Microstructure and Morphology Simulation

Zhou, Huamin; Liu, Fen; Zhao, Peng

doi:10.1002/9781118444887.ch7

Cited by 5 publications

(15 citation statements)

References 138 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These structures are thread-like, highly oriented parallel to the flow direction, and have crystalline lamellae growing perpendicular to the flow direction . Close to the central line of the mold, both the shear rate and temperature gradient will be low, resulting in randomly oriented polymer chains in symmetrical spherulites …”

Section: Introductionmentioning

confidence: 99%

Scanning Small-Angle X-ray Scattering of Injection-Molded Polymers: Anisotropic Structure and Mechanical Properties of Low-Density Polyethylene

Björn,

Melhado Mazza,

Andreasson

et al. 2023

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

Injection molding is known to create a layered anisotropic morphology across the sample thickness due to varying shear and cooling rates during the manufacturing process. In this study, scanning small-angle X-ray scattering was used to visualize and quantify the distribution of hierarchical structures present in injection-molded parts of low-density polyethylene (LDPE) with varying viscosities. By combining scattering data with results from injection molding simulations and tensile testing, we find that oriented shish-kebab structures, as well as elongated spherulite structures consisting of semicrystalline ellipsoids, contribute to high ultimate tensile strength along the flow direction. Furthermore, we show that a higher degree of orientation is found close to the injection gate and in LDPE with higher viscosity, consequently from elevated shear and cooling rates present during the injection molding process.

show abstract

Section: Introductionmentioning

confidence: 99%

Scanning Small-Angle X-ray Scattering of Injection-Molded Polymers: Anisotropic Structure and Mechanical Properties of Low-Density Polyethylene

Björn,

Melhado Mazza,

Andreasson

et al. 2023

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

show abstract

“…However, this publication has shortcomings in the description of rheology and the classification of the 2D approach. Other works, such as [1,[4][5][6], also do not sufficiently address the clear distinction between the different approaches. Commercial software and/or ongoing research activity may remain unclassified.…”

Section: Introductionmentioning

confidence: 99%

“…The focus has shifted from 1D models to 2D, 2.5D, and 3D models. Originally, 1D models were used to simulate simple flow patterns such as tube, disc, and strip flow [1]. However, due to the complexity of injection-molded parts and their non-Newtonian and non-isothermal rheological behavior, 1D models cannot accurately represent the actual filling process [2].…”

Section: Introductionmentioning

confidence: 99%

Approaches for Numerical Modeling and Simulation of the Filling Phase in Injection Molding: A Review

Baum,

Anders,

Reinicke

2023

Polymers

View full text Add to dashboard Cite

Injection molding is a multiphase process that requires accurate simulation of the filling phase. This is a key element in predicting the complete injection molding cycle. The filling phase presents a complex set of challenges, including migrating melt fronts, multi-phase flow, non-Newtonian fluid dynamics, and intertwined heat transfer. Evolving from 1D to 2D, 2.5D, and 3D techniques, filling simulation research has adapted to capture the intricacies of injection-molded parts. However, the need for accuracy in the characterization of the rheological properties of polymers during filling is still of paramount importance. In order to systematically categorize the numerical methods used to simulate the filling phase of injection molding, this review paper provides a comprehensive summary. Particular emphasis is given to the complex interaction of multiple geometric parameters that significantly influence the dynamic evolution of the filling process. In addition, a spectrum of rheological models is thoroughly and exhaustively explored in the manuscript. These models serve as basic mathematical constructs to help describe the complex viscous behavior of polymers during the filling phase. These models cover a spectrum of complexity and include widely recognized formulations such as the Power-Law, second-order, Herschel–Bulkley, Carreau, Bird–Carreau, and Cross models. The paper presents their implementation to include the temperature-dependent influence on viscosity. In this context, the extensions of these models are explained in detail. These extensions are designed to take into account the dynamic viscosity changes caused by the different thermal conditions during the filling process. An important contribution of this study is the systematic classification of these models. This categorization encompasses both academic research and practical integration into commercial software frameworks. In addition to the theoretical importance of these models, their practical value in overcoming challenges in the field of injection molding is emphasized. By systematically outlining these models within a structured framework, this classification promotes a comprehensive understanding of their intrinsic characteristics and relevance in different scenarios.

show abstract

“…In fact, the molecular orientation and refractive index are closely related to the elastic characteristics of the material. Therefore, mathematical modeling of polymer processing flows should, ideally, be based on the use of viscoelastic constitutive equations 10 . With the development of viscoelastic constitutive equations and simulation techniques in the last three decades, it is certainly possible to simulate the rheological behaviors of viscoelastic polymer melts.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, mathematical modeling of polymer processing flows should, ideally, be based on the use of viscoelastic constitutive equations. 10 With the development of viscoelastic constitutive equations and simulation techniques in the last three decades, it is certainly possible to simulate the rheological behaviors of viscoelastic polymer melts. A variety of viscoelastic constitutive equations have been proposed to characterize molten polymer viscoelasticity, among which the Pom-Pom model 11 and Rolie-Poly model 12 developed based on tube theory have been widely concerned currently.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic and mesoscopic simulation of polystyrene melt in the filling process of injection molding

Liu

Jiang

2023

J of Applied Polymer Sci

View full text Add to dashboard Cite

In this article, a fluid flow and heat transfer model which consist of the mass, momentum, and energy conservation equations together with the level set equation and Rolie‐Poly constitution equation is proposed and applied to simulate the rheological behaviors of viscoelastic polystyrene melt in the filling process of injection molding. The macroscopic velocity, pressure, temperature, stress, and mesoscopic molecular conformation of polystyrene melt are shown and analyzed detailedly during the mold filling process. The single‐mode Rolie‐Poly model is employed to describe the stress–strain relationship of polystyrene melt, and the level set method is used to capture the evolution of melt front interface. The governing equations for polymer melt are discretized by the finite volume method on collocated mesh, and solved by the SIMPLE algorithm. Numerical simulations have been implemented based on rectangular cavities with different gate locations, and rectangular and circular inserts. Numerical results indicate that the gate locations, gate numbers, insert size and shape are major factors that affect the rheological behaviors of polystyrene melt in the filling stage of injection molding, and polymer chains experienced higher shear and extension effects in the regions near to mold walls and obstacle. In addition, the length and position of weld lines are discussed in the current study.

show abstract

Microstructure and Morphology Simulation

Cited by 5 publications

References 138 publications

Scanning Small-Angle X-ray Scattering of Injection-Molded Polymers: Anisotropic Structure and Mechanical Properties of Low-Density Polyethylene

Scanning Small-Angle X-ray Scattering of Injection-Molded Polymers: Anisotropic Structure and Mechanical Properties of Low-Density Polyethylene

Approaches for Numerical Modeling and Simulation of the Filling Phase in Injection Molding: A Review

Macroscopic and mesoscopic simulation of polystyrene melt in the filling process of injection molding

Contact Info

Product

Resources

About