Solution and Diffusion in Silicone Rubber. II. Influence of Fillers

1963 ◽  
Vol 36 (3) ◽  
pp. 651-659 ◽  
Author(s):  
R. M. Barrer ◽  
J. A. Barrie ◽  
N. K. Raman
Keyword(s):  
Silicone Rubber ◽  
Porous Silica ◽  
Reference Models ◽  
Silica Filler ◽  
High Area ◽  
Silicone Rubbers ◽  
And Diffusion

Abstract An investigation has been made of the effect of a high area silica filler upon the solubility and diffusion of some C4 and C5 paraffins in silicone rubbers. The membranes studied contained by weight 0, 10, 20, 30 and 40 parts of filler per 100 parts of polymer. The solubilities have been discussed in terms of two reference models: the first in which silica and rubber phases act independently as sorbents; and the second in which the filler is regarded as completely wetted by polymer and is thus a non-sorbent. Diffusion and permeation have also been considered in terms of the models, assuming with the first model an immobile sorbed layer on the porous silica. It has been found that, although some aspects of the behavior can be explained, the results are not fully in agreement with either model, and that the behavior of the heterogenous membrane is complex.

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 Investigation of Hydrothermally Stressed Silicone Rubber/Silica Micro and Nanocomposite for the Coating High Voltage Insulation Applications

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3567
Author(s):  
Faiza Faiza ◽  
Abraiz Khattak ◽  
Safi Ullah Butt ◽  
Kashif Imran ◽  
Abasin Ulasyar ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Structural Changes ◽  
Polymer Chains ◽  
Hydrothermal Conditions ◽  
Silica Filler ◽  
Before And After ◽  
Aging Conditions ◽  
The Stability ◽  
Micro Silica ◽  
Applied Stresses

Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

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>

Review. Fluorescence Microscopy Studies of Porous Silica Materials

2013 ◽  
Vol 68 (5-6) ◽  
pp. 423-444 ◽  
Author(s):  
Bastian Rühle ◽  
Melari Davies ◽  
Thomas Bein ◽  
Christoph Bräuchle
Keyword(s):  
Drug Delivery ◽  
Fluorescence Microscopy ◽  
Single Molecule ◽  
Catalyst Deactivation ◽  
Porous Silica ◽  
Diffusion Dynamics ◽  
Silica Materials ◽  
Microscopy Techniques ◽  
And Diffusion ◽  
Diffusion Properties

In this article, we discuss how fluorescence microscopy techniques are used to investigate important characteristics of porous silica materials. We start with a discussion of the synthesis, formation mechanism and functionalization of these materials. We then give an introduction to single molecule microscopy and show how this technique can be used to gain deeper insights into some defining properties of porous silica, such as pore structure, host-guest interactions and diffusion dynamics. We also provide examples from the literature demonstrating how fluorescence microscopy is used for elucidating important aspects of porous silica materials and heterogeneous catalysis, e. g. diffusion properties, reactivity, morphology, intergrowth, accessibility, and catalyst deactivation. Finally, a short outlook on the scope of porous silica hosts in drug delivery applications is given

Rheological and Thermomechanical Properties of Meso and Non-Porous Silica Filled Epoxy Composites

2015 ◽  
Vol 815 ◽  
pp. 67-71
Author(s):  
Gang Li ◽  
Peng Li Zhu ◽  
Tao Zhao ◽  
Rong Sun ◽  
Daniel Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Mesoporous Silica ◽  
Coefficient Of Thermal Expansion ◽  
Porous Silica ◽  
Thermomechanical Properties ◽  
Epoxy Composites ◽  
Silica Microspheres ◽  
Silica Filler

In the present study, epoxy based composite filled with meso and non-porous silica microspheres with similar size were prepared respectively and their rheological and thermo-mechanical properties were studied systematically. The results showed that the mesoporous silica/epoxy composites showed much higher viscosity, storage modulus and glass transition temperature (Tg) while lower coefficient of thermal expansion (CTE) than did epoxy composites with nonporous silica particles, which could be attributed to the stronger interface interaction between the mesoporous silica filler with larger specific surface area (BET) and the epoxy matrix.

Solution and diffusion in silicone rubber II—The influence of fillers

Polymer ◽  
1962 ◽  
Vol 3 ◽  
pp. 605-614 ◽  
Author(s):  
R BARRER ◽  
J BARRIE ◽  
N RAMAN
Keyword(s):  
Silicone Rubber ◽  
And Diffusion
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