Kinetics of phase separation and crystallization in poly(ethylene-ran-hexene) and poly(ethylene-ran-octene)

Matsuba, Go; Shimizu, K.; Wang, Howard; Wang, Zhigang; Han, Charles C.

doi:10.1016/j.polymer.2003.09.032

Cited by 37 publications

(14 citation statements)

References 24 publications

(22 reference statements)

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“…That is, the domain morphology caused by the phase separation has to coexist with the lamellar morphology (i.e., an alternating structure composed of thin lamellar crystals and amorphous layers) and also spherulite structure owing to the crystallization of constituent homopolymers. There are some experimental studies on the bahavior of such morphology formation [9][10][11] and resulting morphology [12][13][14][15][16] in binary blends of crystalline and amorphous homopolymers.…”

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confidence: 99%

Synchrotron SAXS Studies on Morphology Formation in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Akaba

Nojima

2005

Polym J

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ABSTRACT:The process of morphology formation in a binary blend of poly("-caprolactone) homopolymer (PCL) and poly("-caprolactone)-block-polybutadiene copolymer (PCL-b-PB) has been investigated by synchrotron smallangle X-ray scattering (SR-SAXS). This blend shows an UCST-type phase separation and the crystallization of PCL chains (i.e., PCL and PCL blocks in PCL-b-PB) at a same temperature range, so that these two factors may work simultaneously to yield a complicated morphology formation. When the weight fraction of PCL ( PCL ) is small ( PCL < 0:2) or large ( PCL > 0:8), the blend can directly be quenched into crystallization temperatures without passing through the UCST region. Time-resolved SAXS curves in this case show that overall morphology formation is driven by the crystallization of PCL chains, where a crystallized PCL region always coexists with a crystallized PCL-b-PB region and the volume ratio of two regions is constant throughout. [DOI 10.1295/polymj.37.464] KEY WORDS Morphology Formation / Crystallization / Phase Separation / Crystallineamorphous Diblock Copolymer / Small-Angle X-Ray Scattering / Synchrotron Radiation / Morphology formation in polymer blends is controlled by many factors such as liquid-liquid phase separation between components, crystallization of constituent polymers, and microphase separation of block copolymers.1,2 This morphology formation has widely been investigated when only one factor works to yield a final morphology in the blend. When two or more factors work simultaneously in the morphology formation, however, the mechanism becomes extremely complicated. If we consider a binary blend consisting of amorphous block copolymers and homopolymers, for example, liquid-liquid phase separation and microphase separation may act simultaneously, where the phase diagram is also complicated depending on the combination of macro-(or liquid-liquid) and micro-phase separation regions.3,4 Some experimental results have been reported so far to clarify the mechanism of such morphology formation. 3-8When we suppose a binary blend consisting of crystalline and amorphous homopolymers, the morphology formation is driven by a cooperative effect of liquid-liquid phase separation and crystallization, and eventually we have another kind of complicated morphology formation. That is, the domain morphology caused by the phase separation has to coexist with the lamellar morphology (i.e., an alternating structure composed of thin lamellar crystals and amorphous layers) and also spherulite structure owing to the crystallization of constituent homopolymers. There are some experimental studies on the bahavior of such morphology formation 9-11 and resulting morphology [12][13][14][15][16] in binary blends of crystalline and amorphous homopolymers.We have previously investigated the process of morphology formation in a binary blend of poly("-caprolactone) homopolymer (PCL) and polystyrene oligomer (PSO) by using synchrotron small-angle Xray scattering (SR-SAXS), 9 where this blend had an UCST-type phase ...

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confidence: 99%

Synchrotron SAXS Studies on Morphology Formation in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Akaba

Nojima

2005

Polym J

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“…The Avrami exponent varied from an average value of 3.5 for PE to average values of 3.9 for the copolymer E/H-1 and of 4.8 for E/H-3 and E/H-5 copolymers. A value of n ¼ 3.5 has been reported by Matsuba et al [32] for the isothermal crystallisation of single sample of E/H random copolymer with a low molar content of the comonomer. According to the theoretical model, the observed values of n for PE are consistent with a three-dimensional spherulitic growth of the crystals with a combination of thermal and athermal nucleation mechanism that explain the fractional values of the Avrami's exponent; the higher values of n observed for some copolymers could formally be accounted for by a sheaf-like type of crystallisation.…”

Section: Crystallisation Kineticsmentioning

confidence: 84%

FTIR Microanalysis and Phase Behaviour of Ethylene/1‐Hexene Random Copolymers

Pracellà¹,

D’Alessio

Giaiacopi

et al. 2007

Macro Chemistry & Physics

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Ethylene/1‐hexene random copolymers with 1‐hexene content in the range of 1–5 mol‐%, synthesised in the presence of new heterogeneous catalyst systems based on bis‐carboxylato and ‐bis‐chloro‐carboxylato titanium chelate complexes, have been characterised by FTIR microspectroscopy (FTIR‐M), DSC calorimetry and X‐ray scattering. The co‐monomer content and sequence distribution in the various samples were determined by means of both FTIR‐M and 13C NMR spectroscopy. The deformation bands of methyl groups in the region of 1 400–1 330 cm−1 were used for the structural analysis of these copolymers. The effect of composition on the crystallinity and phase transitions of copolymers was analysed both in 1 500–1 300 and 760–690 cm−1 frequency ranges as a function of the annealing temperature. A neat variation of the absorbance ratio of methyl band at 1 378 cm−1 was recorded between 110 and 130 °C corresponding to the melting range of the copolymer crystals. The crystallisation behaviour of the copolymers was examined by DSC in dynamic and isothermal conditions; the isothermal kinetics were analysed according to the Avrami model. A marked decrease in the bulk crystallisation rate, accompanied by changes in the nucleation and growth of crystals, was found with an increase in the co‐monomer content. The melting behaviour of isothermally crystallised samples was also investigated and the melting temperatures of the copolymers at equilibrium conditions were related to the composition; the experimental data were consistent with the Flory exclusion model of side branches from the crystalline phase. The lowering of crystal growth rate in the copolymers has been accounted for by an increase in the free energy of formation of critical size nuclei due to the effect of the side branches.magnified image

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“…[4][5][6] The melt miscibility of polyolefin blends has long been a challenging subject because the constituting components have similar chemical structures and very close refractive indices, which made it difficult to determine whether an observed transparent sample is truly in a ''homogeneous state'' or not. [7][8][9] The properties of PP alloys are determined not only by miscibility (or compatibility) between the components, but also depend to a large extent on their crystalline structure, therefore many research papers have been published on the morphology and kinetics of crystallization in blends. [10][11][12][13][14][15][16][17] Some studies have been reported on the compositional heterogeneity, chain structure, and properties of the in-reactor-prepared PP alloys.…”

Section: Introductionmentioning

confidence: 99%

Structural and morphological development in polypropylene/poly(propylene‐1‐octene) in‐reactor alloy due to the competition between liquid–liquid phase separation and crystallization

Wang¹,

Han²

2013

J of Applied Polymer Sci

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Relationship between phase separation and crystallization of polypropylene/poly(propylene-1-octene) in-reactor alloy (iPP/PPOc) were studied using optical microscopy, scanning electron microscopy, and differential scanning calorimetry. Optical microscopy was used to monitor nuclei density and spherulite growth rates, providing complementary information about the effect of liquid-liquid phase separation (LLPS) on crystallization behavior. We found that LLPS process had a retardation effect on crystallization rate and had a dominant effect on the final crystalline morphology of the iPP/PPOc alloy. By simply changing the LLPS time or temperature, we could control the size and the distribution of the elastomer phase that dispersed in the iPP spherulites. The growth rate of the spherulites significantly depended on the degree of LLPS. Higher degree of phase separation reduced nuclei density and the growth rate of spherulites. However, it was helpful to the formation of more perfect spherulites. But surprisingly, there seemed to be little variation of crystallinity between the two quenching procedures (i.e., single quench vs. double quench). Overall, the competition between LLPS and crystallization significantly influenced the structural and morphological development of the iPP/PPOc alloy. By controlling the interplay between LLPS and crystallization of iPP/PPOc alloy, it was possible to control the structure and morphology as needed in applications.

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Kinetics of phase separation and crystallization in poly(ethylene-ran-hexene) and poly(ethylene-ran-octene)

Cited by 37 publications

References 24 publications

Synchrotron SAXS Studies on Morphology Formation in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Synchrotron SAXS Studies on Morphology Formation in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

FTIR Microanalysis and Phase Behaviour of Ethylene/1‐Hexene Random Copolymers

Structural and morphological development in polypropylene/poly(propylene‐1‐octene) in‐reactor alloy due to the competition between liquid–liquid phase separation and crystallization

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