Montedison S.p.a.

Icma San Giorgio S.p.a.

Giancarlo Colombo

Silvano Giacomuzzo

Giulio Gavella

Gianalvise Carazzolo

Luciano Martinello

Franco Gianetti

A method of extruding a substantially uniform polymer composition made up of polyvinylchloride, a stabilizing additive composition and at least one of two additional constituents, one of which is a mineral filler and the other of which is a normally liquid plasticizer for the polyvinylchloride; the method is achieved while avoiding use of compounded PVC as a starting material and includes the steps of: (I) providing an extruder; (II) operating the rotors of the extruder for essentially synchronous rotation in a common direction while maintaining in the extruder cavity a temperature sufficient to plasticize the polyvinylchloride; (III) feeding particulate polyvinylchloride and the additive composition without substantial premixing of the polyvinylchloride and the additive composition into the cavity at the first inlet (e.g. a conventional common hopper) provided near the drive end and adjacent a first conveying segment portion of the rotors; (IV) introducing at least one of the additional constituents through at least one second inlet provided downstream of the first inlet adjacent a rotor section downstream of the first conveying section and downstream of at least one kneading segment section; and thereafter (V) degassing the mixture and extruding it through the extrusion die end.

Extrusion method

Method for the recovery of pentaerythritol from a residual mixture of the synthesis from acetaldehyde and formaldehyde, said mixture containing, besides other byproducts, greater amounts of formals, said method being characterized by a transacetalization of said formals, realized by contact of the residual mixture with a saturated aliphatic alcohol having from 1 to 4 carbon atoms.

Method for the recovery of pentaerythritol from the residual mixtures of

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Milan, Italy

Giancarlo Colombo