Crystallization and Crystalline Structure of Syndiotactic Polypropylene and Syndiotactic-Poly(1-Butene) Blend

Abstract

The crystallization and crystalline structure of syndiotactic-polypropylene (sPP) and syndiotactic-poly(1-butene) (sPB) blend containing 10 (Bl-10), 25 (Bl-25), 50 (Bl-50), 75 (Bl-75), and 90 (Bl-90) wt% of sPB, have been investigated by means of differential scanning calorimetry (DSC), FT-IR, and wide-angle X-ray diffraction (WAXD) analyses. The melt-crystallization behavior of the blend samples was studied by DSC on the cooling process at constant rates. Bl-50, Bl-75, and Bl-90 showed lower crystallization temperatures than the neat sPP. sPP in Bl-75 showed the lowest crystallization rate among the blend samples. Bl-90 showed a two-phase molten state, and sPP in Bl-90 crystallized via two-stepprocess. Time evolution of FT-IR spectroscopy at room temperature detected conformational transformation of the sPP polymer chain in the blend samples of Bl-50 and Bl-75. The absorption peaks intensity in the FT-IR spectra derived from the helical conformations in the crystalline phase decreased, and the planar zigzag conformations in the amorphous and mesophase phases decreased over the crystallization time. The time evolution of the WAXD profile of Bl-90 indicated that sPP in the blend accelerated the crystallization of sPB. The crystallized Bl-10, Bl-25, and Bl-50 samples showed diffraction peaks in WAXD profiles and melting endothermic peak in DSC profiles derived from only the sPP crystal. The crystallinity and melting temperature of sPP in the crystallized Bl-10, Bl-25, and Bl-50 samples were almost independent of the sPB content. Both the crystalline structure of sPP and sPB were detected in Bl-75 and Bl-90. Bl-75 showed the lowest crystallinity and melting temperature of sPP among the blend samples.

Morphology, Rheology and Crystallization in Relation to the Viscosity Ratio of Polystyrene/Polypropylene Polymer Blends

“…The crystallization phenomena in polymer blends were studied for various compositions [31][32][33], including two semi-crystalline polymers [34,35], or a semi-crystalline with an amorphous polymer [7,36]. When the semi-crystalline phase was the matrix, the degree of crystallinity was not affected by the addition of the amorphous polymer, and the amount of semi-crystalline phase dominated the evolution of crystallinity [37,38].…”

Bimodal High-Density Polyethylene: Influence of the Stereoregularity of the Copolymer Fraction on the Environmental Stress Crack Resistance

“…A similar model was proposed to explain the crystallization behavior and the crystalline microstructure of syndiotactic polypropylene and syndiotactic poly(1-butene) blends. 24 It is worth mentioning that nonstereoregular copolymer fractions are also excluded from the crystalline domain, but such chains are not crystalline, so they do not impose restrictions on the mobility of the amorphous chains during crystallization. Figure 7a illustrates this approach.…”