The Influence of Fumed Silica Properties on the Processing, Curing, and Reinforcement Properties of Silicone Rubber

1993 ◽  
Vol 66 (1) ◽  
pp. 48-60 ◽  
Author(s):  
H. Cochrane ◽  
C. S. Lin
Keyword(s):  
Surface Area ◽  
Silicone Rubber ◽  
Fumed Silica ◽  
Silica Surface ◽  
Silica Network ◽  
Surface Pretreatment ◽  
Structure Level ◽  
Network Strength ◽  
Reinforcement Model ◽  
Mixing Techniques

Abstract The present study uses a commercial heat cured silicone rubber formula (including a process aid) and mixing techniques to investigate the effect of varying fumed silica properties—including load, surface area, silica structure level, and surface pretreatment levels—on the rubber processing, curing, and cured physical properties. Based on the results, a simple silica network reinforcement model was developed to explain the changes in processing, curing, and vulcanizate properties of the silicone elastomers. The network is held together by silica-silica interactions and silica-polymer-silica bridge bonds between the silica aggregates. Increasing the silica loading, surface area, and structure level increases the number of interactions and hence the network strength. The pretreatment of the silica surface with organosilane molecules reduces the strength of silica-silica and silica-polymer interactions, therefore, weakening the silica network. Furthermore, the good interrelations between the initial plasticity, crepe hardening, curing, modulus yield, and durometer values strongly supports the concept of the presence of a silica network within the compounds under the low strain conditions of the tests.

scholarly journals Spectroscopic study on peculiarities of fumed silica hydridesilylation with triethoxysilane under fluidized bed conditions

2021 ◽  
Vol 12 (4) ◽  
pp. 314-325
Author(s):  
P. O. Kuzema ◽  
◽  
A. V. Korobeinyk ◽  
V. A. Tertykh ◽  
◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Surface Area ◽  
Fumed Silica ◽  
Silica Surface ◽  
High Surface ◽  
Space Filling ◽  
Silica Sample ◽  
Widespread Application ◽  
Silanol Groups ◽  
Heating Mode

Fumed silica has found widespread application in industry due to variety of fascinating properties. Owing to its specific manufacturing process, it consists of finely dispersed particles and is featured with large specific surface area covered by profoundly reactive silanol groups which are available for chemical grafting. Spherical shape of fumed silica particles and lacking porosity provides a space-filling structure. These characteristics implement the fume silica’s utilization as high-surface-area carriers for various catalysts, i.e. metallic nanometer-sized particles, organic moieties, etc. Currently a great attention is called to on-surface grafting to improve the silica-based carrier. Most of research is carried out in area of liquid phase chemistry involving an abundance of expensive and often toxic solvents while the space-filling properties of silica are favoring reactions in fluidized bed conditions. In current research fumed silica (A-300) was a subject for hydridesilylation with triethoxysilane under fluidized bed conditions. In all synthesis reported in current research the insignificant amount of solvent (1.00 wt. % of the amount used in typical wet-chemical modifications method) was spent for the silica surface silylation. While the mass ratio of silica/TES was kept constant, other conditions, i.e. solvent/catalyst presence, surface pretreatment, additional treatment with water, and the fluidized bed heating mode have been varied. FTIR spectroscopy revealed the interaction between groups of triethoxysilane and silica surface silanol groups and demonstrated the effect of modification conditions on the density of the hydridesilyl groups coverage. The results of FTIR spectroscopic studies have confirmed the presence of grafted silicon hydride groups on the surface of modified silica, as well as the presence of ethoxy and/or silanol groups – either intact or formed due to hydrolysis of the ethoxy groups. Titrimetric and spectrophotometric analysis was performed to estimate the concentration of grafted SiH groups (in all samples prepared under fluidized bed conditions their concentration ranged within about 0.28–0.55 mmol/g as dependent on the reaction conditions). Other important aspects of fluidization such as the presence of solvent and/or hydrolyzing agent, bed heating mode and the effect of the silica sample thermal pre-treatment are also discussed.

scholarly journals Peculiarities of Chemisorption of Dimethyl Carbonate on Silica Surface

2016 ◽  
Vol 17 (1) ◽  
pp. 88-92
Author(s):  
I.S. Protsak ◽  
E.M. Pakhlov ◽  
V.A. Tertykh
Keyword(s):  
Ir Spectroscopy ◽  
Fumed Silica ◽  
Dimethyl Carbonate ◽  
Silica Surface ◽  
Chemical Interaction ◽  
Spectroscopy Method ◽  
Silanol Groups

This paper presents the results of studies of dimethyl carbonate interaction with sites of the fumed silica surface. The investigations were performed in a vacuum quartz cuvette using IR spectroscopy method. Chemical interaction of dimethyl carbonate with sites of the dehydrated silica surface was shown to occur at temperature of 200 °C and higher, chemisorption processes take place involving both structural silanol groups and siloxane bridges on the surface.

scholarly journals The Morphology and Conductive Properties of Composite Material SiO2 – C

2015 ◽  
Vol 16 (4) ◽  
pp. 700-705
Author(s):  
I.F. Myronyuk ◽  
V.I. Mandzyuk ◽  
V.M. Sachko ◽  
Yu.O. Kyluk
Keyword(s):  
Composite Material ◽  
Fumed Silica ◽  
Silica Surface ◽  
Weight Ratio ◽  
Nitrogen Adsorption ◽  
Carbon Phase ◽  
Fumed Silica Nanoparticles ◽  
Structure Morphology ◽  
Open Porous Structure ◽  
Conductive Properties

The article explores the structure, morphology and conductive properties of composite material SiO2 – C using XRD, SAXS, low-temperature nitrogen adsorption, and impedance spectroscopy methods. It is set that SiO2 – C composite obtained by thermolytic decomposition of D-lactose, previously chemisorbed on fumed silica nanoparticles surface, has an open porous structure, in which mesopores of 6-12 nm in size are dominate. At weight ratio SiO2/C = 5/1 nanocrystallites of carbon phase in form of lamellar sheets of 0,4 × 0,4 × 5,0 nm3 in size contact with entire silica surface that results in composite material conductivity is 49 Оhm-1·m-1.

The determination of the surface area of silica by laser Raman spectroscopy

1976 ◽  
Vol 29 (3) ◽  
pp. 507 ◽  
Author(s):  
RP Cooney ◽  
NT Tam
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
Surface Area ◽  
Surface Coverage ◽  
Silica Surface ◽  
Quantitative Agreement ◽  
Laser Raman Spectroscopy ◽  
Laser Raman ◽  
Bet Method

Changes in the Raman spectrum of pyridine on a silica surface with increasing surface coverage may be used to determine the monolayer capacity. The method, which is independent of the BET method, produces a result which is in quantitative agreement with the BET result.

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