JPS6080748A - Device for determining thermal change of heat capacity and weight simultaneously - Google Patents

Abstract

PURPOSE:To improve thermal decomposition effect of a determination device and to perform determination of heat capacity with high precision by supporting a sample placed in a heat bath of an AC calorimeter at one end of a beam of a thermobalance device interposing a heat leak resistance. CONSTITUTION:A sample 10 is placed on a sample holder comprising a good conductive thin plate having very small heat capacity as compared to the sample 10 interposing silver paste. The sample holder is supported by two pairs of thermocouple having small heat capacity extended over a stationary ring 23, and the stationary ring 23 is placed on one end of a beam 2 of a thermobalance 1 with a pair of insulating tube 26. Intermittent heat current is fed to the sample 10 from a light source 16, chopper 19, and optical fiber 20. The weight of the sample for this stage is measured by the thermobalance device 1, and the temp. of the sample 10 is measured by the thermocouple.

Description

[Detailed Description of the Invention] Conventionally, a device that combines a differential scanning calorimeter and a thermobalance has been known as a device for simultaneously measuring heat capacity changes and thermogravimetric changes. Since the standard sample container must be fully supported, the overall volume of the sample section becomes large, which makes it difficult to accurately measure thermogravimetric changes due to changes in buoyancy and convection due to temperature changes. Ta.

The purpose of the present invention is to eliminate such inconveniences and to perform heat capacity measurement with higher temperature resolution than a differential scanning calorimeter and with high precision. It is characterized in that a sample placed in a heat bath is supported via a heat leak resistance.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram M showing the configuration of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line T in FIG.

In the figure, (1) is a thermobalance device;
) is a beam angle change reading device (3) consisting of a slit plate interlocked with the inclination of the beam (2) at the fulcrum part of the beam (2), a lamp and a photocell arranged opposite to each other through the slit plate; A magnet attached to one end of the beam (2) (4) '! r A driving solenoid (5) and a weighing circuit that outputs a beam angle restoration signal to the solenoid (5) in accordance with the beam angle change detection signal of the seven otocells and also outputs a weighing signal to the recorder (6). A conventionally known device was used, which is equipped with a force and a weight pan (8) attached to the other end of the beam (2).

(9) is an AC calorimeter;
) is the sample Q whose thermogravimetry is to be measured as well as its heat capacity.
A device αυ for supplying an intermittent heat flow to l, a DC amplifier α2 that amplifies a signal corresponding to the temperature of the sample section, and a lock-in amplifier 0th floor that amplifies a signal corresponding to the AC temperature change of the sample. It is equipped in a known manner.

The device αυ for supplying the intermittent heat flow to the sample is a DC power supply α
A light source (1) comprising a lamp 09 etc. energized by
61, a light intermittent collar (11) rotated by a motor QFtJ connected to a power source αD, and an optical fiber (21) that guides the intermittent light to the sample section. The silver paste is placed on a sample holder (21) made of a thermally conductive thin plate with a very small heat capacity.The sample holder (20 is clearly shown in FIGS. 3 and 4). As shown, two pairs of thermocouples with small heat capacity are attached to a fixing ring made of ceramic or the like (c!).
The fixed ring (c) is supported by a pair of insulating tubes (261 m) and the beam (2) of the thermobalance device (1).
so that it is placed at one end of the

In this AC calorimeter, as is well known, the total thickness of the sample (llll and sample holder (2D) is significantly smaller than the wavelength of the intermittent light, and the sample 0Q and sample holder 0υ are connected to a thermocouple (24) ( It was connected to a heat bath through a heat leak resistance having a predetermined value of 25+.

The optical fiber (A) was interposed between the pair of insulating tubes (21), and its tip was opposed to the lower surface of the sample holder (2υ) so that the sample holder (21) was irradiated with intermittent light from the lower surface.

The thermocouples (1) and (3) were connected to the DC amplifier a2 and the four-in-one amplifier (1) through insulating tubes (1), respectively.

In FIG. 1, the surface shows an electric furnace serving as a heat bath, and (c) shows a temperature controller. Next, to explain its operation, the sample a is heated to a predetermined temperature in the electric furnace (2) controlled by the temperature controller (to), and is emitted from the light source ae through the chopper 4 and the optical fiber IJt. Heated by intermittent light.

The weight of the sample QOI at that temperature is thus measured by the thermobalance device (11) and recorded on the recorder (6).

At this time, the temperature of the sample (1) is detected by the thermocouple (2), and its output is sent to the DC amplifier (1) via the cold junction c!1.
Therefore, it is amplified and recorded on the recorder (6). Also, the sample (
The AC temperature change component of II is detected by a thermocouple (c),
The output is amplified by lock-in amplifier a3, and the recorder (
6) is recorded.

The four-in-one amplifier (13) uses the output of the phototransistor (to) that is irradiated with intermittent light obtained from the chopper a as a reference signal, and only accepts input signals with the same frequency and phase as the chopper frequency. Less error, -! Temperature changes of -°C can be measured with 100% accuracy, and the temperature resolution is 1/10,000.

Since only the sample Ql is supported by one end of the beam (2) of the thermobalance device W(1), the thermogravimetric measurement is less affected by the buoyancy and convection of the sample (11).

In this way, according to the present invention, the sample placed in the heat bath of the AC calorimeter is supported at one end of the beam of the thermobalance device via the heat leak resistance, so the heat capacity is lower than that of the differential scanning calorimeter. It has a high temperature resolution in the measurement of heat capacity, and it is possible to measure the heat capacity with high precision such as a differential scanning calorimeter without the drift of the baseline with zero temperature difference between the sample and the standard sample. This has effects such as not impairing weight accuracy.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an apparatus according to one embodiment of the present invention, and FIG.
Figure 1 is a cross-sectional view taken along line T, Figure 5 is a plan view of the sample section, Figure 4 is
The figure shows the surface survey. (1)...Thermobalance device (9)...AC force ν remeter αQ...sample (16)...light source a9...chopper (21...optical fiber (2D...sample holder) (2ri...silver paste (c)...fixing ring
(Foundation) (c)...Fixing ring ■...Insulating tube Forehead...
・2 people outside the electric furnace

Claims (1)

[Claims] 1. An apparatus for simultaneously measuring heat capacity changes and thermogravimetric changes, characterized in that a sample placed in a heat bath of an alternating current force p meter is supported at one end of a beam of a thermobalance apparatus via a heat leak resistance.