Linear growth rates of random propylene ethylene copolymers. The changeover from γ dominated growth to mixed (α+γ) polymorphic growth

Thermal Behavior, Structure and Morphology of Propene/Higher 1-Olefin Copolymers

“…These results are well in line with the outcome of the extensive investigations reported in the literature [29][30][31][32][33][34][35][36][37][38][39][40][41][42]49,50] on different polypropenes containing random regio, stereo and constitutional defects. The fractional content of gpolymorph strongly depends on the total concentration of defects and on crystallization temperature.…”

“…[21][22][23][24] The availability of structurally well defined isotactic polypropenes has renewed the interest on the formation of the g-polymorph, which displays unique crystallographic structure [25,26] and is typical of polypropenes with short isotactic sequences. [11,27,28] The recent extensive investigations performed on propene homopolymers with various contents of regio and stereo defects and on random copolymers with 1-olefins by Alamo et al [29][30][31][32][33][34] and De Rosa et al [35][36][37][38][39][40][41][42] have shown that random constitutional defects essentially behave as any other type of irregular unit in the development of the g-polymorph. The amount of g-form was found to be strictly correlated with the length of isotactic sequences which, for randomly placement of mistakes, is inversely related to their total content.…”

Characterization and properties of ethylene-propylene copolymers synthesized with homogeneous and supported metallocene catalyst in the whole range of compositions

“…Figure 5 shows the variation of mol% ethylene, f c WAXS and n P versus γ content. It is clear that the γ form content increases with ethylene content, 34 although the behavior is different between the H and S copolymers: as mentioned above, the amount of ethylene needed to obtain a certain amount of γ form is lower in H than in S series. Besides, for the same γ content value, f c WAXS and n P show higher values in H than in S series.…”

Volumetric rheology of polymers

“…The hexagonal b-modification of polypropylene is obtained sporadically at high supercoolings or the presence of selective b-nucleating agents [4,5]. The triclinic c-phase is favored by the presence of structural defects in the polypropylene chain that can be introduced either by incorporating very low molecular weight branches [6,7] or by copolymerization with ethylene co-units of \10% mol [8][9][10][11][12][13]. Moreover, the crystallization of c-phase is enhanced under high pressure [14][15][16][17].…”