No abstract

The polymerization kinetics of acrylamide (AAM) in water initiated by a ternary enzymatic system of horseradish peroxidase (HRP)/H2O2/acetylacetone (ACAC) was investigated. Conversion–time plots were obtained by dilatometry under different conditions of reaction temperatures and initial concentrations of HRP, ACAC, H2O2, and AAM. The results showed that the effect of the initial concentration of ACAC on the inhibition period was significant. The inhibition period decreases with increasing the initial concentration of ACAC. The inhibition period can be even eliminated by the use of a comparatively large amount of ACAC. From the conversion–time plots, the polymerization rate equation was obtained. Some kinetic features were explained on the basis of analysis of the reaction mechanism. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 475–481, 2012

A crosslinkable terpolymer P(MMA‐BA‐HEMA) was prepared by atom transfer radical copolymerization of 2‐hydroxyethyl methacrylate, methyl methacrylate and butyl acrylate. The structure of the terpolymer was characterized by 1H NMR and gel permeation chromatography. The effects on the polymerization of ligand, initiator, solvent, CuCl2 added in the initial stage and reaction temperature were investigated. The optimal reaction conditions were ethyl 2‐bromopropionate as initiator, CuCl/PMDETA as catalyst, cyclohexanone as solvent, catalyst/ligand = 1:1.5, [M]0:[I]0 = 200:1 and temperature 70 °C. The reaction followed first‐order kinetics with respect to monomer concentration, indicating the best control over the polymerization process, a constant concentration of the propagating radical during the polymerization, efficient control over Mn of the polymer and low polydispersity (Mw/Mn < 1.3). © 2013 Society of Chemical Industry

The thermal degradation kinetics of N-phenylmaleimide-styrene-maleic (NSMA) anhydride copolymers was analysed by a non-isothermal kinetic method. Kinetic parameters were obtained using integral and differential methods, and the most probable mechanism functions and kinetic compensation effects were discussed. The activation energy E for the thermal degradation of NSMA was 211.34kJ/mol according to the Flynn-Wall-Ozawa method and the thermal degradation was a first-order chemical reaction. A recommended rate expression for the thermal degradation reaction of NSMA was [Formula: see text] (where α is the conversion, t is time, R is the gas constant, T is the temperature and A is the pre-exponential factor), and the mathematical expressions of compensation effects for the integral and differential methods were lnA=-1.8037+0.1749E and lnA=-2.1974+0.1741E respectively.

Flooding and floating are problems in many paint applications. If pigment concentration is uniform on the surface but not through the thickness of the film, one refers to 'flooding' (horizontal separation). If, however, concentration differences are visible across the surface of the paint film, one refers to 'floating' (vertical separation). In this article, the influence of pigment, filler, additives, and processing conditions on the flooding and floating of colored latex paint were investigated. It was discovered that too broad a distribution of pigment and filler particle size can lead to flooding and floating. Different levels of pigment (TiO 2 ) or filler (kaolin) loading cause diverse degrees of flooding and floating. Waterborne coatings that do not exhibit flooding or floating may show these conditions when diluted. Using dispersants or thickeners with hydrophobic constituents, increasing viscosity, reducing surface tension, etc., all help to prevent or reduce flooding and floating. Comparison tests revealed little influence of processing conditions on flooding or floating.