TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The organosilicon compound (B) is of formula (1).c = 1-4;R = monovalent hydrocarbon group of 1-20C;Z = hydrogen,-Q-M, -Q-Rf, -Q-, -Rf'-, or -Q-Rf'-Q-;M = formula (2);Q = divalent hydrocarbon group of 1-15C which may contain an ether bond;Rf = monovalent perfluoro(oxy)alkyl;Rf' = divalent perfluoro(oxy)alkylene;s = 1-3;t = 0-3; anda, b = 0 or 1, provided that a and b are not 0 at the same time.    TECHNOLOGY FOCUS - POLYMERS - Preferred Compound: The straight-chain fluoropolyether compound is of formula (3) or (4). CH2=CH-(X)p-Rf0-(X)p-CH=CH2 (3) CH2=CH-(X)p-Q-Rf0-Q-(X)p-CH=CH2 (4)X = -CH2-, -CH2O-, or -Y-NR'-CO-;Y = -CH2- or a group of formula (Z) (o, m, or p-position);R' = H, methyl, phenyl, or allyl;Rf0 = divalent perfluoropolyether structure;p = 0 or 1;Q = divalent hydrocarbon group of 1-15C atoms which may contain an ether bond;r = 1-6;u = 2-6; andm and n = 0-200. EXAMPLE - To 100 parts of a polymer of formula (i) having a viscosity of 8500 cs, average molecular wt. of 22000, and vinyl content of 0.009 mol/100g, was added 20 parts of dimethylsiloxy-treated fumed silica with a specific surface area of 200 m2/g. The mixture was heat treated, milled, and added with 2.64 parts fluorinated organosilicon compound of formula (ii), 0.2 part toluene solution of a catalyst in the form of CH2=CHSiMe2OSiMe2CH=CH2-modified chloroplatinic acid, and 0.4 part 50% toluene solution of ethynyl cyclohexanol. The composition was de-aerated in a vacuum, placed in a rectangular frame of 2 mm deep, de-aerated again, and press cured at 100 kg/cm2 and 150 degrees C for 10 minutes. From the cured sample, a specimen was cut out and measured for physical properties. The results showed that the composition had superior acid resistance, a hardness of 40 (initial) and 38 (7 days), elongation of 540% (initial) and 450(-17%) (7 days), tensile strength of 10.7 MPa (initial) and 6.7(-37%) (7 days), and heat loss of 1.9% (7 days). It also showed good solvent swell and low-temperature property, and moisture permeability.