Polyethylene–isotactic polypropylene epitaxy: Analysis of the diffraction patterns of oriented biphasic blends

Lotz, Bernard; Wittmann, J. C.

doi:10.1002/polb.1987.090250509

Cited by 50 publications

(52 citation statements)

References 9 publications

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“…This special reflection can be ascribed to the epitaxial growth of PE lamellae onto PP lamellae, as it has been reported in many researches . PE crystallizes on the surface of the iPP substrate, with its chain ±50° apart from the chain direction of the iPP substrate, and two contact planes are assigned to be (100) PE and (010) PP …”

Section: Resultssupporting

confidence: 56%

“…Although these methods have successfully obtained the epitaxial structures in practical samples, making it possible for the industrial production of iPP/PE blends with special epitaxial structures. One thing to note is that the specific morphology of epitaxial structures in those samples is not clear, even though X‐ray patterns do give a strong proof of the existence of epitaxial structures according to many previous researches . Obviously, there is reason to believe that the morphology is probably a little changed.…”

Section: Introductionmentioning

confidence: 89%

“…Epitaxy is generally defined as one crystal phase growing on the surface of the other one. For polyethylene (PE)/isotactic polypropylene (iPP) system, the epitaxy growth theory is established on the geometric lattice matching for (100) lattice plane of PE and (010) lattice plane of iPP, which has been demonstrated in many researches . Gross obtained this special structure by annealing between the melting points of the two components; the recrystallized PE crystals with its chain inclined from iPP chains turned out to be of great importance for the improvement of the mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

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Insight into understanding the evolution of the epitaxy crystallization in isotactic polypropylene and polyethylene blends

Zhou

Hou

et al. 2017

Polymers for Advanced Techs

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In this article, epitaxial structures have been successfully obtained in the isotactic polypropylene (iPP)/polyethylene (PE) blends by an accessible injection molding methods. By studying a series of iPP/PE blends, the evolution of the epitaxial growth of PE lamellae on the oriented iPP lamellae has been detailedly discussed via wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, scanning electron microscopy and differential scanning calorimetry. Unexpectedly, the exactly epitaxial angles between peculiarly arranged PE lamellae and oriented PP lamellae are all larger than the classical epitaxy theory value of 50°, and it even increases gradually with increasing PP content. It is inferred that the special crystallization of PE is the consequence of joint construction of the oriented PP crystals and the continuous intense shear field provided by pressure vibration injection molding. The epitaxial structures play a positive role in the interfacial connection between two components; thus, the mechanical properties of the blends are improved. This work provides an insight understanding on the formation mechanism of the epitaxy crystallization under shear field. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Insight into understanding the evolution of the epitaxy crystallization in isotactic polypropylene and polyethylene blends

Zhou

Hou

et al. 2017

Polymers for Advanced Techs

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“…5(b,c)]. The herringbone texture, characteristic of epitaxially crystallized polyethylene, 16,17 was evident in several places.…”

Section: Films With Znpementioning

confidence: 96%

“…Epitaxial crystallization of polyethylene on polypropylene is well documented. 16,17 A near lattice match of the unit cells results in the growth of polyethylene lamellae at a characteristic 42°angle to the polypropylene lamellar long axis. The absence of oriented lamellar growth of znPE at the interface with hmsPP indicated that the amorphous interfacial layer prevented intimate contact of the crystallizable hmsPP and znPE constituents.…”

Section: Bulk Morphologymentioning

confidence: 99%

Characterization of an amorphous surface layer on blown polyolefin film

Chang

Chum

Hiltner

et al. 2002

J of Applied Polymer Sci

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This study concerned an amorphous surface layer on blown polyethylene film with a composition different from that of the bulk. The surface layer was characterized by gentle probing with an atomic force microscope. The demonstration of an amorphous layer uniformly covering the surface of a blown Ziegler-Natta-catalyzed polyethylene (znPE) film reproduced previous reports. Removing the surface layer by solvent washing confirmed the hypothesis that the layer consisted of lower molecular weight, higher branch content fractions. A blown film of znPE blended with up to 30 wt % impact-modified high-melt-strength polypropylene (hmsPP) also exhibited an amorphous surface layer. In thin films, it was advantageous for the mobile, amorphous fractions of ethylene-propylene rubber (EPR) to locate at the surface rather than at the phase interface. The amorphous EPR tended to segregate into pools on the film surface, and this pointed to a substantial difference between the amorphous surface layers on the znPE and hmsPP/znPE blend films. Surface enrichment best described the compositional gradient that resulted from the concentration of lower molecular weight, higher branch content chains at the surface of the znPE film. Surface segregation was more appropriate for the emergence of EPR fractions as a separate phase on the surface of the hmsPP blend film. Films blown from a blend of a Ziegler-Natta-catalyzed polyethylene and a metallocene-catalyzed polyethylene (zn/mPE) and its blend with hmsPP reproduced the primary features of surface enrichment and surface segregation. Some differences between the znPE and zn/mPE films were attributed to the metallocene constituent of zn/mPE.

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Epitaxial Crystallization of Polymers: Means and Issues

Thierry

Lotz

2013

Handbook of Polymer Crystallization

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Polyethylene–isotactic polypropylene epitaxy: Analysis of the diffraction patterns of oriented biphasic blends

Cited by 50 publications

References 9 publications

Insight into understanding the evolution of the epitaxy crystallization in isotactic polypropylene and polyethylene blends

Insight into understanding the evolution of the epitaxy crystallization in isotactic polypropylene and polyethylene blends

Characterization of an amorphous surface layer on blown polyolefin film

Epitaxial Crystallization of Polymers: Means and Issues

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