Every day in our daily lives, almost every artificial product including food wraps and toys are made of plastics, which are considered as the most versatile materials in the world. However, these disposable plastics are severely detrimental to the natural environment, regarding their involvement of hazardous chemical substances in plastic fabrications for stabilizing or colorant purposes. These plastics take centuries to decay in nature because the inter molecular bonds prevent the plastics to corrode or decompose. So, bioplastics, also known as the starch-based plastics, were introduced as alternative source for conventional plastics.
Bioplastics are organic material, synthesized from renewable feedstocks including corns, potatoes, and more. They are fully biodegradable that can be used in composting and they are available for producing any products, such as cups, bags, bedding, furniture, as conventional plastics can. Hence, the scientists utilized the bio-based materials and further developed a sustainable method to manufacture bioplastics that is globally beneficial to the environment and economy. (Clerk, 2018)
Accordingly, bioplastics are created in long polymer chain, which 04H are synthesized by the large molecules of monomers.
The main material of bioplastic is the biomass starch that are mixed together with process. There are many forms of bioplastics, PHB, PA 11, PLA, but PLA is considered as the best form of bioplastics, as they are economically beneficial, regarding its low cost for production. So, the polylactide acid (PLA) is the thermoplastic monomers obtained from renewable sources like corn starch and sugar cane. The chemical formula of PLA is (C3H302)n, while 'n' indicates the molecule in parenthesis that can be repeat to form a long chain-like molecule of polymer, which are made up of countless monomers bonded together.
The monomer of PLA consists of two oxygen atoms bonded to one methyl group that is derived from lactic acid formed by fermented corn, cassava roots, and other vegetables. Additionally, the monomer compositions of PLA and lactic acid are very similar. Also, the chains of polymer are capped off by the end of PLA molecules which consist of two oxygen atoms, and a hydroxide ion on each side. The chemists can determine the length of polymer chains by inserting these caps and alter the number of monomers in a polymer through the degree of polymerization, which allows them to have different properties, making the bioplastic to become either rigid or flexible or heat resistant. (Johnson, 2018)
Correspondingly, there are two methods of producing polylactide acid from lactide acid, while the first method is using the cyclic lactide acid dimer of lactide as the main stage that yields PLA with higher molecular weight and the second method is direct polymerization of lactic acid. The first method is more advantageous regards its higher output of PLA. First, the 300L scale fermenter will ferment the biomass for lactic acid production. (Larsson, 2018) During the pilot scale electrodialysis process, the ions will be separated from an aqueous solution and purify the lactic acid. The bipolar exchange technique will be used to exchange membranes with cation and anion exchange to rearrange its ion through the direct current driving force. Then, in the lactide conversion process, the purified acid will be added to the reactor with stirring, vacuum-pumping, and cooling system. The temperature will increase up to 150 °C to form oligomer and remove unnecessary liquid until no water is distilled. In polymerization, the water will be completely removed and the pure form of oligomer will be obtained. The catalysts including amino propanoic acid (C3H12N202) will be added to haste up the reaction through conventional heating, which will finally produce a large molecular weight polylactic acids. (Richardson, 2018)
To compare the basic chemical properties of plastics and bioplastics, both the plastics and bioplastics are made of polymer. Though, polymers of plastics consist of big molecules made of repeating units of monomers and most of them contain about 500 to 20,000 units. Plastics are also synthesized based on the polymerization reaction which joins up these countless monomers. However, these conventional plastics are made of crude oil that undergoes through a chemical reaction to produce monomers that can be formed in polymers, which produce pollutants and CO2 during the manufacture process. On the contrary, bioplastics are made of sugar present in plants into plastics, instead of using crude oil, to produce a large amount of polylactide acid or other materials for producing bioplastics. So, they do not emit much CO2 compared to conventional plastics. (San Clements, 2018)
Since bioplastics are made of renewable raw materials, they are highly beneficial for minimizing pollution from plastic pollutants including dioxin emission, but there are some drawbacks of bioplastics that is required to be remodified by the scientists. The most obvious advantage is that bioplastics could reduce CO2 emission and carbon footprint as biodegradable plastics emit only 0.8 metric tons of CO2 compared to conventional plastics that emit 3.2 metric tons. In addition, bioplastics are economically beneficial as they are comparatively cheap then normal plastics particularly with overwhelming oil prices. They will also reduce wastage as bioplastic do not cause much toxin run-off. Plus, the valuable raw materials could be recycled into other products so bioplastics are considered as multiple end of-life points. (Rogers, 2018)
However, maximizing the use of bioplastics by million tons will require a huge amount of renewable feedstock while people are highly dependent on them. If the bioplastics transform into multi trillion-dollar industries, they may require lots of agricultural land to create food stocks, which is demanded for keeping up their production. Such countries like Australia where do not have any industrial composting facilities may transport the bioplastics containers from the grocery stores to end up in the landfilling areas. So, bioplastics have a risk of contamination because they should not be mixed up with the conventional plastics. If one person does not distinguish and mix bioplastics and plastics while recycling, the bioplastics will be no longer usable as they become contaminated, which will soon end up in the land landfills and increase the wastage amount. Furthermore, bioplastics could also emerge engineering issues as they are plant-based and derived from organic sources but some organic plants may be sprayed with pesticides or fertilizers, which excludes the point of making biodegradable plastics that releases hazardous chemical. (Tracey, 2018)
Even though, bioplastics have outstanding advantages to minimize the dependency of fossil-fuel based resources, reduce greenhouse gas emissions, and enhance the resource efficiency. Furthermore, scientists initiated that bioplastics could be the essential part of the economy, which worth 2 trillion euros of yield annually and account 22 million jobs in the world. The industries of biodegradable products have expanded into diverse sectors, including composting bags, cutlery, food packaging, and plant pots. So, applications in the biomedical field, such as surgical fixation, controlled drug delivery, and tissue-engineering scaffolds, are also growing rapidly. For example, a clothing industry conceptualized the polymerization techniques of producing biopolymers to design and manufacture wedding dresses. Hence, the usage of bioplastic has been generalized in packaging, clothing, and medical industries, which impacted them to boost their domestic incomes as well. (Woodford, 2018)
Overall, the biodegradable and renewable alternatives for conventional plastics are saving the world to reduce both plastic waste and the world's depending limited amount of fossil fuels. Regardless of the disadvantages of bioplastics, chemical engineers and scientists are still working onto improve the qualities of bioplastics or striving to come up with a new product to replace the use of coventional plastics. Thus, the proposal of bioplastics exemplifies how utilizing the phenomenon of polymerizing chemical reaction could sustain the world and reveals the scientists' capability to evolve the field of chemical engineering to develop environmentally sustainable and economically beneficial chemical products than bioplastics.