Abstract: A mixing device for compounding polymers by elongational deformation is described. The device has a casing (1) with an inlet (2) and an outlet (3). The casing has inner walls (4) defining an enclosure (5) which communicates with the inlet and the outlet. A core (6) is arranged in the enclosure and defines a mixing space (7) between the core (6) and the enclosure wall (4). The mixing space (7) is divided into several slits (9) and chambers (10) by protrusions (8). The device is characterised in that the enclosure (5) and the core (6) are concentrically arranged around a common axis (A) and are conically tapered towards the outlet (3), and that the protrusions (8) are circumferentially arranged on at least one of the core (6) and the enclosure wall (4) with a slit gap in the range from about 0.5 mm to about 10 mm and a width of the slit gap in the range of 0 to about 5 mm. Preferably, the enclosure wall (4) and the core (6) are adjustable relative to each other for adjustment of the slit gap.

Abstract: A mixing device for compounding polymers by elongational deformation is described. The device has a casing (1) with an inlet (2) and an outlet (3). The casing has inner walls (4) defining an enclosure (5) which communicates with the inlet and the outlet. A core (6) is arranged in the enclosure and defines a mixing space (7) between the core (6) and the enclosure wall (4). The mixing space (7) is divided into several slits (9) and chambers (10) by protrusions (8). The device is characterised in that the enclosure (5) and the core (6) are concentrically arranged around a common axis (A) and are conically tapered towards the outlet (3), and that the protrusions (8) are circumferentially arranged on at least one of the core (6) and the enclosure wall (4) with a slit gap in the range from about 0.5 mm to about 10 mm and a width of the slit gap in the range of 0 to about 5 mm. Preferably, the enclosure wall (4) and the core (6) are adjustable relative to each other for adjustment of the slit gap.

Abstract: A method of compounding a multimodal, preferably a bimodal polymer composition comprising a low molecular weight ethylene polymer and a high molecular weight ethylene polymer is described. The composition is compounded during a relatively long time at a low temperature which lies in a narrow temperature range including the melting point of the low molecular weight ethylene polymer. More particularly, the polymer composition is compounded, without addition of a beat transfer medium, in a temperature range from about 10.degree. C. below to about 10.degree. C. above the melting point of the low molecular weight ethylene polymer during a time of more than 10 seconds. The viscosity ratio between the ethylene polymers in said temperature range preferably is from about 5:1 to about 1:5.