Kinetics of the Polymerization of Styrene by Friedel–Crafts Catalysts
ALTHOUGH the mechanisms and kinetics of the free-radical catalysed polymerization of styrene have been fairly extensively investigated1,2, the polymerization employing Friedel Crafts catalysts has received much less attention. Williams3 has investigated the stannic chloride catalysed polymerization of styrene in carbon tetrachloride solution and shown that the overall rate of monomer consumption can be represented by the expression: where m is initial styrene concentration, x is styrene consumed in time t, b is initial catalyst concentration. He has also shown that induction periods are present. We are studying the aluminium chloride catalysed polymerization of styrene in carbon tetrachloride solution from a kinetic point of view, and it is proposed to summarize here the principal conclusions reached to date.
Olefin Polymerizations and Copolymerizations with Aluminum Alkyl-Cocatalyst Systems. IV. The Polymerization of Styrene
Abstract The mechanism of cationic styrene polymerization with the AlEt2Cl/RCl (R = alkyl or aryl) catalyst-cocatalyst system has been investigated. Polymerization initiation, i.e., cocatalyst efficiency, is apparently determined by the relative stability and/or concentration of the initiating carbonium ions provided by the cocatalyst RCl. Whereas n-butyl, isopropyl, and sec-butyl chlorides exhibit low cocatalyst efficiencies because of low ion concentrations, triphenyl methyl chloride is a poor cocatalyst because the stability of the derivative triphenyl methyl ion is much higher than that of the propagating styryl ion. Alkyl halides that give ions of intermediate stability are efficient cocatalysts. Isobutyl chloride and benzyl chloride seem to be exceptions and the reasons for this are discussed. A general simple scheme of the polymerization mechanism is proposed.
A Global Optimal Solution With Higher Order Continuity for the Estimation of Surface Velocity From Infrared Images
A global optimal solution (GOS) provides surface velocities from Advanced Very High Resolution Radiometer (AVHRR) remote image sequences using bilinear interpolation algorithms. Although an accurate velocity field can be estimated by GOS from a sequence of infrared images, the field has only first-order continuity. Because an actual coastal ocean has a complex irregular coastland and some ocean studies need vorticity and divergence analysis, which must be extracted from the velocity field, the development of generic GOS algorithms with higher order continuity and smoothed cutouts around these edges is very important. This paper addresses the issues of higher order continuity and smoothed cutouts around coastland edges for using GOS to estimate surface velocities. GOS bilinear polynomials, previously applied to square tiles with first-order continuity, are replaced by surface B-spline functions. The new GOS algorithms can be applied to AVHRR images containing complicated coastal land boundaries, even clouds, to yield smooth velocity fields next to land and higher order continuity velocity fields. The velocity fields obtained through the applications of the first- and higher order GOS techniques to a sequence of two National Oceanic Atmospheric Administration AVHRR images, which were taken from the New York Bight fields, are compared with those measured with the CODAR array. The retrieved velocity fields are used directly to calculate the surface divergence and vorticity. It is found that the angular and magnitude errors of the velocity by the first- and third-order GOSs are quite close for both numerical model data and AVHRR image sequences, and the velocity field estimated by the third-order GOS is globally smoothed.