Calibration of magnitude and phase angle of TMDSC Part1: basic considerations G.W.H. Ho Èhne a , M. Merzlyakov b,1 , C. Schick b,* a Dutch Polymer Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands b University of Rostock, FB Physik, Universita Ètsplatz 3, 18051 Rostock, Germany Received 29 September 2001; received in revised form 29 January 2002; accepted 31 January 2002 Abstract The basic principle of heat transfer in temperature-modulated differential scanning calorimetry (TMDSC) and its in¯uence on the measured signals is presented. Fundamentals of transfer theory are given within the framework of linear response. On this basis different calibration methods are suggested which enable to correct for the in¯uence of heat transfer on the measured (effective) complex heat capacity in TMDSC. It is shown, that the complex calibration function is the reciprocal transfer function, which in turn is the product of the instrumental transfer function and the transfer function of the sample and its thermal connection to the TMDSC. Methods are given how to determine the transfer functions and how to correct the measured complex heat capacity properly. # 2002 Elsevier Science B.V. All rights reserved. Keywords: TMDSC; Calibration; Complex heat capacity; Heat transfer; Correction 1. Introduction Temperature-modulated differential scanning calorimetry (TMDSC) is nowadays widely used to investigate time dependent processes as well as to determine the heat capacity of materials. This is done by calculating the interesting quantities from magni- tude and phase angle (relative to that of the modulated temperature function) of the measured heat ¯ow rate. Unfortunately the measured quantities contain in¯u- ences from the apparatus (the DSC) too and careful ``calibration'' should be done to separate these in¯u- ences from the measured signal and come to reliable results of the properties of the sample itself. Calibra- tion means the quantitative determination of all appa- ratus in¯uences and the proper correction of the measured raw data. In common DSC the calibration procedures for temperature, heat ¯ow rate and heat are well established in practice [1] and for commercial DSC normally part of the software. For TMDSC there is an additional calibration procedure needed which corrects for the huge in¯uence of the frequency on the magnitude and phase angle of the measured complex heat capacity. This paper aim at making a contribution to better understand the in¯uence of the TMDSC on the mea- sured complex heat capacity and to give a procedure to determine the falsi®cation quantitatively and correct it. At ®rst we present the TMDSC and the pathway of Thermochimica Acta 391 (2002) 51±67 * Corresponding author. Tel.: 49-381-498-1644; fax: 49-381-498-1626. E-mail address: christoph.schick@physik.uni-rostock.de (C. Schick). 1 Present address: Chemical Engineering, P.O. Box 43121, Texas Tech University, Lubbock, TX 79409, USA. 0040-6031/02/$ ± see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0040-6031(02)00163-6