The equilibrium melting points of random ethylene-octene copolymers: A test of the Flory and Sanchez-Eby theories

Kim, Man-Ho; Phillips, P. J.; Lin, Jianzhen

doi:10.1002/(sici)1099-0488(20000101)38:1<154::aid-polb19>3.0.co;2-1

Cited by 36 publications

(11 citation statements)

References 23 publications

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“…The bulky side chain plays a role as a defect hindering the crystallization and is expected to be rejected from the crystalline phase formed by the linear backbone segments of the chains. 54,55 For example, if the side chain distribution along the backbone is heterogeneous (an example of the extreme case is shown in Figure 6a (A)), the long defect-free backbone chains (TFE) can fold back adjacently or loosely on the crystalline plane, forming the lamellar phase (Figure 6a (A1)). On the other hand, in the case of a random or homogeneous distribution of the side chains for the membrane with EW ) 1100 (n ≈ 7), only short linear chain segments, free of defects (i.e., side chain), exist in the backbone chain (Figure 6a (B)).…”

Section: Figurementioning

confidence: 99%

SANS Study of the Effects of Water Vapor Sorption on the Nanoscale Structure of Perfluorinated Sulfonic Acid (NAFION) Membranes

et al. 2006

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Several poly(perfluorosulfonic acid) membranes (NAFION, EW ) 1100) with the same sulfonic acid content were systematically investigated with SANS under in-situ water vapor sorption and/or with bulk water to quantify the effects of relative humidity (RH), membrane processing (melt-extruded and solution-casting), prehistory (pretreated at 80°C and as-received), and thickness on the nanoscale structure at room temperature. The sorption isotherm (water uptake vs RH) of the membranes showed a strong correlation between the interionic domain distance (L ion ) and RH. The melt-extruded membranes showed evidence of partial alignment of better organized ionic domains than those solution-cast. Pretreating the membranes resulted in a larger L ion and a broader scattering over the entire range of RH. The ionic peak of the melt-extruded membranes (as-received and pretreated) became more symmetric and narrower with sorption time. Diffusion coefficients of water vapor, based on structural evolution and Fick's second law, are in the range of 1 × 10 -7 -3 × 10 -7 cm 2 /s for both extruded (pretreated and as-received) membranes. A thickness-dependent crystalline feature around Q ≈ 0.03 Å -1 was also observed.

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Section: Figurementioning

confidence: 99%

SANS Study of the Effects of Water Vapor Sorption on the Nanoscale Structure of Perfluorinated Sulfonic Acid (NAFION) Membranes

et al. 2006

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“…1(a) can be observed after annealing for 100 min at 150 8C. This annealing condition is above the equilibrium melting temperature, T m 8 , 142 8C [21,22]. After 102 min, the bicontinuous structure grows in Fig.…”

Section: Methodsmentioning

confidence: 91%

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

Matsuba

Shimizu

Wang

et al. 2003

Polymer

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“…Both samples were initially melted at 443 K for around 10 min, 28 K above the equilibrium melting temperature (T m o ) 415.2 K) of linear polyethylene with M w ∼ 101 kg/mol, 17 to remove any traces of crystalline nuclei. A high crystalline sample (φ Vc ) 78%, PE78) was isothermally crystallized at the preset temperature (T c ) 383.0 ( 0.5 K) for 36 h. A low crystalline sample (φ Vc ) 54%, PE54) was rapidly crystallized at T c ) 296.0 K by quenching the melt in water.…”

Section: Methodsmentioning

confidence: 99%

Correlation between Structure and Vapor Sorption in Semicrystalline Linear Polyethylene: One Dimensional Nano-Swelling Measured Using in Situ Vapor Sorption Small Angle Neutron Scattering (iVSANS)

Kim

Glinka

2009

Macromolecules

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Changes in the nanoscale structure of semicrystalline polyethylene (PE) resulting from the sorption/ diffusion of hexane-d 14 vapor have been observed and quantified by in situ vapor sorption small-angle neutron scattering (iVSANS). We find a linear correlation between vapor sorption/diffusion and nanoexpansion of the amorphous phase within the lamellae confined in the spherulite domains. The expansion depends on the degree of crystallinity and spherulite perfection. We measured the structure-based sorption kinetics and isotherms of samples with two different crystalline volume fractions (φ Vc ). The low crystalline polyethylene shows a larger expansion in the long period, L, than the high crystalline polyethylene. Low crystalline PE shows a Fickian-like diffusion profile with sorption time while the high crystalline PE (φ Vc ) 78%) shows a S-shape diffusion profile (non-Fickian) at P/P°) 0.95. The diffusion coefficient increases with relative vapor pressure (P/P°) in both materials. The apparent diffusion coefficient in the low crystalline polymer is approximately a factor of 2 higher than that of the more crystalline polymer. On the other hand, effective diffusion coefficients, D eff 's, normalized with the amorphous volume fractions at each vapor activity are identical regardless of crystallinity. This indicates that amorphous volume fraction is the predominant factor that controls transport properties, at least for small diffusing molecules. Furthermore, the one-dimensional expansion is reversible during cyclic sorption and desorption processes, suggesting that the crystals were not destroyed unlike the inference of a previous study. 1

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The equilibrium melting points of random ethylene-octene copolymers: A test of the Flory and Sanchez-Eby theories

Cited by 36 publications

References 23 publications

SANS Study of the Effects of Water Vapor Sorption on the Nanoscale Structure of Perfluorinated Sulfonic Acid (NAFION) Membranes

SANS Study of the Effects of Water Vapor Sorption on the Nanoscale Structure of Perfluorinated Sulfonic Acid (NAFION) Membranes

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

Correlation between Structure and Vapor Sorption in Semicrystalline Linear Polyethylene: One Dimensional Nano-Swelling Measured Using in Situ Vapor Sorption Small Angle Neutron Scattering (iVSANS)

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