| Summary: | 博士 === 國立中興大學 === 化學工程學系 === 91 === A series of carbon black containing interpenetrating polymer networks (IPNs) based on unsaturated polyester/epoxy have been developed in this endeavor. Scanning electronic microscopy exhibits that the compatibility was decreased and the morphology seemed to become less rigid as the content of unsaturated polyester increased in IPNs. The results also indicate that the flame retardants were uniformly distributed in the IPN matrices. The compatibility and interaction behavior of these IPNs have been investigated by DMA, DSC, FTIR and solid-state NMR spectroscopies. The Tg’s of IPNs were decreased and their transitions became broader as the content of unsaturated polyester increased in IPNs based on DMA and DSC study. Moreover, DSC measurements reveal that the Tg of the IPN sample became indistinct as the carbon black was added. This is due to the increase of inorganic content. Hydrogen bonding is present between the unsaturated polyester and epoxy as indicated by the FTIR investigation. Insufficient degree of hydrogen bonding brought about immiscibility between IPN components. The analysis of proton spin-lattice relaxation time in the rotating frame (TH1ρ) of the IPNs was also utilized to investigate molecular interaction between unsaturated polyester and epoxy. From relaxation curves, phase separation was found for the IPN samples with unsaturated polyester content higher than 30%. This was also observed by DMA study. Further DMA investigation indicates that the storage moduli were greatly enhanced with the addition of the carbon black to the IPN samples. Moreover, the loss modulus peaks became broader and more distinguished after addition. Based on the above, the addition of carbon blacks to IPN samples does greatly enhance the damping properties (at a wider temperature range) as well as the mechanical properties.
In the aspect of flame retardancy, the carbon black flame retardants would expand as heated over 220℃. Thermal degradation behavior and kinetic parameters of this system were analyzed by conventional and modulated thermogravimetric analysis (MTGA). It was found that the epoxy and unsaturated polyester components decomposed individually in the polymer network. Furthermore, the activation energy calculated from Ozawa method is somewhat lower than that of MTGA method.
This implies that the decomposition reaction is not a single reaction. Moreover, the activation energy of decomposition increased as carbon black flame retardants were added. The curves of activation energy versus residual mass varied in shape and position as the carbon black flame retardants were added. This indicates that the decomposition mechanism of carbon black-containing IPNs was different from that of the pristine IPNs. It was also found from adiabatic calorimeter that the heat of combustion (HOC) of the IPN sample was decreased by the addition of carbon black flame retardants. Moreover, the results of Py-GC-MS study reveal that the degradation of IPNs was derived from the non-interfering thermal decomposition processes of the respective IPN components. The degradation process of IPN was inhibited with the addition of the carbon black. This led to the lower content of low molecular weight compounds and fewer species of degradation products. In summary, the flame resistance, damping and mechanical properties were all improved simultaneously by the addition of the "plate-shaped" carbon black flame retardants to the unsaturated polyester/epoxy IPNs.
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