COUPLING DEVICE FOR THERMOGRAVIMETRIC ANALYSIS

Abstract

The invention relates to a coupling device for thermogravimetric analysis for coupling a thermogravimetric analysis with a spectroscopic analysis, comprising a housing with a connecting element by means of which said housing can be connected in a gas-tight and detachable manner to a sample chamber of a device for gravimetric analysis. The coupling device comprises at least two flange bushings or at least two adsorption elements which are detachably connected to the coupling device and comprise, on a first side, a condensation surface or an adsorption body for gaseous components. A screen is arranged on the coupling device such that it lies between the at least two flange bushings or the at least two adsorption elements and the sample chamber, wherein the screen has at least one opening. A changing device allows the at least two flange bushings, the at least two adsorption elements or the screen to move in such a way that the condensation surface of at least one flange bushing or an adsorption body of at least one adsorption element lies opposite the at least one opening. A cooling device allows the condensation surfaces of the at least two flange bushings to be cooled.

Claims

1. A coupling device for thermogravimetric analysis, comprising: a) a housing with a connecting element by means of which said housing can be connected in a gas-tight and detachable manner to a sample chamber of a device for gravimetric analysis; b) at least two flange bushings or at least two adsorption elements which are detachably connected to the coupling device and comprise, on a first side, a condensation surface or an adsorption body for gaseous components; c) a screen which is arranged such that it lies between the at least two flange bushings or the at least two adsorption elements and the sample chamber, wherein the screen has at least one opening; d) a changing device which allows the at least two flange bushings, the at least two adsorption elements or the screen to move in such a way that the condensation surface of at least one flange bushing or the adsorption body of at least one adsorption element lies opposite the at least one opening; e) a cooling device which allows the condensation surfaces of the at least two flange bushings or the adsorption bodies of the at least two adsorption elements to be cooled.

2. The coupling device according to claim 1, wherein the at least two flange bushings have a cylindrical flange arranged on the first end and a cylindrical bushing arranged on the second end opposite the first end, which are detachably connected to one another.

3. The coupling device according to claim 2, wherein the cylindrical bushing has an outer threading by means of which said bushing can be detachably connected in bores of the changing device.

4. The coupling device according to claim 2, wherein the cylindrical bushing is made of copper and the cylindrical flange is made of stainless steel.

5. The coupling device according to claim 1, wherein the at least two adsorption elements comprise a base by means of which the adsorption elements can be detachably connected to the changing device, wherein the adsorption body which comprises an adsorbent material is fastened to the base.

6. The coupling device according to claim 5, wherein the adsorbent material comprises activated charcoal.

7. The coupling device according to claim 1, wherein the cooling device is a Peltier element.

8. The coupling device according to claim 1, wherein the at least two flange bushings or the at least two adsorption elements have a gas passage line by means of which the gas located in the sample chamber can be suctioned.

9. The coupling device according to claim 1, wherein the connecting element is formed as threaded.

10. A method for analyzing a polymer material, comprising the steps: a) putting the polymer material in a sample crucible of a device for thermogravimetric analysis; b) connecting a coupling device according to claim 1 to a sample chamber of the device for thermogravimetric analysis; c) moving the at least two flange bushings, the at least two adsorption elements or the screen by means of the changing device in such a manner that the condensation surface of a first of the at least two flange bushings or the adsorption body of a first of the at least two adsorption elements lies opposite the opening of the screen; d) heating the sample crucible and moving the at least two flange bushings, the at least two adsorption elements or the screen by means of the changing device in such a manner that, for each outgassed component of the polymer material, the first end of a different flange bushing or an adsorption body of a different adsorption element lies opposite the opening; e) removing the at least two flange bushings or the at least two adsorption elements from the coupling device; f) analyzing the components of the polymer material which lie on the condensation surfaces of the at least two flange bushings or in the adsorption bodies of the at least two adsorption elements by means of spectroscopy.

11. The coupling device according to claim 3, wherein the cylindrical bushing is made of copper and the cylindrical flange is made of stainless steel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings used for explaining the embodiment examples show:

[0047] FIG. 1 a diagrammatic representation of a coupling device according to the invention, which is connected to a device for thermogravimetric analysis, in cross section;

[0048] FIG. 2 a diagrammatic view of the coupling device from below;

[0049] FIG. 3 a detailed side view of a flange bushing;

[0050] FIG. 4 the coupling device according to FIG. 1 with adsorption elements instead of flange bushings.

[0051] In principle, in the figures, identical parts are marked with identical reference numerals.

WAYS OF CARRYING OUT THE INVENTION

[0052] FIG. 1 shows a diagrammatic representation of a coupling device 1 according to the invention, which is connected to a device for thermogravimetric analysis 20, in cross section. The coupling device 1 has a housing 2 which is connected via a connecting element (not shown), for example, via a threading, to the device for thermogravimetric analysis 20. The coupling device has four flange bushings 4.1, 4.2, 4.3, 4.4, in the example shown. Due to the perspective of the representation, the fourth flange bushing 4.4 is not visible, since it is behind the second flange bushing 4.2 in the viewing direction. The four flange bushings 4.1, 4.2, 4.3, 4.4 are connected via a changing device 7 to the housing 2 of the coupling device 2 and each has a condensation surface 10.1, 10.2, 10.3, 10.4. Furthermore, the coupling device 1 comprises a screen 5 which has an opening 6. The screen 5 is arranged in such a manner that, in coupling device 1 connected to the device for thermogravimetric analysis 20, it is located between the condensation surfaces 10.1, 10.2, 10.3, 10.4 of the flange bushings 4.1, 4.2, 4.3, 4.4 and a sample chamber 24 of the device for thermogravimetric analysis 20. The changing device 7 has a drive 8 by means of which the flange bushings 4.1, 4.2, 4.3, 4.4 can be moved in such a manner that selectively a flange bushing 4.4, 4.2, 4.3, 4.4 lies opposite the opening 6 of the screen 5. Furthermore, on the upper side of the housing 2, a Peltier element 19 is attached. By thermal coupling, the condensation surfaces 10.1, 10.2, 10.3, 10.4 of the flange bushings 4.1, 4.2, 4.3, 4.4 can be cooled, so that their temperature can be kept approximately constant, for example, at 15 C.

[0053] The device for thermogravimetric analysis 20 comprises, in the interior of the sample chamber 24, a sample crucible 21 in which a polymer material 23 to be analyzed can be arranged. Via an oven 25, the polymer material can be heated. The outgassing of components is detected as weight loss by a microscale 22. Furthermore, via a gas inlet 26, the sample chamber 24 can be supplied with an inert gas.

[0054] FIG. 2 shows a diagrammatic view of the coupling device 1 from below, i.e., from the side facing the sample chamber 24 of a device for thermogravimetric analysis 20. However, the screen 5 is not represented. The flange bushings 4.1, 4.2, 4.3, 4.4 are detached from the coupling device 1 in the figure shown. Therefore, four bores 9.1, 9.2, 9.3, 9.4 are visible, into which the flange bushings 4.1, 4.2, 4.3, 4.4 can be connected detachably. As can be seen in this figure, the changing device 7 is designed as rotating plate, wherein the bores 9.1, 9.2, 9.3, 9.4 are arranged symmetrically towards the margin of the changing device 7. On the margin of the coupling device 1, a threading 3 is arranged, by means of which the coupling device 1 can be connected detachably to a device for thermogravimetric analysis 20.

[0055] FIG. 3 shows a flange bushing 4 in a detailed side view. On a first end of the flange bushing 4, the condensation surface 10 is arranged. It consists preferably of a polished stainless steel such as stainless steel with material code 1.4301, for example. The flange bushing 4 consists of a cylindrical flange 11 as well as of a cylindrical bushing 12 which are detachably connected to one another. The connection is implemented via a pin 15 which has a threading that engages in a corresponding inner threading of the cylindrical bushing 12. The cylindrical bushing 12 has an outer threading 13 on its lateral surface by means of which the flange bushing 4 can be detachably connected in a bore 9 of the changing unit 7. Furthermore, within the flange bushing 4, a gas passage 14 is arranged, by means of which suctioning can be carried out in the sample chamber 24 of the device for thermogravimetric analysis 20 by means of a pump (not shown). As a result, a gas flow towards the condensation surface 10 is generated, by means of which outgassed components of the polymer material are conveyed in the direction of the condensation surface. For the connection to a pump, the flange bushing 4 has a connection sleeve 16.

[0056] FIG. 4 shows the coupling device 1 according to FIG. 1 in a diagrammatic cross section, wherein the coupling device 1 is again connected to a device for thermogravimetric analysis 20.

[0057] In contrast to the embodiment according to FIG. 1, in the embodiment shown in FIG. 4, no flange bushings 4.1, 4.2, 4.3 are used, but adsorption elements 27.1, 27.2, 27.3 are used instead. The adsorption elements 27.1, 27.2, 27.3 each include a base 28.1, 28.2, 28.3 which can be connected detachably to the coupling device 1. On each base 28.1, 28.2, 28.3, an adsorption body 29.1, 29.2, 29.3 is fastened, which consists of an adsorbent material. Preferably the adsorbent material comprises activated charcoal.