The effect of particle size on the thermal properties of serpentine minerals

The efiects of particle size of chrysotile and platy serpentine on the difierential thermal and thermal gravimetric analyses have been investigated. It 'r,'as found with D'IA that decreasing the particle size decreased the starting and peak temperatures of the endothermic or dehydroxylation reaction and that the peak height of the exotherm was considerably increased although the peak temperature was not appreciably changed As the chrysotile particle size decreased the endothermic peak temperature decreased from a maximum of 710' C. l,r'ith no grinding, to a minimum of 670' C. when it was finely ground. When chrysotile samples from several sources were ground following a standard procedure, the DTA thermograms obtained were quite similar. TGA also showed the dehydroxylation (weight loss) occurring at lower temperatures when the samples were ground. The results indicate that if comparison between serpentine samples is the objective of a DTA-TGA study, the sampie preparation is of utmost importance, otherwise difierences noted may not be true differences but due to variations in particle size between samples. Data obtained with chrysotile and platy serpentine on a thermal increment diffractometer are given. DTA-TGA were also obtained on a brucite-carbonate sample indicating particle size has a similar effect on its endothermic reactions but it is not as larse as those noted for the serpentine minerals.