New models for rotational molding of plastics

Gogos, George; Olson, Lorraine G.; Liu, X.; Pasham, Venkataramana

doi:10.1002/pen.10309

Cited by 34 publications

(46 citation statements)

References 7 publications

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“…18,19 This is a reasonable assumption for most of the mold geometries, where the dimension perpendicular to the mold wall is much smaller than the others.…”

mentioning

confidence: 97%

Simulation of heat transfer during rotational molding

2003

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ABSTRACT:In rotational molding, polymer powders are subjected to heating, melting, cooling, and subsequent solidification in biaxially rotating molds. Heat transfer phenomena during rotational molding are significantly affected by the presence of endothermic and exothermic transitions. In this paper instead of using the traditional moving interface method, a new approach is presented which is applicable to semicrystalline materials like linear low-density polyethylene. Melting is described by a statistical model and crystallization by a kinetic model. The model parameters are determined from differential scanning calorimetry measurements. The one-dimensional unsteady heat conduction equation is solved by a finite difference method. The numerical predictions are in good agreement with experimental data. The overall heat transfer model can be used for process optimization purposes.

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“…18,19 This is a reasonable assumption for most of the mold geometries, where the dimension perpendicular to the mold wall is much smaller than the others.…”

mentioning

confidence: 97%

Simulation of heat transfer during rotational molding

2003

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“…It is thus not surprising that it leads to serious mistakes, and particularly, they were unable to predict existence of a melting stage. Gogos et al 49,50 are first authors to consider melting endothermic character of polymer in model. They have proposed a model with two phases in which liquid polymer is separated from a solid polymer powder by an interface.…”

Section: Rotational Moldingmentioning

confidence: 99%

“…Polymer powder passes from a solid in a liquid state during heating when interface temperature reached melting temperature. However, the numerical results presented here 49 are relatively heavy and complex because of a solid/liquid interface change after each iteration. One conclusion of this work was that melting stage cannot be simulated by this method.…”

Section: Rotational Moldingmentioning

confidence: 99%

Metallocene polypropylene crystallization kinetic during cooling in rotational molding thermal condition

Sarrabi

Boyer

Lacrampe

et al. 2013

J of Applied Polymer Sci

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. ABSTRACT: This article is part of an ambitious project. The aim is to simulate mechanical properties of rotomolded part from microstructure consideration. Main objective here is to consider metallocene polypropylene crystallization kinetic (PP) during cooling stage in rotational molding. Crystallization kinetic of metallocene PP is so rapid that microscopy cannot help to observe nucleation and growth. Crystallization rate can be estimated by a global kinetic. Given that cooling in rotational molding is dynamic with a constant rate, Ozawa law appears more appropriate. Ozawa parameters have been estimated by differential scanning calorimetry. In rotational molding thermal condition, Avrami index identifies a complex nucleation intermediate between spontaneous and sporadic. Ozawa rate constant is 68 times higher than this obtained for Ziegler-Natta PP. By coupling transformation rate from Ozawa model and a thermal model developed earlier, the difference between theory and experimental is less than 1%. To optimize rotational molding, study has been completed by sensitivity to adjustable parameters.

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“…This is because the experimental methods to measure these data are costly and not practical. In the present paper, some new and Gogos et al 10,11 dimensionless groups are used to study the physical, boundary and time conditions of rotational moulding system, quantitatively. The relationships of the key dimensionless groups in Gogos et al 10 to rotational moulding have been evaluated by using various 1D numerical approaches.…”

Section: Introductionmentioning

confidence: 99%

“…In the present paper, some new and Gogos et al 10,11 dimensionless groups are used to study the physical, boundary and time conditions of rotational moulding system, quantitatively. The relationships of the key dimensionless groups in Gogos et al 10 to rotational moulding have been evaluated by using various 1D numerical approaches. The evaluations assumed to be able to compensate for the lack of empirical data for comparisons at the present dimensional analysis.…”

Section: Introductionmentioning

confidence: 99%

Modelling of rotational moulding process: analysis of process parameters and warpage on cycle times

Ianakiev¹,

Lim²

2007

Plastics, Rubber and Composites

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The analysis of heat transfer in the rotational moulding process is a non-linear multi-dimensional matter, which involves a number of process conditions and thermal parameters. The present study mostly involves dimensional analysis, the changing effects of the process parameters and conditions on the process times for different processing circumstances. They have been explored and compared by using the two-dimensional slip flow model from Lim and Ianakiev.1 The modelling helps to further identify and understand the dependence of the key thermal parameters due to external heating, external cooling, external-internal cooling and warpage on cycle times of the rotational moulding. In addition, the detail of the coincident node technique is discussed to present the key components of the conductivity matrix for an element 'abutting' a coincident node interface.

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New models for rotational molding of plastics

Cited by 34 publications

References 7 publications

Simulation of heat transfer during rotational molding

Simulation of heat transfer during rotational molding

Metallocene polypropylene crystallization kinetic during cooling in rotational molding thermal condition

Modelling of rotational moulding process: analysis of process parameters and warpage on cycle times

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