Fossil fuel challenges are an ever-growing predicament worldwide. One of the methods to address this flaring challenge is recycling used polymeric materials. In fact, practical techniques for material and chemical recycling have been devised and put into practice, and plastic recycling is becoming increasingly popular globally. Although plastic recycling needs to be promoted more actively, it cannot be the only solution to serious plastic pollution. Not every time can all the used plastics be recovered. Biodegradable polymers would be essential under such circumstances.
In addition, it can be noted that recycling plastic waste requires a significant amount of thermal energy, whether it be chemical or material recycling; waste plastic cannot be recycled indefinitely and will eventually be burned or buried in the ground. When these factors are taken into account, the necessity of biodegradable polymers that are regenerated by microorganisms without consuming thermal energy is understood.
Biodegradation by Microbes
The effectiveness of microbial biodegradation is low compared to the production of plastic trash, even if it seems sustainable. Additionally, microbial consortia, rather than a single species or strain, biodegrade a variety of natural and even synthetic polymers because the biodegradation of a single polymer is typically a difficult process involving several enzymes. A microbial assemblage will, therefore, probably offer a faster rate of biodegradation. There was a need for a niche that would increase the accessibility and bioavailability of plastic waste to dynamic microbial consortia in order to get beyond these restrictions.
Recent studies have revealed that some invertebrates, particularly insects, have microbial symbioses in their digestive tracts that aid in breaking down diverse natural polymers that resemble the structural configurations of manufactured polymers. As a result, the insect gut microbiome provided a quick alternative for degrading plastic, and greater breakdown inside the gut microbiome was indicated by plastic-degrading bacteria working in conjunction with gut enzymes.
Diseases transmitted by insects are a problem for the public's health. Individual protection is the primary strategy for preventing many of these diseases because there is neither a vaccine nor a curative cure for them. Today, there is a growing effort to develop insect repellents from natural sources, such as essential oils, in place of synthetic compounds. However, most of them are ineffective when compared to repellents made of synthetic materials. Therefore, in order to produce fresh insect repellent formulations, it is necessary to solve problems such as reducing the skin penetration of synthetic repellents or even raising the efficiency of natural repellents.
Polymer-based formulations, in this situation, permit entrapping active components and offer release control. Encapsulation into hydrogels, cyclodextrins, polymeric micelles, or micro/nanocapsules is a method for changing the physicochemical characteristics of the encapsulated molecules. These methods are more effective at extending the duration of repellency and decreasing dermal drug absorption, enhancing the safety profiles of these items. They can modify fabrics for personal protection, create topical formulations, or package food. The primary synthetic and natural insect repellents, as well as their polymeric carrier systems and possible uses, are discussed in this paper.
Due to its capacity to create intricate shapes and geometries that were challenging to accomplish with conventional manufacturing methods, 3D printing is a type of additive manufacturing technology that has recently gained popularity.
The need for raw materials for 3D printing is growing as a result. In order to achieve Sustainable Development Goal No. 12, which is to encourage sustainable consumption and production patterns, it is essential to ensure responsible raw material utilization for 3D printing.
Natural Biopolymer Chitosan in Insects
Chitin, a polysaccharide in the exoskeletons of arthropods like insects and sea creatures like crabs, is the source of the natural biopolymer chitosan. Because of their prevalence, accessibility, and relatively high chitin content in their exoskeletons, terrestrial insects are a possible source of chitosan. Removing chitosan from terrestrial insects may have the following advantages: Eco-friendly and sustainable production: Since they may be easily raised and harvested in great quantities without harming the environment, insects are a sustainable chitosan supply. On the other hand, conventional sources of chitosan, including the shells of prawns and crabs, may not be environmentally friendly and sustainable. However, there is disagreement over the optimal way to utilize chitin and chitosan compounds generated from terrestrial insects.
The study examined the viability of employing 3D printing technology to create an eco-friendly composite material. The research discovered that adding chitin and chitosan, made from terrestrial insects, to the PLA matrix resulted in a loss of strength and stiffness, which got worse with higher chitin and chitosan concentrations. In comparison to other composites created utilizing additive manufacturing, the composite material with 0.5 weight percent chitin reinforcement had the lowest tensile and flexural strength.
The lower interfacial bonding between the reinforcement and matrix was the cause of the chitin/PLA and chitosan/PLA composites' decreased strength and stiffness in comparison to clean PLA. As a result, when the composite was subjected to an external load, there was polymeric slippage. However, compared to neat PLA, the chitin/PLA and chitosan/PLA composites showed improved ductility, with the chitin/PLA composite with 0.1 weight percent having the best ductility. It was determined that chitin and chitosan might help the PLA composite become more durable.
The study also discovered that as chitin and chitosan concentrations rose, so did the density of the composites. FTIR and XRD investigations confirmed the crystalline and chemically bonded character of the composite samples. Microstructural analysis of the composites revealed voids and impurity-like particles linked to the breakdown of chitin and chitosan. Based on their compressive properties, the Chitin/PLA and Chitosan/PLA composites showed good thermal stability and may be used in food product packaging. Further research is needed to investigate interfacial bonding and post-treatment processes to improve the composites' mechanical characteristics and the method's scalability for industrial production. One thing is for sure, using the chitosan (chitin) derived from terrestrial insects as a material for making filaments for 3D printing of parts could lend to a low carbon way of meeting the UN Sustainable Development Goal 12, i.e., promoting sustainable consumption and production patterns.