Mold Material Research Articles

Soft Candy as an Electronic Material Suitable for Salivary Conductivity-Based Medical Diagnostics in Resource-Scarce Clinical Settings.

Soft candy was discovered to be an excellent electronic material and was used to fabricate electrodes for salivary conductivity-based diagnostics. Using a simple molding process, a soft candy (Tootsie Roll) was made into 20 × 20 × 5 mm electrodes with a stable frequency response (0.1-100 kHz). The soft candy electrode-liquid interface circuit model was also developed for the first time. Using 0.01, 0.05, and 0.1 M phosphate-buffered saline and artificial saliva of varying conductivities, the performance of the soft candy (Tootsie Roll) electrode was evaluated. The electrode has a low temperature coefficient of ∼0.02 V/C, and the evaporation-induced mass change during measurement (<3 min) was negligible. Using a trenched surface, a limit of detection (LOD) of ∼1630 μS/cm was obtained and was lower than the saliva conductivity of a healthy adult at ∼3500 μS/cm. Thus, it is suitable for monitoring the ovulation cycle for natural family planning as well as chronic kidney disease diagnosis. Given the ubiquity of soft candy, the simplicity of the molding process, and the negligible medical waste stream, it is a more appropriate approach to diagnostics design for resource-scarce clinical settings, such as those in developing countries. The broader impact of this work will be the paradigm shift of soft candy from food to a new class of edible, moldable, high-resistivity, and stable electronic materials.

Influence of Mould Material on the Mechanical Properties of Wax Models

Influence of Mould Material on the Mechanical Properties of Wax Models

Evaluation of Mechanical and Wear Roperties of AA2024 Through Co2 Casting Using Silica Sand

Silica sand is generally used moulding sand in the casting industries and majority of the castings produced worldwide because of its easy availability and binding properties. In the present study, silica sand is taken as moulding material and studies the effect of different shapes on the mechanical and wear properties, micro hardnessand wear tests. For this casting the selected material (AA2024) into two different shapes (cube and cylinder) using silica sand as the moulding material and study the effect of split piece pattern on the properties and wear of the casted components. Co2 casting is chosen as the industrial process and study mainly focused on to produce the defect free surfaces on AA2024 with split piece pattern which is difficult to control. Destructive tests like hardness, surface roughness are conducted and wear properties of the components is also observed. It is observed from the results that cylinder component has higher hardness due to the faster cooling rate, lower surface roughness and lower wear rate. Analysis concluded that Co2 process is better working for the cylinder type of objects.

A theoretical comparison between the restoration of two contemporary works of art made of plastic

• The research has theoretically compared the restoration of two artworks made of polymeric material, determining their ontological status after the intervention. • It is necessary the hierarchization of the constituent elements of the entity, which can be both material and immaterial. • The conservation-restoration of contemporary artworks requires the study of the conceptual, biographical and material planes in each case. • The conservator has become, in the case of contemporary art, a facilitator of the experimentation of the entity and must know where the substantial lies and where the accessory lies in the artwork. • Decision-making must be based on knowledge of the relative importance of the different constituents of the artwork. The article describes the intervention processes carried out on two contemporary artworks and analyzing them from a theoretical point of view. The first work of art, Silere , is an ink transfer on a moulded polymeric material. The second artwork is entitled Pasos en Falso , and consists of an installation that includes a pair of shoes made by the artist, layer by layer, with vinylic latex. The laces of these shoes are made from human hair. For each of the cases, a description is given of the material plane of the artwork, a description of its conceptual plane and a description of its biographical plane. It then discusses the paradigm in which each of them should be placed, and provides a hierarchy of their constituent elements, both in the material and immaterial planes. Finally, the discrepant factors that have determined the decision-making process are discussed. The study focuses not on the description of the intervention processes carried out, although these have been described for later discussion, but on the theoretical analysis that helps to understand the decision-making process, a decision-making process that is specific to each case. And this, applying the most advanced theoretical concepts on which the theory for the conservation of contemporary art is currently based, which have made it possible to compare the two interventions. In addition, the artworks that serve as examples are particularly interesting, as they have been made with polymeric materials, which, at the time of our intervention, were in a very poor condition.

Design, Production and Evaluation of 3D-Printed Mold Geometries for a Hybrid Rocket Engine

The feasibility of 3D-printed molds for complex solid fuel block geometries of hybrid rocket engines is investigated. Additively produced molds offer more degrees of freedom in designing an optimized but easy to manufacture mold. The solid fuel used for this demonstration was hydroxyl-terminated polybutadiene (HTPB). Polyvinyl alcohol (PVA) was chosen as the mold material due to its good dissolving characteristics. It is shown that conventional and complex geometries can be produced reliably with the presented methods. In addition to the manufacturing process, this article presents several engine tests with different fuel grain geometries, including a short overview of the test bed, the engine and first tests.

Fabrication technique using a core and cavity mold of a hybrid composite ballistic helmet

Material used for helmet technology has transformed moderately little since the introduction of aramids, which ballistic helmets still uses woven aramids with a thermoset resin system. Most widely used strengthening material for ballistic helmet is Kevlar fibers which comprise outstanding impact resistance and high strength to weight ratio. For Kevlar reinforcement and resin shaping process, composite materials uses molding process in the fabrication methods. The most vital fabrication method is the hand lay-up process. Hand lay-up process normally consists of laying a dry fabric layer by hand onto a mold to shape into desirable design and shape. After the lay-up process is done, resin is then applied to the dry plies. There are several accessible curing methods and the most commonly used method is to let the product to cure at room temperature. This paper presents the fabrication process of ballistic helmet using a hand lay-up fabrication process with a core and cavity mold. This paper also describes the helmet mold design, materials and processing methods.

Influence of Mold and Heat Transfer Fluid Materials on the Temperature Distribution of Large Framed Molds in Autoclave Process.

Massive composite components manufactured by autoclave curing in large framed molds are extensively used in the aerospace industry. The high temperature performance of the large framed mold is the key to achieving the desired composite part quality. This paper explores and summarizes the important thermal properties of metal and heat transfer fluid materials influencing the heating performance of large framed molds, with the aim of improving the mold temperature distribution. Considering the fluid–thermal–solid interaction inside the autoclave, a reliable computational fluid dynamics (CFD) simulation model was developed and verified by a temperature monitoring experiment to achieve the prediction of the temperature distribution of the large framed mold. Then, numerical simulations were designed on the basis of the CFD model, and the single-variable method was used to study the effects of the material thermal properties on the temperature performance of large framed molds. Our simulation predicts that when copper is used as the mold material, the temperature difference decreases by 30.63% relative to that for steel, and the heating rate increases by 3.45%. Further, when helium is used as the heat transfer medium, the temperature difference decreases by 68.27% relative to that for air, and the heating rate increases by 32.76%. This paper provides a reference for improvement of large framed mold manufacturing and autoclave process in terms of heating rate and temperature uniformity.

Enhancing the mechanical properties of bismaleimide resin with montmorillonite modified by two intercalators (amino-terminated polyoxypropylene and octadecyl trimethyl ammonium chloride)

PurposeBismaleimide (BMI) is a kind of thermosetting resin and its application is usually limited by low toughness. In this paper, two kinds of reinforcement intercalator amino-terminated polyoxypropylene (POP) and octadecyl trimethyl ammonium chloride (OTAC) were designed and synthesized to toughen BMI resin and the toughening effect was compared and analyzed. The purpose of this paper is to toughen BMI resin and analyze the toughening effect of two reinforcements intercalator amino-terminated polyoxypropylene (POP) and octadecyl trimethyl ammonium chloride (OTAC).Design/methodology/approachSodium-based montmorillonite (Na-MMT) was modified by POP and OTAC, and the ion-exchange reaction obtained organic montmorillonite (POP-MMT and OTAC-MMT). The polymer matrix (MBAE) was synthesized, in which 4,4’-diamino diphenyl methane BMI was used as the monomer and 3,3’-diallyl bisphenol A and bisphenol A diallyl ether were used as active diluents. And then, POP-MMT/MBAE and OTAC-MMT/MBAE composites were prepared using MBAE as matrix and POP-MMT or OTAC-MMT as reinforcement. The Fourier-transform infrared, X-ray diffraction and scanning electron microscope (SEM) of the filler and microstructure and mechanical properties of the composite were characterized to the better reinforcement.FindingsPOP-MMT and OTAC-MMT enhanced BMI-cured products’ toughness by generating microcracks in the polymer to absorb more fracture energy. Meanwhile, POP-MMT and OTAC-MMT were the main stress components and the enhancement of the interface interaction was beneficial to transfer the external force from the matrix to the reinforcement and improved the mechanical properties of the composite. Furthermore, with the intercalation rate increasing, the compatibility of the two phases was increased and the performance of MBAE was also elevated.Research limitations/implicationsBMI is generally used as aerospace structural materials, functional materials, impregnating paint and other fields. However, high crosslinking density leads to moulding material’s brittleness and limits a wider range of applications. Therefore, it has become an urgent priority to explore and improve the mechanical properties of BMI resin.Originality/valuePOP and OTAC have successfully intercalated Na-MMT layers to get POP-MMT and OTAC-MMT, and the interplanar crystal spacing and the intercalation rate were calculated, respectively. The results were corresponding with the SEM images of POP-MMT and OTAC-MMT. After that, the morphology of composites illustrated the compatibility was related to the intercalation rate. According to the mechanism of modified MMT toughening epoxy resin, when they were dispersed uniformly in the matrix, the composite’s mechanical properties had been significantly improved. Additionally, OTAC-MMT with a higher intercalation rate had better compatibility and interfacial force with the matrix, so that the mechanical properties of OTAC-MMT/MBAE were the best.

ADVANCED TYPES OF CHECKERWORK OF REGENERATIVE HEAT EXCHANGERS FOR GLASS FURNACES

One of the ways to increase glass furnaces energy efficiency is to apply heat exchangers for flue gases thermal potential utilization.&#x0D; Flue gases losses is up to 25-40 % of the total amount of heat supplied in the furnace. These losses are influences by such factors as fuel type, furnace and burners design and manufactured product type.&#x0D; Regenerative heat exchangers with various types of heat storage packing is more efficient for high-power furnaces.&#x0D; Such types of regenerator checkerwork as Cowper checkerwork, two types of Siemens checkerwork, Lichte checkerwork and combined checkerwork have already been sufficiently researched, successfully applied and widely used for glass furnaces of various designs. All of its are made of standard refractory bricks. Basket checkerwork and cruciform checkerwork that are made of fused-cast molded refractory materials have been widely used recently as well.&#x0D; Further improvement of regenerative heat exchangers thermal efficiency only by replacing the checkerwork does not seem possible unless their size being increased. But this enlarging is not always realizable during the modernization of existing furnaces.&#x0D; From this point of view heat storage elements with a phase transition, where metal salts and their mixtures are used as a fusible agent look promising for glass furnaces.&#x0D; These elements can accumulate additional amount of heat due to phase transition, which allows to increase significantly heat exchanger thermal rating without its size and operating conditions changing.&#x0D; However, it is necessary to carry out additional studies of this type of checkerwork dealing with analysis of complex unsteady heat exchange processes in regenerators and selection of appropriate materials that satisfy the operating conditions of regenerative heat exchangers so that the checkerwork can be widely used for glass furnaces.

The potential of metal epoxy composite (MEC) as hybrid mold inserts in rapid tooling application: a review

Purpose Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts. Design/methodology/approach The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted. Findings Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles). Research limitations/implications The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available. Originality/value This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.

Decellularized nerve extracellular matrix/chitosan crosslinked by genipin to prepare a moldable nerve repair material.

Decellularized nerve extracellular matrix (NECM) composited with chitosan are moldable materials suitable for spinal cord repair. But the rapid biodegradation of the materials may interrupt neural tissue reconstruction in vivo. To improve the stability of the materials, the materials produced by NECM and chitosan hydrogels were crosslinked by genipine, glutaraldehyde or ultraviolet ray. Physicochemical property, degradation and biocompatibility of materials crosslinked by genipin, glutaraldehyde or ultraviolet ray were evaluated. The scaffold crosslinked by genipin possessed a porous structure, and the porosity ratio was 89.07 + 4.90%, the average diameter of pore was 85.32 + 5.34 μm. The crosslinked degree of the scaffold crosslinked by genipin and glutaraldehyde was 75.13 ± 4.87%, 71.25 ± 5.06% respectively; Uncrosslinked scaffold disintegrated when immerged in distilled water while the scaffold crosslinked by genipin and glutaraldehyde group retained their integrity. The scaffold crosslinked by genipin has better water absorption, water retention and anti-enzymatic hydrolysis ability than the other three groups. Cell cytotoxicity showed that the cytotoxicity of scaffold crosslinked by genipin was lower than that crosslinked by glutaraldehyde. The histocompatibility of scaffold crosslinked by genipin was also better than glutaraldehyde group. More cells grew well in the scaffold crosslinked by genipin when co-cultured with L929 cells. The decellularized nerve extracellular matrix/chitosan scaffold crosslinked by the genipin has good mechanical properties, micro structure and biocompatibility, which is an ideal scaffold for the spinal cord tissue engineering.

Research on Squeeze Casting Composite Mold Materials by Plasma Spraying

Composite mold samples used in squeeze casting was fabricated by plasma spraying with 5CrMnMo and 3YSZ, which was shown high bonding strength and good thermal shock resistance. The best parameters with transition coat were explored by mechanical analyses. As results, the transition layer structure made of 75 percent NiCoCrAlY powders showed bonding strength was higher to 34.35MPa and that thermal cycles were up to 46.8 times. The effect of the transition layer was analyzed by microstructures and the failure mechanism of the coating material with a transition layer was discussed. The conclusion was that the physical mismatch and thermodynamic mismatch between the matrix and ceramic layers were the main cause of the failure.

Synthesis of identical pole permanent magnet

The permanent magnets in this study include the advantages of conventional bonded magnets, and the position of the N (S) poles can be set arbitrarily. This property is realized by using a viscoelastic fluid embedded with magnetization and applying an external magnetic field by another permanent magnet. If the material is modeled into the appropriate shape when an external magnetic field is applied based on the techniques in this study, it contains the potential to create permanent magnets that can achieve any magnetic field (H) envisioned by the user. The possibility of creating permanent magnets that are flexible in terms of the magnetic poles and shape of the molded material (especially compared to bonded magnets) is investigated. As the results, the hardening of the magnetized visco-elastic liquid creates a permanent magnet with identical poles in the same symmetrical direction on an axis. And the identical pole magnet have three peaks in terms of flux density on the surface considered that the reasons of control effect by other permanent magnet on the outside, shift of edge effect and switching magnetic poles in the edge.

Material Databases and Validation in Modelling the Structure of Castings Using the Cellular Automaton Method.

The paper presents the scope of applicability and the usefulness of the method of predicting crystalline structure of castings using a commercially available system called Calcosoft CAFE. The influence of individual values of the parameters of the thermal model and the model predicting the structure (phenomenon of nucleation and crystal growth), and the method of interpretation of the results were identified. In simulation studies, it is important to use reliable and validated material database, under appropriate conditions. It is necessary to predict the properties of castings with a comprehensive, new and practical approach to modelling the formation of phase components of structure in terms of both macroscale and microscale phenomena (Multiscale and Multiphysics). Therefore, in this paper, the experimental-simulation validation of the CAFE code was undertaken. The tests were carried out on castings solidifying under various heat transfer conditions controlled by mould materials such as: a homogenous mould made of moulding sand, moulding sand with chill, and mould made of insulating mass with chill. These conditions directly influence the structure formation. The method of validation of the structure was determined in terms of its three parameters, i.e., the degree of refinement of the crystals, the location of the columnar-to-equiaxed transition zone—CET and the angle of the crystals. The above tests enabled to extend the content of databases, which often lack the necessary values of parameters used in modelling, e.g., crystallization of a specific alloy under given conditions (sand casting, chills or laser surface treatment). On this basis, the basics of correlating the simulation results on a micro- and macroscale were generalized, the limits of the application of individual parameters (mould, alloy materials) and their impact on the structure formation were determined. It resulted in the extension of the database for simulation calculations.

Design and Development of a Mold for Patternless Casting Using AM/3D Printing

Additive manufacturing is a technology that is influencing every facet of manufacturing such as casting. 3D printing in particular has the potential to revolutionize castings in terms of precision and time taken in production. Patternless molds increase the efficiency of the casting process for large scale manufactured components. Therefore, ceramic based molds can be utilized for low temperature alloy parts such as mounting brackets. Nowadays, 3D printing technologies allow the direct printing of these molds. This is possible with the aid of CAD modelling of the casting mold which allows instant printing of patternless molds. The aim of this work is to introduce an approach to prepare a 3D design for a casting mold that can be manufactured using 3D printing technology. Mold design was made using Solidworks software according to standardized calculations from which cope and drag components were extracted. Candidates for potential mold material are highlighted along with advantages &amp; limitations of utilizing 3D printing methodology.

Biobased and mechanically stiff lignosulfonate/cationic-polyelectrolyte/sugar complexes with coexisting ionic and covalent crosslinks

We prepared moldable materials from lignosulfonate, an industrial lignin derivative, using a combination of ionic crosslinking between lignosulfonate and cationic polyelectrolytes and covalent crosslinking via the Maillard reaction. The mechanical properties of the lignosulfonate/cationic-polyelectrolyte/sugar complex at the optimal composition (stress at break: 55.1 MPa; Young’s modulus: 2791.8 MPa; strain at break: 3%) were comparable to those of poly(phenylene sulfide), which is used as a high-performance engineering plastic. In addition to the good mechanical properties, the lignosulfonate/cationic-polyelectrolyte/sugar complex was water-insoluble, in contrast with the high water solubility of the complex without the reducing sugar. Furthermore, the addition of a reducing sugar (fructose) to the complexes increased adhesion to a metal substrate. These improvements in the mechanical properties, water resistance, and adhesive strength of the lignosulfonate complex will expand the applications of lignosulfonate under high mechanical stress conditions and in water and biobased adhesives. Lignosulfonate is one of the major industrial products from wood. To utilize this compound as a moldable and strong material, we prepared a complex of lignosulfonate with cationic polyelectrolytes and reducing sugars. This complex contains two different crosslinking structures, i.e., ionic crosslinking between lignosulfonate and cationic polyelectrolytes and covalent crosslinking via the Maillard reaction of amino groups with reducing sugars. The coexisting of two different crosslinking greatly improved mechanical strength, Young’s modulus, water resistance, and adhesive strength compared with solely crosslinked complexes composed of the same ingredients.

Effect of lamellae orientation on tensile properties of directionally solidified Ti–46Al–0.5W–0.5Si alloy

For full-lamellar TiAl alloys, mechanical properties can be improved in a wide range of temperature by controlling lamellar orientation parallel to growth direction. However, lamellar controlled TiAl alloys with good properties and large scale are difficult to obtain due to sever interface reaction between TiAl melts and mould materials. In this paper, effect of lamellar orientation on tensile properties of directionally solidified (DS) Ti-46Al-0.5W-0.5Si alloy using oxide ceramics crucible was investigated. DS alloys with parallel lamellar structure had better tensile strength (479MPa) and elongation (0.76%) than that of specimen with equiaxed grains (428MPa, 0.22%). Fracture modes of DS alloys were interlamellar, translamellar mode and both, which depended on the lamellae orientation.

Fabrication of highly flexible electromagnetic interference shielding polyimide carbon black composite using hot-pressing method

Traditionally, electromagnetic interference (EMI) shielding material has been occupied by metallic materials due to its high electric conductivity and EMI shielding effect. However, with rising demands from technology development for light-weight, highly durable, and easily moldable materials, metallic materials are gradually being substituted by polymer composite materials. Still, there are limitations on polymer composite as EMI shields: High ratio of fillers in composite achieves excellent EMI shielding effect but it severely compromises its mechanical behaviors. In many studies, they have failed to fabricate the high-ratio filler films with good mechanical durability, but here the initially fragile high-ratio film has been transformed to a flexible film by a very simple method: Hot-pressing. This approach not only solved the problems mentioned above but further provided a possible breakthrough point for composite study by solving threshold of the maximum loading of the fillers in polymer matrix. The stiff composite of polyimide sponge with exceeding carbon black loading became a highly flexible EMI SE film with doubled tensile strength and enhanced EMI SE. As a result, a new way of fabricating flexible EMI shielding polymer composite is demonstrated with great potential applications in aerospace and wireless communications.

Heat and pressure-assisted soft lithography for size-tunable nanoscale structures

Polydimethylsiloxane (PDMS) has been widely used as a mold material to fabricate multiscale patterns, owing to its cost-effectiveness, flexibility, and optical transparency. However, it is important to analyze and understand the deformation of nanoscale patterns due to mechanical and thermal inputs during the replication step. Here, we present an analysis of nanoscale deformation of PDMS molds in response to heat and pressure during the repetitive molding process of thermoplastic polymers. The width and height of the nano-sized ridges of PDMS molds decreased as the number of replications of thermoplastic polymers increased. The decoupling experiments showed that the heat and pressure induced considerable deformation of the width and height of nano-sized ridges of PDMS molds. Using the precisely controlled deformation of nanostructures in PDMS molds, we demonstrated that nanostructures of different sizes can be fabricated on representative thermoplastic and UV-curable polymers consistently.

Comparison and Evaluation of Effectiveness of Different Border Molding and Final Impression Materials on the Retention of Heat Cure Maxillary Denture Bases (AnIn vivoStudy)

Comparison and Evaluation of Effectiveness of Different Border Molding and Final Impression Materials on the Retention of Heat Cure Maxillary Denture Bases (An<i>In vivo</i>Study)