Quantification of non-isothermal, multi-phase crystallization of isotactic polypropylene: The influence of cooling rate and pressure

Drongelen, van M Martin; Erp, van Tb Tim; Peters, Gwm Gerrit

doi:10.1016/j.polymer.2012.08.003

Cited by 121 publications

(185 citation statements)

References 55 publications

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“…Therefore, the temperature dependence of the crystal growth rate needs to be accounted for. The growth rate in quiescent conditions can be calculated with [113] …”

Section: Crystallization Kineticsmentioning

confidence: 99%

“…25. This area acts as the nucleation site for both parents and daughters, and is allocated to either parent or daughter morphology based on their momentary growth rates [113]:…”

Section: Crystallization Kineticsmentioning

confidence: 99%

“…The model presented in the section, which deals with the two issues of validation and multiple phase/multiple morphologies, combines two phenomenological approaches to FIC of iPP that have been validated in previous works: nonisothermal crystallization leading to varying compositions of crystal phases (α, β, γ, meso) [113] and flow-induced structure formation leading to various crystalline morphologies (spherulite, shish-kebab with parent and daughter crystals) (see Sec. 3 of this chapter and [5,116]).…”

Section: Formation Of Multiple Crystal Phases and Morphologiesmentioning

confidence: 99%

“…The starting concept of the model presented in this paper was presented by van Drongelen et al [113]. For each crystal phase, the Schneider rate equations [68,69] are solved to calculate the crystallization kinetics.…”

Section: Crystallization Modelmentioning

confidence: 99%

“…To do so, only temperaturedependent nucleation density and growth rate are required. The growth rates of the α-, β-, and γ-polymorphs were determined by van Drongelen [113]. The kinetics of formation of the mesomorphic phase were also determined, but are not used in this paper because the experiments did not show any of this phase as a result of the relatively low cooling rate.…”

Section: Crystallization Modelmentioning

confidence: 99%

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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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“…Therefore, the temperature dependence of the crystal growth rate needs to be accounted for. The growth rate in quiescent conditions can be calculated with [113] …”

Section: Crystallization Kineticsmentioning

confidence: 99%

“…25. This area acts as the nucleation site for both parents and daughters, and is allocated to either parent or daughter morphology based on their momentary growth rates [113]:…”

Section: Crystallization Kineticsmentioning

confidence: 99%

Section: Formation Of Multiple Crystal Phases and Morphologiesmentioning

confidence: 99%

Section: Crystallization Modelmentioning

confidence: 99%

Section: Crystallization Modelmentioning

confidence: 99%

See 3 more Smart Citations

Modeling Flow-Induced Crystallization

Roozemond

Drongelen

Peters

2016

Polymer Crystallization II

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Cooling rate dependence of the crystallinity at nonisothermal crystallization of polymers: A phenomenological model

Schawe

2015

J of Applied Polymer Sci

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The cooling rate dependence of the crystallinity of polymers is investigated via the example of different technical polypropylenes using fast scanning calorimetry (FSC) in a cooling rate range between 1 and 5000 K s 21 . In the slower cooling rate range (below 100 K s 21 ) the crystallinity increases slightly with decreasing cooling rate. Above cooling at 100 K s 21 the crystallinity decreases substantially and vanishes at the critical cooling rate. We describe this behavior using a simplified model with two components: the generic crystallinity function and the retardation function. For a mathematical description, we use empirically fitted functions that describe the cooling rate dependence of the crystallinity and the critical cooling rate.

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Quantification of the Young's modulus for polypropylene: Influence of initial crystallinity and service temperature

Zhu

et al. 2019

J of Applied Polymer Sci

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In this study, the mechanical properties of isotactic polypropylene (iPP) materials with different crystallinities at room and elevated temperatures were investigated. In order to obtain samples with a certain range of crystallinity, and to ensure a uniform microstructure of these samples, the iPP samples obtained by injection molding required melt compression molding and controlled annealing. In the macromechanical studies, the experimental results showed that the storage modulus and Young's modulus of polypropylene were sensitive to the service temperature. The crystallinity also had a great influence on this relationship. A function was proposed to evaluate the dependence of the Young's modulus of polypropylene on initial crystallinity and service temperature, and tested based on experimental data. The Young's modulus of iPP is reduced by about 90% when the service temperature rises from 25 to 125 C. Moreover, the reduced value in Young's modulus between polypropylene having the highest and lowest crystallinity was reduced from 214.55 to 56.75 MPa.

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Quantification of non-isothermal, multi-phase crystallization of isotactic polypropylene: The influence of cooling rate and pressure

Cited by 121 publications

References 55 publications

Modeling Flow-Induced Crystallization

Modeling Flow-Induced Crystallization

Cooling rate dependence of the crystallinity at nonisothermal crystallization of polymers: A phenomenological model

Quantification of the Young's modulus for polypropylene: Influence of initial crystallinity and service temperature

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