Small-angle neutron scattering studies of isotropic polypropylene

Ballard, D. G. H.; Cheshire, P.; Longman, G. W.; Schelten, J.

doi:10.1016/0032-3861(78)90241-0

Cited by 128 publications

(97 citation statements)

References 8 publications

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“…6 to be significantly larger than the experimental values measured by SANS experiments on the melts of long chain polymers, e.g. iPP: C'm = 6.2 [32]. These differences are mostly due to the small chain lengths studied in this work.…”

Section: Single-chain Statisticscontrasting

confidence: 64%

Self-consistent integral equation theory for polyolefins: Comparison to molecular dynamics simulations and x-ray scattering

Pütz

Curro

Grest

2001

The Journal of Chemical Physics

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We report on self-consistent Polymer Reference Interaction Site Model (PRISM) calculations as well as molecular dynamics (MD) simulations for several types of polyolefins. For all polymer types one single set of potential parameters was used. In general we find good semi-quantitative agreement between PRISM and MD results. Further we compare both MD and PRISM results to experimental X-Ray scattering data and show that the potentials used give a good to excellent description of these data. From the quality of the PRISM calculations it is clear that PRISM can be used as an efficient tool in model development.

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Section: Single-chain Statisticscontrasting

confidence: 64%

Self-consistent integral equation theory for polyolefins: Comparison to molecular dynamics simulations and x-ray scattering

Pütz

Curro

Grest

2001

The Journal of Chemical Physics

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“…The segment length, being of the order of nanometers, attains a sensible magnitude. The same goes for the radius at which shish influence the velocity, being of the order of the radius of [5] gyration (shish radius of 10 nm plus the average radius of gyration of 23.5 nm for this material [112] gives 33.5 nm).…”

Section: Parameter Sensitivity Analysismentioning

confidence: 76%

“…Because of the number of uncertainties in this approach, we treat r eff as an adjustable parameter. A priori, we expect r eff to be about 35 nm, because shish have a typical radius of 10 nm and the average radius of gyration of this material is estimated to be 23.5 nm [112].…”

Section: Structure Formationmentioning

confidence: 99%

Modeling Flow-Induced Crystallization

Roozemond

Drongelen

Peters

2016

Polymer Crystallization II

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A numerical model is presented that describes all aspects of flow-induced crystallization of isotactic polypropylene at high shear rates and elevated pressures. It incorporates nonlinear viscoelasticity, including viscosity change as a result of formation of oriented fibrillar crystals (shish), compressibility, and nonisothermal process conditions caused by shear heating and heat release as a result of crystallization. In the first part of this chapter, the model is validated with experimental data obtained in a channel flow geometry. Quantitative agreement between experimental results and the numerical model is observed in terms of pressure drop, apparent crystallinity, parent/daughter ratio, Hermans' orientation, and shear layer thickness. In the second part, the focus is on flow-induced crystallization of isotactic polypropylene at elevated pressures, resulting in multiple crystal phases and morphologies. All parameters but one are fixed a priori from the first part of the chapter. One additional parameter, determining the portion of β-crystal spherulites nucleated by flow, is introduced. By doing so, an accurate description of the fraction of β-phase crystals is obtained. The model accurately captures experimental data for fractions of all crystal phases over a wide range of flow conditions (shear rates from 0 to 200 s À1 , pressures from 100 to 1,200 bar, shear temperatures from 130 C to 180 C). Moreover, it is shown that, for high shear rates and pressures, the measured γ-phase fractions can only be matched if γ-crystals can nucleate directly on shish.

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“…In the case of isotactic polypropylene (27), where the molecular weight dependence was studied, is was found that the radii of gyration obey the M"2 law also in the crystalline state. In addition it was shown that <s2)1"2 does not depend on crystallization or annealing conditions although a drastic change of the long spacing (120 -250 A) was achieved.…”

Section: ) Morphological Studies Of Semicrystalline Polymers By Meanmentioning

confidence: 99%

“…The fold length is fixed by the matrix and very special and rather artifical assumptions on the widths of the sheets and on their spatial distribution must be introduced in order to arrive at the observed radius of gyration (25,27).…”

Section: ) Morphological Studies Of Semicrystalline Polymers By Meanmentioning

confidence: 99%

Studies of Structure and Dynamics of Solid Polymers by Elastic and Inelastic Neutron Scattering

Fischer

1979

Macromolecular Chemistry

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Small-angle neutron scattering studies of isotropic polypropylene

Cited by 128 publications

References 8 publications

Self-consistent integral equation theory for polyolefins: Comparison to molecular dynamics simulations and x-ray scattering

Self-consistent integral equation theory for polyolefins: Comparison to molecular dynamics simulations and x-ray scattering

Modeling Flow-Induced Crystallization

Studies of Structure and Dynamics of Solid Polymers by Elastic and Inelastic Neutron Scattering

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