Copolymers of ethylene with norbornene derivatives—dynamic mechanical properties

The dynamic mechanical properties have been determined and the β relaxation temperatures T_β have been located for a series of copolymers of ethylene with norbornene, methylnorbornene, dicyclopentadiene, and octahydrodimethanonaphthalene. The T_β values show discontinuous changes with changing comonomer content. The several levels of T_β observed apparently can be associated with the sequence of close multiplets of norbornane moieties ranging from isolated units through pairs to triads and higher. For isolated norbornane units T_β is around 10°C, while for pairs of these units, probably separated by a C₂H₄ unit, it is 55°C. The size of the norbornene-type comonomer has a small but measurable effect on these values of T_β. The bearing of these results on the problem of defining a value of T_g for polyethylene is discussed.     

Measurement of the FeXXV dielectronic recombination rate coefficient in the PLT tokamak plasma

The FeXXV dielectronic recombination rate coefficient associated with the 1s-2p core excitation has been measured as a function of the electron temperature in the range from 0.9–3 keV from the observations of the satellite lines emitted from the PLT (Princeton large torus) tokamak plasma. These measurements are compared with recent theoretical predictions of Bely-Dubau et al. as well as with the approximation formulae of Burgess and Merts et al., and the results of Jacobs et al. Excellent agreement is obtained with the more recent calculations.     

Interfering proton and neutron transfer in the reaction C(N, N)C

Elastic scattering and one-nucleon transfer reactions induced by ¹⁶O have been investigated in the energy region 45–60 MeV on targets of ²⁶Mg, ²⁷Al, ³⁰Si and ⁴⁸Ca. Angular distributions were measured in the angular range 4°–40°. Optical model parameters were derived from the elastic scattering data and the transfer reaction data were analysed using both no-recoil and full-recoil DWBA codes. In the case of proton transfer reactions on ⁴⁸Ca, good agreement was obtained between the data and the DWBA calculations while the data for the lighter targets could not be satisfactorily reproduced. The oscillatory pattern of the angular distributions is discussed in terms of the three-parameter model of Kahana, and it is found that the model qualitatively explains the observed transition from smooth to oscillatory angular distributions.