Study On The Blends Of HTPB/Liquefication MDI-based Polyurethane And Polystyrene By Simultaneous Polymerization

In this paper, a series of blends has been prepared by simultaneous polymerization process respectively with different constitute of the HTPB/Liquefication MDI- based polyurethane and polystyrene. The effects of the PU/PS blended compositions, synthesis temperature, the ratio of NCO/OH, initiator concentration, crosslinker concentration and the molecular weight of HTPB on the mechanical properties thermal stability and morphological structure of the system were investigated by tensile test, impact test, hardness test, thermogravimetry(TG), differential scanning calorimetry (DSC) and scanning electron microscope(SEM). In addition, the kinetics of the system formation were studied by Fourier transform infrared spectrometer(FTIR) and chemical titration.The results indicated that the blends of different constitute shows different mechanical properties. The tensile strength and the hardness of the blends increase with increasing content of the PS. The elongation of break increased at first, but then decreased. To the blends of same constitute, the tensile strength and the hardness increase with increasing the content of crosslinker of any constitute, but the elongation of break decreased. The results of the thermal analysis show that the thermal stability has improved obviously when we added the PS to the PU, two components in the system exhibited the effect of conjunction. The DSC research expresses that the PU( HTPB)/ PS blends of the different constitute have slight change at Tg2 at the high temperature, expresses to move outside slightly. Moreover we get the detection that with the increase of crosslinker DVB dosage, the Tg2 moves toward higher temperature and the Tg2 is more unclearly. The morphological structure of the blends exhibited two phase separation , and the phase inversion take place between 15:85 and 30:70 (PU/PS: weight percentage constitutes). The size of the domain decrease withincreasing the crosslinker content of the system.According to the absorption peaks at 2270cm-1 and 1630cm-1 were chosen for -NCO(PU) and C=C(PS) has showed a gradual decrease as the respective polymerizations proceeded, we have studied the reaction kinetics of the blends of HTPB/Liquefication MDI-based polyurethanes and polystyrene. The research discovered, two components of the blend system will not change the reaction mechanism of oneself, but respond the polymerization velocity to lower than the pure system obviously. It can be found that the apparent activation energy of formation of PU in the blend is about 73.11kJ/mol, obviously higher than in the pure PU.