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Introduction to Polymerization
Published in F. Joseph Schurk, Pradeep B. Deshpande, Kenneth W. leffew, Vikas M. Nadkarni, Control of Polymerization Reactors, 2017
Schurk F. Joseph, Deshpande Pradeep B.
the number average molecular weight possible at a given value of r may be determined as follows. The total number of monomer molecules is given by (NA + NB)/2 or NA(1 + l/r)/2. The extent of reaction is defined as the fraction of A groups which have reacted at a given time. The fraction of B groups which have reacted is given by rp. The total numbers of unreacted A and B groups are NA(l – p) and NB(1 – rp), respectively. The total number of polymer chain ends is the total number of umeacted A and B groups. The total number of polymer molecules is one-half the total number of chain ends or [NA(1 – p) + NB (1 – rp)]/2. The number average chain length is the total number of monomer molecules originally present divided by the total number of polymer molecules:
Isothermal Kinetic Study and Shelf-Life Prediction of Triple Base Propellant Using Vacuum Stability Test in Combination with HPLC and GPC
Published in Combustion Science and Technology, 2022
Maissam Ahi, Manoochehr Fathollahi, Saeed Babaee, Vahideh Zadsirjan
By the plotting of log t against T, undefined constants (a and b) in the shelf-life equation were obtained. Shelf-life equations at each extent of reaction have been illustrated in Table 6, in which shelf-life at various temperatures (25°C, 30°C, 35°C, and 40°C) have been calculated. According to Table 6, shelf-life differs from few days to few decades depending on the storage temperature and reaction extent. But there is a main question, which one is the actual shelf-life for TBP. There are two necessary parameters to answer this question, (1) the storage temperature and (2) the extent of reaction. Storage temperature refers to the storage climate condition. Mountainous areas have low temperatures, and deserts have high temperatures. Thus, the average temperature for a year is essential to predicting TBP shelf-life. On the other hand, the critical point of α is determined by the stabilizer consumption.
Kinetic analysis of urethane formation between castor oil-based ester polyol and 4,4’-diphenyl methane diisocyanate
Published in Indian Chemical Engineer, 2021
Remya Balakrishnan, P.B. Soumyamol, K.P. Vijayalakshmi, Lity Alen Varghese, R. Rajeev, S.K. Manu, V. Sekkar
To deduce input parameters for kinetic analysis, the following procedure was adopted [13]. The DSC thermogram is subdivided into 1°C segments and each 1° segment (Figure 4) is a trapezium for which area (at) equals to [hT-1 + hT] b, where hT and hT-1 are the lengths of the ordinates at two temperatures T and T-1 differing by 1°C and b is the length of abscissa between the two ordinates. Summation of all segments for the entire range from start to end points represents the full extent of reaction (αtotal) and extent of reaction by summing all segments up to a given temperature T is αT. Extent of reaction (αt) at temperature t is then αt/αTotal and dα/dT at temperature t is given by αT – αT-1. Thus α and dα/dT at various temperatures were computed and used as input parameters in various models to compute kinetic parameters. In addition to this, the input parameters from the resolved DSC thermograms were computed.
Multifunctional Graphene-Based Additives for Enhanced Combustion of Cracked Hydrocarbon Fuels under Supercritical Conditions
Published in Combustion Science and Technology, 2020
Hyung Sub Sim, Richard A. Yetter, Terrence L. Connell, Daniel M. Dabbs, Ilhan A. Aksay
In the present paper, we investigate this hypothesis and experimentally study the impact of the graphene-based materials as liquid hydrocarbon fuel additives on the combined processes of endothermic fuel decomposition followed by fuel injection, ignition, and combustion in air at supercritical conditions using a high pressure and temperature windowed combustor, which is coupled to a supercritical flow reactor and feed system. Images of fuel jets and turbulent diffusion flames, captured using high-speed cinematography, are analyzed to provide comparisons of ignition delay times and flame structures between the pure (baseline) fuel and the same fuel containing inert, catalytic, or reactive particle additives. Fumed silica, aluminum (nAl), FGS, and FGS decorated with varying amounts of nanometer sized platinum particles (5.0 and 20.0 percent by weight) are considered. The effectiveness of the different particle additives is evaluated by comparing the pressure rise and extent of reaction in the combustion chamber.