Nanoscale Shear and Indentation Measurements in Transcrystalline α-Isotactic Polypropylene

Amitay-Sadovsky, Ella; Cohen, Sidney R.; Wagner, H. Daniel

doi:10.1021/ma001193d

Cited by 20 publications

(6 citation statements)

References 16 publications

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“…14,15 Of particular interest is the proposal by several authors that a transcrystalline morphology improves the adhesion strength of an interface. Kwei et al 16 and Matsuoka et al 17 showed that the modulus of the transcrystalline region is higher than that of the bulk phase.…”

Section: Introductionmentioning

confidence: 99%

Effect of Substrate Surface Energy on Transcrystalline Growth and Its Effect on Interfacial Adhesion of Semicrystalline Polymers

2003

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The effect of substrate surface energy on transcrystalline growth at the interface of a semicrystalline polymer and its effect on interfacial adhesion were investigated for substrates treated with various silane coupling agents. A thin film of isotactic polypropylene (iPP) crystallized on a high surface energy substrate (treated with γ-(aminopropyl)triethoxysilane) was composed entirely of transcrystallites. On the other hand, when the iPP film was crystallized on a low surface energy substrate (treated with perfluorodecyltrichlorosilane), the interface was dominated by spherulites, and only a very thin transcrystalline region (thickness ∼1 µm) was observed. The substrate surface energy was found to exert a significant influence on the crystallinity, density of nuclei, crystal microstructure (e.g., lamellar thickness and crystal orientation), and thickness of the transcrystalline region near the interface. The adhesion energy measured by the asymmetric double cantilever beam (ADCB) test increased strongly (from 1 to 100 J/m 2 ) with surface energy. Examination of the fractured specimens using atomic force microscopy and scanning electron microscopy revealed fibrillation of the iPP induced by the strong interfacial adhesion; this was found to be associated with the breakdown of the fibrils, which is the characteristic fracture mechanism of transcrystallites at the interface in high surface energy samples. At lower surface energies, however, cracking occurs at the boundary between the transcrystallites and the spherulites because of the weak boundary layer near the interface.

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Section: Introductionmentioning

confidence: 99%

Effect of Substrate Surface Energy on Transcrystalline Growth and Its Effect on Interfacial Adhesion of Semicrystalline Polymers

2003

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“…This microstructure can be related to an increase in mechanical properties. For example, Amitay-Sadovsky et al reported the increase in the shear modulus as a result of an increase of crystal anisotropy in a nanoindentation study [32]. …”

Section: Interfacial Crystallization Of the Ipp Wax-sorbitol Compoundsmentioning

confidence: 99%

Effect of Sorbitol Templates on the Preferential Crystallographic Growth of Isotactic Polypropylene Wax

et al. 2018

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Abstract:The crystallization of isotactic polypropylene wax (iPP) in the presence of different sorbitol structures was studied. Dibenzylidene Sorbitol (DBS), as well as two of its derivatives with one or two methyl groups in the DBS molecule (MDBS and DMDBS, respectively), were tested as nanometer-size fibrillar templates. The early nucleation stage and crystal morphology were analyzed in Real-Time Wide-Angle X-ray Scattering (WAXS) and polarized optical microscopy (POM). It was found that the iPP crystals showed an α-phase unit cell for the three different sorbitols. However, a preferential crystal growth in the plane (040) was observed for iPP-MDBS. The macrostructure morphology of the iPP-DBS and iPP-DMDBS wax compounds was spherulitic, while nodular macrocrystals were observed for the iPP-MDBS compound. It was concluded that the MDBS template promoted a lower interface energy because of its match with the c-axis of the iPP wax crystals, whereas, in the case of the DBS and DMDBS templates, the preferential plane was the (110), characteristic of the iPP spherulitic arrangement.

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“…This type of directional crystal growth, away from the fiber axis, can yield substantial molecular orientation within the transcrystalline layer, thus influencing the materials' mechanical properties 23–26. In the case of carbon fiber reinforced polyether ether ketone (PEEK), the formation of transcrystalline morphology showed higher interfacial adhesion strength and high transverse tensile strength 15, 27–29. Several suggestions have been proposed to account for the formation of the transcrystallinity 30.…”

Section: Introductionmentioning

confidence: 99%

In‐situ microfibrillar PET/iPP blend via slit die extrusion, hot stretching, and quenching: Influence of hot stretch ratio on morphology, crystallization, and crystal structure of iPP at a fixed PET concentration

Shen

et al. 2004

J Polym Sci B Polym Phys

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The in situ microfibrillar blend of poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) was fabricated through a slit die extrusion, hot stretch, and quenching process. The morphological observation indicates that while the unstretched blend appears to be a common incompatible morphology, the hot stretched blends present PET in situ fibers whose characteristics, such as diameter and aspect ratio, are dependent on the hot stretching ratio (HSR). When the HSR is low, the elongated dispersed phase particles are not uniform at all. As the HSR is increased to 16.1, well‐defined PET microfibers were generated in situ, whose diameter is rather uniform and is around 0.6 ∼ 0.9 μm. The presence of the PET phase shows significant nucleation ability for crystallization of iPP. Higher HSR corresponds to faster crystallization of the iPP matrix, while as HSR is high up to a certain level, its variation has little influence on the onset and maximum crystallization temperatures of the iPP matrix during cooling from melt. Optical microscopy observation reveals that transcrystalline layers form in the microfibrillar blend, in which the PET microfibers play as the center row nuclei. In the as‐stretched microfibrillar blends, small‐angle X‐ray scattering measurements show that matrix iPP lamellar crystals have the same orientation as PET lamella. The long period of lamellar crystals of iPP is not affected by the presence of PET micofibers. Wide‐angle X‐ray scattering reveals that the β phase of iPP is obtained in the as‐stretched blends, whose concentration increases with the increase of the HSR. This suggests that finer PET microfibers can promote the occurrence of the β phase. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4095–4106, 2004

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Nanoscale Shear and Indentation Measurements in Transcrystalline α-Isotactic Polypropylene

Cited by 20 publications

References 16 publications

Effect of Substrate Surface Energy on Transcrystalline Growth and Its Effect on Interfacial Adhesion of Semicrystalline Polymers

Effect of Substrate Surface Energy on Transcrystalline Growth and Its Effect on Interfacial Adhesion of Semicrystalline Polymers

Effect of Sorbitol Templates on the Preferential Crystallographic Growth of Isotactic Polypropylene Wax

In‐situ microfibrillar PET/iPP blend via slit die extrusion, hot stretching, and quenching: Influence of hot stretch ratio on morphology, crystallization, and crystal structure of iPP at a fixed PET concentration

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