| abstract |
Rubber mixt. consists of (a) 100 pts. wt. organic rubber polymer, (b) 0.5-30 pts. wt. of >=1 organic Si material consisting of:(i) an organosilane having formula R'SiX4-p (I) (where R' is 1-10C monovalent hydrocarbyl: X is OH or a hydrolysable gp. and p is 1-3 esp 1 or 2; (ii) an organopolysiloxane having average structural formula R2qYrSiO (4-q-r)/2 (II) (where R2 is monovalent hydrocarbyl; Y is OH or a hydrolysable gp.; q is a + ve integer 1-3; r is 0 or +ve integer 2, provided q + r is 1-3) and average degree of polymerisation (DR) =40 (=30), and/or (iii) an organopolysilazane having average structural formula R3s Si(NH) (4-s)/2 (III) (where R3 is monovalent hydrocarbyl and s is a +ve integer 1-3); (c) 10-200 pts. wt. silica filler and (d) 0.1-10 pts. wt. crosslinking agent. Vulcanised shaped articles have high elasticity and low residual pressure deformation, are stable to heat, oil weathering, swelling and solvents and have good electrical properties and strength. Uses include packaging, caps and coatings, apparatus fittings and supports and oil gaskets. |