Análise das propriedades mecânicas e térmicas do polietileno reciclado com fibras sintéticas

Abstract

Constantly, many actions have been maid, to make the population and companies in general, aware of the importance of recycling and the need for proper disposal of polymeric materials, especially those for quick disposal. However, Brazil is far from achieving ideal policies about this issue. Another widely discussed factor about plastic polymers is the fact that, during the reprocessing operation, there is a gradual loss of their properties, such as: change in molar mass, viscosity and decrease in tensile strength. Thus, it is necessary that the mechanical recycling be advantageous, both ecologically and economically, and the maintenance of a minimum limit for some of these properties becomes a relevant variable, to issues involving these materials. Given the above, the objective of this work was to analyze the mechanical and thermal properties of two samples of recycled high-density polyethylene (HDPE), one postconsumer (PEI) and another post-industrial (PE II), using synthetic based additives of ultra-high molecular weight polyethylene fibers (PEUAPM) or encapsulated polyester, both developed for this purpose. In order to facilitate the dispersion of additives in HDPE, a concentrate consisting of 95% of low-density polyethylene with 5% of each of the respective additives was initially prepared. After obtaining the concentrate, four compositions were processed for each one of the recycled materials, namely: one without additives, another containing 4% of the concentrate of each one of the additives and the other only 4% of LDPE. These compositions were submitted to the injection molding process, characterizing them as to their thermal and mechanical properties, using the following techniques: infrared spectroscopy (FTIR), mechanical tests of tensile strength, calorimetry differential scanning (DSC), thermogravimetry (TGA) and melt index (MFI). The PE13 composition (powder industrial polymer), containing 4% of the PEUAPM fiber-based additive concentrate, exhibited the most representative result among all the compositions, with an increase in its elastic modulus, and a greater resistance to deformation, practically maintaining the same maximum voltage. In summary, the alteration of properties does not follow a single path, but is mainly guided by the application that is sought for the object produced with such material. For example, a more rigid composition with greater tensile strength can be very useful in rigid packaging or beverage crates, in the same way that a more ductile polymer can give rise to ducts, hoses, films or any material that requires a greater malleability of the piece. Any control over the behavior of the recycled can be useful to favor the process and generate a positive economic and social result.