Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR) Ceramifiable Composites
Ceramifiable styrene-butadiene (SBR)-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite) and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite.
Effect of mineral filler additives on flammability, processing and use of silicone-based ceramifiable composites
The aim of this work is to describe the changes in the properties of ceramifiable silicone rubber-based composites caused by the incorporation of novel alternative minerals in comparison to other popular, widely utilized fillers. TiO2, calcined kaolin and calcium-based minerals mix (CbMix) consisting of CaO (6.26 wt%), CaCO3 (26.18 wt%) and Ca(OH)2 (67.56 wt%) have not been considered as a dispersed phase of ceramifiable silicone composites destined for wire covers yet. Mineral fillers: TiO2 (anatase), mica (phlogopite), CbMix, CaCO3, Al(OH)3, kaolin and calcined kaolin affect the processing and the various properties of silicone rubber-based composites destined for wire covers differently. The properties—flammability, smoke intensity, micromorphology and mechanical durability after ceramification—are assessed by measuring: the kinetics of vulcanization, stress at different levels of elongation, tensile strength and the elongation at break of the materials. Although the curing process of the composites is disturbed by the addition of CbMix, it benefits from an increase in oxygen index value, which reaches 31.4%. What is more, also its flammability parameters measured by cone calorimetry improve, such as the total heat released (THR) reaching 9.3 MJ/m2. Samples containing kaolin and calcined kaolin exhibit the best mechanical properties before ceramification, whereas composites filled with calcium-based powders (CbMix, CaCO3) mechanically display the strongest mineral char after heat treatment, possibly due to a more homogenous micromorphology and the creation of calcium silicates at elevated temperature. Significant amounts of wollastonite, parawollastonite and pseudowollastonite are visible in their structure after ceramification.
Trends in kiln drives
The heart of the cement plant is the rotary kiln, and continuous quality production of cement clinker depends on the continuous accurate performance of the rotary kiln drive.