Stability of thermosetting bio-plastic prepolymer at room temperature
2010
Okamoto, Y., Mie Univ., Tsu (Japan) | Hashimoto, A. | Suehara, K.
Thermosetting bio-plastic produced from a slurry mixture of saccharide and polyisocyanate by heating includes electric parts demanding heat-resistance as phenol resin. It is generally called 'prepolymer', and is unstable and self-curing at room temperature. The purpose of this study is to understand the self-curing mechanisms of the prepolymerization using tools such as infrared and X-ray spectroscopy. The experimental results suggested that the self-curing process was divided into 4 steps: polyisocyanate hydration, amine group production, urea group production and viewlet group production. They were caused by absorptive water of saccharide, and the cross-linkage formation of the viewlet group provided the cure. It was also possible that the urea group was produced from the proton originating from saccharide and polyisocyanate. We also found that fructose, maltose monohydrate and glucose-supplemented water had long curing characteristics, which was different from the affinity for adsorptive water. But crystal water and the crystallinity of saccharide did not affect the cure. Hence, the absorptive water was very important, since the viewlet group was not produced and the cure was delayed during the urea group production using it. Consequently, this study could be a very important step for stable prepolymer production in industrial processes.
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