• Elastomers and Composites
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• v.35 no.3
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• pp.205-214
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• 2000

The polyurethane resin was prepared by the reaction of tolylenediisocyanate(TDI) and polypropyleneglycol(PPG). Physical properties of the resin were investigated experimentally. Charging catalyst before TDI-dropping induced the rapid increase of viscosity. On the other hand, charging catalyst after TDI-dropping resulted in mild stability without immoderate generation of heat on reaction. The use of phosphoric acid as catalyst led to low viscosity by restraining side-reaction such as forming of branch-chain, buret reaction and allopanate reaction, but it showed low cross-link density and slow drying. The curing speed was more influenced by structures of molecules rather than NCO/OH ratio. Including PPG 400 over 30 wt % showed excellent adhesive strength due to increase of crosslink density.

• Journal of the Korean Applied Science and Technology
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• v.39 no.2
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• pp.161-168
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• 2022

Unmodified castor oil (CO) was used to obtain a castor-based aqueous polyurethane (CPUD) and isophorone diisocyanate (IPDI) was used to obtain a transparent film. The mixing effect of polypropyleneglycole (PPG) was analyzed to increase flexibility. In addition, ethylenediamine (EDA) was used as a chain extender. Tensile strength, elongation, and abrasion resistance were measured according to the change according to the castor oil content and the change in the chain extender, respectively. The tensile strength of the sample containing a lot of castor oil was 1.112 kgf/㎟, and the elongation was 88%. The tensile strength of the sample containing a lot of chain extender was 3.33kgf/㎟, and the elongation was 99%. The surface strength was visually confirmed through SEM. The surface strength was visually confirmed through SEM.