Orientation Of Polypropylene Research Articles

Effects of Sodium Salt and Sorbitol-Derivative Nucleating Agents on Physical Properties Related to Crystal Structure and Orientation of Polypropylene

Although various types of nucleating agents (NA) have been used in polypropylene (PP) for commercial products, the effects of sodium salt and sorbitol based NAs on polymer structures and the relation to the physical properties have been rarely reported. The present work reveals structure and orientation of PP crystal with direct comparison of two types of NAs, i.e., sodium salt and sorbitol-derivative, via X-ray scattering techniques. The results show how those crystal structures are related to the properties of injected-mold PP, with the emphasis on the compressive strength and shrinkage.

Structure development in processing of polypropylene films with additives

AbstractThe crystallization behavior, modification of crystalline form, and orientation in polypropylene processed by blow film extrusion was studied as a function of processing parameters as well as different types of additives. The isothermal crystallization rate was greatly enhanced in the presence of certain additives, especially CaCO3. The crystalline form was predominantly α type in both compression molded or blow extruded films. However, there was an unusually large intensity of the α040 peak in the X‐ray diffraction of the latter case films. The variation of the peak intensities and the increase of birefringence with increase of take‐up speed has been explained on the basis of orientation induced by uniaxial stress in the machine direction. This orientation contained two components, namely the orientation of the b axis of the crystallites and the orientation of loosely bound polymer chains in the amorphous regions. © 1995 John Wiley & Sons, Inc.

Orientation in composite of polypropylene and talc

AbstractX‐ray diffraction and microscopical investigation of test samples prepared by injection molding from composites of isotactic polypropylene with talc revealed a preferred orientation of the talc and polypropylene matrix. Contrary to the situation in polypropylene alone, the preferred orientation in polypropylene–talc composites survived melting and a new crystallization. Crystallization rate measurements confirmed the nucleation activity of talc for polypropylene crystallization.

A comparison of the determination of macromolecular orientation in polypropylene by attenuated total‐reflection fourier‐transform infrared spectroscopy and X‐ray diffraction

AbstractAttenuated total reflection‐infrared (ATR‐IR) spectroscopy and wide‐angle x‐ray diffraction (WAXD) were used to determine the macromolecular orientation of a series of six uniaxially oriented polypropylene sheets with elongations of 0% to 500%. The orientation functions were expressed as fractions of chains oriented along the machine, trasverse, and normal directions in the sheets. Good agreement was found between the orientation functions for the two techniques. Sources of potential difference between the two techniques were discussed. The ATR‐IR technique is surface sensitive to a depth of about 5 or 10 μm into the surface while the WAXD technique is bulk sensitive. The ATR‐IR technique is sensitive to both the crystalline and noncrystalline material while the XRD technique is sensitive only to the crystalline material.

Characterization of surface structure and orientation in polypropylene and poly(ethylene terephthalate) films by modified attenuated total reflection IR dichroism studies

Characterization of surface structure and orientation in polypropylene and poly(ethylene terephthalate) films by modified attenuated total reflection IR dichroism studies