The Morphology of Crystalline Synthetic Polymers

Khoury, F.; Passaglia, Elio

doi:10.1007/978-1-4684-2664-9_6

Cited by 60 publications

(52 citation statements)

References 239 publications

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“…Early morphological studies have shown that PE crystals grown from not‐so‐dilute solutions (as in this report) can take various habits, such as pyramids, rotating terraces, lozenges, and dendrites, depending on the polymer concentration, the degree of undercooling (Δ T ), the molecular weight, and so forth 4–6. Those crystal habits are at length scales of micrometers to tens of micrometers, whereas multilayered crystals (lamellar stacks) dominate the features at tens to hundreds of nanometers 4–6.…”

Section: Theoretical Backgroundmentioning

confidence: 63%

“…Crystallization of long‐chain molecules has been extensively studied over the last half‐century and is reasonably well understood;1–6 nevertheless, some fundamental issues are still under investigation and debate. Those include the experimental determination of the equilibrium melting temperature of polymers,7–10 the metastability of polymer crystals,11, 12 and the mechanism of homogeneous nucleation 13–21.…”

Section: Introductionmentioning

confidence: 99%

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Time‐resolved small‐angle neutron scattering study of polyethylene crystallization from solution

Wang

2004

J Polym Sci B Polym Phys

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With time-resolved small-angle neutron scattering (TR-SANS), the crystallization kinetics of polyethylene from deuterated o-xylene solutions upon a temperature jump have been investigated. On the basis of a morphological model of coexisting lamellar stacks and coil chains in solution, experimental data have been quantitatively analyzed to provide structural information, such as the lamellar long period, the lamellar crystal thickness, the thickness of the amorphous layers between lamellae, the degree of crystallinity, and the crystal growth rate at various degrees of undercooling. The viability of TR-SANS for studying polymer crystallization is demonstrated through the consistency of these measurements and well-established knowledge of polyethylene crystallization from xylene solutions. One unique feature of this experimentation is that both the growth of lamellar crystals and the condensation of coil chains from solution are monitored simultaneously. The ratio of the crystal growth to the chain consumption rate decreases rapidly with a decreasing degree of undercooling. The Avrami analysis suggests that the growth mechanism approaches two-dimensional behavior at higher temperatures, and this is consistent with the observation of an increasing ratio of the sharp-surface area to the bulk crystal growth rate with temperature. The limitations, possible remedies, and potentials of TR-SANS for studying polymer crystallization are discussed.

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Section: Theoretical Backgroundmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Time‐resolved small‐angle neutron scattering study of polyethylene crystallization from solution

Wang

2004

J Polym Sci B Polym Phys

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“…9 7. THEORETICAL ASPECTS OF THE CRYSTALLIZATION OF SUPERCOOLED POLYMERIC MELTS Many polymers crystallize from the melt in the form of spherulites (Mandelkern 1964b, Khoury andPassaglia 1976). The overall rate of crystallization of a supercooled polymeric liquid is determined by the nucleation and growth rates of spherulites.…”

Section: Crystallization Exferiments Under Isobaric-isothermal Conmentioning

confidence: 99%

Temperature dependence under pressure of the kinetics of crystallization of bulk amorphous selenium

Mohan

Singh

1993

Philosophical Magazine B

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“…It has been shown that polymers crystallize in spherulites or axialites [14]. For the same considerations as described by Khoury and Passaglia [15] we do not adopt the fringed micelle model. In order to create ordered crystalline structures two steps are involved.…”

Section: Crystallization In Relation To Mass Transfermentioning

confidence: 99%

Diffusion induced phase separation with crystallizable nylons. I. Mass transfer processes for nylon 4,6

Bulte

Mulder

Smolders

et al. 1996

Journal of Membrane Science

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Mass transfer during membrane formation by means of phase inversion for a polymeric system with both a solid-liquid and a liquid-liquid equilibrium was studied on the basis of the theory developed by Reuvers and Smolders. During the first moments of immersion in the coagulation bath, the concentrations at the interface between bath and film are governed by the virtual liquid-liquid equilibrium. This equilibrium no longer exists at a larger time scale. The interfacial concentrations as a result of the local liquid-liquid equilibrium during mass transfer are located deeply in the crystallization region or solid-liquid demixing area and after an induction time the solid-liquid phase separation (crystallization) takes place when membranes are formed with an initial polymer concentration of 20% or larger. The calculated initial concentration profiles show a shallow pattern in polymer content for the films with initial concentration of 20 and 25%. From the calculated initial concentration profiles an isotropic morphology in the final membrane can be expected. A steep increase of the polymer concentration at the interface was observed for the more concentrated films correlated with a skinned morphology in the final membrane.

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The Morphology of Crystalline Synthetic Polymers

Cited by 60 publications

References 239 publications

Time‐resolved small‐angle neutron scattering study of polyethylene crystallization from solution

Time‐resolved small‐angle neutron scattering study of polyethylene crystallization from solution

Temperature dependence under pressure of the kinetics of crystallization of bulk amorphous selenium

Diffusion induced phase separation with crystallizable nylons. I. Mass transfer processes for nylon 4,6

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