Polybutadiene thermoreversible networks

Fig. 34a-c Proton spin-lattice relaxation time of thermoreversible networks of polybutadiene at different temperatures as a function of the frequency [131], Linear PB (Mm 51,000) was cross-linked by addition of 4-phenyl-l,2,4-triazoUne-3,5-dione (pheny-lurazole, PU). The crossover frequencies between regimes I, 11, and III are shifted depending on the cross-link density. At the lowest temperatures the dispersion slopes tend to be steeper than in ordinary melts (see Eq. 168). a 19 phenylurazole groups per chain, b 28 phenylurazole groups per chain, c 37 phenylurazole groups per chain... 

Peng C-C, Abetz V. A simple pathway toward quantitative modification of polybutadiene a new approach to thermoreversible cross-linking rubber comprising supramolecular hydrogen-bonding networks. Macromolecules 2005 38 5575-5580. 

New elastomeric networks based on saturated ethylene-propylene rubbers grafted with succinic anhydride groups (EPR-g-SA) crosslinked with a hydroxyl-terminated polybutadiene (HTPB) are hereafter described. Infrared techniques are employed to follow the kinetics of the monoesterification reaction and to assess its potential thermoreversibility, either on the macromolecular system (EPR-g-SA-I-HTPB), or on a model system, formed by EPR-g-SA and a low molecular weight diol, namely 1,9-nonandiol. 

---