Dionisio Zaldívar

Study of the thermal degradation of poly(furfuryl methacrylate) by thermogravimetry

Abstract The thermal degradation of poly(furfuryl methacrylate) (PFM) has been studied by means of dynamic thermogravimetric analysis (TGA) in the temperature range 100–600°C under nitrogen and oxygen atmospheres at various heating rates, and the apparent activation energy for the interval 230–340°C corresponding to the first degradation step was determined. Isothermal TGA at 250°C, 275°C and 300°C was carried out and the apparent activation energy values obtained were compared with those determined in dynamic experiments. The residues from isothermal degradation experiments were analysed by infrared spectroscopy and the results seem to indicate that in the thermal degradation of PFM the formation of cyclic structures of 2,4-dimethylglutaric anhydride occurs in the macromolecular chains, together with partial depolymerization of polymer segments, as well as intermolecular crosslinking through oxidation of the CH bond in position 5 of some furfuryl rings.

Free radical copolymerization of furfuryl methacrylate and N-vinylpyrrolidone

Abstract Copolymers of furfuryl methacrylate (F) and N -vinylpyrrolidone (P) were prepared by free radical polymerization in N , N -dimethylformamide solution at 50°C, using 2,2′-azobisisobutyronitrile as initiator. The reactivity ratios of both monomers were calculated according to the general copolymerization equation using the Fineman-Ross and Kelen-Tudos linearization methods, as well as the Tidwell and Mortimer non-linear least-squares treatment. The reactivity ratios obtained were r F = 3.92 and r P = 0.004. The microstructure of the copolymer chains is described on the basis of first-order Markov statistics, and the copolymer glass transition temperatures ( T g s) were determined calorimetrically. The variation of T g with copolymer composition is discussed according to modern methods, considering the sequence distribution of monomeric units along the copolymer chains. Also the T g of the corresponding homopolymers was determined giving the values T g (F) = 392 K and T g (P) = 358 K, whereas the T g of the corresponding alternating diad has an average value of T gFP = 347 K.

Activity of the furfuryl ring in the free radical polymerization of acrylic monomers

The effect and the participation of the furfuryl ring, in particular the hydrogen at position C-5 in the free radical polymerization are analyzed following the polymerization of furfuryl acrylate (FA) and furfuryl methacrylate (FM) initiated by AIBN under photochemical activation. The results obtained indicate that the polymerization of FA deviates from the classical free radical kinetic scheme, giving rise to crosslinked polymers even at a degree of conversion lower than 7%. This behavior is well explained taking into consideration the participation of the furfuryl ring which acts as a degradative transfer agent. This was demonstrated by the kinetic analysis of the free radical polymerization of MMA initiated by the thermal decomposition of AIBN in the presence of different concentrations of furfuryl acetate.

High conversion copolymerization of furfuryl methacrylate and N-vinyl-pyrrolidone. A kinetic approach to Skeist's treatment for free radical copolymerization in different reaction media

Abstract The influence of reaction conditions and temperature on the free radical copolymerization of furfuryl methacrylate with N -vinylpyrrolidone, initiated by 2,2′-azobisisobutyronitrile (AIBN) is studied. The initiation step is promoted by the thermal decomposition at 50°C of the AIBN molecules in N , N -dimethylformamide (DMF) solution or photochemically at 0 and 40°C in bulk. The variation of the average composition of copolymer chains with the conversion for two different compositions of the monomer feed, f o F =0.02 and 0.50, is analysed from the classical integrated copolymerization equation. Since the reactivity ratios of this pair are very different, r F =3.92 and r P =0.004, a simplified approximation of the integrated Skeists equation is proposed. The experimental data obtained under different experimental conditions fit adequately the theoretical predictions, suggesting that the reaction medium (solution or bulk) or initiation technique (thermal or photochemical) do not affect the average composition of the copolymer chains at different conversions. However, the variation of the cumulative composition of copolymer chains with the degree of conversion is very sensitive to the initial composition of monomer feed. In addition, the average rate of copolymerization seems to be also dependent on the feed composition.