Steam cracking of hydrocarbons: 4 analysis of high-boiling products from naphtha in a quartz reactor

Part 3 of this series reported on the steam cracking of straight-run naphtha in a stainless steel and a quartz reactor. High-boiling polynuclear aromatic hydrocarbons were formed in a quartz reactor but were not found as products from a stainless-steel reactor. In this paper the analysis of the polynuclear aromatic hydrocarbons is discussed. The high-boiling fraction was separated by high performance liquid chromatography and by capillary gas chromatography. About 200 of the compounds present were separated by the latter method. Twenty profiling compounds, with boiling points up to 462 OC, were identified by the coelution technique and by combined gas chrmtography/mass spectrometry. The influence of the wall effects on the proceeding of secondary reactions in metal and quartz reactors is discussed

Preparation and Thermal Stability of Elastomers Based on Irregular Poly(urethane-isocyanurate) Networks

The objective of this study was to investigate the thermal stability of poly(urethane-isocyanurate) networks with increasing amount of dangling chains. In order to improve thermal stability of elastomeric materials, networks were prepared by adding some heat resistant isocyanurate rings as a junction points by catalytic cyclotrimerisation of telechelic diisocyanates. The thermal degradation kinetics of samples has been studied by means of high-resolution thermal analyzer SDT Q600 TA Instruments, under nitrogen atmosphere. The activation energy for the two step reactions of thermal decomposition of different species was calculated and compared

The waterborne polyurethane dispersions based on polycarbonate diol: Effect of ionic content

Three water-based polyurethane dispersions (PUD) were synthesized by modified dispersing procedure using polycarbonate diol (PCD), isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), triethylamine (TEA) and ethylenediamine (EDA). The ionic group content in the polyurethane-ionomer structure was varied by changing the amount of the internal emulsifier, DMPA (4.5, 7.5 and 10 wt.% to the prepolymer weight). The expected structures of obtained materials were confirmed by FTIR spectroscopy. The effect of the DMPA content on the thermal properties of polyurethane films was measured by TGA, DTA, DSC and DMTA methods. Increased DMPA amounts result in the higher hard segment contents and in the increase of the weight loss corresponding to the degradation of the hard segments. The reduction of hard segment content led to the elevated temperature of decomposition and to the decrease of the glass transition temperature and thermoplasticity. The atomic force microscopy (AFM), results indicated that phase separation between hard and soft segment of PUD with higher DMPA content is more significant than of PUD with lower DMPA content. The physico-mechanical properties, such as hardness, adhesion test and gloss of the dried films were also determined considering the effect of DMPA content on coating properties. (C) 2012 Elsevier B.V. All rights reserved