Desenvovimento de recipiente interno para gás liquefeito de petróleo

Abstract

A pressure container for the storage of LPG of type IV was developed with polymeric reinforced with composite materials using different technological processes such as injection molding, hot plate welding, filament winding and vacuum co-injection molding. In addition to being light, the container is ecological and has better resistance to corrosion. A problem of this container is that it permits high levels of gas permeation and accumulation of electrostatic charge, problems that prevent the substitution of the metallic container. This is the main objective of this work. Initially different materials were studied: high density poly(ethylene), HDPE, poly(propylene), PP, poly(ethylene terephthalate), PET and poly(amide), PA to assess their mechanical properties in stress versus strain, thermal transitions, resistance to n-pentane, permeability to oxygen. The mechanical results showed that HDPEs deform at low stress, however PET is more rigid. In addition, the HDPEs maintained their thermal properties after being submitted to technological processes. In particular PP presented an increase in mass (13%) after immersion in n-pentane to a level above that permitted. The permeability calculations show that the HDPE that was selected to produce the container is permeable to gas, in a value above that allowed. In this way the idea of using an internal barrier film that is impermeable was proposed. Functional tests were performed with the container to assess the pressure in rupture and after pressure cycles, impact, fire and electrostatic discharge. The container with barrier film has taken the pressure cycles, impact and fire considering the criteria found in the norms. However, after the electrostatic discharge tests, a reduced charge transfer was found in the internal part of the container where the barrier film was placed. This behavior has been eliminated by inserting a pressure valve that fills the container differently from the traditional way.