| 摘要 |
A process for the production of expanded polyester, in particular PET, is performed by extrusion of polyester starting material have an intrinsic vircosity of at least 0.8 dl/g and an added expanded agent. To this end a twin screw extruder (14) is utilized provided with two interpenetrating screws (26) having a ratio between their axial separation and diameter lying between 0.6 and 0.8 and co-rotating at a speed of between 15 and 40 rpm. Preferably the ratio between the axial separation and diameter of the screws (26) lies between 0.69 and 0.78 and the ratio between the length and diameter of the screws (26) lies between 20 and 26.
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