Triene-isobutene copolymers

In the case of peroxide-cured EPTMs or EPDMs, the cross-linking density (vt) was obtained throu swelling measurements (in n-heptane at 30 °C) and using the interaction parameter proposed in Ref whereas in the case of isobutene-triene copolymers the interaction parameter suggested by Sheenan and Bisio was adopted. 

5-Hexattiene-isobutene copolymer (HU) was dissdved (4 wt%) in n-heptane (or CHQ3) and allowed to react at 0 °C in the dark with a slight molar excess of CI2 (dissolved in CCI4) with reqtect to the content of conjugated unsaturation. After ten minutes the reaction solution was treated with a K1 solution, then was washed with H2O and the polymer recovered by collation from methanol. The dried polymer was analyzed for chlorine and conjugated double braid (UV) content  

The HQ addition to HTI was carried out at —20 °C by buttling at atmospheric pressure an excess of anhydrous HQ into a stined QIQs solurirai of copolymer. Samples of the polymer were withdrawn periodically from the reaction mixture and analyzed, after purification, for chlorine and conjugated unsaturation content. The chlorine content was obtained by burning the polymer accordir to the Shdniger method. 

A) S3mriie is of Hydrocarbon Polymers Having Conjugated Unsaturation 

Ethylene and Propylene Copolymers Contaning Different S tems of Two Conjugated Double Bonds 

---

The novelty of isobutene-triene copolymers does not allow us to present a complete series of results since further work is in progr However, some interesting features shown by these copolymers, e. g. radical and Diels-Alder curing, hi efficiency in radical grafting, possibility of easy and controlled halogenation, allow us to expect a parallel behavior in terpol3nners containing similar unsaturations and hence permit us to draw some conclusions which comjdete thc obtained from the terpolymers study. 

Other recants and details ccmceming the isobutene-triene copolym synthesis and structural characterization were reported elsewhere 2,4-Hexadiene (HD, a mixture of 30/70 cis-tram and trans-tram isomers) and 2,5-dimethyl-2,4-hexadiene (DMHD) were used as model compounds of isobutene-triene ccipolyn rs and were pure grade cxjmmercdal products, distilled before use. 

The presence in polyisobutene chains of conjugated unsaturations highly reactive toward free radicals, as it occurs in tire case of isobutene-triene copolymers, induced us to investigate radical crc sdinking of these copolymers. 

As EPTMs containing dienic unsaturations easily undergo Diels-Alder reactions, isobutene-triene copolymers are also subjected to viscosity increase on prolonged storage as a consequence of a slow but progressive self-curing occuring even at room temperature. 

---