Obtención y caracterización de un material termoplástico a partir de polivinil alcohol y almidón de fréjol negro (Phaseolus vulgaris) como película de mantillo agrícola

Abstract

The objective of this research consisted of the development of a thermoplastic material from polyvinyl alcohol (PVA) and black bean starch (Phaseolus vulgaris) which was developed with an 2e2experimentaldesignwhere five formulations were obtained and three replications were considered for each formulation, giving a total of 15 experimental units. To obtain the thermoplastic, formulations were tested at the laboratory level with mixtures of PVA, starch, plasticizer and water. Of the tested formulations, formulation 4 (F4) containing 3% of PVA, 7% starch and 3.5% glycerin and formulation 5 (F5) with 2% PVA, 6% starch and 3.5% glycerin were the thermoplastics with the best characteristics for subsequent evaluation. Such thermoplastics were characterized in terms of their thermal behavior through thermogravimetric analysis trials(TGA) and Differential Scanning Calorimetry (DSC) where the results obtained by TGA revealed that the degradation maximum temperature of F4 is 56.5 degrees Celsius and for F5 62.8 degrees Celsius; in the case of DSC the glass transition temperature is between 50 and 80 degrees Celsius for both formulations. Additionally, mechanical tests were carried out on thermoplastics in which it was concluded that F4 is the most resistant with a maximum stress of 2.68MPa because the formulation contains a higher content of PVA. Finally, soil biodegradability, weather and water trials were carried out; in reference to the results, the thermoplastics exhibit good biodegradability within 30 days of exposure with 51.75% degradation for F4 and 53.05% for F5. Other types of tests are recommended for the thermoplastic characterization such as infrared spectroscopy, scanning electron microscopy.