Study on Physicochemical Properties of Biocomposite Films with Spent Coffee Grounds as a Filler and Their Influence on Physiological State of Growing Plants

• Published in: International journal of molecular sciences Vol. 24; no. 9; p. 7864
• Main Authors: Zdanowicz, Magdalena, Rokosa, Marta, Pieczykolan, Magdalena, Antosik, Adrian Krzysztof, Chudecka, Justyna, Mikiciuk, Małgorzata
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26.04.2023; MDPI
• Subjects: Addition polymerization; Biocompatibility; biocomposites; Biodegradation; Biological products; Biomaterials; Biomedical materials; Choline; Coffee; coffee grounds; Compacting; Composite materials; Compression; deep eutectic solvents; Excipients; Extrusion molding; Extrusions; fertilization; Fillers; Glycerol; Investigations; Mechanical properties; Nitrogen; Phthalates; Physicochemical properties; Physiological aspects; Physiology; Polymers - chemistry; Pressure molding; Soil; Soil investigations; Starch - chemistry; Temperature; Tensile strength; thermoplastic starch; Urea; Poland; coffee grounds; thermoplastic starch; fertilization; deep eutectic solvents; biocomposites; urea
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24097864

The aim of the study was to plasticize corn starch with two selected urea (U)-rich plasticizers: choline chloride (CC):U or betaine (B):U eutectic mixtures at a molar ratio of 1:5 with a presence of spent coffee grounds as a filler. The biomaterials were prepared via a solventless one-step extrusion method and then extrudates were thermoformed using compression molding into sheets. The materials were characterized using mechanical and sorption tests, TGA, DMTA and FTIR. Additionally, a study on the biodegradation and remaining nitrogen content in soil was conducted. For the first time, an influence on physiological state of growing plants of the materials presence in soil was investigated. The addition of the coffee filler slightly increased the mechanical properties and decreased the swelling degree of the materials. The DMTA results indicated that biocomposites were easily thermoformable and the high filler addition (20 pph per polymer matrix) did not affect the processability. According to the biodegradation test results, the materials disappeared in soil within ca. 70 days. The results from this study on the physiological state of growing plants revealed that the materials, especially plasticized with CCU, did not exhibit any toxic effect on the yellow dwarf bean. The percentage of total nitrogen in the soil substrate in comparison with the control increased indicating an effective release of nitrogen from the TPS materials into the substrate.