Of Ipdi-based Thermoplastic Polyurethane Elastomer Preparation, Characterization And Application

Thermoplastic polyurethane elastomers (TPUE) based on ethyleneoxide-tetrahydrofuran copolyether (PET) and isophorone diisocyanate(IPDI), were prepared successfully by one step process method with different expander, such as l,4-butanediol(BDO) /ethyleneglycol(EDO) /propanediol(PDO)/ hexamethylenediol(HDO). The structure and properties of these elastomers were characterized with FTIR Analysis, Differential Scanning Carlometry(DSC), Gel Permeation Chromatography (GPC) , Tensile test and Rheologic test.The fabrication process of TPUE have been investigated. The result shows that the viscosity of the reactive system increases rapidly in the first hour, and then slow down. The reaction almost completes in 6hrs. The best ratio of isocyanate and hyroxyl grous is between 0.95~1.05. The water content must be controlled under 0.5%. The reactive speed increases sharply when catalyst T-12 is added, but Ea only little decreases.The relationship between the micro-phase separation and the glass temperation of the soft phase was established. The higher relative molecular mass of PET and the hard phase content, the better microphase separation was. Therefore the Tg of soft phase is decreased and the tensile strength increases. The tensile strength of the TPUE prepared with melt-polymerization method is higher than that with solvent-polymerization method. As temperature increases the tensile strength decreases sharply. The result of frequency scan test shows that the melt flow of TPUE is pseudo plastic fluid, the viscosity is decreasing as frequency increases. The result of temperature scan test shows that the complex modulus decreases sharply as temperature increases, but a turn peak on the curve shows the rheologic microphase separate temperature.Strong interaction between TPUE and high explosives were proved through the studies of surface tension. According to Hotspot theory and investigative result, the mechanisms for desensitization of TPUE bonded RDX were discussed. Compatibility Analysis showed that TPUE were compatible with the components of high explosives.