THERMALLY STABLE COMPOSITIONS CONTAINING RESIN-LINEAR ORGANOSILOXANE BLOCK COPOLYMERS

摘要

Solid compositions of organosiloxane block copolymers are disclosed having a tensile strength greater than 1.0 MPa and a % elongation at break greater than 40%. The organosiloxane block copolymers comprise: 40 to 90 mole percent disiloxy units of the formula [R1 2SiO2/2] 10 to 60 mole percent trisiloxy units of the formula [R2SiO3/2] 0.5 to 35 mole percent silanol groups [=SiOH] where R1 is independently a C1 to C30 hydrocarbyl, R2 is independently a C1 to C20 hydrocarbyl, wherein; the disiloxy units [R1 2SiO2/2 ] are arranged in linear blocks having an average of from 10 to 400 disiloxy units [R1 2SiO2/2 ] per linear block, the trisiloxy units [R2SiO3/2] are arranged in non-linear blocks having a molecular weight of at least 500 g/mol, and at least 30% of the non-linear blocks are crosslinked with each other, each linear block is linked to at least one non-linear block, and the organosiloxane block copolymer has a molecular weight (Mw) of at least 20,000 g/mole.