Abstract: The present invention relates to an initiator mixture, a composition, use thereof, a process of preparing polymer polyol, and a polymer polyol obtained by the process. The initiator mixture comprises: a first peroxide of formula (I) R1—O—O—R2, wherein R1 and R2 are independent an alkyl group or an alkanoyl group comprising 1 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 4 to 20 carbon atoms; and a second peroxide of formula (II) R3—O—O—R4—O—O—R5, wherein R3 and R5 are independently an alkyl group comprising 1 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 5 to 10 carbon atoms, and R4 is a cycloalkylene group comprising 3 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 5 to 10 carbon atoms.

Abstract: The present invention relates to an initiator mixture, a composition, use thereof, a process of preparing polymer polyol, and a polymer polyol obtained by the process. The initiator mixture comprises: a first peroxide of formula (I) R1—O—O—R2, wherein R1 and R2 are independent an alkyl group or an alkanoyl group comprising 1 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 4 to 20 carbon atoms; and a second peroxide of formula (II) R3—O—O—R4—O—O—R5, wherein R3 and R5 are independently an alkyl group comprising 1 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 5 to 10 carbon atoms, and R4 is a cycloalkylene group comprising 3 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 5 to 10 carbon atoms.

Abstract: A method for preparing a synthetic rubber, including a step of graft-polymerizing a main polymer with a methyl-methacrylate monomer in the presence of a peroxide initiator of formula (I): R1—O—O—R2, wherein each of R1 and R2 is independently an alkyl group or an alkanoyl group including from 1 to 30 carbon atoms.