INFLUENCE OF THE MICROSTRUCTURE ON THE INCOHERENT NEUTRON-SCATTERING GLASS-FORMING POLYBUTADIENES

This paper presents the first neutron scattering measurement of 1,2-1, 4-polybutadienes with varying microstructure. Incoherent inelastic sca ttering experiments have been performed in the range of moderate (Delt a E approximate to 300 mu eV) and high (Delta E approximate to 20 mu e V) energy resolution. For the moderate resolution experiments the vibr ation-relaxation model has been used as a guideline for interpretation . The most striking influence of the microstructure variation can be f ound in the position of the boson peak. Its position at low temperatur e as well as its temperature dependence is significantly different amo ng the measured samples. The high resolution data have been Fourier tr ansformed into the time domain yielding the intermediate incoherent sc attering function in a time range of 5,...,150 ps. There, the basic pr operties found for 1,4-polybutadiene earlier could be reproduced (sepa ration of alpha and beta(slow) regimes of the slow relaxation, Kohlrau sch-Williams-Watts function with beta approximate to 0.4). On the basi s of the new data, no microstructure induced differences can be detect ed except for the changes of temperature dependence due to the strongl y different glass-transition temperatures and different fragility. (C) 1996 American Institute of Physics.