Thermal and photochemical degradation of polyurethanes based on renewable materials
In recent years, the use of polymers made from renewable materials has been developed in diverse areas especially in furniture, mattresses, automotive or building components. Polyurethanes (PU's) made from renewable materials are one of the most important groups of polymers because of their...
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| Format: | Thesis |
| Language: | English |
| Published: |
2006
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/7297/1/24p%20ANIKA%20ZAFIAH%20MOHD%20RUS.pdf |
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| Summary: | In recent years, the use of polymers made from renewable materials has been
developed in diverse areas especially in furniture, mattresses, automotive or building
components. Polyurethanes (PU's) made from renewable materials are one of the most
important groups of polymers because of their versatility and they can be manufactured
in a wide range of grades, densities and stiffness. In this project, polymers based on
renewable materials such as rapeseed (RS) and sunflower oil (SF) were synthesized and
cross-linked with methylene di-/>-phenyl diisocyanate (MDI) to form polyurethanes.
Treatment with titanium dioxide (TiCh) was found to affect the physical
properties of the polyurethane in a systematic way. As the loadings of TiOj were
increased (up to 10% of monomer weight), large strain responses were obtained; thus
the stress vs. strain curves plotted by the Instron tensile test showed an increase from
5% to 31%). This study also revealed a remarkable characteristic in the pigmented
polymer exhibiting soft - but - tough behaviour at high TiC>2 loading.
The DMTA test also showed that the properties of the sample loaded with 10 %
TiC>2 increased its tan delta peak (damping factor) from 0.43 to 0.7. The tan delta peak
showed that the damping properties of the material were improved markedly upon
loading with TiC>2. This is useful since noise is radiated by vibration, and the application
of damping materials to the vibrating surface converts the energy into heat, which is
dissipated within the damping materials rather than being radiated as airborne noise.
Increase in TiC>2 loading also gave a progressive increase of hardness (Shore D) for both
RS and SF oil - based polyurethanes.
The effect of prolonged exposure to UVB light, in general promotes
photodegradation for both RS and SF-based polyurethanes, both neat and also material
loaded with TiCh- The photodegradation of the PU's depends on the grade of titanium
dioxide. The addition of 10 % Degussa P25 pigment, gives the greater degradation
while PUs loaded with 5 % Kronos 2220 show the slowest rates of degradation due to
the effect of the coating of this pigment.
The photostabiliser Tinuvin 770 also offers high protection from UVB, while the
combination of Tinuvin 770 and Degussa P25 gave the highest protection from UVB.
Addition of Tinuvin 770 at the stage of preparation of the PUs also greatly reduced the
undesirable yellow colouration prevalent during PU syntheses. |
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