influence of catalysts, the one-step process requires a more active catalyst than the prepolymer process, and a composite catalytic system of organotin and tertiary amines is usually used. in the past, organotin catalysts generally used dibutyltin dilaurate. however, this compound is prone to thermal oxidative aging. the ether bond accelerates the cracking under heating and degrades the polymer molecules. therefore, most stannous compounds are currently used, such as stannous octoate. tin et al. moreover, the compression load value of the obtained products is also larger, as shown in the following table:
