Characterization of microinjection molding process for milligram polymer microparts

This paper presents the fabrication of a 3D microchannel whose sidewalls and bottom surface are patterned with ratchets using a modified 3D molding process. In the modified 3D molding process the surface of poly(methyl methacrylate) (PMMA) is first patterned using a brass mold having ratchet structures. Then PDMS prepolymer was spin coated over the surface of micropatterned PMMA and cured followed by the primary molding using a brass mold having a T-conjunction protrusion. After primary molding demolding was done by first demolding the brass mold and then peeling off PDMS stamp from PMMA substrate. By setting a 45° angle between direction of ratchets patterned on the surface of PMMA and the brass mold protrusion prior to primary molding 45° slanted ratchets were formed on the sidewall and bottom surface of microchannel using the modified 3D molding. The scanning electron microscope (SEM) micrographs show a successful integration of micropatterns inside the microchannel. Holes were drilled in the inlet and outlet area of the 3D channel before bonding. A solvent bonding technique was used for bonding of 3D channel to a plain cover plate. After bonding capillary tubes were inserted into the holes and glued to the chip using an epoxy glue. For characterization of mixing fluorescence intensity was quantified in the 3D microchannel as deionized water and fluorescein dye injected from different inlets of 3D micromixer were mixed along the 3D microchannel and mixing efficiency was calculated. The results were compared with the data obtained for similar microdevice whose surfaces were not patterned. The results demonstrate at a specific flow rate a faster mixing occurs in a microdevice whose sidewall and bottom surface are patterned with slanted 45° ratchets.

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Thermal regeneration of waste foundry phenolic sand in a lab scale fluidized bed

Matéria (Rio de Janeiro) ◽

10.1590/s1517-707620170001.0319 ◽

2018 ◽

Vol 23 (1) ◽

Author(s):

Johny Anderson Severo ◽

Regina Célia Espinosa Modolo ◽

Carlos Alberto Mendes Moraes ◽

Flávia Schwarz Franceschini Zinani

Keyword(s):

Fluidized Bed ◽

Regeneration Process ◽

Process Conditions ◽

Loss On Ignition ◽

Molding Process ◽

Partial Removal ◽

Thermal Regeneration ◽

Previously Treated ◽

Regeneration Efficiency

ABSTRACT Improper disposal of sand used in molding processes after casting increases logistical costs and environmental impact because of the presence of the phenolic resin in its composition. The regeneration process of waste foundry phenolic sand (WFPS) aims to recycle this material. As mechanical regeneration methods are not efficient to guarantee 100% cleaning of the sand grains and their use again in the molding process, this work investigated the efficiency of a method of thermal regeneration of this type of residue that can be employed as a complementary procedure. A laboratory-scale fluidized bed reactor was designed and built to regenerate WFPS that was previously treated by a mechanical method. The methodology used to design and construct the fluidized bed prototype is described, as well as the characterization of the residual, the standard clean sand and the regenerated sand. The results of the thermal regeneration in the fluidized bed were very satisfactory with respect to the regeneration efficiency. For the nine process conditions tested, loss on ignition values were reduced when compared to standard clean sand. This study presents the advantages of a combination of two processes, mechanical and thermal regeneration, which allows to reduce the time and eventual temperature of resin removal due to the partial removal of the resin layer or its weakening during the mechanical regeneration process. Of the nine process conditions tested, six had loss on ignition values below the CSS. Thus, the thermal regeneration in the fluidized bed results was quite satisfactory in relation to the regeneration efficiency.

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Characterization of effective permeability of prepreg fibers under autoclave molding process conditions using process model simulations

Journal of the Textile Institute ◽

10.1080/00405000.2020.1748803 ◽

2020 ◽

Vol 112 (1) ◽

pp. 1-7

Author(s):

Prosenjit Maji ◽

Arpit Jain ◽

Nibedita Dutta ◽

Ahmed Ovais Siddiqui ◽

Debdarsan Niyogi ◽

...

Keyword(s):

Process Model ◽

Effective Permeability ◽

Process Conditions ◽

Molding Process ◽

Model Simulations

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Characterization of Engineering Plastics Plasticized Using Supercritical CO2

Polymers ◽

10.3390/polym12010134 ◽

2020 ◽

Vol 12 (1) ◽

pp. 134

Author(s):

Masaki Watanabe ◽

Yoshihide Hashimoto ◽

Tsuyoshi Kimura ◽

Akio Kishida

Keyword(s):

Molecular Weight ◽

Supercritical Co2 ◽

Chemical Properties ◽

Molding Process ◽

Test Pieces ◽

Engineering Plastics ◽

Transition Points ◽

Physical And Chemical ◽

And Chemical Properties

The purpose of this study was to evaluate the physical and chemical properties of engineering plastics processed using supercritical CO2. First, we prepared disk-shaped test pieces via a general molding process, which were plasticized using supercritical CO2 at temperatures lower than the glass-transition points of engineering plastics. Amorphous polymers were plasticized, and their molecular weight remained nearly unchanged after treatment with supercritical CO2. The mechanical strength significantly decreased despite the unchanged molecular weight. The surface roughness and contact angle increased slightly, and electrical properties such as the rate of charging decreased significantly. These results suggest that supercritical CO2 could be used for a new molding process performed at lower temperatures than those used in general molding processes, according to the required properties.

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Dimensional and Locational Integrity in the Replication of Polymeric Microdevices

ASME 2007 InterPACK Conference, Volume 2 ◽

10.1115/ipack2007-33482 ◽

2007 ◽

Author(s):

Byoung Hee You ◽

Daniel S. Park ◽

Ping-Chuan Chen ◽

Wilfredo M. Caceres ◽

Dimitris E. Nikitopoulos ◽

...

Keyword(s):

Linear Thermal Expansion ◽

Hot Embossing ◽

Microtiter Plate ◽

Microfluidic Platforms ◽

Molding Process ◽

Thermal Expansion Coefficients ◽

Molded Parts ◽

Expansion Coefficients ◽

Geometric Variation

In molding, geometric variation of molded parts is inevitable since the parts have a thermal history, including expansion and shrinkage, during the molding process. Shrinkage induces variation between the designed dimensions and locations of features on molded parts while the parts are cooled. Characterization of the variation is necessary to ensure dimensional and location integrity. Hot embossing and injection molding were performed in order to assess variation. Measurements were made using a Measurescope (MM-22, Nikon Corp., Kawasaki, Japan). The measured locations and dimensions were compared to estimates obtained using a simple model based on the linear thermal expansion coefficients (CTE) of the molded materials. The measured and the estimated shrinkage from hot embossing were incorporated in the fabrication of microtiter plate-based polymer microfluidic platforms.

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A stress induced crystallinity model under the microinjection molding process

2020 1st International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET) ◽

10.1109/iraset48871.2020.9092040 ◽

2020 ◽

Author(s):

Anass Benayad ◽

Abdelhadi El Hakimi ◽

Rabie EL Otmani ◽

Abdelhamid Touache ◽

M'hamed BOUTAOUS

Keyword(s):

Molding Process ◽

Microinjection Molding

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Microwave characterization of nickel-based nanocomposites — High EMI shielding and radar absorption capability

Modern Physics Letters B ◽

10.1142/s0217984917503018 ◽

2017 ◽

Vol 31 (32) ◽

pp. 1750301 ◽

Cited By ~ 2

Author(s):

Heeralal Gargama ◽

Awalendra Kumar Thakur ◽

Sanjay Kumar Chaturvedi

Keyword(s):

Electromagnetic Interference ◽

Polyvinylidene Fluoride ◽

Optimum Level ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Molding Process ◽

Free Standing ◽

Wave Absorption ◽

Microwave Characterization

This work reports, microwave characterization of nanocrystalline nickel-polyvinylidene fluoride (n-Ni/PVDF) composites with an aim to explore their electromagnetic interference (EMI) shielding and absorption properties. The composites were fabricated using compression hot molding process at an optimum level of temperature and pressure. The electrical properties of the samples are computed using the measured scattering parameters in the X-band. The wave absorption capability of a single layer absorbing structure is theoretically evaluated by employing the computed electrical parameters. Besides, the shielding effectiveness (SE) of free standing samples are also calculated using transmission line model and compared with the experimentally obtained results to validate the theoretical model. High SE (42.87 dB) and absorption (−14.37) obtained in this work, suggest futuristic applications of n-Ni/PVDF composites for EMI shielding and wave absorption.

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