Plastics play a vital role today in both industries and household appliances. Plastics are widely used for various applications, such as hand baggage, cool drink bottles, toys, food packages, components and containers of electronic equipment, modules of vehicles, office block segments, furniture, dress materials, etc. [1
]. The annual production of petroleum-based plastics was recorded as more than 300 million tons until 2015 [2
]. During the manufacturing of plastic bags, the emission of carbon and many other dangerous gases causes environmental concerns [3
]. Generally, polyethylene plastic films, such as low-density polyethylene (LDPE) and high-density polyethylene (HDPE), are being used to produce a variety of polyethylene plastic films, and the drawback of this plastic is its non-degradability. Over 1000 million tons of plastic were predisposed of as unwanted elements, and they might take several hundreds of years to decay. The percentage of plastics in municipal solid waste continues to grow rapidly. When plastic wastes are dumped in landfills, they interact with water and form hazardous chemicals, and the quality of drinking water may also be affected [2
]. Hence, efforts are taken to reduce the use of synthetic plastics and to promote bioplastics.
Biodegradable plastics are made from starch, cellulose, chitosan, and protein extracted from renewable biomass [4
]. The development of most bioplastic is assumed to reduce fossil fuel usage, and plastic waste, as well as carbon dioxide emissions. The biodegradability characteristics of these plastics create a positive impact in society, and awareness of biodegradable packaging also attracts researchers and industries [5
]. Decomposable plastics are widely used in a large variety of products where recycling of plastics is encouraged [6
]. Generally, the polymers are produced from the petroleum yields, so the production of these plastics needs additional fossil fuels, which causes pollution. At present, bioplastic signifies approximately one percent of the almost 300 million tons of plastic formed once a year. On the other hand, due to an increased demand for erudite biopolymers for various applications and products, the market is unceasingly rising. It is estimated that the overall bioplastics fabrication volume will be around 2.44 million tons in 2022. Bioplastics may be openly taken out from natural resources like lignins, proteins, lipids, and polysaccharides (e.g., starch, chitin, and cellulose) [7
Approximately 50% of the bioplastics used commercially are prepared from starch. The production of starch-based bioplastics is simple, and they are widely used for packaging applications [8
]. The tensile properties of starch are suitable for the production of packing materials, and glycerol is added into the starch as a plasticizer. The required characteristics of the bioplastics are achieved by fine-tuning the quantities of the additives. For trade applications, the starch-based plastics are regularly mixed with eco-friendly polyesters.
Most green plants produce this polysaccharide as an energy store. Human diets also consist of this carbohydrate, and it is contained in enormous volumes in primary foods, including rice, cassava, maize (corn), wheat, and potatoes. Among them, the most important starch is cassava starch, which contains more than 80% starch in dry mass. Starch is a carbohydrate that contains a great amount of glucose units, combined through glycosidic links. For the residents of tropical regions, cassava starch is the third most essential nutrition source. A biodegradable polymer from cassava starch for various applications was developed with different surface treatments. The various physical, mechanical, and thermal properties were addressed [10
]. Researchers prepared sugar starch-based bioplastic film for packaging applications [16
] with various reinforcements [17
Pure starch is white in color. The starch powder does not possess any specific taste or odor. Furthermore, pure starch cannot be dissolved in cold water or alcohol. It is non-toxic, biologically absorbable, and semi-permeable to carbon dioxide. The linear and helical amylose and the branched amylopectin are the two types of molecules present in starch [19
]. The amylose content may vary from 20 to 25%, while the amylopectin content varies from 75 to 80% by weight, depending on the type of plant. Amylopectin is a far greater molecule than amylose. If heated, starch would become soluble in water, and the grains swell and burst. Due to this, the semi-crystalline arrangement is also lost, and the minor amylose particles begin percolating out of the granule [20
], forming a network. This network compresses water and increases the mixture’s viscosity. This procedure is known as starch gelatinization, and amylose shows an imperative part through the initial stages of corn starch gelatinization [21
]. While heating, the starch becomes a paste and the viscosity is also increased. High amylose starch is a smart reserve for use as an obstruction in packing materials. Due to the low price, renewability, and having decent mechanical properties, it was used to produce decomposable films to partly or else completely substitute the plastic polymers [22
]. The percentage of amylose and amylopectin content in various starches is shown in Table 1
The tensile properties of the bioplastics would rise when the amylose content was increased [24
]. As rice and corn starches have a higher concentration of amylose content, the present work concentrates on this. Ghanbarzadeh et al. [25
] investigated the films produced from pure starch and concluded that these films were brittle and difficult to handle. This problem was solved by adding either citric acid or carboxymethyl cellulose with varying concentrations. The addition of glycerol may also reduce this drawback [26
]. Falguera et al. [27
] studied the bioplastics and concluded that the microbiological steadiness, bond, interconnection, wettability, solubility, pellucidity, and mechanical properties were the most critical properties in an edible coating. Muscat et al. [6
] studied the performance of low amylose and high amylose starches to form films. They determined the water vapor penetrability of the starch and starch–plasticizer films, using an amended ASTM E96-05 technique. Anti-plasticization behavior was not perceived when the starch films were plasticized by combining the glycerol and xylitol plasticizers. An increase in the concentration of plasticizers would lead to an increase in the tensile strength. Higher tensile strength is observed in films with high amylose content too.
Ghasemlo et al. [28
] investigated the performance of oil-coated starch and concluded that the mechanical and water vapor permeability properties were improved for the use of packaging applications. Fakhouri et al. [29
] investigated the performance of starch/gelatin films. Glycerol and sorbitol were used as plasticizers. The effect of processing techniques on the characteristics was also considered. They investigated four diverse processing methods, viz. pressing, pressing trailed by blowing, and extrusion trailed by blowing and casting. Schirmer et al. [30
] varied the amylose/amylopectin ratio of different starches and studied the physicochemical and morphological characterization. Borges et al. [31
] analyzed the properties of biodegradable films of different starch sources by changing the plasticizers. The operational properties and the microstructure morphology of potato starch/gelatin/glycerol edible biocomposite films were reported by Podshivalov et al. [32
]. They further investigated the phase separation mechanisms and their consequence on the size of starch granules during the drying process and the frictional, thermal, mechanical, thermal, optical, and water-barrier properties. Gómez-Heincke et al. [33
] manufactured bioplastics from the proteins derived from potato and rice. Glycerol with different concentrations was mixed with the proteins. They concluded that the increases in temperature would decrease the water absorption values when the rice protein-based bioplastics were plasticized with glycerol. Kulshreshtha et al. [34
] developed a corn starch-based material for building construction.
Luchese et al. [35
] used blueberry powder, corn starch, and glycerol to produce the bioplastic films by casting and concluded that the film could be used for food packaging or even for sensing food deterioration. Song et al. [36
] prepared biodegradable films, using diverse concentrations of lemon essential oil plus surfactants into corn and wheat starch film and described the microstructure, antimicrobial, and physical properties. Zakaria et al. [37
] used a solution casting technique to prepare the potato starch film, in which glycerol was the plasticizer. They studied the tensile and microstructure properties of the film by varying the mixing temperature. Zhang et al. [38
] investigated the impact of the various sizes of nano-SiO2
on the physical and mechanical properties of potato starch film.
Though extensive studies were carried out on the starch for packaging applications [39
], the study of hybrid starch based on corn and rice starch is not found in the literature for packaging applications. Hence, in the present work, both the corn and rice starches are combined, as they have a higher amylose concentration. This research aims to produce bioplastics from starch extracted from corn starch and rice starch. This would be very useful for developing countries where environmental problems have a significant impact on the economy. The bioplastics prepared from corn and rice starch were found to exhibit properties that are comparable to the already available commercial packaging materials. The bioplastics were also found to be soluble in water and degradable in soil by conducting respective tests, thereby making it environment-friendly. Such bioplastic formulations can be effectively used in packaging applications, due to their advantageous characteristics.