Abstract: An in-line fiber optic probe interface includes a sample cell with a bore therein defining an optical axis. A controller housing is centered by o-ring seals in the bore and a pathlength controller is mounted on the housing. A fiber optic probe is disposed in the housing and controller, sealed thereto by o-ring seals at multiple points to maintain the probe in appropriate alignment on the optical axis.

Abstract: A foam pulse rheometer measures the total integrated stress response of a foaming polymer to a short duration strain pulse applied to the polymer, from which can be calculated the equilibrium modulus and the zero shear viscosity of the foaming polymer during the foaming reaction. A shear plate mounted to a load cell above a jacket extends downwardly into a foaming polymer within the jacket. Under the application of a vertical square wave strain pulse to the jacket, the load cell senses the shear force exerted upon the shear plate by the foaming polymer. Simultaneously, a video camera and recorder monitors the surface area of the plate acted upon by the jacket. For each pulse, simultaneously occurring discrete sensed force values and discrete monitored surface area values can be used to compute the total integrated stress response, from which can be calculated the equilibrium modulus and the zero shear viscosity.