**1. Introduction**

The problems of increasing the strength of polymer materials are important for both fundamental science and applied research. For example, the polydimethylsiloxane (PDMS) CKTH rubbers, as representative of organosilicon polymers, are of the great importance in industry. Materials made on the basis of such CKTH rubbers are resistant to temperatures from −90 to +300°С, as they possess high hydrophobicity, chemical inertness, dielectric properties, vibration resistance, resistance to fungi and microorganisms, and resistance to ozone, oxidizers, and ultraviolet rays. Also they are physiologically inert, tissue and hemocompatible, gas permeable (the highest permeability of all known polymers), selective for gas permeability, and easily sterilized. Unlike organic, CKTH silicone rubbers are more economical, reliable, and durable even under extreme conditions; and are also easy to process. However, they have low

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

mechanical strength. Reinforcement of these polymers is usually achieved with fillers. The nature of the interaction of matrix elastomers with fillers is determined by the chemical nature, dispersion, shape, activity of the filler particles, the possibility of chemical bonds between the components of composites, and the relationship between the processes of amplification and structuring. In the works of Mark and coworkers [1, 2], which generalize numerous studies, it is stated that the physical and mechanical properties of synthetic low-molecular-weight siloxane elastomers filled with silica are significantly enhanced. It is of great interest also for the search for new reinforcement fillers to PDMS. One of favorable proposals may be schungit [3]. In the development of advanced composites, it is advisable preliminary to perform the molecular computational modeling, which is an effective method of a virtual analysis of the structural, energetic, and micromechanical properties of micro- and nanomaterials. As reported in [4–6], the energetic and structural characteristics of elastomer complexes with silica or schungit have been calculated quantum chemically under developed NDDO/sp-spd semiempirical original program [7]. Numerical calculations on the supercomputer MBC-5000 in the Interdepartmental Supercomputer Center were performed. The microscopic characteristics of nanomechanical behavior, deformation, and strength characteristics of silica or schungit adsorbates with polydimethylsiloxane oligomer molecules during uniaxial tension based on this program in the cluster approximation were examined. It was deduced that one could expect a substantial reinforcement of physical-mechanical properties for such composites.

Fillers were both the original schungit from provider and the original schungit milled by us in a ball planetary mill PM100 (Retsch, Germany) under different environments. The fillers were added to the CKTN-A rubber according to the compositions given in **Table 2**, kneaded by hand, and then passed through rolls. The resulting mixtures were evacuated for 15 minutes; then, a catalyst No 68 was introduced with a certain concentration for each composition and again evacuated. The samples were placed in Teflon forms and cured [8]. **Table 2** shows the

CKTN-A composites with silica fillers, precipitated silicon dioxide, and SIPERNAT 360 (Evonik Industries AG, Germany), were prepared analogues to composites with schungit.

The atomic-force microscope (AFM) easyScan (Nanosurf, Switzerland), operating in a contact mode at ambient conditions, using also the force modulation mode, or in the semi-contact mode with the phase contrast mode, was used. In a semi-contact mode, a SuperSharpSilicon probe (Nanosensors, Switzerland) with a tip radius of about 2 nm was

**O K2**

**С300 С301 С302 С303 С304 С305 С306 С307 С308**

**С 300 С 309 С 310 С 311 С 312 С 313**

**O S C H2**

Atomic Force and Electron Scanning Microscopy of Silicone Composites

http://dx.doi.org/10.5772/intechopen.79537

17

**Ocryst**

ingredients of the samples used and corresponding code of synthesized composites.

**Table 3** shows the ingredients of the samples studied.

**Table 1.** Chemical composition of schungit (weight percentage).

**Composite ingredients name Code of composites**

**O3 FeO MgO CaO Na2**

**Weight percentage**

Schungit (original) 10 20 30 40

**Table 2.** Ingredients of the synthesized composites with schungit filler.

**No Composite ingredients name Code of mixture**

**Table 3.** Ingredients of the synthesized composites with silica filler.

CKTH-A rubber 100 90 80 70 60 90 80 70 60

Schungit (milled) 10 20 30 40 Total 100 100 100 100 100 100 100 100 100

**Weight percentage** CKTH-A rubber 100 80 90 80 70 60 SIPERNAT 360 — 20 10 20 30 40 Total 100 100 100 100 100 100

57.0 0.2 4.0 2.5 1.2 0.3 0.2 1.5 1.2 29.0 4.2

**SiO2 TiO2 Al2**

We used the conclusions of these calculations in the practical synthesis of siloxane composites with schungit and silica. The multistage physical-chemical modification technology for obtaining the active nanostructured schungit filler for rubbers, based on these quantumchemical calculations, has also been developed.

According to the results of [8], there is an increase in the tear resistance and in the specific work of the deformation during fracture, with preservation of the increased strength properties of synthetic thermally stable low-molecular-weight silicone elastomers based on CKTH-A, filled with micro- and nanoscale schungit and silica SIPERNAT 360.

To further elucidate the nature of the onset of strengthening effects, knowledge of the distribution of fillers in these elastomeric matrices is necessary. The surface structure of these composites, using atomic force and electron scanning microscopy, in the present chapter was studied as extension of the studies [8–11].
