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. 2019 Dec 24;12(1):33.
doi: 10.3390/polym12010033.

Assessment of Photodegradation and Biodegradation of RPU/PIR Foams Modified by Natural Compounds of Plant Origin

Joanna Liszkowska  1 , Marcin Borowicz  1 , Joanna Paciorek-Sadowska  1 , Marek Isbrandt  1 , Bogusław Czupryński  1 , Krzysztof Moraczewski  2
Affiliations

Assessment of Photodegradation and Biodegradation of RPU/PIR Foams Modified by Natural Compounds of Plant Origin

Joanna Liszkowska et al. Polymers (Basel). .

Abstract

Four types of rigid polyurethane-polyisocyanurate foams (RPU/PIR) were obtained. Three of them were modified by powder fillers, such as cinnamon extract (C10 foam), green coffe extract (KZ10), and cocoa extract (EK10) in an amount of 10 wt %. The last foam was obtained without a filler (W foam). The basic properties and thermal properties of obtained foams were examined. All foams were subjected to degradation in the climatic chamber acting on samples of foams in a defined temperature, humidity, and UV radiation for 7, 14, and 21 days. The physico-mechanical properties of foams were tested. The compressive strength of degraded foams after 7, 14, and 21 days was compared with the compressive strength of nondegraded foams (0 days). The chosen properties of degraded foams, such as cellular structure by scanning electron microscopy (SEM) and changes of chemical structure by FTIR spectroscopy were compared. The obtained foams were also subjected to degradation in a circulating air dryer in an increased temperature (120 °C) for 48 h. Additionally, W, C10, ZK10, EK10 foams were placed in a soil environment and subjected to 28 days biodegradation process. The biochemical oxygen demand (BOD), the theoretical oxygen demand (TOD), and the degree of biodegradation (Dt) of foams were determined in this measurment. Test results showed that the compressive strength of foams decreased with the longer time of foam degradation in the conditioner. The foam subjected to degradation darkened and became more red and yellow in color. The addition of natural compounds of plant origin to foams increased their susceptibility to biodegradation.

Keywords: DSC; FTIR; biodegradation; cinnamon extract; climatic chamber; cocoa extract; coffee extract; rigid RPU/PIR foam; thermal degradation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Change in the color of foams after the drying process in the air dryer (2-day) and degradation in the climatic chamber (7, 14, 21-day) and nondegraded foam.
Figure 2
Figure 2
Foam color measurement results of foams after the drying process in the air dryer (2-day) and degradation in the climatic chamber (7, 14, 21-day) and nondegraded foam: (a). Change in brightleness-L and amount of red and green -a; (b) Change in difference between the two colours in the space -∆E and amount of yellow and blue -b.
Figure 3
Figure 3
Dependence between compressive strength and degradation time of foams.
Figure 4
Figure 4
FTIR spectra of: (a) W series; (b) C series; (c) KZ series; and (d) EK series.
Figure 4
Figure 4
FTIR spectra of: (a) W series; (b) C series; (c) KZ series; and (d) EK series.
Figure 5
Figure 5
DSC thermograms of: (a) Unmodified foam (W series); (b) foam modified by cinnamon extract (C series); (c) foam modified by green coffee extract (KZ series); (d) foam modified by cocoa extract (EK series).
Figure 5
Figure 5
DSC thermograms of: (a) Unmodified foam (W series); (b) foam modified by cinnamon extract (C series); (c) foam modified by green coffee extract (KZ series); (d) foam modified by cocoa extract (EK series).
Figure 6
Figure 6
SEM micrographs of foams: (a) W_0, (b) W_7; (c) C10_0; (d) C10_7; (e) KZ10_0t; (f) KZ10_7; (g) EK10_0; (h) EK10_7; (i) W_21; (j) C10_21; (k) KZ10_21; (l) EK10_21.
Figure 6
Figure 6
SEM micrographs of foams: (a) W_0, (b) W_7; (c) C10_0; (d) C10_7; (e) KZ10_0t; (f) KZ10_7; (g) EK10_0; (h) EK10_7; (i) W_21; (j) C10_21; (k) KZ10_21; (l) EK10_21.
Figure 7
Figure 7
Dependence of BOD changes in time.
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