scholarly journals Fluorosilicone as an Omnimold for Microreplication

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 406 ◽  
Author(s):  
Teng Zhang ◽  
Xiaokui Yue ◽  
Dan Sameoto
Keyword(s):  
Silicone Rubber ◽  
Soft Lithography ◽  
Mold Material ◽  
Material Compatibility ◽  
Thermosetting Polymers ◽  
Molded Parts ◽  
New Material ◽  
Multiple Materials ◽  
Silicone Rubbers ◽  
Micro Structures

Soft lithography and replica molding have been an integral part of polymer basic microfabrication for over 20 years. The use of silicone rubber materials as either molds or directly molded parts are well described in the literature and have provided researchers with an easily accessible technique to reproduce complex micro and nanostructures with minimal costs and technical challenges. Yet, for many applications, the use of standard silicones may not necessarily be the best choice, either as a mold material or as a replicated surface. For those instances where a mold is required that is high temperature tolerant, flexible, durable and capable of being used as a mold for multiple materials including silicone rubber, the most commonly used silicone rubber, Sylgard-184, has substantial deficiencies. In this work, we introduce a new material, Fluorosilicone that has not been described in the microfabrication field in detail and determine it is capable of reproducing micro structures via soft lithography techniques and being used as a mold for thermoplastic and thermosetting polymers, including silicone rubbers. Material compatibility, appropriate processing conditions for quality replicas and demonstration of extremely fast production of silicone microstructures are reported.

Fabricating With Liquid Silicone Rubber

1978 ◽  
Vol 10 (2) ◽  
pp. 163-172
Author(s):  
W. R. Hays ◽  
G. P. Kehrer ◽  
C. M. Monroe
Keyword(s):  
Silicone Rubber ◽  
New Technology ◽  
Heat Stability ◽  
Ease Of Use ◽  
Labor Costs ◽  
Cycle Times ◽  
Liquid Silicone Rubber ◽  
Molded Parts ◽  
Liquid Silicone ◽  
Silicone Rubbers

During the last several years, new systems have been developed for the production of silicone rubber parts. These systems offer major reductions in both capital and labor costs. This paper discusses these developments with an emphasis on material properties and potential benefits to the user. The principal methods used to produce molded parts and supported extrusions from liquid silicone rubber are described. Advantages of these systems include quick cure, pumpability, ease of use and lack of solvents. Data documenting the good heat stability, flame retardance, and improved compression set characteristics of the liquid silicone rubbers are presented. In addition, case histories will illustrate the primary benefit of reduced cost per finished part derived from the fast cycle times, lower energy requirements and automation available from this new technology.

scholarly journals Micromechanical Punching: A Versatile Method for Non-Spherical Microparticle Fabrication

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 83
Author(s):  
Ritika Singh Petersen ◽  
Anja Boisen ◽  
Stephan Sylvest Keller
Keyword(s):  
Drug Delivery ◽  
High Resolution ◽  
Physicochemical Properties ◽  
High Throughput ◽  
Liquid State ◽  
Soft Lithography ◽  
Glycolic Acid ◽  
Thermosetting Polymers ◽  
Spherical Microparticle ◽  
Spherical Microparticles

Microparticles are ubiquitous in applications ranging from electronics and drug delivery to cosmetics and food. Conventionally, non-spherical microparticles in various materials with specific shapes, sizes, and physicochemical properties have been fabricated using cleanroom-free lithography techniques such as soft lithography and its high-resolution version particle replication in non-wetting template (PRINT). These methods process the particle material in its liquid/semi-liquid state by deformable molds, limiting the materials from which the particles and the molds can be fabricated. In this study, the microparticle material is exploited as a sheet placed on a deformable substrate, punched by a robust mold. Drawing inspiration from the macro-manufacturing technique of punching metallic sheets, Micromechanical Punching (MMP) is a high-throughput technique for fabrication of non-spherical microparticles. MMP allows production of microparticles from prepatterned, porous, and fibrous films, constituting thermoplastics and thermosetting polymers. As an illustration of application of MMP in drug delivery, flat, microdisk-shaped Furosemide embedded poly(lactic-co-glycolic acid) microparticles are fabricated and Furosemide release is observed. Thus, it is shown in the paper that Micromechanical punching has potential to make micro/nanofabrication more accessible to the research and industrial communities active in applications that require engineered particles.

Attribute Based Selection of Thermoplastic Resin for Vacuum Infusion Process

2011 ◽  
Vol 1 (3) ◽  
pp. 31-52 ◽  
Author(s):  
R. T. Durai Prabhakaran ◽  
Aage Lystrup ◽  
Tom Løgstrup Andersen
Keyword(s):  
Material System ◽  
Mathematical Tool ◽  
Thermoplastic Resin ◽  
Thermoplastic Polymers ◽  
Vacuum Infusion ◽  
Thermosetting Polymers ◽  
Current Scenario ◽  
New Material ◽  
Selection Of ◽  
Vacuum Infusion Process

The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection for vacuum infused of a wind turbine blade—is shown to demonstrate the intricacies involved in the proposed methodology for resin selection.

scholarly journals DC inline plane test of silicone rubber samples with different filler for high-voltage insulation

2020 ◽  
Vol 18 (2) ◽  
pp. 607
Author(s):  
Nurbahirah Norddin ◽  
Intan Mastura Saadon ◽  
Najwa Kamarudin ◽  
Norain Rahim ◽  
Jeefferie bin Abd Razak
Keyword(s):  
Calcium Carbonate ◽  
High Voltage ◽  
Silicone Rubber ◽  
Hot Press ◽  
Rubber Composites ◽  
High Voltage Insulation ◽  
Internal Mixer ◽  
Silicone Rubbers ◽  
Material Preparation ◽  
Inclined Plane Test

<span>This paper is about preparation of silicone rubber (SiR) samples with different filler for high-voltage insulation purpose. The fillers used were silica from waste glass, calcium carbonate from cockle shell, silica/calcium carbonate and wollastonite. All the fillers were crushed into powder and undergo internal mixer and hot press as a material preparation. It was expected that the combination of filler with silicone rubber would give better result when experiencing ageing process. The direct current (DC) inclined plane test was used to investigate the tracking and erosion on silicone rubber composites. The tracking length was observed between the top and bottom electrode. Comparison would then be made between the silicone rubbers with different fillers based on the result obtained from the experiment.</span>

Attribute Based Selection of Thermoplastic Resin for Vacuum Infusion Process

2012 ◽  
pp. 267-288
Author(s):  
R. T. Durai Prabhakaran ◽  
Aage Lystrup ◽  
Tom Løgstrup Andersen
Keyword(s):  
Material System ◽  
Mathematical Tool ◽  
Thermoplastic Resin ◽  
Thermoplastic Polymers ◽  
Vacuum Infusion ◽  
Thermosetting Polymers ◽  
Current Scenario ◽  
New Material ◽  
Selection Of ◽  
Vacuum Infusion Process

The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection for vacuum infused of a wind turbine blade—is shown to demonstrate the intricacies involved in the proposed methodology for resin selection.

Network Scission Processes in Peroxide Cured Methylvinyl Silicone Rubber

1967 ◽  
Vol 40 (2) ◽  
pp. 629-634
Author(s):  
D. K. Thomas
Keyword(s):  
Silicone Rubber ◽  
Elevated Temperatures ◽  
Main Chain ◽  
Methyl Groups ◽  
Chain Polymer ◽  
Filled Rubber ◽  
Oxidative Reactions ◽  
Silica Filler ◽  
Silicone Rubbers ◽  
Hydrolysis Of

Abstract In what appeared to be a complex system it transpires that network scission in methylvinyl silicone rubbers at temperatures below 250° C is due largely to hydrolytic reactions in the main chain polymer. At temperatures of 250° C and above there are indications that a significant amount of scission arises from oxidative reactions in the crosslinks, and that this reaction is catalyzed by acidic residues in the rubber. There is no indication that acidic byproducts of the vulcanization reaction catalyze the hydrolysis of siloxane bonds in the polymer. In conventional heat aging tests in which the rubber remains in an unstrained condition the effects of hydrolysis will only be observed if the concentration of water in the system is allowed to rise. Under these circumstances softening will occur because of a shift in the position of equilibrium in the reaction ∼Si—O—Si—O∼ + H2O→∼Si—OH+ HO—Si—O∼ On aging the material in a well ventilated situation the effects of hydrolysis are not seen and the silicone rubber becomes brittle after long exposure at high temperature. This embrittlement must result from additional crosslinking caused by oxidative reactions in the methyl groups of the main chain polymer. When the rubber is used in compression or tension, hydrolytic scission will affect performance, and in applications of this sort it is important to dry the rubber before use and prevent access of moisture to the component during use. With filled rubber the silica filler is a further source of moisture and drying needs to be carried out at elevated temperatures immediately before use. In order to improve the confined heat aging performance of silicone rubber an alternative filler to fine silica is needed which does not have the same affinity for water. It may be, however, that ability to reinforce silicone rubber and affinity for water are inseparable.

scholarly journals Compatibility Study of Silicone Rubber and Mineral Oil

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5899
Author(s):  
Smitha Karambar ◽  
Stefan Tenbohlen
Keyword(s):  
Dielectric Properties ◽  
Moisture Content ◽  
Silicone Rubber ◽  
Mineral Oil ◽  
Acid Number ◽  
Compatibility Study ◽  
Total Acid ◽  
Silicone Rubbers ◽  
Conductive Silicone Rubber ◽  
Solid Insulation

In this study, three types of silicone rubbers, namely, insulative silicone rubber, conductive silicone rubber and silicone rubber with conductive as well as insulative layers are investigated for their compatibility with mineral oil. Mineral oil with different silicone rubber samples is thermally aged at 130 °C for 360 h, 720 h and 1080 h and at 23 °C, 98 °C and 130 °C for 360 h. At the end of each ageing interval, mineral oil and oil-impregnated silicone rubbers are investigated for their dielectric properties. Aged mineral oil samples are investigated for their moisture content, breakdown voltage, colour number, dissolved gases and total acid number, whereas solid insulation samples are investigated for their moisture content. Additionally, pressboard samples in mineral oil and mineral oil without any solid insulation materials are also aged under the same conditions and are investigated for their dielectric properties. From the obtained results, it can be assessed that the presence of carbon particles in conductive silicone rubber negatively impacts the dielectric properties of mineral oil. Among the investigated silicone rubbers, the insulative silicone rubber exhibits good compatibility with mineral oil and a strong potential for being used in mineral oil.

scholarly journals Research on the electric field intensity distribution of high-voltage cable terminal improved by non-linear material

2021 ◽  
Vol 8 ◽  
pp. 23
Author(s):  
Guowei Li ◽  
Yong Wang ◽  
Xuexia Xu
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
High Voltage ◽  
Silicone Rubber ◽  
Internal Field ◽  
Field Distortion ◽  
Non Linear ◽  
Calculation Results ◽  
Linear Material ◽  
Silicone Rubbers

The electric field distortion caused by the high voltage current environment in the cable terminal will greatly increase the failure probability and reduce the operation safety; therefore, it is necessary to ensure the uniform distribution of the electric field in the terminal. This paper briefly introduced the high-voltage cable terminal and non-linear materials. The traditional silicone rubber and the silicone rubber added with nano-SiO2 were prepared. The electrical conductivity of the two silicone rubbers was tested, and the electric field of the cable terminal was simulated. The results demonstrated that the nano-SiO2 improved silicone rubber had a higher non-linear conductivity and was less affected by temperature. The calculation results of the simulation model also showed that the distribution of the internal field strength was more uniform, and the maximum field strength on the reinforced insulation was smaller after the improved silicone rubber was used as the reinforced insulation.

scholarly journals SEMI-ACTIVE DAMPING PERFORMANCE OF IRON PARTICLE FILLED SILICONE RUBBER

2016 ◽  
Vol 3 ◽  
pp. 7-10 ◽  
Author(s):  
Florian Dirisamer ◽  
Umut Cakmak ◽  
Edmund Marth ◽  
Zoltan Major
Keyword(s):  
Magnetic Field ◽  
Silicone Rubber ◽  
Field Effect ◽  
Iron Particle ◽  
Active Damping ◽  
Damping Coefficient ◽  
Silicone Elastomers ◽  
Silicone Rubbers

The aim of this work was to design, produce and evaluate a demonstrator to visualize the magneto-induced damping behaviour of materials. In contrast to standard materials, the damping coefficient of iron particle filled silicone rubbers can be controlled by a semi-active magnetic field. This field effect should be characterized in order to evaluate the suitability of these magnetorheological silicone elastomers for the use in different configurations and applications.

Experimental determination of modulation power of lung tissue for particle therapy

2021 ◽  
Author(s):  
Jan Michael Burg ◽  
Veronika Flatten ◽  
Matthias Witt ◽  
Larissa Derksen ◽  
Uli Weber ◽  
...  
Keyword(s):  
Lung Tissue ◽  
Ex Vivo ◽  
Ion Beam ◽  
Particle Beam ◽  
Particle Therapy ◽  
New Material ◽  
Carbon Ion Beam ◽  
Porcine Lungs ◽  
Micro Structures

Abstract In particle therapy of lung tumors, modulating effects on the particle beam may occur due to the microscopic structure of the lung tissue. These effects are caused by the heterogeneous nature of the lung tissue and cannot be completely taken into account during treatment planning, because these micro structures are too small to be fully resolved in the planning CT. In several publications, a new material parameter called modulation power (P mod ) was introduced to characterize the effect. For various artificial lung surrogates, this parameter was measured and published by other groups and ranges up to approximately 1000 µm. Studies investigating the influence of the modulation power on the dose distribution during irradiation are using this parameter in the rang of 100 to 800 µm. More precise measurements for P mod on real lung tissue have not yet been published. In this work, the modulation power of real lung tissue was measured using porcine lungs in order to produce more reliable data of P mod for real lung tissue. For this purpose, ex-vivo porcine lungs were frozen in a ventilated state and measurements in a carbon ion beam were performed. Due to the way the lungs were prepared and transferred to a solid state, the lung structures that modulate the beam could also be examined in detail using micro CT imaging. An optimization of the established methods of measuring the modulation power, which takes better account of the typical structures within lung tissue, was developed as well.

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