Effect of Modification on the Physicochemical and ThermalProperties of Organophilic Clay Modified with Octadecylamine
Organophilic clay was modified by ion exchange reactions using Octadecylamine. The reaction process was carried out at a temperature of 70oC for 90 minutes reaction time in a batch reactor equipped with a mechanical stirrer rotating at a speed of 300 rpm. Physicochemical and thermal 
properties of the clay before and after modification were determined and compared using Field Emission Scanning Electron Microscope/ Energy Dispersive X-ray spectroscopy (FESEM/EDX),Fourier transform infrared spectroscopy (FT-IR) and Thermogravimetric Analyzer (TGA). FESEM images show clearly the micro structural differences between the modified and unmodified clay while EDX shows a compositional changes between modified and unmodified 
clay with the presence of 7.27% carbon in the modified clay. The analysis of FT-IR spectra shows the attachment of some functional groups which are mostly alkyl and hallo-alkyl groups. This is an indication of proper modification. TGA plots of both pure unmodified and organically modified clay attained stability at a temperature between 500oC and 900oC after reduction in weight due to evaporation of moisture and decomposition of the adhered Alkylammonium salts between 30oC and 500oC. This confirmed that thermal stability of the organically modified clay compared favorably with pure natural clay under TGA.
Organomodification of Indian bentonite clay and its influence on fire behavior of nanoclay/vinylester composites
This article reports the organomodification of Indian bentonite clay with three modifiers and the fire behavior of organomodified Indian bentonite clay/vinylester/glass nanocomposites. Indian bentonite (Na-IB) clay was organomodified using hexadimethyl ammonium bromide (HDTMA-Br), tetra-n-butylammonium bromide (TBA-Br) and triphenyl methyl phosphonium bromide (TPP-Br) by varying the cation exchange capacity. Basal spacing of 34 Å was observed in Na-IB modified with HDTMA-Br (HDTMABr-IB) followed by 28 Å in Na-IB modified with TPP-Br (TPPBr-IB) and 26 Å in Na-IB modified with TBA-Br (TBABr-IB). Fourier transform infrared spectra of HDTMABr-IB confirmed the attachment of functional groups, its zeta potential increased from −36.34 to 5.35 mV indicating greater surface potential and thermogravimetric analysis showed greater weight loss confirming Na+ ion exchange with alkyl amines. Energy-dispersive X-ray analysis showed compositional changes between modified and unmodified clay with the presence of 37.03% carbon in the HDTMABr-IB. Horizontal and vertical burning rates of vinylester/glass composites decreased with the addition of HDTMABr-IB. Limiting oxygen index increased by 40% with the addition of 5 wt% HDTMABr-IB to vinylester/glass.
Phase formation during mechanical alloying in the Ti–Si system
Abstract Mechanical alloying of Ti–Si powder mixture or TiH 1.924 –Si powder mixture was performed by high-energy ball milling, in which the Ti to Si mole ratio was 1:2. The phase formations in both mixtures during milling were investigated by X-ray diffraction. Mechanical alloying a mixture of elemental powders led to the formation of TiSi 2 equilibrium compound, while when starting from Si + TiH 1.924 , a metastable phase was formed. The metastable phase completely transforms to TiSi 2 when the mechanically alloyed powder is annealed at temperatures above 800 °C. Two different pathways of phase transitions during mechanical alloying are attributed to the existence of hydrogen atoms, i.e., when starting from Si + TiH 1.924 compared to Si + Ti, the kinetics for the formation of the TiSi 2 intermetallic compound slows down. The kinetics related to the different phase transitions depending on the starting powder mixture are discussed.