Thermochimica Acta, 63 (1983) 351-362 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands 351 zyxwvutsrqp IGNITION STUDIES ON CO’ITON CELLULOSE BY DTA D. DAVIES, A.R. HORRGCKS * Textile Department, Bolton Institute of Higher Education, Bolton BL3 5AB (Gt. Britain) M. GREENHALGH School of Colour Chemistry and Colour Technology, University of Bradford, Bradford (Gt. Britain) (Received 27 October 1982) ABSTRACT Differential thermal analysis is used to investigate the spontaneous combustion of cotton cellulose in an atmosphere of flowing air. The temperature at which the onset of spontaneous ignition occurs, Ti, is determined as a function of sample mass, air flow rate and heating rate. For sample masses between 1 and 15 mg, Ti is constant although complete sample ignition occurs only for masses in excess of 8 mg where char residues fall below 5%. Air flow rates between 50 and 300 cm3 min- ’ do not significantly influence Ti recorded for cellulose samples having a given mass and subjected to a known heating rate, H,. However, for heating rates ranging from 4 to 20°C min- ‘, Ti is observed to increase according to a simple power law Ti = 295 HEo5790C. Th e overall reproducibility of the technique shows Ti = 350.5 & 1.5”C when 10 mg cellulose samples are subjected to a heating rate of 20°C min-’ and air flowing at 200 cm3 mm-‘. A simple steady-state model of pyrolysis and subsequent combustion predicts that the function (2 log Ti -log HR) will be linearly dependent upon l/Ti. From the slope, an upper limit value for the activation energy of pyrolysis, E,, is found to be 146 kJ mole-‘. This value compares well with measurements of EP made by other workers using a variety of alternative methods. INTRODUCTION The pyrolysis, ignition and subsequent combustion of cellulose, although extensively studied, involve physical and chemical reactions of such interac- tive complexity that full understanding has still to be achieved. Most workers agree that the initial heating of cellulose yields pyrolytic formation of a non-flammable residue fraction and flammable volatiles which, in the presence of oxygen, may or may not ignite, depending on whether both the relative and total volatile/oxygen concentrations are * To whom correspondence should be addressed. 0040-603 l/83/$03.00 0 1983 Elsevier Science Publishers B.V.