The origin of heteroepitaxy in the system of uniaxially oriented isotactic polypropylene and polyethylene

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

“…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 …”

“…In the skin layer, more compact shish‐kebab structure of PE phase, with some perfect shish‐kebab structure of PP phase inserting, can be seen. In the shear layer, PE lamellae arrange inclined about ±40° apart from the flow direction; this peculiar lamellae arrangement is exactly the typical epitaxy crystalline morphology, which is quite identical with the transmission electron microscopy morphology of epitaxy crystalline in many previous researches . In particular, the corresponding 2D‐SAXS pattern also shows a typical six‐spots pattern, which has been widely believed to be a proof of the existence of epitaxy structures.…”

“…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.…”

“…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.…”

Epitaxial recrystallization of HDPE-quenched ultrathin films on oriented iPP substrates

“…The experimental results for PE/iPP systems are, however, on the contrary. Therefore, Petermann et al 11 suggested that polyPolymer epitaxy has been extensively studied in mer epitaxy results from the oriented nucleation the past 15 years. A number of publications have of the epitaxial layer on the substrate and the already appeared on their morphologies and propcrystal growth of the epitaxial layer along its fasterties.…”