Silicon equivalent weights

To this liquid mixture was added a mixture of 50 parts by weight (0.473 equivalent) of a polyol of equivalent weight 105.6 (the adduct of propylene oxide and a mixture of polyamines containing 50% by weight of methylenedianiline obtained by the acid condensation of aniline and formaldehyde) 50 parts by weight of dimethyl sulfoxide and 10 parts by weight of a silicone surfactant. 

Masamune et alJ1001 reported the preparation of the first series of high molecular weight, silicon-branching macromolecules by means of the procedure shown in Scheme 4.21. Their iterative procedure utilized two differently branched synthetic equivalents a trifunctional, hydrido-terminated core 71 and a trigonal monomer 72. Syntheses of the polysiloxane core 71 and building block 72 were each accomplished by the treatment of trichloromethylsilane with three or two equivalents of the siloxane oligomers, HO[Si-(Me)20]5Si(Me)2H and H0[Si(Me)20]3Si(Me)2H, respectively. 

Procedure (See Chromatography, Appendix IIA.) Use a gas chromatograph equipped with a flame-ionization detector and a 4-m x 2-mm (id) stainless-steel column, or equivalent, packed with 15%, by weight, methyl trifluoropropyl silicone (DCFS 1265, or QF-1, or OV-210, or SP-2401) stationary phase on 80- to 100-mesh Gas Chrom R, or the equivalent. Condition a newly packed column at 120° and with a 30-mL/ min helium flow for at least 2 h (preferably overnight) before it is attached to the detector. For analysis, maintain the column isothermally at 105° the injection port and detector at 250° the carrier gas flow rate at 11 mL/min with fuel gas flows optimized for the gas chromatograph and detector in use. Change the experimental conditions as necessary for optimal resolution and sensitivity. The signal-to-noise ratio should be at least 10 1. 

Procedure (See Chromatography, Appendix IIA.) Use a suitable gas chromatograph equipped with a thermal conductivity detector (F and M Model 810, or equivalent), containing a 0.61-m x 6.35-mm (od) stainless steel column (Perkin Elmer Instruments, or equivalent) packed with 20% Silicone SE-30, by weight, and 80% Diatoport S (60- to 80-mesh), or equivalent materials. Program the column temperature from 100° to 270°, heated at a rate of 15°/min. Set the injection port temperature to 300° the bridge current at 140 mA and the sensitivity, lx for the integrator (Infotronics CRS-100, or equivalent) and 2x for the recorder. Use helium as the carrier gas, with a flow rate of 100 mL/min. 

The ring-and-ball softening point is the temperature at which a disk of the sample held within a horizontal ring is forced downward a distance of 25.4 mm under the weight of a steel ball as the sample is heated at a prescribed rate in a water, glycerin, or silicone oil (Dow Corning 200 fluid 50 cs or an equivalent is suitable) bath. 

For production of methylchlorosilanes, copper equivalent to about 10 per cent of the weight of the silicon is preferred as a catalyst. This may be added as a powder to the pulverized silicon and the mixture sintered in a hydrogen furnace, or it may be added in other ways. On a molar basis, this copper requirement represents 0.049 mole of copper per mole of silicon entering into the reaction, and all of it remains behind as the silicon is consumed. It Is at least theoretically possible to recover the copper after the reaction has run its course, but the limited recovery value of this small amount allows only the simplest methods to be considered. 

Dissolution of magnesium and silicon in water from E-glass rovings at k0°, 50 , and 60°C after different time periods is shown in Figures 1 and 2, in which the dissolved amounts are in milligrams of these components per liter (equivalent to parts per million by weight). The dissolutions were relatively rapid in the early stage, but the rate tapered off with time. 

Compared to a common thixotrope such as fumed silica, pulp provides equivalent viscosity at less than one tenth the weight in a typical epoxy resin. In addition, fluid viscosity is unaffected by further processing (agitation) or aging—in contrast to fumed silica modified resin where viscosity drops and is not fully recovered under similar conditions. Pulp can also provide reinforcement in an adhesive matrix as shown by the significant increase in tensile strength, modulus, and tear strength of both a PVC plastisol adhesive and a silicone sealant on the addition of pulp [137,140]. 

Two approaches were used to incorporate these elastomers into the base LARC-13 resin at a concentration of 15% by weight. The first method was to physically blend the Silastic and Sylgard silicone rubbers into the LARC-13 amic acid prepolymer solution. The second method was to chemically react the rubber directly onto the prepolymer backbone by replacing a portion of the MDA diamine with an aromatic amine-terminated elastomer, ATBN or ATS, so that the elastomer was equivalent to 15% by weight of the total solution solids. The addition of the elastomeric materials to LARC-13 caused a reduction in the viscosity of the amic acids in all cases. 

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