HYDROGEN MOMENTUM DISTRIBUTION IN ANISOTROPIC RIGID-CHAIN POLYMERS

We have performed a trial deep inelastic neutron scattering (DINS) experiment on an aligned sample of a copolymer of poly(hydroxybenzoic acid) and poly(hydroxynaphtoic acid). The experiment has been carried out on the eVS inelastic spectrometer of the ISIS facility, at the Rutherford Appleton Laboratory (UK). The hydrogen atomic momentum distributions n parallel-to(p) and n perpendicular-to(p), corresponding to momentum transfer Q parallel and perpendicular to the polymer main chain direction respectively, have been obtained as functions of the atomic momentum p. The experiment offers evidence of the insensitivity of the DINS technique to the degree of rigidity of the polymer main chain. Through the use of a quantum mechanical model we show that the hydrogen momentum distribution is defined by the C-H bond and that bonds connected to the carbon or other interactions have no significant influence.