ISO 11358-3:2021 Plastics — Thermogravimetry (TG) of polymers —Part 3: Determination of the activation energy using the Ozawa-Friedman plot and analysis of the reaction kinetics

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Plastics — Thermogravimetry (TG) of polymers —Part 3: Determination of the activation energy using the Ozawa-Friedman plot and analysis of the reaction kinetics是ISO于2021-01发布的ISO标准,适用于全球。

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Plastics — Thermogravimetry (TG) of polymers —Part 3: Determination of the activation energy using the Ozawa-Friedman plot and analysis of the reaction kinetics
Plastics — Thermogravimetry (TG) of polymers —Part 3: Determination of the activation energy using the Ozawa-Friedman plot and analysis of the reaction kinetics(截图)

 

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Plastics — Thermogravimetry (TG) of polymers —

Part 3: Determination of the activation energy using the Ozawa-

Friedman plot and analysis of the reaction kinetics

1 Scope

This document specifies an analysis method for determining the activation energy using the Ozawa-

Friedman plot. It also specifies the preparation of master plots for verification of the reaction kinetics determined by thermogravimetry.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 11358-1, Plastics — Thermogravimetry (TG) of polymers — Part 1: General principles

ISO 11358-2, Plastics — Thermogravimetry (TG) of polymers — Part 2: Determination of activation energy

3 Terms a nd definiti ons

For the purposes of this document, the terms and definitions given in ISO 11358-1, ISO 11358-2 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://w ww .iso. org/o bp

— IEC Electropedia: available at http:// www.e lectropedia .org/ 3.1

generalized time

t

gen

t

E

 

a

t =−exp dt

 

gen

RT

 

0

where

E is the activation energy, expressed in kJ/mol;

a

R is the gas constant, expressed as 8,314 J/(mol K);

T is the absolute temperature, expressed in Kelvin;

t is time, expressed in minutes.

3.2

generalized rate of conversion

dC/dt

gen

E

dC  dC

a

=exp

 

dt RT dt

 

gen

Note 1 to entry: For the definition of the degree of conversion, refer to ISO 11358-2.

3.3

master curve

plot that can be used to evaluate the results and investigate the reaction kinetics models

EXAMPLE Conversion versus the generalized time, conversion versus the generalized rate of conversion, generalized time versus the generalized rate of conversion.

4 Principle

Test specimens are heated using any temperature profile and the change in mass is measured as a function of temperature and time. At a given conversion, the logarithm of the rate of conversion is plotted versus the reciprocal of the absolute temperature, and the activation energy is calculated from the slope of the straight line fit to the data thus obtained.

At least two of the master curves enable verification of the reaction kinetics analysis.

5 Apparatus

The apparatus shall be in accordance with ISO 11358-1.

6 Test specimens

Test specimens shall be in the form of powder, pellets, flakes, filaments, or film. The test specimens shall be prepared by cutting the material, as necessary, to a size appropriate for the apparatus (see ISO 11358-1).

7 Mass and temperature calibration

7.1 Mass calibration

The procedure of mass calibration is given in ISO 11358-1.

7.2 Temperature calibration

The procedure of temperature calibration is given in ISO 11358-1.

8 Procedure

8.1 General

The determination of the rate of conversion dC/dt is necessary for the analysis in this document. The rate of conversion versus absolute temperature shall be determined.

See ISO 11358-1 and ISO 11358-2.

Perform tests using either an isothermal run, constant rate heating, sample mass controlled rate thermal analysis, temperature jump, repeated temperature scanning, or any combination of the above,

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