ISSN:
1572-8935
Schlagwort(e):
Anionic
;
Polymerization
;
Hydrogenation
;
Head-to-head
;
2,3-Dimethyl-1,3-butadiene
;
Polypropylene
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
Abstract Poly(2,3-Dimethyl-1,3-butadiene) (PDMB) with varying contents of 1,4-and 1,2-structures has been anionically synthesized using either n-butyllithium or sec-butyllithium as an initiator. The addition of tetrahydrofuran could enhance the rate of synthesis and effect the microstructure. The Tm was higher for PDMB with a lower content of 1,2-structure, and the Tg was lower. This PDMB was then hydrogenated with a nickelocene/n-butyllithium catalyst system leading to the formation of HPDMB. The trans 1,4-structure unit was more difficult to hydrogenate due to its steric hindrance. Repetitive hydrogenation was necessary in order to achieve a high degree of hydrogenation. The hydrogenated PDMB is an amorphous elastomeric material. The Tg’s were found to decrease with an increase in the degree of hydrogenation, concurrent with a gradual disappearance of the Tm’s. Since a HPDMS with a low content of 1,2-structure resembles a head-to-head polypropylene, our data suggest that the Tg of an atactic head-to-head polypropylene lie between −30 and −35 °C.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s10965-006-0061-8
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