Development of Bioplastic Film for Application in the Footwear Industry

There is a growing interest in the use of biodegradable polymers that can help minimize the environmental impact of plastics. Biopolymers have been considered the most promising materials for this purpose. However, they generally have poorer mechanical properties. Starch is a low-cost polysaccharide derived from agricultural plants. To improve starch processing, the molecular order within the granules must be destroyed. This is generally achieved by heating the granular starch mixed with plasticizers. With this process, a conversion of the biopolymer’s molecular structure into thermoplastic starch is obtained. In this way, much of the starch changes from a crystalline structure to an amorphous structure. Of the various plasticizers used, the most common are polyols, in which glycerol is included, allowing a good structuring, although it induces the phenomenon of recrystallization. Four bioplastics were developed, based on corn flour, which differed in thickness (0.25 mm and 0.45 mm, on average), with and without a natural pine resin. Regarding the tests carried out in bioplastics, it was concluded that the bioplastic with 0.25 mm and with resin is the one that presents a greater transparency and a greater tensile strength. In turn, the bioplastic with the highest elongation was the one presenting 0.45 with resin. It was also concluded that up to a certain thickness of bioplastic (0.34 mm), the resin adds a certain resistance, from which it withdraws. Through the FTIR analysis, it was confirmed that the resin provides transparency to the bioplastic and that it causes interference in the bonds between the starch and the glycerol.