Interfacial Interactions in Silica Reinforced Silicones

1989 ◽  
Vol 170 ◽  
Author(s):  
Mirta I. Aranguren ◽  
Christopher W. Macosko ◽  
Bima Thakkar ◽  
Matthew Tirrell
Keyword(s):  
Low Molecular Weight ◽  
Complex Structures ◽  
Small Particles ◽  
Carbon Blacks ◽  
Silica Surfaces ◽  
Reinforcing Fillers ◽  
Fractal Characteristics ◽  
Physical Forces ◽  
A New Technique ◽  
Silicone Rubbers

AbstractThe study of the type and strength of the filler-polymer linkages is of great importance in understanding the reinforcement of elastomers. Silicone rubbers are weak elastomers and the addition of reinforcing fillers is essential in order to obtain useful, strong materials. The best reinforcing filler for these elastomers are fumed silicas. These fillers, like reinforcing carbon blacks, have very complex structures. Both have fractal characteristics, small particles fused together forming open aggregates that can cluster by physical forces. Silicas have sometimes more complex structures than carbon blacks, but have a better understood surface chemistry. Interactions between polydimethylsiloxanes and silica surfaces have been studied using heat of adsorption measurements of mostly low molecular weight analogs or inferring the strength of the adsorption by the shift of particular peaks in the infrared spectrum [1]. Here we will present a new technique that measures directly the strength of the adsorption of the polymer segments onto glass and between themselves. It also allows for comparison of the strength of such bonds with the strength of a polymer entanglement “link”.

Biogenic silica short fibers as alternative reinforcing fillers of silicone rubbers

2006 ◽  
Vol 101 (1) ◽  
pp. 290-299 ◽  
Author(s):  
V. P. Silva ◽  
M. C. Gonçalves ◽  
I. V. P. Yoshida
Keyword(s):  
Biogenic Silica ◽  
Short Fibers ◽  
Reinforcing Fillers ◽  
Silicone Rubbers

A New Technique to Photograph Small Particles in Motion

1972 ◽  
Vol 43 (10) ◽  
pp. 1456-1459 ◽  
Author(s):  
S. Temkin ◽  
J. M. Reichman
Keyword(s):  
New Technique ◽  
Small Particles ◽  
A New Technique

Filler Aggregates and Their Effect on Reinforcement

1974 ◽  
Vol 47 (2) ◽  
pp. 411-433 ◽  
Author(s):  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Fine Particles ◽  
High Surface ◽  
High Surface Area ◽  
Experimental Studies ◽  
Spherical Particles ◽  
Rubber Compound ◽  
Carbon Blacks ◽  
Reinforcing Fillers ◽  
Aggregate Nature

Abstract The most highly reinforcing fillers, namely carbon blacks and silicas, consist of aggregates of quasi-spherical particles fused together. In the absence of direct experimental studies with single-particle carbon blacks or silicas of high surface area, we cannot be sure if aggregated structure is essential for good reinforcement, or whether aggregation and fusion just happen to accompany the formation of fine particles at practical concentrations. In any case, there is no doubt that the aggregate nature of the filler plays a major role in determining the properties of the rubber compound. Here I would like to review what we know about filler aggregates, especially of carbon black, and suggest some mechanisms for their effects on rubber; and also indicate where our knowledge seems inadequate at the present time.

Fitting the environment by modifying water structure

1968 ◽  
Vol 171 (1022) ◽  
pp. 59-65 ◽  
Keyword(s):  
Molecular Weight ◽  
Surface Water ◽  
Solar System ◽  
Water Structure ◽  
Low Molecular Weight ◽  
Complex Structures ◽  
Complex Processes ◽  
Relative Neglect

Earth is distinguished from other planets of the solar system by an abundance of surface water. Water is a part of man’s environment from the womb onwards and we tend to take it and its properties completely for granted. It is too seldom consciously regarded as a significant metabolite, an essential substrate for very many enzymes, but tends to be thought of merely as an end product of the divertingly complex processes of oxidation in the cell. Its low molecular weight and the facts that it comes out of a tap, and that its formula is one of the two or three known to non-scientists all perhaps contribute to its relative neglect by a science occupied with unravelling the complex structures and functions of polymers. Yet water itself is a polymer, perhaps the most unstable and structurally labile we know of at present.

The Effect of Fillers on the Permeability of Rubber to Gases

1955 ◽  
Vol 28 (3) ◽  
pp. 821-832 ◽  
Author(s):  
G. J. Van Amerongen
Keyword(s):  
Carbon Black ◽  
Oxygen Adsorption ◽  
High Rate ◽  
Considerable Decrease ◽  
Rubber Mixture ◽  
Carbon Blacks ◽  
Energy Factors ◽  
Reinforcing Fillers ◽  
Inorganic Fillers ◽  
Mechanical Nature

Abstract The purpose of the investigation was to study the effects of fillers, especially various types of carbon black and new light-colored reinforcing fillers. In the discussion of the problem, it is shown that permeability to gases is related to the rate of diffusion, and to the solubility of the gas in rubber, and it is also shown how these properties were measured. The effect of carbon black on the permeability of rubber to gases is relatively small. Independent of the type of carbon black, the permeability is reduced only about 30 per cent by the addition of 50 parts by weight of carbon black per 100 parts of rubber. The permeability of a rubber mixture to a gas is increased considerably, however, by the presence of fine types of carbon blacks, while the rate of diffusion of the gas is decreased. This fact can be explained by assuming that gas is adsorbed by carbon black in rubber and thereby rendered inactive. The high oxygen adsorption of the finer types of carbon blacks in rubber mixtures explains the high rate of oxidation of such mixtures. A whole series of inorganic fillers, among them some light-colored reinforc- ing agents, have no noteworthy effect on permeability. With 20 parts by volume of such fillers per 100 parts of rubber, the permeability is decreased only about 25 per cent, irrespective of the particular filler. A considerable decrease of permeability, i.e., about 75 per cent, is observed, however, with lamellar fillers, such as powdered aluminum and powdered mica. A rubber mixture containing powdered mica shows, at 100° C, the same permeability to hydrogen and nitrogen that Butyl rubber does. The relation of permeability to the temperature of rubber containing fillers is practically the same as that for an unloaded rubber mixture. The decreases of permeability to gases which are observed, are, therefore, not related to energy factors, but are of a purely mechanical nature.

A new technique for measuring size distributions of fine ingesta/digesta particles

2000 ◽  
Vol 27 (2) ◽  
pp. 191 ◽  
Author(s):  
Murray Logan ◽  
Gordon D. Sanson
Keyword(s):  
Image Analysis ◽  
High Power ◽  
Focal Plane ◽  
Constant Volume ◽  
New Technique ◽  
Size Distributions ◽  
Small Particles ◽  
Microscope Slide ◽  
Food Material ◽  
A New Technique

Techniques were developed to enable convenient, high-power image analysis of (ingested) food material. A constant volume of diluted gut sample was delivered to a large microscope slide before being slowly evaporated in still air to leave all particles statically on the same focal plane. Evaporation also allowed a meniscus to develop around each particle, forcing them to separate and thereby preventing overlap and aggregation of particles. Sub-samples were measured under four high-power magnifications (2050, 1290, 510 and 190) to permit precise estimates of size distributions of the very small particles. The techniques developed avoid the need for large ingesta/digesta samples, sieving, and filtering, all of which have limited previous studies.

Effect of Carbon Blacks on Swelling of Neoprene GRM-10 Vulcanizates

1949 ◽  
Vol 22 (3) ◽  
pp. 812-819 ◽  
Author(s):  
N. L. Catton ◽  
D. C. Thompson
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Physical Properties ◽  
Compression Modulus ◽  
Tension Stress ◽  
Limited Extent ◽  
Carbon Blacks ◽  
Reinforcing Fillers ◽  
Swelling Characteristics ◽  
Natural Rubber Vulcanizates

Abstract Reinforcement of elastomers with fillers has generally been measured by physical properties, such as tension stress-strain, tear resistance, hardness, and compression modulus. To a more limited extent, swelling in solvents has been recognized as associated with reinforcement. In natural-rubber vulcanizates it has been demonstrated that reinforcing fillers impart greater resistance to solvents and oils than do nonreinforcing types. Addition of the latter gives only the reduction in swelling attributable to elastomer dilution. In the case of Neoprene vulcanizates, Catton and Fraser reported that fillers function only as elastomer diluents and that those fillers commonly considered as of the reinforcing type impart no greater resistance to solvents than the nonreinforcing type. More recently, however, Buist and Mottram, in describing the effects of carbon blacks on the physical properties of natural rubber and Neoprene, reported that with both of these elastomers compounds containing thermal type carbon black gave slightly greater swelling in benzene than compounds containing equal loadings of other types of carbon black. With Neoprene, they reported good correlation between moduli and swelling characteristics.

Interaction between Carbon Black and Polymer in Cured Elastomers

1951 ◽  
Vol 24 (3) ◽  
pp. 597-615
Author(s):  
R. S. Stearns ◽  
B. L. Johnson
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Chemical Bonding ◽  
Physical Adsorption ◽  
Three Dimensional ◽  
Physical Property ◽  
Carbon Black Particle ◽  
Low Molecular Weight ◽  
Carbon Blacks ◽  
Black Particle

Abstract This research was initiated to determine whether the interaction at the interface between the surface of finely divided solids, such as carbon black, and cured elastomers is primarily physical or chemical in nature. Further, it was desired to correlate some physical property of the reinforced stock with the surface properties of the solid pigment. Through an examination of the thermodynamic changes accompanying the deformation of loaded stocks it is shown that physical adsorption of the van der Waals type occurring at the interface between pigment and polymer is inadequate to account for the experimental observations. However, if chemical bonding occurs at the interface between polymer and pigment, then the entropy of deformation of the stock may be correlated with the extent of this bonding. By a calorimetric method it was demonstrated that the surface of a carbon black particle contains sites that react with bromine to liberate the same amount of heat as low molecular-weight olefins. It is, therefore, proposed that a carbon black particle be considered as a disordered agglomerate of polymeric benzenoid type molecules which contain around their perimeters various functional groups. The existence of olefinic-type unsaturation on the surface of carbon blacks suggests strongly that, in the case of carbon blacks, the polymer and pigment are combined chemically through pigment-sulfur-polymer bonds into a continuous three-dimensional cross-linked matrix.

Spontaneous Formation of Ag and Au Particles in Alcohols

1994 ◽  
Vol 351 ◽  
Author(s):  
Z.-Y. Huang ◽  
M. Quinn ◽  
G. Mills ◽  
W. Galef
Keyword(s):  
Light Scattering ◽  
Metal Particles ◽  
Small Particles ◽  
Plasmon Band ◽  
Spontaneous Reduction ◽  
Silica Surfaces ◽  
Spontaneous Formation ◽  
Ag Particles ◽  
Solvent Molecules ◽  
Small Metal Particles

ABSTRACTMetal particles are generated via the spontaneous reduction of Ag+ and AuCl4− ions by solvent molecules that takes place in air-saturated alcoholic solutions containing hydroxide ions. Changes in the plasmon band of the Ag particles are observed when the metal particles are in contact with Ag20 particles. The optical changes are explained in terms of surface effects of the metal particles. Larger shifts of the Au plasmon band and light scattering were observed at the initial stages of the particle formation process. These effects are explained in terms of formation of networks consisting of small metal particles. It is proposed that generation of small Au particles occurs mainly on silica surfaces, and that particle-networks are formed when small particles desorb from the surfaces.

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