Biocomposites Based on Plasticized Wheat Flours: Effect of Bran Content on Thermomechanical Behavior

Biocomposites Based on Wheat Flour with Urea-Based Eutectic Plasticizer and Spent Coffee Grounds: Preparation, Physicochemical Characterization, and Study of Their Influence on Plant Growth

In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw extrusion and then thermocompression. Their physicochemical characterization included mechanical tests, dynamic mechanical thermal analysis (DMTA), and sorption tests. XRD analysis revealed that the eutectic plasticizer led to a high degree of WF amorphization, which affected the physicochemical properties of TPWF. The results indicated that it was easy for the TPWF biocomposites to undergo thermocompression even with a high amount of the filler (20 pph per flour). The addition of the cf into TPWF led to an increase in tensile strength and a decrease in the swelling degree of the biocomposites. Biodegradation tests in soil revealed that the materials wholly degraded within 11 weeks. Moreover, a study of cultivated plants indicated that the biocomposites did not exhibit a toxic influence on the model rowing plant.

The Bran and Grain Grinding Level Affect the Tensile Characteristics of Bioplastics Derived from Wholegrain Wheat Flours

The mechanical performance of thermoplastic bulk samples obtained by plasticizing wheat flours differing in grain hardness, alveographic parameters, absence or presence of bran, and grinding level was assessed. Grains of four bread wheat (Triticum aestivum L.) cultivars (Altamira, Aubusson, Blasco, and Bologna) were milled with the aim of producing single-cultivar refined flour (R), or wholegrain flour with fine (F) or coarse (C) grinding. The flours were plasticized, injection molded and tested for tensile properties. The results confirmed that the presence of bran increased the strength (σ) and reduced the elongation at break (ε) of thermoplastics obtained from the flours of each cultivar. The grinding level had an effect, since σ was higher and ε was lower in F than in C samples. SEM analysis of samples revealed that the bran and its texture affected the exposure of starch granules to plasticizer. Composting experiments also revealed that the formulations are able to disintegrate within 21 days with a mass loss rate higher in plastics from F than C flours, while germination tests carried out with cress seeds indicated that it takes two months before the compost loses its phytotoxic effects. Overall, the refining and bran particle size of wheat flours, besides their gluten composition and baking properties, represent novel choice factors to be considered when tailoring the manufacturing of plastic materials for selected requirements and uses.

Study of the Degradation of a TPS/PCL/Fique Biocomposite Material in Soil, Compost, and Water

The degradability of the biocomposite produced from a binary mixture of thermoplastic banana starch (TPS) and polycaprolactone (PCL) reinforced with fique fibers (Fs) was evaluated in three different environments (soil, compost, water). An experimental design with two factors (soil and compost) and three levels (5, 10, and 20 cm) was used, with additional tests for a third aqueous environment (water from the lake of the Universidad del Valle) at a depth of 20 cm. The biocomposite was prepared from the implementation of a twin-screw extrusion process of the binary mixture TPS/PCL and fique fibers (54, 36, and 10% composition, respectively), followed by hot compression molding, and after that, generating ASTM D638 type V specimens using a stainless-steel die. The specimens were dried and buried according to the experimental design, for a total experimental time of 90 days, and removing samples every 30 days. After 90 days, all samples showed signs of degradation, where the best results were obtained in the compost at a depth of 20 cm (34 ± 4% mass loss and a decrease in tensile strength of 77.3%, which indicates that the material lost mechanical properties). TPS was the fastest disappearing component and promoted the degradation of the composite material as it disappeared. Finally, the aqueous media presented the lowest degradation results, losing only 20% of its initial mass after 90 days of the experiment, being the least effective environment in which the biocomposite can end up.

Sustainable Management of Organic Waste and Recycling for Bioplastics: A LCA Approach for the Italian Case Study

The collection of the organic fraction in Italy recorded significant growth in the decade 2010–2019 (+74%) due to both the increase in the spread of separate waste collection as well as the increase in the biological treatment plants of municipal waste. However, within the organic fraction there remains a share of non-compostable material (NCM) (plastic, glass, aluminum, etc.), equal to ~5% of the total, which affects the efficiency of composting practices as well as decreasing both the yield and the quality of the final compost, causing a portion of organic material to be subtracted from composting and ending up in landfills. Therefore, the purpose of this work is to evaluate how the sustainability of the organic fraction collection and the amount of compost obtained in the composting plants could improve, following the use of biodegradable and compostable bioplastic bags (shoppers), in replacement for conventional plastic ones. The Life Cycle Assessment (LCA) and Carbon Footprint (CF) methodology was used for the assessment, comparing two different scenarios based on data relating to the collection of the organic fraction in Italy in 2019. Scenario 1 relates to the composting of organic material that also contains plastics, bioplastics, and non-compostable materials, while in scenario 2 the share of plastic material in the first scenario has been entirely replaced by bioplastics. The results show that scenario 2 assumes the lowest values for 15 impact categories out of the 18 analyzed, and, among these, in three categories it assumes negative values: ozone formation-terrestrial ecosystems (−1.64 × 10−2 kg NOX eq), ozone formation-human health (−8.50 × 10−3 kg NOX eq), and fossil resource scarcity (−4.91 × 102 kg oil eq). Furthermore, scenario 2 has a negative carbon footprint (−3.80 kg CO2 eq) compared to scenario 1 (79.71 kg CO2 eq), and in general it is the most sustainable scenario as a direct consequence of the greater amount of compost obtained (307.4 kg vs. 269.2 kg).