Characterization of bioplastic: a systematic review

Plastic is highly sought after due its durability, cheapness and convenience. It has been an important part of our lives, and this leads to large plastic waste disposal and due to its non-biodegradability, plastic nowadays is recognized as a severe anthropogenic issue in the coastal and marine ecosystems across the world1. In relation to this, the concept of designing and engineering new biodegradable materials, that has almost the same performance as those petrochemical-based plastics and completely biodegrade or can be broken down into simple molecular compounds through the action of microorganisms when no longer needed, seems to be more appropriate. Due to that, the term bioplastic has been coined and popularized in recent years as it offers necessary characteristics in the plastic microstructure to resolve the issue of plastic waste disposal. The purpose of this systematic review is to identify the characteristic of the bioplastic from different sustainable resources. The framework of this study followed the Preferred Reporting Items for Systematic Reviews (PRISM)2. There is one main database that the literature search was conducted on which are ScienceDirect until December 31st, 2021, with no language restrictions. The reference list of the included studies was crosschecked, and a partial grey literature search was undertaken. The methodology of the selected studies was evaluated using Grading of Recommendations, Assessment, Development and Evaluations (GRADE)3 methodology. The main characteristic of the bioplastic that is focused on in this systematic literature review (SLR) are tensile strength, thermal properties, biodegradation test, and morphological analysis. Fig. 1 shows the flow diagram of identification of studies that was conducted. Based on Fig. 1, there are about 1761 studies that were selected in the identification phase and out of those studies, 138 were chosen after the screening process. The studies were further filtered and 53 of them met the inclusion criteria. It is found that 8 starch resources were used in the selected studies, which are cassava, corn, cocoa pod husk, sugarcane bagasse, babassu mesocarp and rice. In addition, 33 studies focused on improving the mechanical properties of the bioplastic by introducing secondary composite such as chitosan. The remaining 16 studies investigated on optimizing and characterizing the effects of mixture of different starch resources on bioplastic characteristics. Fig. 1: Flow diagram of literature search and selection criteria adapted from PRISMA2 Overall, cassava has been widely used in the selected studies due to its higher starch content compared to other resources. In conclusion, this systematic review demonstrated that different starch resources which are used to produce bioplastic have huge potential in providing the alternative to petrochemical plastic. However, the technology is still not yet fully mature to reproduce similar performance as the petroleum-based plastic. Combining renewable natural resources and fossil resources produces better material properties compared to the bioplastic synthesized from renewable resources only. Further investigations especially in the mechanical properties and biodegradation of bioplastics are required to fully utilize the technology which would serve many real-world applications