Poly(hexamethy1ene sulfide) fractions, ranging in molecular weight from 4600 to 20000, were isothermally crystallized from the melt state in the temperature range 50-70°C. The dependence of the melting temperature on the crystallization temperature was analyzed in experiments involving low and high levels of crystallinity. The equilibrium melting temperature corresponds to 366 K and the enthalpy of fusion was found to be 40,5 cal/g ( = 170 J/g). The isothermal overall crystallization rates were analyzed using dilatometric and calorimetric techniques. The Avrami exponent is an integral value, n = 3, and the crystallinity varies with increasing molecular weight from 65% to 55%. The morphology is spherulitic and it was found that the growth rate is linear in the whole range of crystallization temperatures. The temperature coefficient of the crystallization was analyzed using nucleation theory, and comparison between dilatometric and growth data revealed that the overall rate and growth rate-temperature coefficients are approximately equal.

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Poly(trimethy1ene sulfide) (PTS) synthesized by means of anionic polymerization was studied with regard to its solubility behaviour and unperturbed chain dimensions. The Flory-Huggins interaction parameter was used to determine the solubility parameter of PTS, 6 = 10,O cal"* . cm-3'2, which agrees with the calculated one. PTS fractions were isolated by means of fractional precipitation from chloroform/hexane at 50 "C. Their number-average molecular weight, 4, and the intrinsic viscosity, [ q ] , were measured in chloroform at 25 "C. From these data the relation [q] = 3,IO. @76 (dl . g -l ) was estimated. A value of the characteristic ratio, (?)o/(n f 2 ) = 4,0, was determined from the Burchard-Stockmayer-Fixman plot, whichshows that this chain molecule has high flexibility.

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Carbon steel has gained wide applications as a structural material due to its combination of strength, ductility, and low cost; in fact, this material has been studied as one of the proposals for the manufacture of radioactive waste containers in countries such as Japan, France, and the United States. One of the biggest problems of carbon steel is its susceptibility to general corrosion, while copper and its alloys, despite not having high mechanical resistance, are materials with good corrosion resistance properties. This work evaluates the reliability of protective films developed from copper nanoparticles to improve the corrosion resistance of carbon steel plates. The nanoparticles were synthesized by a chemical reduction method using copper sulphate (CuSO4) as a precursor, sodium borohydride (NaBH4) as a reducing agent, and citric acid as an antioxidant. These nanoparticles were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), as well as by Dynamic Light Scattering (DLS) before and after being treated with citric acid. Finally, they were deposited on the carbon steel surface by Electrophoretic Deposition using a current of 0.5 mA/cm2. The protective capacity of the films developed from copper nanoparticles was evaluated by means of Electrochemical Impedance Spectroscopy and Linear Polarization Resistance techniques in 0.1 M HCl solution.