Effect of Melt and Mold Temperatures on the Solidification Behavior of HDPE during Gas‐Assisted Injection Molding: An Enthalpy Transformation Approach

Yang, Bin; Fu, Xiao‐Rong; Yang, Wei; Liang, Siming; Sun, Nian X.; Hu, Shanting

doi:10.1002/mame.200900017

Cited by 38 publications

(45 citation statements)

References 40 publications

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“…[23][24][25][26] First of all, the cooling process takes place instantly after the end of the melt injection (i.e. the short shot stage), which is in agreement with the conventional definition of the cooling stage.…”

Section: Mathematical Modelling Assumptionsmentioning

confidence: 73%

Effect of thermal gradient field with phase change on crystal morphologies of HDPE during GAIM process

Wang

Yang

Huang

et al. 2010

Plastics, Rubber and Composites

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To understand the effects of thermal gradient field with phase change on the crystal morphologies of high density polyethylene (HDPE) during gas assisted injection moulding (GAIM) process, the combination of the simulation of the temperature field via an enthalpy transformation method and the hierarchical structures and the crystalline morphology of HDPE were investigated in this work. The GAIM parts of HDPE 6098 can be grouped into four layers in the direction of thickness: skin layer, subskin layer, intermediate layer and core layer. Besides, the cooling logarithmic curves were adopted in this experiment, and it is found that they can clearly display the phase change plateaus even at the skin layer zone.

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Section: Mathematical Modelling Assumptionsmentioning

confidence: 73%

Effect of thermal gradient field with phase change on crystal morphologies of HDPE during GAIM process

Wang

Yang

Huang

et al. 2010

Plastics, Rubber and Composites

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show abstract

“…To distinguish the effect of different gas delay times on the temperature gradient developed across the thickness, the acquisition of temperature distribution immediate after the short shot (SS) injection process is imperative. From our previous research [13,14,20,34,35], a great deal of work has been carried out to simulate the temperature field during the GAIM process as well as conventional injection process. In order to validate the simulated results, experiments have been conducted to assess the calculated cooling curves and found the experimental results and the theoretical values fit well.…”

Section: Resultsmentioning

confidence: 99%

“…In order to validate the simulated results, experiments have been conducted to assess the calculated cooling curves and found the experimental results and the theoretical values fit well. The temperature fields after the SS process at different gas delay times were simulated via an enthalpy transformation method described before [13,14,20,34,35], as shown in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

“…The detailed experimental and theoretical values of the thickness of the skin zone was compared in Fig. 7b), it can be seen that the theoretical values is a little larger than that of the experimental values, which was mainly due to the assumption of the enthalpy transformation method described before [13,14,20,34,35] as well as the solidification process after the S-S process. Also, the areas of the sub-skin zone increased with increasing gas delay time, which was confirmed by the following mechanical property of the GAIM parts.…”

Section: Hierarchy In Crystal Structuresmentioning

confidence: 92%

“…First of all, many researches have been reported on the computer-aided engineering (CAE) and modeling/ simulation of the melt filling stage of GAIM [6][7][8], the primary and secondary gas penetrations [9][10][11], the inmold cooling process [3,[12][13][14], and so on. On the other hand, a great deal of work has been conducted on the hierarchical structures [such as isotactic polypropylene (iPP) and polycarbonate/high-density polyethylene (PC/ HDPE), linear low-density polyethylene (LLDPE), PP, glass fiber reinforced isotactic polypropylene (GF/iPP), PC/PE, etc.]…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Role of gas delay time on the hierarchical crystalline structure and mechanical property of HDPE molded by gas-assisted injection molding

et al. 2012

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The relationship among the processing parameters, crystalline morphology, and macroscopic properties in injected molded bar becomes very complicated due to existence of temperature gradient and shear gradient along the sample thickness. To enhance the shear strength, gasassisted injection molding (GAIM) was utilized in producing the molded bars. The aim of our research was to explore the relationship between processing conditions and the spatial variation of the hierarchy structure as well as the mechanical properties of high-density polyethylene (HDPE) obtained via GAIM. In our previous work [Wang L, Yang B, Yang W et al (2011) Colloid Polym Sci 289:1661-1671], we found that the enhancement of the gas pressure can remarkably increase the degree of molecular orientation in the HDPE samples, which turns out to improve the mechanical performances of GAIM parts. In this work, the hierarchy structure, orientation behavior, and mechanical properties of molder bars under different gas delay time were investigated using a variety of characterization techniques including rheological experiments, scanning electron microscope, tensile testing, differential scanning calorimetry, and two-dimensional wide-angle X-ray scattering. Moreover, the temperature field during the short shot stage of GAIM process was simulated using an enthalpy transformation approach. Our results indicate that these properties were intimately related to each other, and with prolonged gas delay time, GAIM samples with higher degree of orientation and improved mechanical properties were obtained.

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A simple method for forecast of cooling time of high‐density polyethylene during gas‐assisted injection molding

Liang

Yang

et al. 2010

J of Applied Polymer Sci

Self Cite

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Gas-assisted injection molding (GAIM) is an innovative plastic processing technology, which was developed from the conventional injection molding, and has currently found wide industrial applications. About 70% of the whole gas-assisted injection molding cycle is actually occupied by the cooling stage. The quality and production efficiency of molded parts are considerably affected by the cooling stage. Hence, it is necessary to study the solidification behaviors during the cooling stage. In this work, a simple experimental method was designed to simulate the solidification behaviors of high-density polyethylene during cooling stage of GAIM. The enthalpy transformation approach, coupled with the control-volume/finite difference techniques, was adopted to deal with the transient heat transfer problems with phase change effects. In situ measurements of the temperature decreases in the cavity were also carried out. Reasonable agreements between the experimental values and the simulated results such as cooling time, cooling rates, and temperature curves were obtained, which proved that this simple experimental method was effective.

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Effect of Melt and Mold Temperatures on the Solidification Behavior of HDPE during Gas‐Assisted Injection Molding: An Enthalpy Transformation Approach

Cited by 38 publications

References 40 publications

Effect of thermal gradient field with phase change on crystal morphologies of HDPE during GAIM process

Effect of thermal gradient field with phase change on crystal morphologies of HDPE during GAIM process

Role of gas delay time on the hierarchical crystalline structure and mechanical property of HDPE molded by gas-assisted injection molding

A simple method for forecast of cooling time of high‐density polyethylene during gas‐assisted injection molding

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