RELAXATION DYNAMICS OF BIDISPERSE TEMPORARY NETWORKS

Simultaneous measurement of infrared dichroism and birefringence is us ed to examine the component relaxation in bidisperse, fully entangled melts of polybutadienes with 1 % of the repeating units modified with 4-phenyl-1,2,4-triazoline-3,5-dione (urazole) groups. Since the urazol e groups are capable of forming interchain hydrogen bonds, the rheolog ical properties of these materials differ significantly from those of the analogous polybutadiene melts without polar stickers. Samples with 30,50, and 70 % long chains are examined by step strain and oscillato ry shear experiments. In addition, the step strain experiments are car ried out at two temperatures. All samples show a higher orientational coupling coefficient (epsilon = 0.6-0.72) than corresponding polybutad iene melts (epsilon = 0.47). The fact that orientational coupling depe nds on temperature and sample composition indicates that the relaxatio n of the chain containing stickers is strongly coupled. This feature i s not incorporated in the current theory describing the relaxation of the chain containing stickers.8