Study of the degradation of biodegradable polymers by light, heat and microorganisms in composted soil

Abstract

The vast majority of plastics produced from petrochemical sources is not easily degraded due to its molecular structure and hydrophobic character, causing accumulation in the environment, representing a significant source of environmental pollution. The mixture of natural materials such as starch, natural fibres and biodegradable polymer is a promising alternative for replacing part of the non-biodegradable plastics in appropriate applications. The starch, a type of polysaccharide reserves of most plants, is a biopolymer low cost. This can be processed with thermoplastic and mixed with other natural fibres and polymers. The poly (e-caprolactone) (PCL), is potentially biodegradable due to the presence of hydrolysable ester groups and presents low melting temperature. This work aims to assess the thermodegradation, photodegradation and degradation of PCL mixed with starch and natural fibre in composted soil, using a semi-automatic analysis of the carbon dioxide released, based on biodegradation tests of polymers (method of Sturm). The samples, in different compositions of PCL, starch and natural fibre will be treated with light and heat. Following are treated with composted soil microorganisms and microorganisms such as Trogia buccinalis and Phanerochaete chrysosporium, known to degrade materials persistent in the environment for the period of 120 days. The physical and chemical characteristics of composted soil, such as pH, humidity, temperature, organic matter and nutrients will be monitored during of the microbial treatment. After microbial treatment, samples will be analyzed by exploratory differential calorimetry (DSC), scanning electron microscopy (SEM), loss of weight, dynamic thermal mechanical analysis (DMA) and tensile mechanical tests.