Polymethyl Siloxane Resin Research Articles

Binder and polymeric-ceramic material filled with nanosized Al2O3

The production of polymer-ceramic materials with high technological and mechanical properties requires the development of effective binders. The article considers the influence of modifiers on the curing process of polymethylsiloxane resin. It is shown that the introduction of modifiers helps to reduce the viscosity of the resin, and in the presence of a hardener, it makes it possible to obtain a binder with a low viscosity and an acceptable gelation time. Polymer-ceramic material based on the developed binder and nanoscale plasma-chemical Al2O3 powder has high mechanical properties, reduced shrinkage and porosity.

A microstructural study of carbon–carbon composites impregnated with SiC filaments

Porous multidirectional carbon/carbon composite obtained by pulse chemical vapour infiltration (PCVI) was impregnated with silicon carbide (SiC) derived from pyrolysis of polymethylsiloxane resin (PMS). The impregnation process was made to improve oxidation resistance and mechanical properties of MD C/C composite. The resin was used as a source of silicon carbide component of the composite forming after heat treatment above 1000 °C. During this process SiC thin filaments were formed inside the porous carbon phase. The aim of this work was to investigate the structure and microstructure of the constituents of carbon composite obtained after pyrolysis of SiC PMS precursor. Microscopic observations revealed that during careful heat treatment of crosslinked polymethylsiloxane resin up to 1700 °C, the filaments (diameter 200–400 nm) crystallized within porous carbon phase. The filaments were randomly oriented on the composite surface and inside the pores. FTIR spectra and XRD analysis of the modified C/C composite showed that filaments had silicon carbide structure with the crystallite size of silicon carbide phase of about 45 nm. The Raman spectra revealed that the composite contains two carbon components distinctly differing in their structural order, and SiC filaments present nanocrystalline structure.

Linear-expansion coefficients of glass-fiber-reinforced plastics based on polymethylsiloxane resin, up to 1000�C

The authors give the results of an investigation of the linear-expansion coefficients of glass-fiber-reinforced plastics based on polymethylsiloxane resin and various types of filler when heated to 1000°C.

Solid Organic Filters for 2000 Å to 3000 Å

Earlier work on the development of organic, narrow bandpass solution filters with transmittance maxima in the 2000-3000-A range is extended to the fabrication of solid filters using a polymethyl siloxane resin as the host material. Three transmission filters are described having maxima at 2250 A, 2265 A, and 2840 A, respectively, with bandwidths <or=225 A. Transmittance and spectral response curves with CsTe photocathodes are given. Results of environmental tests show that these filters are well suited for balloon and space missions.