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.
Preparation and properties of ceramifiable flame-retarded silicone rubber composites
Ceramifiable flame-retardant silicone rubber composites were prepared by silicone rubber (SR) as the base polymer, and ammonium polyphosphate, calcium carbonate, sericite mica, and glass frits were utilized as additives. The flammability and thermal stability properties of ceramifying silicone rubber composites were studied by the limiting oxygen index (LOI), microscale combustion calorimetry (MCC), and thermogravimetric analysis (TG). The ceramic residues formed at various temperatures were studied by mechanical testing, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results indicated that the ceramifying silicone rubber achieved a LOI value of 31.2% and the flexural strength of ceramic residues formed at 1000 °C was 19.7 MPa. Moreover, the MCC results demonstrated that the heat release rate and total release rate of the composites were reduced significantly compared to the corresponding value of neat SR. The TG showed that the residue of composites was approximately 61.5% at 700 °C, as significantly higher than that the residue of neat SR. The XRD results demonstrated that fluoroapatite and Ca2SiO4 crystals were produced in the ceramic residue at high temperatures. The SEM analysis depicted that the number of holes was reduced and a dense structure was formed as the sintering temperature increased, leading to the excellent mechanical properties of formed ceramics at high temperatures.
Google Earth: Mathematical Art Forms
We trace the development of Google Earth and consider various artifacts, natural and anthropogenic, ancient and modern. These artifacts are only obvious from high elevations and some have a mathematical form and artistic appeal. We also illustrate how Google Earth's high-altitude imagery can be fruitful inspiration for mathart and provide some example.