Thermoplastic rubbers have been shown to have unusual solid state
properties which must derive from the structure of the melt prior to
solidification. The melt phase has been studied in some detail. The
molecular architecture of these block copolymers comprises of hard
segments (usually polystyrene) connected by a flexible rubbery chain
(polybutadiene or polyisoprene) in a linear or radial structure. Their
flow characteristics have been studied and the results correlated with
measurements in the solid state. They have been modelled mathematically
based on two particular theoretical models. A liquid phase transition
was recorded for both models, with appreciable reduction in the apparent
activation energy of flow above this temperature. The quality of the
domain structure depends on the continuity of the polystyrene phase and
has been measured by the stress at yield and by the optical birefringence.
A change in response was associated with the liquid-liquid transition. [Continues.]
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.
Great Britain, Department of Education and Science (ORS Award). Brazil, CAPES (Brazilian Research Council). Universidade Federal de São Carlos, Brazil.