Estudo da degradação de misturas poliméricas à base de PEBD, amido, quitosana e fibra de coco em diferentes ambientes aquosos

Abstract

Water quality is related to the anthropogenic impact on water resources and their availability, and this quality is regulated by the National Environmental Council - CONAMA, through resolutions 357 of 2005 and 396 of 2008, from the boundaries quality standards of water bodies. The materials of organic origin, including natural polymers have an inherent tendency to degradation. The presence of oxidizable or hydrolysable groups in the chains of these polymers, in addition to hydrophobicity and hydrophilicity characteristics and degree of conformational flexibility of the chain are factors that contribute to the biodegradation of the polymer. Water pollution by hydrocarbons, including biodegradable polymers, can be an environment conducive to the presence of potentially degrading microorganisms from a variety of recalcitrant molecules released in the middle. The combination of different types of environmental effects can cause slow or fast decay, which depends on the predominant factor or degrading agent (photochemical, thermal, chemical, hydrolysis, oxidation, biodegradation). This work was carried out an investigation into the quality of water facilities (river water - RW distilled water - DW and water with nutrients - NW) after the biodegradation of polymeric blends and composites containing low density polyethylene (LDPE), thermoplastic starch (TPS), chitosan (Ch) Coconut fiber (CF). The samples were subjected to biodegradation test water in these media for a period of fifty-two days. After the test period may be seen that mixtures of TPS/Ch and TPS/CF undergone the process of biodegradation, confirmed the almost complete loss of their mass, increased conductivity, in spite of the turbidity values and the consumed oxygen concentration, decrease in the last days of rehearsal. As expected mixtures containing LDPE (LDPE/TPS, LDPE/TPS/Ch and LDPE/TPS/CF) showed less weight loss, and lower turbidity and O2 consumption in the chemical degradation of organic matter. Comparing the results of different means water, as expected, the results conductivity and pH of the river water (RW) were higher than the values found for the water with nutrients (NW) and distilled water (DW). The turbidity values and concentration of O2 consumed in the COD for the different blends containing LDPE as shown depended on the diffusion of water in the various polymeric materials and consequently influence the first stage of biodegradation, i.e., water penetration into the material surface attack of the chemical bonds of the amorphous phase and converting long chain of biodegradable polymers into smaller pieces and eventually into soluble fragments