Thermal behavior of ground talc mineral

Abstract

Microstructure development and thermal behavior of ground talc mineral samples (from locality Puebla de Lillo, Spain) was characterized by X-ray diffraction, scanning electron microscopy(SEM),surface area measurements differential thermal analysis, thermogravimetry and emanation thermal analysis (ETA).A vibratory mill and grinding time 5 min. was used to prepare the ground talc sample. It was found that grinding caused an increase in the surface area of the natural talc from 3 m2g-1 to 110 m2g-1. A decrease of particle size after sample grinding was observed by SEM. The increase of structure disorder of the ground sample and the crystallite size reduction from 40 to 10 nm were determined from the XRD results. ETA results revealed a closing up of surface micro-cracks and healing of microstructure irregularities on heating in the range 200-500ºC of both un-ground and ground talc samples. For the ground talc sample a crystallization of non-crystalline phase into orthorhombic enstatite was characterized as by a decrease of radon mobility in the range 785-825ºC and by a DTA exothermal effect with the maximum at 830ºC. ETA results were used for the assessment of transport properties of the talc samples on heating

Influence of Grinding and Sonication on the Crystal Structure of Talc

“…A similar shift of the maximum dehydroxylation temperatures and significant mass loss at low temperature were observed by Dellisanti and Valdrè (2008). The same relationship, but without changes of mass loss in the 760À1000ºC TG interval, was observed by Balek et al (2008). According to those authors, the process of mass loss at low temperature (30À150ºC) is associated with the removal of weakly bound OH groups on the broken edges of treated talc particles.…”

Nonisothermal Cold Crystallization Kinetics of Poly(lactic acid)/Bacterial Poly(hydroxyoctanoate) (PHO)/Talc

“…These results revealed a lack of chemical interactions and immiscibility between PLA and PHO. Because talc particles began to lose weight at temperatures higher than 800°C [49,50], the weight loss of PLA/PHO/talc blends between 200 and 400°C was attributed mainly to the degradation of PHO and PLA. It was expected that the thermal degradation temperatures for PLA/PHO in the presence of talc are slightly shifted to lower values.…”

MAS NMR and EPR study of structural changes in talc and montmorillonite induced by grinding

“…Solid-state mechanochemical activation of materials includes milling to increase their reactivity, allows reactions in the solid state and decreases the decomposition temperature, causing structural defects and structural transformation, formation of metastable amorphous or hybrid materials, etc. (Mingelgrin et al, 1978;Garcia et al, 1991;Sanchez-Soto et al, 1997;Mendelovici, 2001;Christidis et al, 2004Christidis et al, , 2005Dellisanti & Valdré, 2005;Balek et al, 2007Balek et al, , 2008Ramadan et al, 2010;Vizcayno et al, 2010;Djukic et al, 2013;Dumas et al, 2013;Galimberti et al, 2014;Petra et al, 2015). One of the applications of this process is to obtain material for sustainable slowrelease fertilizers (Zhang et al, 2009;Solihin et al, 2010Solihin et al, , 2011, by combining an insoluble clay mineral and a soluble phosphate, yielding phases with low solubility.…”