Resin Mold Research Articles

A pillar-based microfilter for isolation of white blood cells on elastomeric substrate.

Our goal is to design, fabricate, and characterize a pillar-based microfluidic device for size-based separation of human blood cells on an elastomeric substrate with application in the low-cost rapid prototyping of lab-chip devices. The single inlet single outlet device is using parallel U-shape arrays of pillars with cutoff size of 5.5 μm for trapping white blood cells (WBCs) in a pillar chamber with internal dead-volume of less than 1.0 μl. The microstructures are designed to limit the elastomeric deformation against fluid pressures. Numerical analysis showed that at maximum pressure loss of 15 kPa which is lower than the device conformal bonding strength, the pillar elastomeric deformation is less than 5% for flow rates of up to 1.0 ml min(-1). Molding technique was employed for device prototyping using polyurethane methacrylate (PUMA) resin and polydimethylsiloxane (PDMS) mold. Characterization of the dual-layer device with beads and blood samples is performed. Tests with blood injection showed that ∼18%-25% of WBCs are trapped and ∼84%-89% of red blood cells (RBCs) are passed at flow rates of 15-50 μl min(-1) with a slight decrease of WBCs trap and improve of the RBCs pass at higher flow rates. Similar results were obtained by separation of mixed microspheres of different size injected at flow rates of up to 400 μl min(-1). Tests with blood samples stained by fluorescent gel demonstrated that the WBCs are accumulated in the arrays of pillars that later end up to blockage of the device. Filtration results of using elastomeric substrate present a good consistency with the trend of separation efficiencies of the similar silicon-based filters.

Manufacturing of Metal Micro Pillar with High Aspect Ratio using Negative-type Resin Mold

Manufacturing of Metal Micro Pillar with High Aspect Ratio using Negative-type Resin Mold

Control of Surface Graphite Degeneration in Ductile Iron for Windmill Applications

The objective of this paper is to review the factors influencing the formation of degenerated graphite layers on the surfaces of ductile iron castings for chemical resin-acid moulding and coremaking systems and how to reduce this defect. In the resin mould technique the sulphur in the P-toluol sulphonic acid (PTSA), usually used as a hardener, has been identified as one factor causing graphite degeneration at the metal mould interface. Less than 0.15% S in the mould (or even less than 0.07% S) can reduce the surface layer depth. Oxygen may also have an effect, especially for sulphur containing systems with turbulent flows in the mould, water-bearing no-bake binder systems, Mg-Silica reactions, or dross formation conditions. Despite the lower level of nitrogen in the iron melt after magnesium treatment (less than 90 ppm), nitrogen bearing resins have a profound effect on the frequency and severity of surface pinholes, but a limited influence on surface graphite degeneration. The specific characteristics and optimum conditions for the manufacture of heavy sectioned ductile iron windmill castings were reviewed. The paper concludes on the optimum iron chemistry, melting procedure, Mg-alloys and specific inoculants systems, as well as the practical solutions to limit graphite degeneration to ensure castings with the highest integrity.

S134012 ニッケル粉末混入放電加工面の表面特性に関する研究([S134]先進特殊加工技術)

Recently, EDM finishing technology has remarkably progressed, and very small surface roughness can be readily obtained by controlling the electrical discharge conditions. Also, EDM using powder mixed working fluids can improve the surface characteristics, such as wear resistance and corrosion resistance. Therefore, the EDM finished surface is well expected to be applied as a final metal mold surface in the near future. In that case, the surface characteristics of EDMed surface would influence the molding performance and the life of metal mold. As a new surface functionalization of EDMed surface, the surface characteristics of EDMed surface using a nickel powder mixed fluid is experimentally discussed in this study, since nickel coating has been widely applied to improve the corrosion resistance and the mold releasability of metal mold surface. Experimental analysis clarified that the resolidified layer containing nickel content could be formed on the surface by EDM in nickel powder mixed fluid. Also, the water repellency and the releasability of molded resin from the EDMed surface could be improved.

Characterization of Velocity Profile of Highly-Filled GFRP-BMC through Rectangular Duct-Shaped Specimen during Injection Molding from SEM Fiber Orientation Mapping

There is an extensive body of research and texts on numerical simulation to obtain rheological properties of injection molded resins and composites, however to our knowledge there is no or little research on estimating velocity profile from fiber orientation mapping of GFRPBMCs (glass fiber reinforced polymer bulk molding compounds). This study reports a simple analysis of specific laminar creep flow properties of highly-filled short-fiber GFRP-BMC through a dogbone specimen as a rectangular duct during injection molding from SEM fiber orientation mapping which is found to exhibit a 3-layer [skin-core-skin] structure resembling classical laminar flow through a conduit. Therefore, to characterize the BMC with extremely low Reynolds number 32 © 1014, velocity profile, primary and secondary boundary layers were estimated from Hermans fiber orientation parameter across gauge section thickness. [doi:10.2320/matertrans.M2013143]

Fabrication of Integral Core/Shell Ceramic Casting Mould for Hollow Turbine Blade

The paper presents an integral core/shell fabrication of ceramic casting mould for hollow turbine blades by combining SL (Stereolithography) with gelcasting. This method could guarantee the positional accuracy between ceramic cores and shell, thus achieving the rapid fabrication of complex turbine blade castings. The paper focuses on the design of resin mould for gelcasting, the preparation of ceramic slurry, the pyrolysis of resin prototype and the sintering of ceramic green body. The feasibility and effectiveness of above mentioned method were verified through successful manufacturing of hollow turbine blades with double-walled structure.

A Finite Element Simulation of Mold Filling Process in Resin Film Infusion Based on Material Properties and Mechanics Properties

A finite element method (FEM) has been developed to simulate the isothermal resin infusing process in resin film infusion. The FEM is based on conservation of resin mass at any instant of time and is objective of resin film infusion (RFI) fiber impregnation and mold filling. The developed computer code was able to simulate the resin infusing visually. A numerical example presented here demonstrated that compared with traditional finite element/ control-volume (FE/CV), FEM is physically accurate and computationally efficient.

Factors Affecting on the Bond Strength of Dental Zirconia to Veneering Porcelains

The bond strengths between two kinds of zirconia and three kinds of feldspathic veneering porcelains were measured. The specimens were prepared at four firing temperatures for three holding periods, respective opaque porcelain was painted and vacuum-fired. Then, each dentin porcelain was condensed in an acrylic resin mold and vacuum-fired under the conditions mentioned above. Cross sections of the interface between zirconia and porcelain were observed with a scanning electron microscope. The specimens were fixed to specimen holder on a universal testing machine. Data of the bonding test were statistically analyzed. The results showed that all the four factors statistically affected the bonding strength (p<0.01). The contribution of the firing temperature was highest and that of the porcelain type was lowest (p<0.01).

High resolution UV roll-to-roll nanoimprinting of resin moulds and subsequent replication via thermal nanoimprint lithography

UV roll-to-roll nanoimprinting at high resolution is still a relatively unexplored field of study with far-reaching application potential. One enabling technology that is particularly worthy of attention is mass production of high resolution resin moulds via UV roll-to-roll nanoimprinting at such high throughput and low cost that they can be used only once and disposed of or recycled economically. Low cost, high resolution resin moulds can greatly improve the production cost profile for a number of applications in biomedicine, nanofluidics, data storage and electronics with relatively low unit values but which require one or more nanoscale lithography steps. In this report, UV roll-to-roll nanoimprinting was employed to fabricate high fidelity resin moulds with nanoscale as well as mixed micro- and nanoscale features down to 50 nm feature diameter, at up to 120 cm2 area and at 10 m min−1 throughput. UV roll-to-roll nanoimprinted resin moulds were subsequently segmented out, employed in a batch mode thermal nanoimprinting process, and characterized to study performance and demonstrate viability. The results show that high resolution mixed nanostructures can be faithfully replicated in PMMA on silicon substrates with minimal volumetric shrinkage. Process details and challenges specific to roll-to-roll fabrication of resin moulds are discussed at length, particularly with respect to the curvature uniformity of the imprint roller.

The use of gamma irradiation to induce the miscibility between urea‐formaldehyde and vinyl acetate versatic ester copolymer latex blend

AbstractThe objective of this research was to investigate the miscibility behavior of urea‐formaldehyde (UF) resin and vinyl acetate versatic ester copolymer latex (VAcVe) blends. Blend of various compositions of UF resin as thermoset polymer and VAcVe as thermoplastic polymer were prepared. This study shows how the addition of VAcVe latex can alter the behavior of UF resin toward hardness, press‐ability, and inhibition of cracks occurred in the UF resin films and moulds. After that, these blends (UF/VAcVe) were irradiated with gamma rays in different doses. Physical properties such as solubility percent, water absorption behavior in water, and effect of dilute acid and dilute alkali were studied. Thermogravimetric analysis shows that VAcVe is more stable against thermal decomposition than UF resin over the entire temperature range studied. Also, the thermal stability of polymer blends (UF/VAcVe) increases with increasing the ratio of VAcVe component in the blend. The influence of addition of VAcVe on compressive strength was studied. The results showed an improvement with a decrease in compressive strength due to the flexibility, this improvement is related to the amount of VAcVe. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Three‐dimensional multi‐material electromagnetic band‐gap structure: design, fabrication and property studies

PurposeThe purpose of this paper is to bring up the concept of multi‐material electromagnetic band‐gap structure (EBGs) and develop a method for its fabrication. Meanwhile, its microwave properties were studied and compared with the traditional EBGs consisting of two kinds of material.Design/methodology/approachStereolithography (SL) and gel casting were used to fabricate 3D multi‐material EBGs. Resin mold was designed and fabricated based on SL process, slurries loaded with 55vol per cent Al2O3 and 55vol per cent TiO2, respectively, were prepared, and using gel casting, multilayer EBGs with diamond structure were fabricated. T/R method was used to obtain the characteristic parameter S21 of the EBGs; meanwhile, characters of their band structure were studied based on plane wave expansion method.FindingsThe fabricated EBGs with a TiO2‐resin‐air structure showed a band gap from 11.7 GHz to 16.0 GHz along <1, 1, 0> direction; the EBGs with a TiO2‐resin‐Al2O3 structure showed a band gap from 11.4 GHz to 11.9 GHz along <1, 1, 0> direction. Both of them agreed well with the simulation result. Also, through the study of multi‐material EBGs' microwave properties, it could be seen that this structure was a good approach to adjust the band gap.Originality/valueWith the concept of multi‐material EBG structure brought up, multilayer 3D EBGs were designed and fabricated based on SL combined with gel casting. It could be seen that multi‐material EBGs was a good approach to adjust the band gap. Also, the fact that the testing result matched the simulation validates the feasibility of the process.

Evaluation of Chemical Treatment on Zirconia Surface with Two Primer Agents and an Alkaline Solution on Bond Strength

This study evaluated the effect of an alkaline solution and two 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer agents on bond strength to zirconia (yttria-stabilized tetragonal zirconium polycrystal [Y-TZP]) through the shear bond strength (SBS) test. Sixty square-shaped Y-TZP samples were embedded in an acrylic resin mold, polished, and randomly assigned to one of six groups (n=10) according to treatment surface: group CR, no treatment (control); group NaOH, 0.5 M NaOH; group AP, Alloy Primer; group ZP, Z-Primer Plus; group NaOH-AP, 0.5 M NaOH + Alloy Primer; and group NaOH-ZP, 0.5 M NaOH + Z-Primer Plus. The resin cement (Rely X U100) was applied inside a matrix directly onto the Y-TZP surface, and it was light-cured for 40 seconds. The samples were stored in distilled water at 37°C for 24 hours prior to the test, which was performed in a universal machine at a crosshead-speed of 0.5 mm/min. The data were analyzed by one-way analysis of variance and Tukey tests (p<0.05). Light stereomicroscopy and scanning electron microscopy were used to assess the surface topography and failure mode. The SBS was significantly affected by the chemical treatment (p<0.0001). The AP group displayed the best results, and the use of NaOH did not improve SBS results relative to either AP or ZP. The samples treated with Alloy Primer displayed mainly mixed failures, whereas those conditioned with Z-Primer Plus or with 0.5 M NaOH presented a balanced distribution of adhesive and mixed failure modes. The use of a NaOH solution may have modified the reactivity of the Y-TZP surface, whereas the employment of a MDP/6-4-vinylbenzyl-n-propyl amino-1,3,5-triazine-2,4-dithione-based primer enhanced the Y-TZP bond strength.

Lifetime evaluation of release agent for ultraviolet nanoimprint lithography

Ultraviolet-nanoimprint lithography (UV-NIL) is a powerful tool for mass production of nano-scale patterns. In UV-NIL, it is very important to coat the mold surface with a release agent to prevent the adhesion of UV curable resin. However, the release agent has a lifetime and by repeated UV-NIL transfer, the release layer is degraded and finally, UV curable resin adheres to the mold surface. To clarify the lifetime of the release agent, this study measured the contact angles of a silicon (Si) mold surface coated with various release agents during repetition of the UV-NIL process. Three types of fluorinated silane coupling agent were used for the release layer and the durability was measured on a patternless Si surface. The results showed that the C8H4Cl3F13Si release agent has high durability. A patterned Si mold was then coated with this release agent and evaluated during repetition of the UV-NIL process. After 1000 repetitions, the contact angle was still high, but a defect occurred at the 900th repetition. Therefore, the lifetime of this release agent when using a Si mold and UV curable resin is approximately 800times.

Effective fabrication method of 3D ceramic photonic crystals with diamond structure

PurposeThe purpose of this paper is to present a novel and effective fabricating method of 3D ceramic photonic crystals with diamond structure.Design/methodology/approachThe reverse diamond‐structure resin molds are fabricated by stereolithography (SL), then ceramic slurry is prepared and injected into the molds under vacuum condition. Subsequently, ceramic photonic crystals are obtained after vacuum freeze‐drying and sintering.FindingsThe combination of SL, gel‐casting and freeze‐drying could be used to fabricate the 3D ceramic photonic crystals with diamond structure which have intact structure and minimal shrinkage. The samples have been tested and the experimental results indicate that their band gap is in the range of 10.14‐12.20 GHz, consistent with the simulation results.Research limitations/implicationsThe influence of fabrication process on the photonic band gap needs further study.Originality/valueThis paper presents a novel fabricating method of 3D diamond‐structure ceramic photonic crystals based on SL, gel‐casting and freeze‐drying. The method fabricates complex ceramic photonic crystals with high accuracy and helps further research in this field.

High-Throughput UV Nanoimprint Process Using Flexible Resin Mold for High-Brightness Light-Emitting Diodes

This paper demonstrated a high-throughput fabrication process of resin mold and nanostructures for high-brightness light-emitting diodes (LED). The fabrication process includes roll-to-roll (RtR) UV imprinting for resin mold fabrication and perpendicular UV imprinting on wafers. The measurement results of pattern sizes in UV imprinted sample indicate that the resin mold was uniform enough to use for subsequent UV imprinting, and highly uniform UV imprinting was achieved by means of developed high-throughput UV imprinting equipment. Thickness of the residual layer was highly uniform and repeatable. This fabrication process is expected to be applied to fabricate nanostructures for actual high-brightness LEDs.

Thin PoP: Warpage Control for Thinner PoP Package in Mobile Applications

In order to significantly improve warpage of a PoP bottom package, Shinko developed an enhanced PoP structure. The inclusion of a support material attached to the backside of the flip chip die and over molded resin is the structure's key attribute. By adjusting the balance of each material (mold resin, substrate and support material thickness), we can better control warpage at both room temperature and reflow temperature. This enhanced thin PoP structure can be easily incorporated into a standard assembly process with existing equipment sets. This paper describes simulation results, along with measured warpage characteristics of the new package.

Photoacid- and Photobase-Generating Monomers for Surface Modification of Cured Resin: Application to Novel Resin Mold for UV Imprint

Photoacid- and Photobase-Generating Monomers for Surface Modification of Cured Resin: Application to Novel Resin Mold for UV Imprint

Fabrication of a point defect photonic crystal based on diamond structure with a cavity and its microwave properties

This paper presents a novel fabrication method for three-dimensional (3D) ceramic point defect photonic crystals. The 3D defect photonic crystal, which possesses an air cavity, has been designed by cutting a rectangular shape (3.5 mm × 3.5 mm × 7 mm) in the centre of a photonic crystal with a diamond lattice structure model (50 mm × 30 mm × 20 mm) with a lattice constant of 7 mm. Stereolithography (SL) technology was applied to fabricate resin moulds with an inverse-diamond structure incorporating the defect, and high solid content aqueous ceramic slurry was prepared and injected into the moulds. After gel-casting, drying, and high-temperature sintering, ceramic 3D photonic crystals with intact structure and minimal shrinkage were obtained. The penetration of an electric field with resonant modes of about 3 mm into the host lattice was observed by measuring the &lt;110&gt; direction of the samples, which resulted from the rectangular air cavity resonator. The results show that this method can be used to fabricate ceramic 3D point defect photonic crystals with a complex 3D structure.

Vacuum casting replication of micro-riblets on shark skin for drag-reducing applications

A vacuum casting method to replicate shark skin surface accurately in large area was investigated to overcome some difficulties in the replication process. The fresh shark skin was pretreated as a replication sample, and the replication mold of shark skin was manufactured by casting the unsaturated polyester resin under vacuum and laying the multilayer glass fibers. Under vacuum condition, silicone rubber was poured into the resin mold to obtain the replication film of the shark skin with micro-riblets. The contour of the micro-riblet was measured by a Talysurf CLI2000 machine to evaluate the replication accuracy. Based on the contacting angle measurement, the hydrophobic property of the micro-riblet's surface was investigated. It was found that the vacuum casting method was an effective replication technology which was suitable to form large-area and highly accurate micro-riblets on the surface of the shark skin. The experiment of drag reduction was conducted in a water tank. Based on the experimental results, the replicated film of shark skin played a significant role in reducing drag. The maximum and minimum of drag reduction rate were 18.6% and 9.7%, respectively.

Sensitivity analysis of influencing factors on impregnation process of closed mould RTM

This paper reports on different parameters that influence the closed mould resin transfer moulding (CM-RTM) process for fiber-reinforced plastics. A sensitivity study of selective parameters is performed. This includes material parameters (i.e., viscosity, permeability), process parameters (i.e., temperature) and geometrical parameters (i.e., position of preform in the tool). Furthermore, fiber type and targeted fiber volume content are considered to validate the full range of fiber-reinforced plastics. As an example for the sensitivity study, the aeronautical carbon fabric G0926 and epoxy resin system RTM6 (both manufactured by Hexcel) are analyzed for targeted fiber volume contents in a range of ~60%. The infiltration of a rectangular panel was simulated with the flow simulation software RTM-Worx by Polyworx. It was found that the infiltration of a simple geometry can differ by app. Factor 3 in terms of duration, when only considering the tolerances of material and process parameters (“upper tolerance limit” vs. “lower tolerance limit” scenario). For different types of composite materials observed in this study, it can even go up to Factor 1,000. To achieve a reliable RTM process, these aspects—material types and range of tolerance—have to be considered.