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Critically evaluated propagation rate coefficients, kp, for free-radical polymerization of methacrylic acid, MAA, in aqueous solution are presented. The underlying kp values are from two independent sources, which both used the IUPAC-recommended technique of pulsed-laser-initiated polymerization (PLP) in conjunction with molar mass distribution (MMD) analysis of the resulting polymer by size-exclusion chromatography (SEC). Different methods of measuring the MMD of the poly(MAA) samples have, however, been used: (i) direct analysis via aqueous-phase SEC and (ii) standard SEC with tetrahydrofuran as the eluent carried out on poly(methyl methacrylate) samples obtained by methylation of the poly(MAA) samples from PLP. Benchmark kp values for aqueous solutions containing 15 mass % MAA are presented for temperatures between 18 and 89 °C.
The Arrhenius pre-exponential and activation energy of kp at 15 mass % MAA are 1.54 × 106 L mol–1 s–1 and 15.0 kJ mol–1, respectively. Also reported are critically evaluated kp values for 25 °C over the entire MAA concentration range from dilute aqueous solution to bulk polymerization.
Pure Appl. Chem., Vol. 79, No. 8, pp. 1463–1469, 2007.
IUPAC Technical Report
© 2007 IUPAC
IUPAC permission is acknowledged
Abstract
Some analytical techniques, such as voltammetry, are relatively little used in undergraduate experimental disciplines in chemistry (and related sciences), although addressed in theoretical ones. Since, in contrast to what one thinks, voltammetric measurements are still often used in routine analysis, some of the most direct techniques will be highlighted in this text, with suggestions to the reader who seeks more knowledge on this theme. The experiments presently proposed present a well defined conceptual and methodological character and have been tested in the experimental classes of the Instrumental Analytical Chemistry discipline of the Institute of Chemistry at UNICAMP. Each module is proposed for four hours of activities in the laboratory, with low risk.
Keywords
voltammetry, water, sugarcane liquor, fruit juices, nickel, cobalt, copper, cadmium, zinc, ascorbic acid
Authors
João Carlos de Andrade
Audrey de Arruda Falcão
Elaine Castilho Guedes
Universidade Estadual de Campinas, Instituto de Química
Translated by
João C. de Andrade
Revised by
Carol H. Collins
Warning
Attention: “Read carefully the procedure before starting the experiment. Do not perform the experiment without being monitored by your teacher. In doubt ask for help!”
