Mulch film made of petroleum-based black plastic has effectively helped to increase crop yields for many agricultural products worldwide; however, it creates plastic waste and leaves microplastics in the soil and increases water runoff. Bio-based mulch film is gaining popularity as a suitable alternative, but commercially viable compounds require synthetic or polylactic acid-derived additives. In this work, studies are done regarding the processing and characteristics of thermoplastic starch (TPS) extracted from potato scraps for applicability as a mulch film. Our proposed potato starch based TPS comprises of 1.0 grams (g) of acetic acid, 1.5 g of glycerol, 100 g of water, and 5 g of potato starch (PS). The materials are heated to 60 °C, where the mixture then is poured onto a flat receptacle to form the film size desired. The film is dried at room temperature for ~24 hours. The plastic biodegradability is assessed using ASTM (American Society of Testing and Materials) D6400. The product obtained survives over 3 weeks with minimal structure loss or degradation when exposed to the open environment. Sheets fabricated with less acetic acid degraded more rapidly, demonstrating the importance of this starting reagent for mulch longevity. The mulch sheets have been tested on flora/soils while also being exposed to over 15 mL of rainwater, retaining their structure. They are also stable for 14 days fully immersed in 20 °C deionized (DI) water, though fully degraded when exposed to DI water at 100 °C for 22 minutes. The plastics formed are fully compostable and safe for all organic life. This is an advance toward the goal of developing fully compostable, plant safe material of customizable physical structure.

Processing and characterization of biodegradable mulch films made of potato thermoplastic starch

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