Vol.:(0123456789) 1 3 Journal of Polymers and the Environment https://doi.org/10.1007/s10924-022-02449-7 ORIGINAL PAPER Biodegradable Film from Mango Seed Kernel Starch Using Pottery Clay as Filler Asmare T. Admase 1  · Zenamarkos B. Sendekie 2  · Adugna N. Alene 1 Accepted: 1 April 2022 © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2022 Abstract Fillers improve the thermal stability and mechanical properties of bio-plastics. This research aims to synthesize and char- acterize biodegradable flm from mango seed kernel starch reinforced with micro-pottery clay using glycerol as a plasti- cizer. The mango seed kernel starch was extracted and characterized in terms of solubility (75.01 ± 0.35%), swelling power (22.3 ± 0.24%), moisture content (10.33 ± 0.21%), ash content (0.41 ± 0.13%), and yield of starch (19.97 ± 0.021%). Pottery clay to starch ratios of 0, 5, 7, and 10% w/w, and glycerol to starch ratios of 0, 25, 30, and 35% w/v were evaluated. The flm was analyzed for its physicochemical properties such as tensile strength, thickness, transparency, and biodegradability. Fur- thermore, the surface functional groups, morphology, and thermal properties of the flm were analyzed using FT-IR, SEM, 3D optical surface profler, and TGA. The control flm has a tensile strength of 3.33 ± 0.008Mpa whereas the tensile strength of the reinforced flm is 7.66 ± 0.012 MPa. The maximum biodegradation rate of the flm is 74.38 ± 0.012 at 35% glycerol concentration. Increasing the amount of glycerol increased the solubility of the biodegradable flm due to its strong afnity towards water molecules. Glycerol increases flm thickness and reduces its transparency. The microstructure results indicate that clay particles are homogeneously dispersed with reduced surface roughness of reinforced flms compared to the control. The mango seed kernel starch flm reinforced with 5% pottery clay and 25% glycerol was selected based on tensile strength, thermal stability, and biodegradability properties. In summary, the addition of glycerol and pottery clay signifcantly afects the physicomechanical and thermal properties of flms. Keywords Mango seed kernel · Pottery clay · Biodegradability · Starch · Gelatinization Introduction Mango is a tropical fruit of the family Anacardiaceae and is grown in the whole tropical and subtropical areas of the world [1, 2]. It is the second most traded tropical fruit and the ffth largest production globally [3–6]. In addition to direct consumption (80%), the remaining (20%) is used in the production of juices, nectars, purees, squash, slices, jams, and pickles [6]. The main problem in mango fruit pro- cessing is the disposal of the seed kernels generated. The seed kernel is the residue left after fruit processing, such as juice extraction [7, 8]. In the fruit processing industry, edible portions of mango fruits are processed into canned slices and juice, whereas seed kernels often are discarded as a waste since they have not been utilized for commercial purposes [4, 5]. The disposal of mango seed waste induces ecological problems and environmental pollution which are directly related to the spreading of insects and rodents and economic problem [9, 10]. In Ethiopia, there are many large and small-scale mango juice processing industries. During mango processing, peel and seed kernel constitutes about 17–22% of the fruit [11]. The total mango production in Ethiopia was 72,187 tons in 2013/2014, and it accounts for 7219 tons of mango seed ker- nel annually generated during mango fruit processing [11, 12]. Mango seed kernels are the leading waste of fruit pro- cessing industries, an annual generation of 123,000–210,000 * Zenamarkos B. Sendekie zenamar23@gmail.com 1 Chemical and Biotechnology Chair, Chemical Engineering Program, Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology-Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia 2 Process Engineering Chair, Chemical Engineering Program, Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology-Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia