The structural features of propylene-styrene-ethylene terpolymer (sP/(S-E)) prepd. using syndiospecific Cs-sym. metallocene catalyst, isopropylidene(cyclopentadienyl)-(9-fluorenyl)zirconium dichloride with MAO co-catalyst were studied. The polymorphism studies of as-prepd., melt-crystd., and fiber sP/(S-E) confirmed that ethylene units are mainly bound to styrene units arising from catalyst reactivation after the secondary insertion of styrene. Styrene-ethylene units are mainly segregated in the amorphous phase. The bulky styrene units, bound to ethylene, prevent the inclusion of ethylene units in the crystals of syndiotactic polypropylene (sPP), as generally occurs for copolymers of sPP with ethylene. This explains the fact that the effect of styrene-ethylene units on polymorphism of sPP is smaller than that obsd. in copolymers of sPP contg. only ethylene or butene comonomer units.
Structural characterization of syndiotactic propylene-styrene-ethylene terpolymers
CAPORASO, Lucia;OLIVA, Leone
2003-01-01
Abstract
The structural features of propylene-styrene-ethylene terpolymer (sP/(S-E)) prepd. using syndiospecific Cs-sym. metallocene catalyst, isopropylidene(cyclopentadienyl)-(9-fluorenyl)zirconium dichloride with MAO co-catalyst were studied. The polymorphism studies of as-prepd., melt-crystd., and fiber sP/(S-E) confirmed that ethylene units are mainly bound to styrene units arising from catalyst reactivation after the secondary insertion of styrene. Styrene-ethylene units are mainly segregated in the amorphous phase. The bulky styrene units, bound to ethylene, prevent the inclusion of ethylene units in the crystals of syndiotactic polypropylene (sPP), as generally occurs for copolymers of sPP with ethylene. This explains the fact that the effect of styrene-ethylene units on polymorphism of sPP is smaller than that obsd. in copolymers of sPP contg. only ethylene or butene comonomer units.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
