Abstract
Polybutadiene crosslinkable under moisture was synthesised by modification of hydroxy telechelic functions of low molecular weight polybutadiene with isocyanato propyl triethoxy silane. At 50°C and with dibutyl tin dilaurate (DBTL) as catalyst, silane moities were introduced quantitatively at the rate of 1.2, 2 and 2.4 per polymer chain. Two analytical methods ( FTi.r. spectroscopy and volumetric titration) were used to follow isocyanate consumption. Two kinetic treatments were investigated (2nd and 3rd order) and influence of catalyst concentration and temperature were studied. A 2nd order kinetic seems to be better fitted for our experimental results. Nevertheless, in each case, Arrhenius law suggests an entropically controlled reaction with probably ethoxy silane groups participating in a transition state in the presence of DBTL.
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