SYNOPSISThe thermal degradation of poly (N-vinyl-2-pyrrolidone) (PVP) was studied by dynamic thermogravimetric analysis (TGA) in the range 200-600°C under nitrogen and oxygen atmospheres a t various heating rates. The apparent activation energy of the degradative process was determined by the application of kinetic treatments, giving an average value of 242 kj/mol in Nz, whereas in the presence of oxygen, two trends may be considered At relatively low temperatures (200-400°C) and degrees of conversion, a, lower than 0.5, we obtained an average value of 199 kjlmol, whereas in the temperature interval 400-600°C with degrees of conversion higher than 0.5, the value of E, was 306 kjlmol. Isothermal experiments carried out in N2 in the interval 350-400°C gave an average value of E. = 231 kj/mol, in good agreement with that obtained from dynamic treatments. The FTIR spectra of the volatile compounds evolved in degradation experiments carried out in Nz as well as in the presence of oxygen suggest that PVP is thermally degraded, predominantly, by the release of the pyrrolidone side group and the subsequent decomposition of polyenic sequences. 0 1993 John Wiley & Sons, Inc.

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SYNOPSISThe thermal behaviour of random copolymers of furfuryl methacrylate (F) and N-vinylpyrrolidone ( P ) was studied by means of dynamic thermogravimetric analysis (TGA) in the range 100-600°C. The dynamic experiments show that these copolymers exhibit two degradation steps in the intervals 260-320°C and 350-520°C, respectively. The normalized weight loss in the low temperature interval increases as the mole fraction of F in the copolymer mF increases, whereas an inverted trend in the high temperature interval is observed. The apparent activation energy E. of the first degradation step for copolymers prepared with different composition, was obtained according to the treatment suggested by Broido. A plot of the values of E. versus the F diad molar fraction in the copolymer chains m F F gave a straight line that indicates that there is a direct relationship between the thermogravimetric behaviour of these systems and their corresponding microstructure, that is, the distribution of comonomeric units along the copolymers chains. The first decomposition step was also studied by isothermal TGA and a good linearity for the variation of the weight loss percentage AN' versus mF at least during the first 30 min of treatment was obtained. These results also indicate that from a kinetic point of view the isothermal degradation in these conditions follows a first order behaviour and the corresponding reaction rate constants increase linearly with ~F F .

Copolymers of furfuryl acrylate (F) and 2‐hydroxyethyl methacrylate (H) were prepared by free radical polymerization in DMF solution at 50°C, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The reactivity ratios of both monomers were calculated according to the general copolymerization equation using the Fineman‐Ross and Kelen‐Tüdös linearization methods, as well as the Tidwell and Mortimer nonlinear least‐squares treatment. The reactivity ratios obtained were rF = 0.93 and rH = 1.42. The microstructure of copolymer chains is described on the basis of first‐order Markov statistics, and the copolymer glass transition temperatures were determined calorimetrically. The variation of Tg with the copolymer composition is discussed according to modern methods, considering the sequence distribution of monomeric units along the copolymer chains. Also the Tg of the corresponding homopolymers was determined giving the values Tg(F) = 321 K and Tg(H) = 358 K, whereas the Tg of the corresponding alternating diad has an average value of TgFH = 326 K. © 1993 John Wiley & Sons, Inc.

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