Dual Growth Rates and Morphologies of Isothermally Crystallized Miscible Polymer Blends

Mareau, Vincent H.; Prud’homme, Robert E.

doi:10.1021/ma011989s

Cited by 23 publications

(46 citation statements)

References 12 publications

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“…We noticed that the S-spherulites become more birefringent as the PCL content and crystallization temperature increases as seen by comparing the crossed polar optical microphotographs of Figures 4c and 5c, but even more clearly if these two examples are compared to the 60/40 example given in Figure 1c in the previous article. 22 Similar observations were done at the two other compositions.…”

Section: Resultssupporting

confidence: 73%

“…This phenomenon, briefly described in our previous communication, 22 is more precisely illustrated in Figures 6-8. Figure 6 is composed of six microphotographs taken at the same position on a 30 µm PCL/PVC blend film of 65/35 composition, crystallized at 40°C.…”

Section: Resultssupporting

confidence: 57%

“…For the two compositions illustrated by Figures 4 and 5, the growth rate of the C-spherulites is about 60% slower than that of the S-spherulites, a smaller difference than with the 60/40 PCL/PVC composition where the C-spherulites grow 2-3 times more slowly than the S-spherulites. 22 As in Figure 4 with the 75/25 PCL/PVC composition, the two types of spherulites of Figures 5 exhibit different morphologies. The S-spherulite exhibits an open structure with wavy edges and no Maltese cross whereas the C-spherulite is circular, with a compact structure and a well-defined banded Maltese cross.…”

Section: Resultsmentioning

confidence: 93%

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Growth Rates and Morphologies of Miscible PCL/PVC Blend Thin and Thick Films

Mareau

Prud’homme

2003

Macromolecules

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Growth rates and morphologies of thin (0.1-2 µm) and thick (30 µm) films of miscible poly-( -caprolactone)/poly(vinyl chloride) (PCL/PVC) blends have been investigated. Under isothermal crystallization, PCL growth rates decrease in blend films thinner than 1 µm. However, in pure PCL films, no growth rate dependence is seen at the same thicknesses. In thick films of blends isothermally crystallized at a slow growth rate, two types of spherulites are observed with different growth rates and morphologies. One type of spherulites develops at the free surface of the film whereas the other is located in the bulk. The surface enrichment of the blend in PCL appears to be a key factor explaining the crystallization and morphological behavior of this system.

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Section: Resultssupporting

confidence: 73%

Section: Resultssupporting

confidence: 57%

Section: Resultsmentioning

confidence: 93%

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Growth Rates and Morphologies of Miscible PCL/PVC Blend Thin and Thick Films

Mareau

Prud’homme

2003

Macromolecules

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“…Moreover, the reduction in dimensionality in going from a three‐dimensional (3D) to quasi‐two dimensional (2D) system further limits the amount of crystallizable material in the vicinity of the growth front. Indeed a number of previous studies have reported the observation of diffusion‐limited crystal growth in sufficiently thin polymer films 7–29. These previously observed diffusion‐limited morphologies include dense‐branched morphologies, dendrites, and fractal structures.…”

Section: Introductionmentioning

confidence: 98%

“…Decreasing film thickness dramatically alters molecular mobility,1, 2 glass transition temperatures,3, 4 and segmental orientation5, 6 of semicrystalline polymers. These factors influence the transport of chain segments to the growth front of a crystallizing lamella, resulting in growth rates, degrees of crystallinity, morphologies, and melting behavior that differ from bulk crystals 7–29. Moreover, the reduction in dimensionality in going from a three‐dimensional (3D) to quasi‐two dimensional (2D) system further limits the amount of crystallizable material in the vicinity of the growth front.…”

Section: Introductionmentioning

confidence: 99%

Dendritic growth of poly(ε‐caprolactone) crystals from compatible blends with poly(t‐butyl acrylate) at the air/water interface

Marand

Esker

2007

J Polym Sci B Polym Phys

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Thermodynamic analyses of surface pressure-area (P-A) isotherms and Brewster angle microscopy (BAM) reveal that poly(e-caprolactone) (PCL) with a weight average molar mass of M w ¼ 10 kg mol À1 and polydispersity index of M w /M n ¼ 1.25 and poly(t-butyl acrylate) (PtBA, M w ¼ 25.7 kg mol À1 ; M w /M n ¼ 1.07) form compatible blends as Langmuir films below the dynamic collapse transition for PCL at P ¼ 11 mN m À1 . For PCL-rich blends, in situ BAM studies reveal growth of PCL crystals for compression past the PCL collapse transition. PCL crystals grown in the plateau regime of the P-A isotherm exhibit a dendritic morphology presumably resulting from the rejection of PtBA from the growing PCL crystals and hindered diffusion of PCL from the surrounding monolayer to the crystal growth fronts. The ability to transfer the PCL dendrites as Langmuir-Schaefer films onto silicon substrates spincoated with a polystyrene layer facilitates detailed morphological characterization by optical and atomic force microscopy (AFM). AFM reveals that the dendritic branching occurs along the {100} and {110} sector boundaries and is essentially independent of composition. AFM also reveals that the average thickness of PCL dendrites formed at room temperature (22.5 8C), $7-8 nm, is comparable with that of PCL crystals grown from single-component PCL Langmuir films and spincoated thin films. In contrast, for PtBA-rich blend films PCL crystallization is suppressed. These findings establish PCL blends as an ideal system for exploring the interplay between chain diffusion and crystal growth in a two-dimensional confined geometry.

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Melting and crystallization behaviors of isotactic polypropylene/acrylonitrile–butadiene rubber blends in the presence and absence of compatibilizers and fillers

Joseph¹,

George

Joseph³

et al. 2006

J of Applied Polymer Sci

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The melting and crystallization behaviors of isotactic polypropylene (PP)/acrylonitrile-butadiene rubber (NBR) blends were investigated with differential scanning calorimetry. The samples were scanned at a heating rate of 208C/min in a nitrogen atmosphere. The effects of blend ratio, compatibilizer, and filler addition on the melting and crystallization characteristics of the blends were analyzed. Analysis showed that blend ratio had a predominant effect on the values of onset of crystallization and crystallization temperature, although the heat of fusion (DH f ), onset of melting, and melting temperature were unaffected. The presence of compatibilizer in the blend had an appreciable influence on the crystallization behavior. DH f , heat of crystallization, and percentage crystallinity of the compatibilized blends were higher than those of the uncompatibilized blends. Fillers had little impact on the melting behavior of the blends. The morphology of the blends were analyzed with scanning electron microscopy. Hot-stage polarizing optical microscopy was used to study the spherulitic morphology of PP on the addition of NBR. The addition of a few percentage NBR significantly reduced the average spherulite size of PP in the blend followed by a marginal decrease. Blend ratio had a pronounced impact on the growth rate of PP spherulites.

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Dual Growth Rates and Morphologies of Isothermally Crystallized Miscible Polymer Blends

Cited by 23 publications

References 12 publications

Growth Rates and Morphologies of Miscible PCL/PVC Blend Thin and Thick Films

Growth Rates and Morphologies of Miscible PCL/PVC Blend Thin and Thick Films

Dendritic growth of poly(ε‐caprolactone) crystals from compatible blends with poly(t‐butyl acrylate) at the air/water interface

Melting and crystallization behaviors of isotactic polypropylene/acrylonitrile–butadiene rubber blends in the presence and absence of compatibilizers and fillers

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