Observations of crystallization and melting in poly(ethylene oxide)/poly(methyl methacrylate) blends by hot-stage atomic-force microscopy

Pearce, R.; Vancso, Gyula J.

doi:10.1002/(sici)1099-0488(199810)36:14<2643::aid-polb17>3.0.co;2-b

Cited by 41 publications

(35 citation statements)

References 28 publications

(44 reference statements)

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“…The AFM was fitted with a hot-stage to observe the quiescent crystallization in real-time. AFM studies of crystallization [70][71][72][73][74][75][76] have been reported, but none have focused on the quiescent crystallization of polyethylene-a-olefin copolymers. Because the melt is relatively ''sticky,'' hard tapping force was used to image the crystallization as it occurred.…”

Section: Resultsmentioning

confidence: 99%

Crystallization and melting of polyethylene copolymers: Differential scanning calorimetry and atomic force microscopy studies

Mirabella

2006

J Polym Sci B Polym Phys

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ABSTRACT:The HoffmanLauritzen theory of secondary, surface nucleation and growth was primarily relied upon for about 40 years after its introduction in about 1960 to rationalize the crystallization of flexible chain polymers into lamellar crystals. However, in about 1998, Strobl and coworkers introduced a different model for crystallization, based on the stagewise formation of lamellae. Two major components of this model were as follows: (1) the concept of the formation of a mesomorphic melt as a precursor to crystallization and (2) the control of the melting temperature range of lamellar crystals of homogeneous polyolefin copolymers by an inner degree of order or perfection rather than on the crystal thickness. The first concept is in disagreement with the HL theory and the second with the Gibbs-Thomson theory, which associates melting temperature with lamella thickness. In the present study, differential scanning calorimetry and atomic force microscopy were successfully employed to monitor the in situ quiescent crystallization of polyethylene homopolymer and copolymer. In the present study, evidence was not found to support the concept of lamellae with equal thickness melting over a broad temperature range. Some evidence was found that might be interpreted to support the concept of a mesomorphic melt as a precursor to crystallization. At present, the model promoted by Strobl and coworkers appears to be at an uncertain stage at which strong proof or disproof are not available. However, this alternative model has injected a new vitality into the study of crystallization of flexible chain polymers.

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Section: Resultsmentioning

confidence: 99%

Crystallization and melting of polyethylene copolymers: Differential scanning calorimetry and atomic force microscopy studies

Mirabella

2006

J Polym Sci B Polym Phys

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“…But, in an ultrathin or thin film, a constrained geometry system, the properties of polymer chains, such as crystallinity, chain packing and orientation, are different from the bulk state. Atomic force microscopy (AFM) studies of thin polymer films have visualized the growth [1][2][3][4][5][6][7][8] and melting [7,9] of crystalline lamellae in spherulites and the lamellar growth in shishkebab structures, [10,11] and also given rise to some controversial topics in the field of existing polymer crystallization theories. [3] Branched crystalline patterns different from spherulite have been observed in ultrathin polymer films.…”

Section: Introductionmentioning

confidence: 99%

Branched Crystalline Patterns Formed Around Poly(ethylene oxide) Dots in Humidity

Wang¹,

Braun

Meyer

2002

Macromol. Rapid Commun.

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Branched patterns reminiscent of diffusion‐limited aggregation form around poly(ethylene oxide) dots on Au surfaces in humidity by crystallization of polymer chains in water‐assisted diffusion, involving fractal‐like structure and dense branching‐like morphology (DBM). Higher humidity leads to a slower growth of crystal lamellae. Crystal growth promotes outward diffusion. Fractal‐like lamellae are viewed flat‐on. Due to the reduction of chain availability in the diffusion field, the fractal‐like structure turns into DBM.

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“…The characteristic feature of PEO lamellae is their aggregation in a radial pattern. When formed this way, much larger structures (spherulites) typical for PEO crystallization from solutions or from molten polymers have been observed with optical polarizing microscopy because of their optical anisotropy 47, 48…”

Section: Resultsmentioning

confidence: 99%

Studies of photooxidative degradation of poly(vinyl chloride)/poly(ethylene oxide) blends

Kaczmarek

Kowalonek

Klusek

et al. 2004

J Polym Sci B Polym Phys

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The photooxidative degradation of blends (in a full range of compositions) of amorphous poly(vinyl chloride) (PVC) with semicrystalline poly(ethylene oxide) (PEO) in the form of thin films is investigated using absorption spectroscopy (UVvisible and Fourier transform infrared) and atomic force microscopy (AFM). The amount of insoluble gel formed as a result of photocrosslinking is estimated gravimetrically. It is found that the PVC/PEO blendsí susceptibility to photooxidative degradation differs from that pure of the components and depends on the blend composition and morphology. Photoreactions such as degradation and oxidation are accelerated whereas dehydrochlorination is retarded in blends. The photocrosslinking efficiency in PVC/ PEO blends is higher than in PVC; moreover, PEO is also involved in this process. AFM images showing the lamellar structure of semicrystalline PEO in the blend lead to the conclusion that the presence of PVC does not disturb the crystallization process of PEO. The changes induced by UV irradiation allow the observation of more of the distinct PEO crystallites. This is probably caused by recrystallization of short, more mobile chains in degraded PEO or by partial removal of the less stable amorphous phase from the film surface. These results confirm previous information on the miscibility of PVC with PEO. The mechanism of the interactions between the components and the blend photodegradation are discussed.

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Observations of crystallization and melting in poly(ethylene oxide)/poly(methyl methacrylate) blends by hot-stage atomic-force microscopy

Cited by 41 publications

References 28 publications

Crystallization and melting of polyethylene copolymers: Differential scanning calorimetry and atomic force microscopy studies

Crystallization and melting of polyethylene copolymers: Differential scanning calorimetry and atomic force microscopy studies

Branched Crystalline Patterns Formed Around Poly(ethylene oxide) Dots in Humidity

Studies of photooxidative degradation of poly(vinyl chloride)/poly(ethylene oxide) blends

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