Estudo da tenacificação de materiais à base de polietileno submetidos a temperaturas extremas

Abstract

The development of polymer blends can lead to the production of new materials with improved properties. The family of polyethylenes has a series of advantages, such as high design flexibility and relatively low cost, that can enable new applications. However, the use of polyolefins in industry is limited due to its low impact resistance at low temperatures.Polymer blends can improve thermo-mechanical properties of polyethylene to meet the most severe and specific industrial applications, such as protective elements for screw pipes for petroleum industry that require high values of toughness in extreme ambient temperatures.This project studied the thermo-mechanical behavior of different polymer blends based on high density polyethylene matrix, in order to develop materials with improved impact resistance at extreme temperatures. In this work, different polymer components, such as UHMWPE and EVA, were used to increase the toughness of high density polyethylene(HDPE). The polymer blends were processed by extrusion and injection molding and characterized by techniques such as infrared spectroscopy, electron microscopy, rotational rheometry and thermal analysis. The mechanical properties of the obtained materials were also evaluated through tensile and impact tests at different temperatures, as well as dynamic mechanical analysis. The obtained results showed that the incorporation of low concentrations of UHMWPE and EVA (such as 5 and 10 wt.%, respectively) in HDPE increased substantially the impact strength of HDPE at room temperature as well as in extreme ambient temperatures (-46ºC and 66ºC). This result indicates that these HDPEblends can be considered good candidates to replace pure HDPE in applications in which high values of toughness are required at extreme ambient temperatures.