Biodegradable Composites with Functional Properties Containing Biopolymers

There is a major focus on natural biopolymers of bacterial, animal, or plant origin as ecological materials, replacing petrochemical products. Biologically derived polylactide (PLA), polyhydroxybutyrate (PHB), and polyhydroxyalkanoates (PHA) possess interesting properties, but they are currently too expensive for most applications. Therefore, researchers try to find other biopolymers that are both durable and cheap enough to replace plastics in some applications. One possible candidate is gelatin, which can be transformed into a thin, translucent film that is flexible and has stable and high mechanical properties. Here, we present a method of synthesizing a composite material from gelatin. For preparation of such material, we used gelatin of animal origin (pig skin) with the addition of casein, food gelatin, glycerin, and enzymes as biocatalysts of chemical modification and further extraction of gelatin from collagen. Compositions forming films with homogeneous shapes and good mechanical properties were selected (Tensile strength reaches 3.11 MPa, while the highest value of elongation at break is 97.96%). After administering the samples to microbial scaring, the composites completely decomposed under the action of microorganisms within 30 days, which proves their biodegradation.

Investigation of the Orientational Mechanical Properties of Biodegradable Extrusion Films Based on Polyolefins and Beet Pulp

The article discusses the possibility of obtaining biodegradable films based on polyolefins and beet pulp by the extrusion method. Biodegradable composites of two mixes with 15% and 25% beet pulp content have been obtained. Compounding was carried out on a twin-screw extruder, and then samples of biodegradable films were obtained by cast film extrusion. The influence of the vegetable filler particles’ orientation on the composites mechanical properties has been studied. It has been shown that composites mechanical properties significantly increase in the direction of polymer melt stretching.

Obtaining and characterizing biodegradable composites from agroenergetic residues

The study aimed to produce biodegradable composite materials from sugar cane straw and castor oil-based resin. The fibers were used in two sizes: 0 <fibers ≤4.27mm and 4.27 <fibers <10mm; resin in the proportion of 10%, 15% and 20%. The preparation method was carried out according to NBR 14810-2: 2018, using the compression molding technique at room temperature. Physical assays were carried out: moisture and swelling; mechanical assays: static bending and compression. The morphological assay was evaluated: scanning electron microscopy; and the composite biodegradability assay, over a three-month period. In order to validate the results, the statistic graphic was performed with significance at 5% by the F test, compared to the means by the Scott-knott test of the physical and mechanical treatments. The results showed that the values of the physical assays have met the minimum limits established by the standard, resulting in 8.72% swelling of the composite material. In the mechanical assay, the composite with less fiber and 20% resin was more resistant in the bend test with a capacity of 3.69 N/mm², and in the compression assay with 2.98 N/mm². The morphological analysis showed a wide interaction at the matrix/reinforcement interface. The biodegradation assay showed that over the months the composites started to lose weight, which shows the improvement of the degradation. Therefore, the composite produced has great potential in the market, it is considered biodegradable and of low cost compared to composites produced from synthetic fibers.

Sustainable bioproducts through thermoplastic processing of wheat gluten and its blends

Proteins are unique biopolymers extensively used for food and non-food applications. In addition to animal proteins such as poultry feathers that are generated as byproducts, plant proteins such as wheat gluten and soy proteins are also available in large quantities at reasonable cost. Since proteins are inherently non-thermoplastic, they cannot generally be processed by thermal treatments. Further, most proteins do not dissolve in common solvents either. Hence, most of the non-food applications of plant proteins require extensive chemical and physical modifications which increases cost and also reduces the biodegradability of the products developed. However, studies have shown that proteins including wheat gluten and keratin can become thermoplastic under specific conditions, when adequate pressure, heat and moisture are applied. Similarly, proteins can be made thermoplastic after physical or chemical modifications or by using plasticizers and compatibilizers. Based on such modifications, completely biodegradable composites with proteins as matrix and natural fibers as reinforcement and even all protein composites have been developed. Proteins as matrix offer new avenues to obtain sustainable, green composites with unique properties. Wheat gluten is a novel protein that has many distinct properties and characteristic behavior. Wheat gluten has been used for several non-food applications mostly by dissolving and solution casting which is a cumbersome process and restricted to only a few types of materials that can be developed. Alternatively, wheat gluten has been made thermoplastic using chemical, physical modifications or a combination of both. Several organic and inorganic additives, crosslinkers and plasticizers have also been added to ensure thermoplastic processing of wheat gluten and to obtain products with properties suitable for commodity applications. In this review, we discuss the processes and possibility of converting wheat proteins into thermoplastic products and as matrix for composites and the properties and applications of the wheat gluten based thermoplastics.

Assessment of Dimensional Stability, Biodegradability, and Fracture Energy of Bio-Composites Reinforced with Novel Pine Cone

In this investigation, biodegradable composites were fabricated with polycaprolactone (PCL) matrix reinforced with pine cone powder (15%, 30%, and 45% by weight) and compatibilized with graphite powder (0%, 5%, 10%, and 15% by weight) in polycaprolactone matrix by compression molding technique. The samples were prepared as per ASTM standard and tested for dimensional stability, biodegradability, and fracture energy with scanning electron micrographs. Water-absorption and thickness-swelling were performed to examine the dimensional stability and tests were performed at 23 °C and 50% humidity. Results revealed that the composites with 15 wt % of pine cone powder (PCP) have shown higher dimensional stability as compared to other composites. Bio-composites containing 15–45 wt % of PCP with low graphite content have shown higher disintegration rate than neat PCL. Fracture energy for crack initiation in bio-composites was increased by 68% with 30% PCP. Scanning electron microscopy (SEM) of the composites have shown evenly-distributed PCP particles throughout PCL-matrix at significantly high-degrees or quantities of reinforcing.