| 摘要 |
<p>A method for producing expandable polystyrene (EPS) or extruded polystyrene foams (XPS), starting from polystyrene already present in the polymerized state or polystyrene melts, the same containing at least one expanding agent and/or at least one flame or fire retardant and/or at least one radical former as a flame retarding synergist, either from the start and/or being added during the production process. To reduce the extent to which the molecular weight is decreased as a result of the chain decomposition occurring during the heating as part of the production process, at least one stable free radical from the group of organic nitroxyl radicals of the general formula (1) is added to the polystyrene and/or the melt thereof. In the formula R1, R2, R3, R4, R5 and R6 are either identical or different, linear or branched, optionally substituted alkyl groups, or R2, R3, R5 and R6 have these meanings, however R1 and R4 are closed forming a chain with each other, the chain being made of (—CH2—)—units or a combination of the (—CH2—)—units with oxygen and/or nitrogen atoms, the chain optionally being connected to a further saturated, unsaturated, or aromatic ring, wherein the further ring-shaped organic (aliphatic) and/or aromatic structure is optionally substituted. Alternatively, the chain itself carries at least one arbitrary substituent, or at least one compound forming or comprising such a nitroxyl radical of the formula (1) is added to the polystyrene and/or the melt thereof.</p> |
