The epoxy group of GMA on rGO-PGMA reacted with the end groups of both PLA and PTT and localized at the interface between PLA and PTT by a two-step blending procedure to form the conductive path between PLA and PTT. From transmission electron microscopy observation, it was found that rGO-PGMA localized between the interface of PLA and PTT. Both electrical and thermal conductivities of the composite were improved, which was confirmed by the electrical volume resistivity and thermal diffusivity measurements, compared with neat polymers and other blends.

Polyurethane-based nanofibrous structures can be used as adsorbents for arsenic in water. Their adsorption capacity can be significantly increased by doping the structure with ferrous sulphate.

Magnetorheological elastomers (MREs) are widely studied materials, however not many research papers have been initiated on their reprocessing. This paper presents a new type of recyclable MRE which is composed of thermoplastic polyurethane (TPU) and carbonyl iron particles (CI). The chosen TPU can be processed by injection moulding (IM) and allows several reprocessing cycles. Numerous types of injection moulded MREs, which have undergone several recycling cycles, have been prepared. The effect of thermo-mechanical degradation on the recycled MREs has been investigated. An apparent decrease in molecular weight of all examined matrices during reprocessing cycles was observed. These changes are attributed to the intermolecular bonding between the hydroxyl groups on the surface of the CI particles and the matrix. An evaluation of the mechanical properties of the matrices was conducted via tensile strength tests. Generally, MREs suffer from minor degradation due to reprocessing, yet the rheological and piezoresistivity properties are at an acceptable level despite using 100% of recyclates while in real applications only up to 30% of recycled material is used.

This study investigated the effect of natural antioxidants inherent to beetroot (Beta vulgaris var. Vulgaris) on the ageing of environmentally friendly plastics. Certain properties were examined in this context, comprising thermal, mechanical, and morphological properties. A visual evaluation of relevant changes in the given polymers (polylactide and polycaprolactone) was conducted during an ageing test in a UV chamber (45 °C, 70% humidity) for 720 h. The films were prepared by a casting process, in which samples with the extract of beetroot were additionally incorporated in a common filler (bentonite), this serving as a carrier for the extract. The results showed the effect of the incorporated antioxidant, which was added to stabilize the biodegradable films. Its efficiency during the ageing test in the polymers tended to exceed or be comparable to that of the reference sample.