Capillary rheometer plunger pressure transducer and measurement technique

A capillary rheometer apparatus for characterizing a polymer melt's pressure-volume-temperature relationship, comprising:

• a housing;
• a plunger having a piston at one end thereof;
• the housing having a reservoir for receiving the piston and the polymer melt;
• means for blocking flow of the melt out of the reservoir;
• a driving mechanism for driving the plunger and piston longitudinally within the reservoir;
• means, coupled to the plunger, for determining pressure of the melt;
• means, coupled to the reservoir, for determining the temperature of the melt;
• and
• means, coupled to the plunger, for sensing a longitudinal position of the plunger.

A capillary rheometer apparatus for characterizing a polymer melt's pressure-volume-temperature relationship, comprising:

• a housing;
• a plunger;
• the housing having a reservoir for receiving the plunger and the polymer melt;
• a plug for blocking flow of the melt out of the reservoir;
• a driving mechanism for driving the plunger longitudinally within the reservoir to move one end of the plunger in contact with the melt;
• a diaphragm, coupled to one end of said plunger, for deflecting in response to melt pressure in the reservoir;
• and
• means, responsive to diaphragm deflection, for determining pressure of the melt.

A method for characterizing a polymer melt's pressure-volume-temperature relationship, comprising:

• introducing the polymer material into a reservoir contained within a housing;
• heating the housing to melt the polymer;
• applying pressure to the polymer with a plunging apparatus introduced into an aperture of the reservoir;
• measuring a pressure of the polymer melt with a pressure sensing apparatus coupled to the plunger;
• and
• measuring a temperature of the polymer melt with a probe introduced into the reservoir.