Session QC14 - Mechanical Properties.
ORAL session, Wednesday morning, March 24
Room 266W, GWCC
When a plastically deformed polymer is annealed at an elevated temperature, the plastic strain decreases rapidly in the beginning and levels off at long times. The recovery processes appear to follow two second-order kinetics taking place in parallel. The earlier stage of the recovery seems to be dominated by a second order kinetic process which has a higher rate constant. The later stage second order kinetic process has a lower rate constant with a higher activation energy than that of the earlier stage. These two kinetic processes appear to correspond to a large scale and a small scale chain motions taking place simultaneously during recovery. These chain motions are probably driven by the annihilation of conformational defects which carry opposite signs introduced by deformation. Examples of such parallel processes in the recovery of deformed polystyrene, biaxially oriented styrene-acrylonitrile copolymer films and the volume recovery after deformation will be examined in the light of the defect annihilation mechanisms. JCML acknowledges support from NSF through DMR 9623808 monitored by Dr. Bruce MacDonald.