MEASURING APPARATUS FOR SURFACE TENSION OF THERMOPLASTIC RESIN

PURPOSE:To reliably and accurately measure the surface tension of thermoplastic resins with a simple apparatus, by vertically movably providing a gas extruder, a gas-introducing pipe and a die with a horizontal blow-off surface in a closed vessel which can be heated as well as evacuated. CONSTITUTION:Polyester pellets or other pulverulent and granular bodies are placed in a measuring container 27, which is mounted on a holder 26 of a vessel 1 and hermetically sealed. After a nitrogen replacement, the inside of the vessel 1 is reduced in pressure and maintained under a high vacuum. At the same time, the vessel 1 is heated by a heater 2 to melt the sample. After a predetermined temperature is confirmed by means of a thermometer inserted in a detecting end 19, the vacuum suction is suspended, and nitrogen gas having a predetermined temperature is introduced from a supply nozzle 23. Then, a pinion 17 is rotated to immerse a parallel surface 12 of a die 10 attached to an introducing pipe 9 into the sample in the measuring container 27. Nitrogen is released into the sample by employing an extruder 14 to form a bubble on the parallel surface 12. The size of the bubble is measured through a peep window 6 to measure the surface tension of the sample.