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Publication
CircularSeas
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| 5.18 MB | Adobe PDF |
Authors
Abstract(s)
In recent years the problem of pollution has been increasingly debated, and one of the
main issues discussed is related to the degradation of the oceans as a consequence of human
activities. Polymeric materials are one of the main elements identified both on the coast
and in the ocean itself, which causes several consequent adversities, both for human life
and for the natural world. In order to analyze the possibility of reusing or reprocessing material
usually considered waste, it is important to determine the type of properties that have
been altered and what effect it would have on its use as a new raw material. Due to the limited
amount of literature available on this subject, a large amount of polymeric material was
collected from Peniche and Vieira beaches, Leiria, Portugal. As most identifiable objects
were octopus traps and fishing nets, and knowing that this type of product is usually made of
high-density polyethylene and polyamide, respectively, these were the materials chosen for
analysis. The high density polyethylene was analysed both before and after processing, while
on the case of the polyamide, only the processed material was analysed. Tensile, Dynamic
Mechanical Analysis and hardness tests were performed after the necessary preparation.
Comparing the values obtained in each case with the respective measurement of the virgin
material, it was possible to observe that some properties, such as Young’s modulus, tension
and tensile strength decreased considerably. Hardness was also affected, although it
was less notorious. Seawater absorption tests were also carried out on virgin high density
polyethylene in order to determine the amount of time the waste was under the influence
of environmental degradation by comparing its density values over time with the density of
waste material. However it was not possible to draw concrete conclusions since, in the case
of density, it can easily vary depending on the type of conditions to which the material was
subjected, which are unknown; on the other hand, the Dynamic Mechanical Analysis tests,
used in the determination of the glass transition temperature, were inconclusive regarding
high-density polyethylene since the value of this characteristic in the virgin material is lower
than zero and, as the initial temperature used in the tests was the ambient temperature, it
was not possible to determine the desired result, while this characteristic on the nylon waste
decreased due to the material’s deterioration. After this project was carried out it was concluded
that it is very important to correctly characterize this type of materials, not only at
the mechanical level, but regarding other engineering fields, for example, at chemical level.
Although some advantageous characteristics of virgin materials are lost, waste is still usable
in different forms for new purposes, and can be treated as a new source of raw material.
Description
Keywords
Marine litter Ocean pollution Mechanical properties High density polyethylene Polyamide