Morphological comparison of isotactic polypropylene parts prepared by micro-injection molding and conventional injection molding

2011 ◽  
Vol 23 (3) ◽  
pp. 686-694 ◽  
Author(s):  
Fanghui Liu ◽  
Chao Guo ◽  
Xian Wu ◽  
Xinyuan Qian ◽  
Hong Liu ◽  
...  
Keyword(s):  
Injection Molding ◽  
Isotactic Polypropylene ◽  
Micro Injection Molding ◽  
Morphological Comparison ◽  
Conventional Injection Molding

Morphological comparison of isotactic polypropylene molded by water-assisted and conventional injection molding

2011 ◽  
Vol 46 (24) ◽  
pp. 7830-7838 ◽  
Author(s):  
Xianhu Liu ◽  
Guoqiang Zheng ◽  
Kun Dai ◽  
Zhenhua Jia ◽  
Songwei Li ◽  
...  
Keyword(s):  
Injection Molding ◽  
Isotactic Polypropylene ◽  
Morphological Comparison ◽  
Conventional Injection Molding

An Investigation into the Influencing Factors for Polymer Melt at the Filling Stage in Micro Injection Molding

2013 ◽  
Vol 562-565 ◽  
pp. 1380-1386
Author(s):  
Jian Zhuang ◽  
Da Ming Wu ◽  
Ya Jun Zhang ◽  
Lin Wang ◽  
Xiong Wei Wang ◽  
...  
Keyword(s):  
Injection Molding ◽  
Influencing Factors ◽  
Polymer Melt ◽  
Theoretical Models ◽  
Injection Molding Process ◽  
Melt Flow ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Filling Stage ◽  
Conventional Injection Molding

The flow behaviors for polymer melt at the filling stage in micro injection molding are different from those in conventional injection molding due to the miniaturization of plastic parts. This paper focuses on the study of the effects of three main influencing factors, including the microscale viscosity and wall slip, on melt filling flow in microscale neglected those in conventional injection molding process. The theoretical models and the interrelation of these factors in microscale channels were constructed by means of the model correction method. Then, the micro melt flow behaviors were investigated with comparisons of the available experimental data. The results indicate that the dimensions affect the shear rates and viscous dissipation, which in turn affects the apparent viscosity. Finally, the conclusion is that the melt flow behaviors in microchannels are different from those in macrochannels owing to these significant influencing factors.

Comparative study of crystallization and lamellae orientation of isotactic polypropylene by rapid heat cycle molding and conventional injection molding

e-Polymers ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Jiquan Li ◽  
Shaoguang Yang ◽  
Lih-Sheng Turng ◽  
Wei Zheng ◽  
Shaofei Jiang
Keyword(s):  
Injection Molding ◽  
Isotactic Polypropylene ◽  
Heated Surface ◽  
Skin Layer ◽  
Multilayered Structure ◽  
X Ray Diffraction ◽  
Heat Cycle ◽  
Molded Parts ◽  
Part Thickness ◽  
Conventional Injection Molding

AbstractThe crystallization and orientation of isotactic polypropylene (iPP) molded by rapid heat cycle molding (RHCM) and conventional injection molding (CIM) were studied. Due to the varying cooling rates and shearing, the molded parts exhibited a multilayered structure (skin, shear and core) across the part thickness, reflecting different degrees of crystallization and lamellae orientation of iPP. The morphology evolution of RHCM products was discussed based on the comparative research of morphology and structure at multiple sites on the RHCM and CIM specimens. Scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD) were used to analyze the thickness, crystallinity and lamellae orientation of these three distinct layers. The crystallization and lamellae orientation of iPP correlated strongly with the multilayered structure. In the RHCM process, one side of the mold is equipped with the rapid heat cycle function. The thickness and lamellae orientation next to the heated surface were less than that of the opposite skin layer without heating. Meanwhile, the crystallinity was greater than that of the opposite skin layer.

Unusual hierarchical structures of micro-injection molded isotactic polypropylene in presence of an in situ microfibrillar network and a β-nucleating agent

RSC Advances ◽  
2015 ◽  
Vol 5 (54) ◽  
pp. 43571-43580 ◽  
Author(s):  
Zhongguo Zhao ◽  
Qi Yang ◽  
Miqiu Kong ◽  
Dahang Tang ◽  
Qianying Chen ◽  
...  
Keyword(s):  
Injection Molding ◽  
Isotactic Polypropylene ◽  
Hierarchical Structures ◽  
Nucleating Agent ◽  
Morphological Development ◽  
Micro Injection Molding ◽  
Injection Molded

The morphological development of iPP in presence of an in situ microfibrillar network and a β-nucleating agent under micro-injection molding.

scholarly journals Vacuum Venting Enhances the Replication of Nano/Microfeatures in Micro-Injection Molding Process

2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Seong Ying Choi ◽  
Nan Zhang ◽  
J. P. Toner ◽  
G. Dunne ◽  
Michael D. Gilchrist
Keyword(s):  
Injection Molding ◽  
Quantitative Study ◽  
Vacuum Pressure ◽  
Injection Molding Process ◽  
Anodized Aluminum ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Sample Shape ◽  
Final Sample ◽  
Qualitative And Quantitative Study

Vacuum venting is a method proposed to improve feature replication in microparts that are fabricated using micro-injection molding (MIM). A qualitative and quantitative study has been carried out to investigate the effect of vacuum venting on the nano/microfeature replication in MIM. Anodized aluminum oxide (AAO) containing nanofeatures and a bulk metallic glass (BMG) tool mold containing microfeatures were used as mold inserts. The effect of vacuum pressure at constant vacuum time, and of vacuum time at constant vacuum pressure on the replication of these features is investigated. It is found that vacuum venting qualitatively enhances the nanoscale feature definition as well as increases the area of feature replication. In the quantitative study, higher aspect ratio (AR) features can be replicated more effectively using vacuum venting. Increasing both vacuum pressure and vacuum time are found to improve the depth of replication, with the vacuum pressure having more influence. Feature orientation and final sample shape could affect the absolute depth of replication of a particular feature within the sample.

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