IJUP08 - Universidade do Porto

UV PROTECTION OF GEOTEXTILES BY CHIMASSORB 944
Inês Valente 1 , Paulo Almeida 1 , José Ricardo Carneiro 2 and Maria de Lurdes Lopes 2
1 Department of Chemistry, Faculty of Science, University of Porto, Portugal.
2 Department of Civil Engineering, Faculty of Engineering, University of Porto, Portugal.
Geosynthetics are polymeric materials widely applied in construction of infrastructures
(landfills, roads, tunnels, railways, dams) due to economical, technical and environmental
advantages. Geotextiles are the most applied geosynthetics, as they can perform functions
like separation, filtration, drainage, protection and reinforcement. In those applications,
geotextiles can be exposed to several agents (such as, UV radiation and other weathering
agents, atmospheric oxygen, high temperatures, acids or alkalis and microorganisms) that
may affect their durability and, consequently, their useful lifetime. The degradation
suffered by these materials is often retarded and/or inhibited by the incorporation of
chemical additives, such as UV stabilisers and antioxidants in their composition. So, it is
extremely important to study these compounds during the degradation process of the
geotextiles.
In this work, it was developed a new methodology for the determination of the additive
Chimassorb 944 (C944) in polypropylene (PP) geotextiles. C944 is an additive widely used
in the stabilisation of polyolefins against the damaging effects of UV radiation and
oxidation induced by heat.
The methodology developed for the determination of C944 can be divided in two main
steps: (1) ultrasonic extraction with chloroform at 60 ºC for removing C944 from the
geotextile sample; (2) separation and determination of the additive by liquid
chromatography with UV detection at 244 nm. This method was used to monitor the level
of C944 in geotextile samples exposed to UV radiation in a laboratory weatherometer (the
QUV). Unstabilised PP geotextiles were also exposed to UV radiation in the QUV.
Morphologic changes on the PP fibres of the geotextiles were characterised by scanning
electron microscopy (SEM).
C944 proved to be important in the stabilisation of the PP geotextiles against UV radiation
(the unstabilised PP geotextiles were destroyed after UV-ageing tests in the QUV).
However, the level of C944 in stabilized geotextiles decreased during UV radiation
exposure. SEM analysis showed that polymeric structure of the geotextiles exposed to
higher UV radiation was more damaged.
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