Flow Birefringence of Molten Polyethylene

Dexter, F. D.; Miller, J C; Philippoff, W.

doi:10.1122/1.548894

Cited by 36 publications

(10 citation statements)

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“…The SIPLI technique has already been successfully applied to measure the dynamics of shear‐induced crystallization in polymers . Using the effect of birefringence in semi‐crystalline polymers, the flow parameters associated with the onset of shear‐enhanced nucleation and the shish formation (fibrillation) have been identified (and measured) by SIPLI.…”

Section: Examples Of Applications Of the Mechano‐optical Rheometermentioning

confidence: 97%

“…Since the second normal stress difference

N_{2} = true| σ_{22} - σ_{33} true|

is much smaller than the first normal stress difference

N_{1} = true| σ_{11} - σ_{22} true|

, h is close to zero and can be neglected in eq . Thus, if both N 1 and SOC values are known, the birefringence of the polymer melt in the plane of PLI observations can be calculated from

Δ n_{1, 3} \approx C (σ_{11} - σ_{22}) = C N_{1} .

…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…For example, birefringence occurs due to the flow‐induced orientation of polymer chains or particles in polymer melts, solutions or particle suspensions which creates optical anisotropy. There was a strong period of activity in this field during the 60s and 70s of the last century (comprehensively described in two excellent books) including a number of fundamental mechano‐optical rheological studies based on rotational shear geometries and flow birefringence …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

Mykhaylyk

Warren

Parnell

et al. 2016

J. Polym. Sci. Part B: Polym. Phys.

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A new experimental method for studying the mechano-optical rheology of polymeric liquids and soft matter materials is presented. The method is based on a combination of rotational rheology and a recently developed optical technique-shear-induced polarized light imaging (SIPLI). The method provides a unique opportunity to monitor a complete sample view during rheological measurements in plate-plate and cone-and-plate geometry. Applications of the method are presented including simultaneous SIPLI and the rheology of the oriented lamellar phase of block copolymers and liquid crystals as well as a study of the thermally induced reversible transformation of worm-like micelles to spherical micelles. In addition, a direct relation between the shish formation and the polymer melt viscosity upturn during flow-induced crystallization of semi-crystalline polymers is demonstrated. An application of SIPLI for quantitative birefringence measurements is also shown.

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Section: Examples Of Applications Of the Mechano‐optical Rheometermentioning

confidence: 97%

“…Since the second normal stress difference

N_{2} = true| σ_{22} - σ_{33} true|

is much smaller than the first normal stress difference

N_{1} = true| σ_{11} - σ_{22} true|

, h is close to zero and can be neglected in eq . Thus, if both N 1 and SOC values are known, the birefringence of the polymer melt in the plane of PLI observations can be calculated from

Δ n_{1, 3} \approx C (σ_{11} - σ_{22}) = C N_{1} .

…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

Mykhaylyk

Warren

Parnell

et al. 2016

J. Polym. Sci. Part B: Polym. Phys.

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“…At this point, however it is important to recognize that serious doubts as to the possibility to apply the described method to extrusion problems are caused by the fact, recently published by Dexter, Miller and Philippoff (10) that the time for the establishment of steady flow birefringence of polyethylene is rather long, i. e. in the order of 10 seconds for a special sample.…”

Section: Discussionmentioning

confidence: 99%

On the relationship between stored free energy and end-correction in capillary viscometry

Dekker

Janeschitz‐Kriegl

1962

Kolloid-Z.u.Z.Polymere

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“…Um dos primeiros aparatos experimentais para medir a birrefringência em fluidos poliméricos foi proposto por Dexter et al [21] e consiste em dois pratos paralelos de vidro, em que um deles move-se provocando o deslocamento do fluido entre eles, enquanto um feixe de luz propaga-se na direção perpendicular do escoamento. Desde então, diferentes geometrias/equipamentos surgiram na literatura [22][23][24][25] e entre eles está o reômetro multipasse [15,17] (Multipass Rheometer -MPR).…”

Section: Conforme Mostrado Por Muller E Vergnesunclassified

Utilização da técnica de birrefringência em reômetro multipasse para a diferenciação de grades de poliestireno cristal

et al. 2014

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Resumo: O entendimento de como as propriedades reológicas afetam o comportamento dos polímeros nas operações de processamento, por meio de diferentes técnicas experimentais, é de fundamental importância para ser possível prever e avaliar a estrutura final destes materiais. Neste contexto, o objetivo deste trabalho é aplicar a técnica de birrefringência para diferenciar dois grades de poliestireno cristal. Foram realizados experimentos em um reômetro multipasse que permitiram a aquisição de imagens de birrefringência, que representam o campo de tensão do escoamento, e obteve-se a queda de pressão durante os experimentos. Ao se compararem os padrões de birrefringência dos dois poliestirenos foi possível distinguir os materiais e verificar que o escoamento da amostra de maior massa molar é mais complexo, com maior birrefringência e tensão mais elevada. Os resultados obtidos, além de contribuírem para a caracterização reológica, podem ser empregados no estudo comparativo de modelos constitutivos e desenvolvimento de códigos computacionais. Palavras-chave:Birrefringência, reômetro multipasse, poliestireno. The Use of Birefringence Technique in a Multipass Rheometer for the Differentiation of General Purpose Polystyrene GradesAbstract: Polymers must go through processes that transform raw materials in a final product for consumption, and therefore it is crucial to understand how their rheological properties affect processability and final product quality. This study is aimed at applying the birefringence technique to differentiate two grades of general purpose polystyrene. Flow experiments were carried out using a multi-pass rheometer and flow-induced birefringence images and pressure profile were obtained. It was possible to distinguish between the different materials by examining their birefringence patterns. The flow of the higher molecular weight sample is more complex, with higher birefringence and tension. These data are important for the rheological characterization of the material and can be used in the validation of constitutive models in computational fluid dynamics. Universitária, Fundão, Av. Horácio Macedo, 2030, CEP 21941-914, Rio de Janeiro, RJ, Brasil, e-mail: arge@peq.coppe.ufrj.br Introdução O conhecimento do comportamento reológico de polímeros fundidos é de suma importância nas operações que transformam a matéria-prima em produto final para o consumo. Polímeros, tais como polietileno, polipropileno, policarbonato e poliestireno, são processados em elevadas temperaturas e, durante as operações como extrusão e moldagem por injeção, o material é submetido a altas taxas de deformação, causando a orientação e alongamento das cadeias. O processamento de polímeros é diretamente afetado pelas propriedades reológicas em estado fundido, sendo necessário conhecer o comportamento desses materiais nas condições práticas de escoamento para ser possível prever e avaliar a estrutura final do material [1] . Assim, com o intuito de evitar ou diminuir a necessidade de procedimentos de tentativa e erro, que represe...

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Flow Birefringence of Molten Polyethylene

Cited by 36 publications

References 0 publications

Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

On the relationship between stored free energy and end-correction in capillary viscometry

Utilização da técnica de birrefringência em reômetro multipasse para a diferenciação de grades de poliestireno cristal

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