iPP Films Research Articles

Epitaxial crystallization of trans‐1,4‐polybutadiene on highly oriented isotactic poly(propylene) films

AbstractEpitaxial crystallization of trans‐1,4‐polybutadiene (PBD) on highly oriented isotactic poly(propylene) (iPP) has been investigated at different crystallization temperatures and rates. From electron microscopy and electron diffraction, it is confirmed that epitactic growth of the low‐temperature modification (monoclinic) with microcrystals of PBD on the iPP films takes place with their chain directions about ±50° apart. No epitaxial relationship occurs between the high‐temperature modification (hexagonal) of PBD and the iPP substrate. Thermal analyses of PBD‐PP layered films indicate that the epitaxy has an important effect on the formation of the high‐temperature modification of PBD.

Morphology, phase structure and thermal behaviour of films of isotactic polypropylene/hydrogenated oligocyclopentadiene blends: 1. Extruded isotropic films

The effect of hydrogenated oligocyclopentadiene (HOCP) on the structure and morphology of isotropic isotactic polypropylene (iPP) films obtained by melt extrusion has been studied using wide-angle X-ray scattering, thermal analysis and electron microscopy. It was found that the addition of HOCP causes the formation of the smectic phase of iPP at temperatures where bulk iPP crystallizes only in the monoclinic form. The amount of smectic phase present in the blend is dependent on the blend composition. The spherulitic morphology of iPP is completely modified by the presence of HOCP. For blends containing up to 10% HOCP, the iPP spherulite dimensions are drastically reduced. In the case of blends of higher HOCP content, the film crystallinity is reduced, no spherulites are visible and the film surface appears smoother.

Structural changes in solvent-induced crystallization of quenched isotactic polypropylene

Solvent-induced crystallization of quenched isotactic polypropylene (iPP) films in dichloromethane, cyclohexane, carbon tetrachloride, and chloroform has been investigated.

STRUCTURAL CHARACTERIZATION OF HIGHLY REDRAWN ISOTACTIC POLYPROPYLENE FILMS

The preoriented isotactic polypropylene (iPP) film, which was prepared by drawing and annealing, was redrawn at the angles of α (α=0, 30, 45 and 60°) to the preoriented direction (named the first draw direction FDD). By high redrawing, the preoriented iPP films were highly reoriented to the redrawing direction (named the second draw direction SDD). The films had the high crystal and amorphous orientation factors; such as fc=0.992 and fam=0.714. The dependence of Tm on DSC scan speed was examined and it was found that the degree of superheating increased with fam. A history of the preorientation remained in the highly redrawn films and it appeared during thermal shrinkage at higher temperatures.