Surface tension measurement and process equipment for use with polymer melts

摘要

A droplet (7) of the sample is placed in a temperature controlled chamber (1) and the surface tension determined by measuring the outer contour of the droplet with a camera (17) and computer imaging equipment (18,19). The mass of the droplet is determined before and/or after surface tension measurement to enable the density of the sample to be calculated. An Independent claim is included for the apparatus including a heated chamber (1) with a sample table (4), a heated droplet injector (2) with an outlet for suspending a droplet (14) and/or introducing a fiber into a melt droplet (7) on the table. Droplets are arranged between a light source (15) and the camera lens. A second camera (17') and lens (16') at an angle to the first camera allow assessment of the droplet from a different angle. Preferred Features: The outer contours of a droplet are determined using the same polymer sample. Droplet volume is determined from the contours displayed on a monitor (19) and can be used with the mass to calculate density and surface tension. Surface tension may also be measured using the Wilhemy principle by immersing a fiber into a polymer droplet on the table. Wavelengths of the monochromatic light source are selected according to the optical properties of the sample and/or a fiber immersed in the droplet. Chamber temperature is measured and controlled by sensors at different points. Pressure is also measured at different points and used to control gas flow in and out of the chamber. Polymer samples are degassed during melting by evacuating the chamber. A punch in a temperature controlled chamber has a circular flat face on which the droplet rests or from which the droplet is suspended when the punch is turned through 180 deg . The punch surface is at 60-90 deg to the conical side surfaces.