Effects of polymer melt compressibility on mold filling in micro-injection molding

Nguyen, Q M P; Chen, X; Lam, Yee Cheong; Cui, Yue

doi:10.1088/0960-1317/21/9/095019

Cited by 21 publications

(17 citation statements)

References 21 publications

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“…Ideally, the manufacturing of micro-/nanostructured devices for practical research and applications should fulfill the following requirements: (i) ease of mass production, (ii) low material costs, (iii) high flexibility, (iv) high replication accuracy and (v) good controllability of micro-/nanoscale patterns. Polymer-based replication methods, such as hot embossing (subset of nanoimprint lithography (NIL)) [40][41][42] and injection molding [43][44][45], are compatible with the requirements of low material costs and high replication accuracy. Among these methods, injection molding is more suitable for mass production due to the short cycle times.…”

Section: Introductionmentioning

confidence: 99%

Effect of nanostructures orientation on electroosmotic flow in a microfluidic channel

Lim

Lam

et al. 2017

Nanotechnology

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Electroosmotic flow (EOF) is an electric-field-induced fluid flow that has numerous micro-/nanofluidic applications, ranging from pumping to chemical and biomedical analyses. Nanoscale networks/structures are often integrated in microchannels for a broad range of applications, such as electrophoretic separation of biomolecules, high reaction efficiency catalytic microreactors, and enhancement of heat transfer and sensing. Their introduction has been known to reduce EOF. Hitherto, a proper study on the effect of nanostructures orientation on EOF in a microfluidic channel is yet to be carried out. In this investigation, we present a novel fabrication method for nanostructure designs that possess maximum orientation difference, i.e. parallel versus perpendicular indented nanolines, to examine the effect of nanostructures orientation on EOF. It consists of four phases: fabrication of silicon master, creation of mold insert via electroplating, injection molding with cyclic olefin copolymer, and thermal bonding and integration of practical inlet/outlet ports. The effect of nanostructures orientation on EOF was studied experimentally by current monitoring method. The experimental results show that nanolines which are perpendicular to the microchannel reduce the EOF velocity significantly (approximately 20%). This flow velocity reduction is due to the distortion of local electric field by the perpendicular nanolines at the nanostructured surface as demonstrated by finite element simulation. In contrast, nanolines which are parallel to the microchannel have no effect on EOF, as it can be deduced that the parallel nanolines do not distort the local electric field. The outcomes of this investigation contribute to the precise control of EOF in lab-on-chip devices, and fundamental understanding of EOF in devices which utilize nanostructured surfaces for chemical and biological analyses.

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Section: Introductionmentioning

confidence: 99%

Effect of nanostructures orientation on electroosmotic flow in a microfluidic channel

Lim

Lam

et al. 2017

Nanotechnology

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“…The volume shrinkage induces residual stress, while the viscoelasticity releases a portion of the formed stress. The empirical Tait equation, shown in Equation (4), is used to describe the specific volume, as a function of temperature and pressure [ 11 , 12 ]. The temperature-dependent density in Equation (1), and the coefficient of thermal expansion, can also be deduced from the specific volume:

where V 0 and B are calculated from Equations (5)–(7):

…”

Section: Theorymentioning

confidence: 99%

Stress Evolution of Amorphous Thermoplastic Plate during Forming Process

Ogasawara

Yoshikawa

et al. 2018

Materials

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Amorphous thermoplastics, as a type of engineering plastic material, are used in various industrial sectors. In order to manufacture high-performance products, it is important to optimize their forming process to mitigate residual stresses. However, stress in a plate is difficult to measure, therefore, modeling provides a powerful way to investigate and understand the evolution of stress. In this study, the forming process of a polyetherimide (PEI) plate was modelled using finite element analysis, and then validated through a comparison with a warpage experiment. This study reveals that the whole forming process can be divided into three stages by the glass transition temperature Tg of the PEI. The second stage, corresponding to the plate cooling from above Tg to below Tg, contributes a large portion of the residual stress in a short time. The final residual stress, the magnitude of which is affected by the cooling rate and plate thickness, shows a parabolic distribution through the thickness of the plate. These important conclusions are beneficial for improving the quality of an amorphous thermoplastic plate, while allowing highly efficient production.

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“…Thirdly, surface tension resulting from unbalanced forces of the molecules at the material surface may have an influence on the microscale flow . Lastly, microscale elasticity, variable heat transfer coefficients, and compressibility effects exist in µIM and is different from conventional IM, which needs to be included in any computer simulation analysis in order to obtain a more accurate prediction for flow behavior within microfeatures.…”

Section: Simulation Of Variable Heat Transfermentioning

confidence: 99%

The use of variotherm systems for microinjection molding

Zhang

Gilchrist

2015

J of Applied Polymer Sci

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Microinjection molding (lIM) is a fast-developing technology which is used to produce polymeric microcomponents or components with micro/nanoscale features, such as are used in many fields including microfluidic diagnostics, microneedle drug delivery devices, microgears, and microswitches. The capabilities and performance of the microinjection molding process can be improved by incorporating a variotherm system. This leads to improved component quality, especially for high aspect ratio features. It can also help to increase the polymer flow path, improve feature replication, reduce residual stresses and molecular orientations, and also can eliminate weld lines. This article reviews the use of different variotherm systems in lIM, and describes how simulation of its use can provide insight when designing a mold cavity or a component with challenging microfeatures. The article highlights important problems, challenges and areas for further research. An increased understanding of these issues will provide opportunities to enhance further developments in the lIM process.

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Effects of polymer melt compressibility on mold filling in micro-injection molding

Cited by 21 publications

References 21 publications

Effect of nanostructures orientation on electroosmotic flow in a microfluidic channel

Effect of nanostructures orientation on electroosmotic flow in a microfluidic channel

Stress Evolution of Amorphous Thermoplastic Plate during Forming Process

The use of variotherm systems for microinjection molding

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