scholarly journals Enhancement of dielectric permittivity by incorporating PDMS-PEG multiblock copolymers in silicone elastomers

RSC Advances ◽  
2015 ◽  
Vol 5 (65) ◽  
pp. 53054-53062 ◽  
Author(s):  
Aliff Hisyam A. Razak ◽  
Peter Szabo ◽  
Anne Ladegaard Skov
Keyword(s):  
Dielectric Permittivity ◽  
Silicone Elastomer ◽  
Multiblock Copolymers ◽  
Silicone Elastomers ◽  
Multiblock Copolymer

A silicone elastomer from PDMS-PEG multiblock copolymer has been prepared by use of silylation reactions for both copolymer preparation and crosslinking.

scholarly journals Evaluation of Some Mechanical Properties of a Maxillofacial Silicon Elastomer Reinforced with Polyester Powder

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Yagthan Mohammed Haider ◽  
Zainab Salih Abdullah ◽  
Ghasak H. Jani ◽  
Norehan Mokhtar
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Hardness Test ◽  
Silicone Elastomer ◽  
Control Group ◽  
Silicone Elastomers ◽  
Tear Strength ◽  
To Come ◽  
Post Hoc

Maxillofacial silicone elastomers are used to replace and reconstruct missing facial parts for patients with trauma or a certain disease. Although commonly favorable silicone elastomers are not ideal in properties, many studies have been carried out to improve their mechanical properties and to come out with ideal maxillofacial prosthetic materials, so as to render patients with the best maxillofacial prostheses. The aim of the current study is to evaluate the effect of addition of different concentrations of polyester powder on hardness, tear strength, surface roughness, and tensile strength of maxillofacial A-2186 RTV silicone elastomers. Polyester powder was added to the silicone elastomer in the concentrations of 1%, 3% and 5% by using an electronic digital balance, compared with the control group of 0% polyester filler. The shore A hardness test was done according to ASTM D 2240 standards. The tear test was done according to ASTM D624 type C standards. The tensile test was done according to ISO specification number 37:2011. The surface roughness test was performed according to ISO 7619-1 2010 specifications. The data collected were then analyzed using one-way analysis of variance (ANOVA) and post hoc and Fisher’s LSD tests. All three groups showed a highly significant increase in tear strength, tensile strength, hardness, and roughness, compared to the control group. Reinforcement of A-2186 Platinum RTV Silicone Elastomer with 5% polyester significantly improved the mechanical properties tested in this study.

Effects of Fumed Silica Treated with Functional Disilazanes on Silicone Elastomers Properties

1982 ◽  
Vol 55 (1) ◽  
pp. 233-244 ◽  
Author(s):  
M. T. Maxson ◽  
C. L. Lee
Keyword(s):  
Fumed Silica ◽  
Silica Surface ◽  
Silicone Elastomer ◽  
Treatment Level ◽  
Silicone Elastomers ◽  
Hardness Values

Abstract The reinforcement obtained with disilazane-treated silica in the platinumcatalyzed silicone elastomer was found to be dependent upon not only the amount of disilazane employed but also the structure of the disilazane and its distribution on the silica surface. Incorporation of a small amount of vinyl-functional disilazane such as (ViMe2Si)2NH along with (Me3Si)2NH (major treating agent) can significantly increase the modulus and hardness of the resulting elastomer. [ViMe2Si(OMe2Si)3]2NH gave higher modulus and hardness than (ViMe2Si)2NH, whereas (HMe2Si)2NH gave lower modulus and hardness values. The random treatment resulted in greater improvement of cured elastomer properties than the heterogeneous treatment at the same treatment level.

Investigating the Roles of Crystallizable and Glassy Switching Segments within Multiblock Copolymer Shape-Memory Materials

MRS Advances ◽  
2018 ◽  
Vol 3 (63) ◽  
pp. 3741-3749
Author(s):  
Wan Yan ◽  
Liang Fang ◽  
Ulrich Noechel ◽  
Oliver E. C. Gould ◽  
Marc Behl ◽  
...  
Keyword(s):  
Shape Memory ◽  
Tensile Tests ◽  
Multiblock Copolymers ◽  
Molecular Architecture ◽  
Memory Mechanism ◽  
Multiblock Copolymer ◽  
Relationship Of ◽  
Synergistic Relationship ◽  
Vapor Treatment ◽  
Insight Into

ABSTRACTThe variation of the molecular architecture of multiblock copolymers has enabled the introduction of functional behaviour and the control of key mechanical properties. In the current study, we explore the synergistic relationship of two structural components in a shape-memory material formed of a multiblock copolymer with crystallizable poly(ε-caprolactone) and crystallizable poly[oligo(3S-iso-butylmorpholine-2,5-dione)] segments (PCL-PIBMD). The thermal and structural properties of PCL-PIBMD films were compared with PCL-PU and PIBMD-PU, investigated by means of DSC, SAXS and WAXS measurements. The shape-memory properties were quantified by cyclic, thermomechanical tensile tests, where deformation strains up to 900% were applied for programming PCL-PIBMD films at 50 °C. Toluene vapor treatment experiments demonstrated that the temporary shape was fixed mainly by glassy PIBMD domains at strains lower than 600%, with the PCL contribution to fixation increasing to 42±2% at programming strains of 900%. This study into the shape-memory mechanism of PCL-PIBMD provides insight into the structure-function relation in multiblock copolymers with both crystallizable and glassy switching segments.

scholarly journals Long-term stable modifications of silicone elastomer for improved hemocompatibility

2016 ◽  
Vol 2 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Cécile Boudot ◽  
Sarah Burkhardt ◽  
Miriam Haerst
Keyword(s):  
Thrombin Generation ◽  
Platelet Adhesion ◽  
Medical Engineering ◽  
Surface Modifications ◽  
Silicone Elastomer ◽  
Silicone Elastomers ◽  
Thrombin Generation Assay ◽  
Electron Microscope Analysis ◽  
Cost Efficient

AbstractSilicone elastomers are well established in medical engineering and particularly in blood-contacting applications such as catheters and medical tubing. Still, their intrinsic surface properties have potential for improvement. For example, hydrophobicity reduction can be a way to provide better hemocompatibility. In this study, several bulk and surface modifications of silicone elastomers using polyethylene glycol (PEG) were investigated. All modifications induced long-term (2 months), stable wettability of the surface. Moreover, cytotoxicity testing demonstrated their suitability as implant material. Hemocompatibility was investigated through a thrombin generation assay as well as a platelet adhesion study combining an enzymatic assay and a scanning electron microscope analysis. That the hemocompatibility of silicone was considerably improved thanks to the PEG modifications could be shown. The study introduces easily processable, cost-efficient, and long-term stable hydrophilic modifications of silicone elastomer for improved hemocompatibility.

Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on dipolar copolymers

Polymer ◽  
2014 ◽  
Vol 55 (24) ◽  
pp. 6212-6219 ◽  
Author(s):  
Frederikke Bahrt Madsen ◽  
Liyun Yu ◽  
Anders Egede Daugaard ◽  
Søren Hvilsted ◽  
Anne Ladegaard Skov
Keyword(s):  
Dielectric Permittivity ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Silicone Elastomers ◽  
Dielectric Breakdown Strength ◽  
High Dielectric Permittivity ◽  
Strength Based ◽  
High Dielectric

scholarly journals Modification of Silicone Elastomers Using Silicone Comonomers Containing Hydrophilic Surface Active Endgroups

2014 ◽  
Vol 1626 ◽  
Author(s):  
Jonathan Goff ◽  
Barry Arkles ◽  
Santy Sulaiman
Keyword(s):  
Contact Angle ◽  
Mechanical Performance ◽  
Silicone Elastomer ◽  
Hydrophobic Contact ◽  
Silicone Elastomers ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Friction Measurements ◽  
Time Frames

ABSTRACTA facile technique was developed for a long-term increase in silicone elastomer surface hydrophilicity, eliminating the need for post-cure surface treatment (e.g. oxygen plasma or surface grafting). Well-defined silicones (1-4 kDa) with a central vinyl functionality and discrete PEG2, PEG3 and tetrahydrofurfuryl (THF) pendant endgroups were synthesized, characterized and used as comonomers in addition-cure, platinum catalyzed 2-part silicone elastomer formulations. The modified silicone elastomers were optically clear and maintained the mechanical performance characteristic of this class of material with up to 20 wt.% comonomer in the 2-part formulation. Contact angle measurements of deionized water on the silicone elastomer surface showed improved wettability with comonomer content. The elastomer surface shifted from hydrophobic (contact angle ∼120°C) to hydrophilic (contact angle < 90°C) at ∼5 wt.% comonomer loadings for extended time frames (> 5 months). Coefficient of friction measurements of the modified silicone elastomers revealed an increase in surface lubricity with comonomer loadings.

Novel Wet Process Silica Prepared from Alkyl Silicates. Part III: Use in Silicone Elastomers for Optical Applications

1985 ◽  
Vol 58 (5) ◽  
pp. 965-972 ◽  
Author(s):  
Keith E. Polmanteer ◽  
Harry L. Chapman ◽  
Michael A. Lutz
Keyword(s):  
Temperature Change ◽  
Silicone Elastomer ◽  
Refractive Indices ◽  
Silicone Elastomers ◽  
Wet Process ◽  
Elastomeric Material ◽  
Specific Temperature ◽  
Optical Applications ◽  
High Consistency ◽  
Silica Synthesis

Abstract The first two papers of this three-part series of papers dealing with a novel wet-process hydrophobic (WPH) silica technology covered the silica synthesis (Part I) and reinforcement performance (Part II) respectively. The WPH silica was highly reinforcing and provided optically clear compositions as well. The first optically clear, high consistency silicone elastomer was developed in the midnineteen fifties by Polmanteer et al., using different technology from that described in this paper. Optical clarity was accomplished in the earlier work by matching the refractive indices of the filler and polymer at 25°C, making them isorefractive at this specific temperature. This paper will discuss the unique features of this new silica technology as it relates to optically clear silicone elastomers. The term, optically clear, in the context of this paper refers to an elastomeric material, 2.54 mm in thickness, that exhibits less than 4% haze, and more than 85% transmission. It will be shown that, when using the older technology based on isorefractive compositions, optical clarity is reduced with temperature change from the isorefractive temperature, due primarily to an increase in haze. The new silica technology eliminates this problem and effectively broadens the application temperatures for optically clear, thermally stable silicone elastomers.

Preparation and characterization of luminescent silicone elastomer by thiol–ene “click” chemistry

2014 ◽  
Vol 2 (15) ◽  
pp. 2724-2734 ◽  
Author(s):  
Yujing Zuo ◽  
Haifeng Lu ◽  
Lei Xue ◽  
Xianming Wang ◽  
Liang Ning ◽  
...  
Keyword(s):  
Click Chemistry ◽  
Ultraviolet Light ◽  
Silicone Elastomer ◽  
Silicone Elastomers ◽  
Very High

Novel transparent and luminescent silicone elastomers were prepared by thiol–ene chemistry. They show very intense photoluminescence under ultraviolet light and have very high coloric purity.

scholarly journals Looped flow RAFT polymerization for multiblock copolymer synthesis

2017 ◽  
Vol 8 (21) ◽  
pp. 3249-3254 ◽  
Author(s):  
Agnès Kuroki ◽  
Ivan Martinez-Botella ◽  
Christian H. Hornung ◽  
Liam Martin ◽  
Elizabeth G. L. Williams ◽  
...  
Keyword(s):  
Raft Polymerization ◽  
Scale Up ◽  
Multiblock Copolymers ◽  
Multiblock Copolymer

A flexible, robust and time-efficient scale-up of multiblock copolymers with low dispersity and high livingness.

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