Apparatus for testing plastic compositions

An apparatus for testing the extrudability of platic compositions, comprising:

• a housing provided with two mutually parallel and intersecting cylindrical bores and with an inlet for introducing material to be tested into said bores;
• a pair of plasticizing screws in said bores provided with drive means for continuously counterrotating same, each of said screws having a first thread section proximal to said inlet and a second thread section remote from said inlet, the first and second thread sections of each screw being separated from each other by an axial gap and being formed from turns of mutually opposite pitch, the gaps of said screws being axially separated from each other by a recirculation zone axially spaced from said inlet, the turns of the first thread sections of said screws being of mutually opposite pitch and intermeshing between said inlet and said recirculation zone, the turns of the second thread sections of said screws being of mutually opposite pitch and intermeshing in a region beyond said recirculation zone, an extension of the first thread section of one screw and an extension of the second thread section of the other screw overlapping each other in said recirculation zone with turns of the same pitch shaped and dimensioned to avoid clashing with one another during counterrotation;
• first sensing means coupled with said drive means for continuously monitoring the torque applied to said screw in rotating same;
• second sensing means in said recirculation zone for continuously monitoring the pressure of a mass of plastic material transported therein by said overlapping extensions;
• and
• third sensing means in said recirculation zone for continuously monitoring the temperature of the transported mass.