Temperature modulated thermogravimetric analysis

1. A method for analyzing a sample using a temperature-modulated thermogravimetric analysis (TMTGA), wherein the method comprises the steps of:

placing a sample on a measuring position in a thermogravimetric analysis (TGA) instrument that comprises a furnace arranged in a furnace housing, an electronic balance with a load receiver arranged in a balance housing so that the load receiver extends into the furnace housing with the measuring position being arranged at one end of the load receiver within the furnace housing, and a control unit for controlling at least one of the balance and the furnace;

subjecting the sample to a temperature program provided by the control unit, which varies the temperature of the furnace;

measuring, with the electronic balance, a change of the mass (m(T,t)) of the sample as a function of time while the sample is subjected to the temperature program; and;

using the measured mass change to determining at least one kinetic parameter of the sample;

wherein the temperature program provides temperature-time setpoints for controlling the sample temperature (T(t)) as determined by the formula:

T ( t )= T ( t )+δ T ( t )

where T (t) represents an underlying temperature change superimposed by a temperature perturbation (δT(t)) with a characteristic time of modulation (τ); and

wherein the temperature program is one or both of a stochastic program and an event-controlled program.

2. The method of claim 1 , further comprising the step of determining the sample temperature as a function of time using a temperature sensor arranged in the vicinity of the measurement position.

3. The method of claim 1 , wherein:

the temperature program includes at least a stochastic program; and

the characteristic time of modulation of the stochastic temperature perturbation fluctuates randomly.

4. The method of claim 3 , wherein:

the stochastic temperature perturbation comprises pulse sequences, each having a pulse length that represents the characteristic time of modulation, each pulse length generated by a random number generator to be between a predetermined minimum and a predetermined maximum.

5. The method of claim 1 , wherein:

the temperature program includes at least a stochastic program; and

the temperature program varies an intensity of the stochastic temperature perturbation.

6. The method of claim 1 , wherein:

the temperature program includes at least an event-controlled program; and

the temperature program modulates the event-controlled temperature perturbation by modulating at least one of:

the characteristic time of modulation, and

the temperature modulation intensity,

in relation to changes in at least one of:

the mass,

the conversion of the mass, and

derivatives thereof,

during a TGA experiment.

7. The method of claim 1 , further comprising the step of adapting an underlying heating rate of the temperature program.

8. The method of claim 1 , further comprising the step of providing, from the temperature program, non-periodic temperature-time data for controlling the sample temperature.

9. The method of claim 1 , further comprising the step of using the mass change of the sample as a function of time and temperature that are measured in a single TGA measurement to determine the at least one kinetic parameter.

10. The method of claim 1 , further comprising the steps of:

determining, from a TGA test-measurement of the sample, the parameters of the temperature perturbation;

performing a TMTGA measurement by measuring at least one like sample with the TGA instrument, using a temperature program comprising the temperature perturbation with the previously determined parameters; and

determining at least one kinetic parameter of the sample from the TMTGA measurement.

11. The method of claim 1 , further comprising the step of determining the apparent activation energy as a kinetic parameter.

12. A thermogravimetric analysis (TGA) instrument for carrying out a temperature-modulated thermogravimetric analysis (TMTGA), the instrument comprising:

a furnace arranged in a furnace housing;

an electronic balance having a load receiver arranged in a balance housing, such that one end of the load receiver extends into the furnace housing and comprises a measuring position for receiving a sample;

a control unit that controls the operation of at least one of the electronic balance and the furnace, the control unit including a temperature program that controls the temperature of the furnace;

wherein the electronic balance measures changes in the mass of the sample as a function of time and temperature while the sample is being subjected to the temperature program;

wherein the control unit comprises means for determining at least one kinetic parameter of the sample by analyzing the sample's changes in mass over time and temperature; and

wherein the temperature program is one or both of a stochastic and event-controlled temperature program that provides temperature-time setpoints for controlling the sample temperature (T(t)) and produces an underlying temperature change ( T (t)) that is superimposed by a temperature perturbation (δT(t)) with a characteristic time of modulation (τ) according to the equation:

T ( t )= T ( t )+δ T ( t ).

13. The instrument of claim 12 , further comprising a temperature sensor arranged in the vicinity of the measurement position for measuring the sample temperature.

14. The instrument of claim 12 , wherein the at least one kinetic parameter is the apparent activation energy.

15. A method for analyzing a sample using a temperature-modulated thermogravimetric analysis (TMTGA), wherein the method comprises the steps of:

placing a sample on a measuring position in a thermogravimetric analysis (TGA) instrument that comprises a furnace arranged in a furnace housing, an electronic balance with a load receiver arranged in a balance housing so that the load receiver extends into the furnace housing with the measuring position being arranged at one end of the load receiver within the furnace housing, and a control unit for controlling at least one of the balance and the furnace;

subjecting the sample to an event-controlled temperature program provided by the control unit, which varies the temperature of the furnace;

measuring, with the electronic balance, a change of the mass (m(T,t)) of the sample as a function of time while the sample is subjected to the temperature program; and;

using the measured mass change to determining at least one kinetic parameter of the sample;

wherein the temperature program provides temperature-time setpoints for controlling the sample temperature (T(t)) as determined by the formula:

T ( t )= T ( t )+δ T ( t )

where T (t) represents an underlying temperature change superimposed by a temperature perturbation (δT(t)) with a characteristic time of modulation (τ); and

wherein the temperature program modulates the event-controlled temperature perturbation by modulating at least one of:

the characteristic time of modulation, and

the temperature modulation intensity,

in relation to changes in at least one of:

the mass,

the conversion of the mass, and

derivatives thereof,

during a TGA experiment.

16. The method of claim 15 , further comprising the step of determining the sample temperature as a function of time using a temperature sensor arranged in the vicinity of the measurement position.

17. The method of claim 15 , further comprising the step of adapting an underlying heating rate of the temperature program.

18. The method of claim 15 , further comprising the step of providing, from the temperature program, non-periodic temperature-time data for controlling the sample temperature.

19. The method of claim 15 , further comprising the step of using the mass change of the sample as a function of time and temperature that are measured in a single TGA measurement to determine the at least one kinetic parameter.

20. The method of claim 1 , further comprising the steps of:

determining, from a TGA test-measurement of the sample, the parameters of the temperature perturbation;

performing a TMTGA measurement by measuring at least one like sample with the TGA instrument, using a temperature program comprising the temperature perturbation with the previously determined parameters; and

determining at least one kinetic parameter of the sample from the TMTGA measurement.

21. The method of claim 15 , further comprising the step of determining the apparent activation energy as a kinetic parameter.