Thermodynamic parameters of transformation of γ-butyrolactone into poly-γ-butyrolactone at normal pressure in the range of 0–400°K

Crosslinking of mixtures of DGEBA with 1,6‐dioxaspiro[4,4]nonan‐2,7‐dione initiated by tertiary amines. I. Study of the reaction and kinetic analysis

“…Moreover, both formulations exhibited a heat released (see Table II) close to 100 kJ/equiv, on the basis that the opening of the epoxy ring is responsible for the heat release during curing, 5 which is not unreasonable if it is considered that, for instance, the ring-opening of gBL is only 5 kJ/equiv. 31 From the shape of the curves of the 212 and 122 formulations in Figure 1 it can be sensed what was stated by Sikes and Brady 11,12 and other authors 13,14 as to the curing mechanism. It is supposed that in formulation 212 (excess of DGEBA) a copolymerization between DGEBA and s(gBL) first occurs, and once the s(gBL) is exhausted homopolymerization of DGEBA takes place, which produces a quasi bimodal exotherm.…”

Vapour pressures and enthalpies of vapourization of a series of the γ-lactones

“…The vapour pressures of c-lactones (see table 2) have been reported in references [6][7][8][9][10][11][12][13][14][15][16], but these authors did not calculate the enthalpy of vapourization from their results. Therefore, enthalpies of vapourization D g l H m (298.15 K) have been derived in this work for the first time using equations (2) and (3) and the results obtained have been compared with our findings (see table 2).…”

New Thermosets Obtained by Thermal and UV‐Induced Cationic Copolymerization of DGEBA with 4‐Phenyl‐γ‐butyrolactone

“…By increasing the amount of lactone, the experimental reaction enthalpy Dh exp decreases because of the lower ring strain of g-lactones in comparison to epoxy rings. [8,9] From the Dh exp of the pure DGEBA a heat of 93 kJ Á eq À1 was estimated. This value is similar to the reported for other epoxy groups, [22] and it was used, along with a theoretical heat of 7 kJ Á eq À1 , [8,9] for the opening of a lactone ring, to determine a theoretical reaction heat Dh theo associated with the complete conversion of all the reaction species.…”

“…[8,9] From the Dh exp of the pure DGEBA a heat of 93 kJ Á eq À1 was estimated. This value is similar to the reported for other epoxy groups, [22] and it was used, along with a theoretical heat of 7 kJ Á eq À1 , [8,9] for the opening of a lactone ring, to determine a theoretical reaction heat Dh theo associated with the complete conversion of all the reaction species. The similarity between the theoretical and experimental heat values (Table 1) indicates that both the epoxy groups and the PhBL units reacted almost completely.…”

“…[4][5][6] We used this kind of lactone because its homopolymerization is thermodynamically unfavourable. [7][8][9] During the cationic copolymerization of epoxy/ lactone systems, an intermediate spiroorthoester (SOE) is formed. SOEs can subsequently react with epoxides or homopolymerize by ring-opening with some degree of expansion.…”