FCT within the project PTDC/CTM/71491/2006_FCOM-01-0124-FEDER-007156
In this work, the ability of Aspergillus niger to degrade two lignin-based rigid polyurethane (RPU) foams
was evaluated and compared with a control RPU foam based on a commercial polyether-polyol,
Lupranol 3323. The foams degradation was studied according to different procedures, namely by
setting different series of batch cultures, either using liquid media or soil conditions, for 90 days at 30 C.
For the soil conditions, two different assays were performed, namely with and without A. niger addition.
The changes in the morphology of the RPU foams were evaluated by optical (OM) and scanning electron
microscopy (SEM), whereas the structural modifications were inspected by FTIR spectroscopy.
After 90 days treatment, morphological changes were clearly visible at the surface (cell wall) of the
two lignin-based foams indicating a stronger effect of the microorganisms’ activity in these samples. FTIR
spectra confirmed that the chemical structure of the polymer suffered modifications after the respirometry
assays due to microorganisms attack. Comparatively to the commercial foam, it was observed
that both the lignin-based foams presented a higher degradation level.
The environmental impacts arising from the use of polymeric materials is a serious problem since they can present long periods of degradation and hence being accumulated in the environment. Polyurethanes (PU) are considered as one of the most versatile polymeric materials offering a wide range of products with applications in diverse sectors. Rigid polyurethane (RPU) foams, due to its excellent insulation and mechanical properties, are widely used in construction, automotive, freeze industry and nautical applications. In this context, the use of green polyols with value-added properties, such as biodegradability, will contribute to reduce environmental impacts.
In this work the ability of Aspergillus niger to degrade lignin-based RPU foams in comparison with a control (RPU foam based on a commercial polyol), was tested according to various procedures.
