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The kinetics of the thermal cure reaction of Bisphenol A dicyanate (BACY) in presence of various transition metal acetyl acetonates and dibutyl tin dilaurate (DBTDL) was investigated using dynamic differential scanning calorimetry (DSC). The cure reaction involved a pregel stage corresponding to around 60% conversion and a postgel stage beyond that. Influence of nature and concentration of catalysts on the cure characteristics was examined and compared with the uncatalyzed thermal cure reaction. The activation energy (E), preexponential factor (A), and order of reaction (n) were computed by the Coats–Redfern method. A kinetic compensation correction was applied to the data in both stages to normalize the E values. The normalized activation energy showed a systematic decrease with increase in catalyst concentration. The exponential relationship between E and catalyst concentration substantiated the high propensity of the system for catalysis. At fixed concentration of the catalyst, the catalytic efficiency as measured by the decrease in E value showed dependency on the nature of the coordinated metal and stability of the acetyl acetonate complex. Among the acetyl acetonates, for a given oxidation state of the metal ions, E decreased with decrease in the stability of the complex. A linear relationship was found to exist between activation energy and the gel temperature for all the systems. Manganese and iron acetyl acetonates were identified as the most efficient catalysts. In comparison to DBTDL, ferric acetyl acetonate proved to be a more efficient catalyst. The activation parameters computed using the Coats–Redfern method agreed well with the results from two other well known integral equations. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1103–1114, 1999

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In order to characterize surface molecular orientation in three dimensions and to obtain other structural information such as the degree of crystallinity and the different conformer contents at the surface, a new ATR (attenuated total reflection) attachment was designed for FT IR ATR dichroism studies. This holder allows a wide range of well-defined incidence angles to the crystal, thereby allowing depth profiling, and when combined with an improved optical arrangement, provides increased sensitivity. In order to demonstrate the applicability of this new attachment, films of uniaxially drawn polypropylene (PP), polyethylene terephthalate) (PET), and biaxially drawn PP were characterized in this study, along with undrawn polypropylene for comparison. For uniaxially drawn polymers, the three-dimensional absorbances show that even though the major anisotropy exists between the draw direction (x) and the transverse direction (y) or between x and the thickness direction (z), the absorbance along the y or z direction is not identical in some bands, suggesting a certain extent of deviation from transverse symmetry. The surface degree of crystallinity in PP, averaging a depth of about 3 µ , has been estimated from the three absorbance values, after correction for the orientation effect, to be 0.62, 0.72, and 0.45 for uniaxially, biaxially, or undrawn films, respectively. These values agree favorably with their bulk crystallinity values obtained by other techniques. On the surface of uniaxially drawn PET, the amount of trans conformer in the ethylene glycol unit of PET is estimated to be at least 49%, and the surface degree of crystallinity to be 0.27. In equally biaxially drawn PP, surface orientation shows a slight imbalance in the two draw directions, while the orientation in the thickness direction is much smaller, as expected. The amorphous orientation functions calculated from our results always show smaller values than the crystalline orientation functions in both PP and PET regardless of whether they were uniaxially or biaxially drawn. Depth-profiling studies within the depth range 1-15 µ enable detection of the gradient in orientation as well as the changing degree of crystallinity near the surface. This technique therefore represents a new, rapid, nondestructive way to characterize surface structure and orientation in polymer fdms as a function of surface depth.