1. Introduction
Plastics and other items made of plastic are created from a variety of organic substances that are flexible. Most organic polymers with a high molecular weight and other materials are compounds of plastics (fillers, colors, and additives); usually, they are created synthetically. When referring to unfilled and uncolored plastics rather than compounds, the phrase “natural plastics” is occasionally used in the industry. Every year, 12 million tonnes of plastic end up in the ocean. Of these, 9.5 million tonnes reach the ocean via land, with 1.75 tonnes coming directly from the fishing and shipping industries [
1]. It is estimated that there are 51 trillion microscopic fragments of plastic, comprising around 269,000 tonnes. As evidenced by the endurance of natural materials, it is anticipated that since the 1950s, some 1 billion tonnes of plastics have been dumped, some of which may endure for centuries or perhaps substantially longer [
2].
Based on how they respond to heat, all plastics may be categorized into the following two basic groups: thermosetting and thermoplastic. Thermoplastics are polymers that can be heated, melted, and molded into the desired shape before cooling. The produced thermoplastic softens and remelts when heated. Polyacrylates, polyesters, polyolefin, polyamides, etc., are examples of well-known thermoplastics. In addition to other products, these polymer materials are used to make packaging, disposable utensils, carpets, lab equipment, apparel, and other items [
3]. Unlike thermoplastics, thermosetting polymers are permanently stiffened by the curing of soft solid or liquid resins. Curing is brought on by heat or radiation, and it can be accelerated by adding catalysts. Considerable research has been performed on bioplastics, which are currently the subject of significant research among scientists all over the world due to their susceptibility to water exposure, lack of compatibility, and lower melting point than polymers derived from petroleum [
4]. Bioplastics are made from biological or biodegradable components, such as corn starch, food scraps, or even agricultural byproducts. Bio-based plastics are simple to break down in a natural environment, as compared to petroleum-based plastic. They are made from fossil fuels and petrochemical polymers. These results are less negative environmental impacts and global sustainability. The durability of plastics, which is one of their greatest benefits, is also one of their greatest drawbacks as follows: the rate of disintegration (biodegradation) does not correspond to their intended service life, leading to environmental accumulation [
5,
6].
Compared to commercial plastics used to make polyethylene bags and containers, bioplastics are typically produced at a faster rate [
7]. These bioplastics aid in lowering greenhouse gas emissions to reduce environmental pollution [
8]. Nevertheless, bioplastics deteriorate gradually depending on the environment’s soil quality [
9,
10]. Starch, plasticizers, and fillers are the main components of bioplastics in general [
11]. Starch-based polysaccharides are thought to be a cost-effective material since they contain a mixture of amylose and amylopectin [
12,
13,
14]. Starch is commonly available and can be found in foods including rice, corn, wheat, potatoes, tapioca, and others; therefore, thermoplastic starch is their primary usage (TPS). Amylopectin and amylose of glucose molecules make up starch, and several types of starches have variable amounts of amylose and amylopectin. Additionally, tensile strength and elongation both increase as the amylose level rises. Plasticized starch will replace synthetic polymers as a material. Tensile strength will rise as molecular interactions and hydrogen bonding intensify. The rigid films’ flexibility will suffer if the tensile strength is too great. Due to package degradation brought on by the environment or product moisture, bioplastic solubility for food packaging applications must be minimal [
15,
16,
17,
18]. Mechanical qualities are significant for applications involving food packaging. A sample’s tensile strength varies depending on the type of polymer used, the processing environment, the additives, and the blends. Depending on how it is processed and stored, this will alter. When creating bioplastic samples, several agents, such as additives, catalysts, antioxidants, fillers, and so forth, are added to improve the qualities of the bioplastics [
19,
20]. According to the tensile and mechanical properties, the main purpose of the fillers is to increase the strength of the bioplastic compound. Starch content is combined to create composite bioplastics, which are formed of the following two major materials: matrix and reinforcement [
21,
22]. Due to their hydrophilic characteristics, glycerol and sorbitol are used as plasticizers because they have excellent mechanical qualities.
Starches that are compatible with plasticizers, like sorbitol and glycerol, which are inexpensive and abundantly available, are used in the blends of bioplastics. The recyclability of the material is another important factor, and the created bioplastic samples have better mechanical qualities that are comparable to conventional plastics [
23,
24]. Compared to bioplastics based on individual starch content, the mechanical qualities of composite bioplastics have higher mechanical strength [
25,
26]. The water solubility and mechanical qualities should be compared to the standard plastic material to replace it for applications such as food packaging [
27,
28,
29]. The composite bioplastics have different starch contents, including rice, corn, and tapioca. The cassava plant, which is readily available, inexpensive, and has qualities like being odorless and colorless, is typically used to extract tapioca starch [
30,
31]. The amylose and amylopectin content for tapioca starch is 21.2% and 78.8%, respectively. The sample of cassava-based bioplastic is translucent and white in color, and it has a better level of biodegradability. The tensile strength increases with an increase in tapioca starch. The bioplastic sample made of maize starch is transparent. Composite-based bioplastic degrades much more slowly than corn-based bioplastic, and the material’s capacity to degrade is also impacted by humidity. The degradation of composite bioplastics made of cassava and corn starch and cassava-based bioplastics is best at 15% relative humidity. A cassava-based bioplastic degrades substantially more effectively than a corn-based bioplastic when the relative humidity is below 15% [
32,
33,
34]. Understanding the structure and characteristics of the bioplastic compound is made easier by the morphology of the starch content [
35,
36]. The quick degradation of bioplastic materials will happen as a result of their weak integrity [
37]. Above this point, the tensile strength will drop, with an increase in starch content of around 5%, producing an increase. The glycerol level of about 1.5% will be effective up to a point where the plasticizing capability starts to decline. The glycerol will have limited solubility and swell in water if it is kept at 5–10%. Furthermore, strong mechanical properties and resistance were also attained [
38,
39,
40]. The innate nature of protein-based (β-glucans) bioplastics has increased their performance and improved their tensile strength, water vapor permeability, water retainability, and thermal stability under atmospheric conditions. These grains of protein are strongly bonded together through hydrogen bonds that exhibit the enhanced properties of the bioplastics [
41,
42].
High starch concentrations resulted in a loss of the tensile and mechanical characteristics of albumen/starch-based bioplastic blends. Also, it was observed that the transparency of the film reduced significantly when the starch concentration increased [
43]. The bioplastic film made from the potato and rice protein compositions has shown an acceptable range of viscoelastic and water absorption properties that would be utilized in the food packaging industry. The glycerol concentration and thermo molding temperature treatment seem to have an impact on the viscoelastic characteristics of rice protein-based bioplastics. Bioplastics made from potato protein, however, did not appear to be affected [
44,
45]. As per the researcher, a microbial enzyme, on which use of an aqueous solution with a level exceeding 10%, is required for the bioplastic to prevent microbial growth; therefore, it appears to be the most resilient microbe as a result. Protein-based bioplastics have been studied; however, they are unable to stop formic acid from migrating to water. Gradually moving away from the WG-based matrix, this material is ideal for long-term applications; moreover, essential oil-infused bioplastics may even prevent the growth of germs. These enzymes assist in the creation of an antimicrobial environment inside the container if they are not in direct contact with them [
46,
47,
48]. Recent research has been established on bioplastics to develop the current trend in the bioplastics market. The major contributing factors, such as starch, PLA, and PHA on bioplastic production, provide future implementing ideas onto the market. Bioplastics are favored more in the food packaging industry [
49,
50]. From research and studies of lateral years on plastics, it is proven that for the next ten years, the bioplastics industry is anticipated to be dominated by non-biodegradable bioplastics, such as bio-based PE, PP, and PET that can be recycled in current systems [
51,
52].
Whey protein bioplastics of biopolymers: natural latex and egg white albumin on combining these and fabricated by compression molding. Water is added as a plasticizer in that mixture. It is found that the addition of about 10% latex and albumin to the whey-based bioplastics would increase its toughness properties and also enhance the characteristics of whey-based materials without compromising their strength and stiffness [
27]. This article contemplates that current trends in bioplastics are focused on bio-based technology production rather than conventional methods. Such resource technologies were genetically modified organism cell lines and biomass refinery methods. All these modern bio-based aspects were meant to drive sustainable industry development and regulate the ability of bioplastics to degrade at a certain rate [
53,
54]. Incorporating glycerol with larger-sized plasticizers, such as xylitol or sorbitol, in the bioplastic film results in the stickiness of the film, promoting separation onto double wall areas and indicating improved tensile strength, stiffness, and oxygen-regulating properties. Thermoplastic starch-blown films having high quantity of plasticizers would not be recommended due to their high water/moisture sensitivity and surface stickiness [
55]. In biochemical and soil conditions, PLA breaks down quickly for about a few weeks [
56]; however, because of its high price and excessive brittleness relative to typical synthetic materials, it is not extensively utilized. Plastics that have poor mechanical characteristics are typical of PLA composites made with other natural polymers. The natural polymer and the PLA matrix were not bound well together. Recently, polyethylene glycol, polyethylene, glucose, monoesters, and partial fatty acid esters have been utilized to enhance the flexibility and impact resistance of PLA. Many compounds, including citrate esters, have been tested as plasticizers. As a result, PLA polymers’ properties and possible uses have been identified and they are greatly improved [
57,
58]. The starch is promoting a pathway for the manufacturing of bioplastics, which could result in the creation of materials with exponentially better performance in the food packaging industries. It follows that the properties of various materials are connected to how well starch materials cling to them and how they are compounded. As thermoplastics are processed using extrusion technology, which is one of the basic techniques that has been investigated and developed to treat starch-rich products [
59]. The solubility of the substance and the values of the intrinsic viscosity of the synthetic component both demonstrate the remarkable transformation of the structure of the unstabilized sample during photo-oxidation. The positive effect of the stabilizers on the durability of produced biodegradable polymer would have been interpreted by the amount of absorbance proportionate to a lower wavelength region of these compounds [
60]. Biopolymers are polymers derived from renewable biological sources, such as plants, animals, and microorganisms. They offer several advantages over traditional petroleum-based polymers (plastics) and have gained increasing interest in various applications due to their eco-friendly and sustainable nature. Biodegradability, compostability, energy-efficient processing, reduced dependence on fossil fuels, non-toxic, and safety are some of the key advantages of using biopolymers. While biopolymers offer many advantages, it is important to note that their adoption is not without challenges. Issues such as cost, scalability, performance, and competition with well-established petroleum-based polymers remain considerations for widespread implementation. Nonetheless, ongoing research and technological advancements continue to address these challenges and further expand the use of biopolymers in various industries.
Figure 1 illustrates the lifecycle of the bioplastics.
This investigation focuses on the use of renewable waste from organic agricultural sources, such as corn starch, rice starch, and tapioca starch, to make bioplastics. Using widely available, plentiful, biodegradable, and renewable natural waste as reinforcing fillers, can help reduce the risks and problems associated with conventional plastics as well as the degradation of mechanical properties.