Small‐angle light scattering from a distribution of spherulite sizes

Wissler, G.; Crist, Buckley

doi:10.1002/pol.1985.180231112

Cited by 11 publications

(5 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The values are about double the size observed in AFM. This is expected as the average spherulite size determined by small‐angle light scattering is always larger, as it relates to the ratios of large moments of size distribution, as discussed by Wissler and Crist 14. Additional possible factors could be that either surface regions of the films possess smaller spherulites due to rapid cooling or AFM inaccurately measures the average diameter of the spherulites by not capturing their full diameter.…”

Section: Resultsmentioning

confidence: 93%

The influence of molten fraction on the uniaxial deformation behavior of polypropylene: Real time mechano‐optical and atomic force microscopy observations

Koike

Çakmak

2006

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

In this study, we have coupled the real time mechano‐optical measurements with the off‐line structural characterization techniques including AFM, WAXS, and DSC to establish the quantitative relationships between the “true mechano‐optical behavior and developed morphology” as influenced by the fraction of molten phase present in the polypropylene films. Stretching PP in the solid state invariably leads to formation of fibrillar texture. The evolution of surface morphology in partially molten state was found to depend on the fraction of the molten phase present at the start of the deformation. If the samples are strained past the yielding in partially molten state, the birefringence begins a rapid rise. Concurrent with this, the equatorial zones of the spherulites begin to crack while meridional regions remaining intact. This leads to temporary reduction of crystallinity because of destruction of some of the crystals. If held in this strained state, the crystallite thickening was observed while the birefringence increases while the lost crystallinity is recovered. If the films are strained past the strain hardening point, the microfibrillar structure was found to dominate the surface morphology. When the films are stretched in the melting temperature range, they exhibit substantial nodular surface topology. These nodules that were absent in the solid state deformed samples are hard lamellae buried inside amorphous “soft matter”. The tangential lamellae increasingly become dominant as the processing temperature approaches substantially molten state leading to the observation of a* oriented crystallites in the X‐ray analysis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 925–941, 2006

show abstract

Section: Resultsmentioning

confidence: 93%

The influence of molten fraction on the uniaxial deformation behavior of polypropylene: Real time mechano‐optical and atomic force microscopy observations

Koike

Çakmak

2006

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

“…For an assembly of spherulites, the average radius is given by the ratio of the fifth and fourth moment of the size distribution and is shifted toward the larger sized spherulites in the distribution due to their larger scattering power . Also, in case of spherulite truncation, the meaning of the spherulite radius R is lost but it rather defines their size in terms of an average distance r from the nucleus to the spherulite boundary.…”

Section: Resultsmentioning

confidence: 99%

Phase Transformation Behavior of Polylactide Probed by Small Angle Light Scattering and Calorimetry

Schmidt

Keuker‐Baumann

Meyer

et al. 2019

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

Small angle light scattering (SALS) and differential scanning calorimetry DSC have been applied to investigate the melting of spherulites isothermally crystallized polylactide. At an isothermal crystallization temperature high enough, pure α-phase crystals are formed. Exposed to a temperature gradient, the crystals first melt and then recrystallize before they finally melt. With decreasing crystallization temperature, an increasing fraction of polylactide is crystallizing in the less stable α 0 -phase.α 0 -crystals also melt upon increasing the temperature but recrystallize to the more stable α-phase. A constant spherulite size is revealed by SALS for both processes, the α/α and α 0 /α meltrecrystallization, until completion of the final melting, thereby supporting integrity of the spherulites throughout the entire processes. Joint DSC and SALS experiments demonstrate that the depolarized scattering invariant correlates with the heat flow recorded by DSC and thus offer an alternative measure for the degree of crystallinity. The following mechanism is identified for both processes: initial melting and recrystallization overlay each other. Crystallinity is not fully recovered upon recrystallization because only part of the original lamellae survives the melt-recrystallization, though with an increased thickness. While lamellae are melting and reforming or simply transforming their phase, the spherulites survive the process until final melting.

show abstract

“…The ratio of the distance ( L ) from the center of the pattern to the brightest part of the four “four‐lobed” pattern and the vertical distance ( D ) from the sample to the paper‐receiving screen is the tangent of scattering angle θ m. The average radius ( R ) of the spherulites in the sample can be calculated according to the following formula (Equation 2), where λ is the wavelength of the laser (532 nm). [ 27 ]

R = \frac{4.09 λ}{4 π \sin \frac{θ normalm}{2}} .

…”

Section: Methodsmentioning

confidence: 99%

Crystallization, structure, morphology, and properties of linear low‐density polyethylene blends made with different comonomers

Shi

Wang

et al. 2021

Polymer Engineering & Sci

View full text Add to dashboard Cite

Linear low‐density polyethylene (LLDPE) 7042, which has a butene comonomer, is widely used but has poor tear and dart strengths. For practical applications, small amounts of other materials can be blended with 7042 to effectively improve its properties. In this study, four blend resins and films (cast and compressed films) were prepared by blending 7042 with four LLDPEs (2045G, 9030, 23F, and 9085) in 8:2 ratios. The results indicated that after blending 2045G, 23F, or 9030 with 7042, the crystallization ability of the three blends was significantly suppressed and crystal size decreased. Moreover, the molecular chain can pass though more lamellar stacks in the blends, leading to an increased tie‐chain concentration. Therefore, the tear and dart impact strength of the blend films improved. In contrast, the crystallization ability of the 7042/9085 blend was only slightly suppressed and did not significantly impact its properties. These findings contribute to our understanding of the relationship between material structures and properties, demonstrating that LLDPE blends can be used to improve the tear and dart strengths of 7042.

show abstract

Small‐angle light scattering from a distribution of spherulite sizes

Cited by 11 publications

References 12 publications

The influence of molten fraction on the uniaxial deformation behavior of polypropylene: Real time mechano‐optical and atomic force microscopy observations

The influence of molten fraction on the uniaxial deformation behavior of polypropylene: Real time mechano‐optical and atomic force microscopy observations

Phase Transformation Behavior of Polylactide Probed by Small Angle Light Scattering and Calorimetry

Crystallization, structure, morphology, and properties of linear low‐density polyethylene blends made with different comonomers

Contact Info

Product

Resources

About