Isothermic spherulitic growth and the shape of grain boundaries and growth fronts

Schulze, G. E. W.; Wilbert, H. P.

doi:10.1007/bf01410348

Cited by 14 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The eye-like region is similar to the teardrop morphology observed in polyethylene adipate and α isotactic polypropylene spherulite surrounded by the β spherulite due to their different growth rates . Theoretical modeling of the grain boundary between the two impinging spherulites growing at different rates has been reported in literature. ,− …”

Section: Resultssupporting

confidence: 63%

“…32 Theoretical modeling of the grain boundary between the two impinging spherulites growing at different rates has been reported in literature. 31,[33][34][35] The radial size of the eye-like region depends on the difference in the growth rates along the two axes, the orientation and the position of the baby lamellae. The bigger difference in the growth rates along a and b axis, the smaller the eye-like region.…”

Section: Formation Mechanism Of Two Growth Axes In the Same Spherulitementioning

confidence: 99%

See 1 more Smart Citation

Left- or Right-Handed Lamellar Twists in Poly[(R)-3-hydroxyvalerate] Banded Spherulite: Dependence on Growth Axis

Ye¹,

Xu²,

Guo³

et al. 2009

Macromolecules

View full text Add to dashboard Cite

Novel morphology of banded spherulite was observed in poly[(R)-3-hydroxyvalerate) (PHV) during its isothermal crystallization at temperatures between 50 and 80 °C. A novel optical technique, Polscope was applied to obtain both the birefringence retardation and azimuth angle of the slow optical axis at each pixel in the micrograph of the polycrystalline specimen. It is revealed that two different morphological regions, normal and eye-like regions, are derived from different growth axes of the lamellae along the radial direction. In the normal region, lamellae grow and twist along b axis, leading to the alternative strong and weak positive birefringence. In the eye-like region, they grow and twist along a axis, resulting in the alternative positive and negative birefringence. It is of particular interest to note that PHV lamellae in the two regions exhibit the opposite twist senses. To the best of our knowledge, it is the first report that an optically pure chiral polymer contains two lamellar twist senses in one spherulite. We attribute the driving force of lamellar twist in PHV spherulite to the unbalanced anisotropic surface stresses. A mechanical model is proposed to interpret the opposite twisting senses along the two orthogonal growth axes. The results demonstrate that the growth axis is one of the factors determining the twist handedness of the lamellae of chiral polymers.

show abstract

Section: Resultssupporting

confidence: 63%

Section: Formation Mechanism Of Two Growth Axes In the Same Spherulitementioning

confidence: 99%

Left- or Right-Handed Lamellar Twists in Poly[(R)-3-hydroxyvalerate] Banded Spherulite: Dependence on Growth Axis

Ye¹,

Xu²,

Guo³

et al. 2009

Macromolecules

View full text Add to dashboard Cite

show abstract

“…For example, polymers are known to exhibit diverse morphologies [34,35] that closely resemble those presented in this paper. While the lamellar structure of semicrystalline polymers is not identical to the planar stacking geometry assumed in this model [36], the qualitative concepts presented here regarding the interplay between kinetics and thermodynamics as well as the manifestation of polymorphism are nevertheless relevant to polymers as well as other spherulite-forming systems.…”

Section: Discussionmentioning

confidence: 54%

Crystallization in organic semiconductor thin films: A diffuse-interface approach

Fang

Haataja

2014

Phys. Rev. E

View full text Add to dashboard Cite

The crystallization of organic semiconductor thin films from an amorphous phase often results in a broad range of microstructures and molecular arrangements that in turn critically impact the electronic properties of the film. Here we present a diffuse-interface model of thin film crystallization that accounts for out-of-plane tilting of the kinetically favored crystalline orientation as well as the simultaneous appearance of multiple polymorphs. By adjusting the relative thermodynamic stability of grains oriented with the fast-growing axis either parallel or perpendicular to the substrate, crystallization can be made to occur in the form of either commonly observed spherulites or more complex morphologies such as sectors and centers. Furthermore, tuning the relative kinetic coefficients and free energies of multiple polymorphs can result in a spherulite of one crystal structure embedded within a spherulite of another crystal structure. A parametric study of the effects of anisotropy, densification, time-varying treatments, and substrate patterning reveals a wide variety of morphologies that are possible in these thin films, driven by a combination of kinetic and thermodynamics effects.

show abstract

“…Generally, due to their slower growth, α-spherulites are seen to be delimited by convex boundaries. Although 3D shapes of boundaries between spherulites of different forms have been discussed quantitatively in several publications, ,− they have never been experimentally observed. They are shown in Sections and .…”

Section: Results and Discussionmentioning

confidence: 99%

“…Simulation of Teardrop-Shaped α-Spherulite. The 3D shape of a teardrop α-spherulite was simulated based on previous reported 2D equations 44 with distance between the centers of the two spherulites being 18 μm and growing rates being 0.14 and 0.21 μm/s for αand β-spherulites, respectively, based on experimental rates. The β-spherulite nucleated 5 s before than α-spherulite.…”

Section: Confocal Microscopymentioning

confidence: 99%

3D Morphology of Different Crystal Forms in β-Nucleated and Fiber-Sheared Polypropylene: α-Teardrops, α-Teeth, and β-Fans

et al. 2023

View full text Add to dashboard Cite

Polymorphism of semicrystalline polymers has significant influence on their physical properties, with each form having its advantages and disadvantages. However, real-life polymer processing often results in different coexisting crystal polymorphs, and it remains a challenge to determine their shape, spatial distribution, and volume fraction. Here, i-polypropylene (i-PP) sheets containing both αand β-forms were prepared either by adding β-nucleating agent or by fiber pulling-induced crystallization. By adding a compatible dye that is partially rejected from the growing crystalline aggregates (spherulites and cylindrites), we visualize the shape of these objects in 3D using two-photon fluorescence confocal microscopy. To distinguish between crystal forms, we take advantage of the difference in dye-retaining ability of the αand β-aggregates. Even in 2D, fluorescence microscopy (FM) distinguishes the two crystal forms better than polarized microscopy. In 3D imaging, the volume fraction and spatial distribution of αand β-forms in different morphological types could be determined quantitatively. Morphologies described as α-teeth, β-fans, and α-teardrops were visualized for the first time in 3D. Furthermore, internal and surface microcracks were seen to be associated predominantly with the β-form and around the fiber. Spatial distribution of αand β-forms was also determined by scanning with a synchrotron X-ray beam. Good agreement was obtained with 3D microscopy, but XRD could not match the detail obtainable by the tomography. The work demonstrates the ability of the 3D imaging method to distinguish different crystal forms and their specific morphologies.

show abstract

Isothermic spherulitic growth and the shape of grain boundaries and growth fronts

Cited by 14 publications

References 5 publications

Left- or Right-Handed Lamellar Twists in Poly[(R)-3-hydroxyvalerate] Banded Spherulite: Dependence on Growth Axis

Left- or Right-Handed Lamellar Twists in Poly[(R)-3-hydroxyvalerate] Banded Spherulite: Dependence on Growth Axis

Crystallization in organic semiconductor thin films: A diffuse-interface approach

3D Morphology of Different Crystal Forms in β-Nucleated and Fiber-Sheared Polypropylene: α-Teardrops, α-Teeth, and β-Fans

Contact Info

Product

Resources

About