PHYSICAL TESTING SERVICE - DSC-TGA

							    PHYSICAL TESTING SERVICE - DSC-TGA
    by: YEONG, S K; ZAHARIAH, I; ROSNAH, I; ZAFARIZAL, A
    and SALMIAH, A
                                                                                                                                          303
 MPOB INFORMATION SERIES • ISSN 1511-7871 • JUNE 2005                                                                                MPOB TS No. 4




T
       hermal analysis is defined as the                                         measures both heat flow and weight changes in
       measurement of changes in chemical or                                     a material as a function of temperature or time
       physical properties of a sample as a                                      in a controlled atmosphere is a very useful
       function of temperature or time in a                                      technique. Simultaneous measurement provides
       controlled atmosphere. A special                                          additional information simplifies interpretation
instrument called the TGA (thermogravimetric                                     of the results. The complimentary information
analysis) which consists of a furnace, weight                                    obtained allows differentiation between
balance and photodiode sensors is designed to                                    endothermic and exothermic events which have
make such measurements (Figure 1).                                               no associated weight loss (e.g. melting and
                                                                                 crystallization) and those which involve a weight
TGA measures the amount and rate of change                                       loss (e.g. degradation).
in the weight of a material as a function of
temperature or time in a controlled atmosphere.                                                      WHAT TGA CAN DO
Such measurements are used primarily to
determine the composition of materials and to                                    • Thermal stability of materials;
predict their thermal stability at temperatures up                               • Oxidative stability of materials;
to 1000oC. The technique can also be used to                                     • Composition of multi-component systems;
characterize materials that exhibit weight loss                                  • Moisture and volatiles content of materials;
or gain due to decomposition, oxidation or                                         and
dehydration.                                                                     • Bound water/bulk water in an emulsion
                                                                                   system.
Differential scanning calorimetry (DSC)
measures the heat flow of a material as a function                                                 WHAT SIMULTANEOUS
of temperature or time in a controlled                                                              DSC-TGA CAN DO
atmosphere. But simultaneous DSC-TGA
                                                                                 •   Oxidative/thermal stability of materials;
                                                                                 •   Composition of multi-component systems;
                                                                                 •   Moisture and volatiles content of materials;
                                                                                 •   Transition temperatures;
                                                                                 •   Heat of fusion and reactions; and
                                                                                 •   Melting point.

                                                                                            PHYSICAL TESTING SERVICES

                                                                                 • TGA/DTA or TGA/DSC

                                                                                 Sample Volume Required
                                                                                 5 ml or 5 g.

         Figure 1. TGA/DSC instrument.



            Malaysian Palm Oil Board, Ministry of Plantation Industries and Commodities, Malaysia
            P. O. Box 10620, 50720 Kuala Lumpur, Malaysia. Tel: 03-89259155, 89259775, Website: http://mpob.gov.my Telefax: 03-89259446
             WHEN TO EXPECT FOR RESULTS                                                      REPORTS

Under normal circumstances, client can expect                             A test report will be sent to client together with
to receive report within three weeks. In case of                          the data printout from the instrument where it
unforeseen circumstances, client will be                                  is applicable. Example of data printout is shown
informed.                                                                 in Figure 2.

                   Sample:PO-80
                   Size: 10.5682 mg                                                   File: C:...\SDT\Yeong\Po-60.002
                   Method: Dynamic OIT                          TGA-DTA               Operator: Yeong
                   Comment: 10oC/min@100 ml/min Air                                   Run Date: 17-Feb-2003 10:11

             120                                                                                                       15
                                                             31.91 min



             100


                                                                                                                       10
Weight (%)




             80




                                                                                                                            Deriv. Weight (%/min)
             60

                                                                                                                       5

             40



             20
                                                                                                                       0
                                                 25.41 min                                            Residue:
                                                                                                      0.0000%
                                                                                                      (0.0000mg)
              0



             -20                                                                                                    -5
                   0        10           20             30                 40          50           60             70
                                                             Time (min)               Universal V2.5H TA Instruments

                                        Figure 2. An example of TGA thermagram.




                                              For more information kindly contact:

                                                     Director-General
                                                          MPOB
                                                     P. O. Box 10620
                                               50720 Kuala Lumpur, Malaysia.
                                                   Tel: 03-89259155, 89259775
                                                   Website: http://mpob.gov.my
                                                        Telefax: 03-89259446