Glass-transition temperature-conversion relationship for an epoxy-hexahydro-4-methylphthalic anhydride system

Abstract

The DGEBA–MHHPA epoxy system has found increasing applications in microelectronics packaging, making crucial the ability to understand and model the cure kinetics mechanism accurately. The present article reports on work done to elucidate an appropriate model, modified from the empirical DiBenedetto's equation, to relate the glass‐transition temperature (Tg) to the degree of conversion for a DGEBA–MHHPA epoxy system. This model employs the ratio of segmental mobility for crosslinked and uncrosslinked polymers, λ, to fit the model curve to the data obtained. A higher ratio value was shown to indicate a more consistent rate of increase of Tg in relation to the degree of conversion, while a lower value indicated that the rate of Tg increase was disproportionately higher at higher degrees of conversion. The best fit value of λ determined by regression analysis for the DGEBA–MHHPA epoxy system was 0.64, which appeared to be higher than for those previously obtained for other epoxy systems, which ranged from 0.43–0.58. The highest Tg value obtained experimentally, Tg max, was 146°C, which is significantly below the derived theoretical maximum Tg∞ value of 170. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 511–516, 2000

Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion

“…The λ value obtained was close to the maximum value of 1, in contrast to lower values in the range of 0.3 to 0.64 obtained for thermal curing of other epoxy systems. 10 It has been indicated in an earlier paper 10 that the value of λ represents the degree to which the curve is 'skewed'. A lower value indicates that the increase in the T g lags significantly behind the increase in the degree of conversion.…”

“…10 µm) and dried in a vacuum oven, in a similar manner to that described above. The resin-coated KBr pellets were passed through the electron-beam accelerator to expose the samples at different dosages (5,10,20,30 and 50 Mrad). The samples, after postcuring under identical conditions, were stored in a refrigerator at −4 • C. The FTIR spectroscopic measurements were carried out by placing the resincoated KBr pellets directly in the path of the IR beam in transmission mode.…”

“…Optimal use of thermoset systems precludes the ability to understand its curing mechanisms and kinetics. 9,10 Physically, because of the dramatic change in physical properties at this transition, T g , is an important material property in polymer applications, with the most important being that it becomes an upper limit for the service temperature of the material. This is simply because of the considerable drop in the bulk resin modulus 10 once the material transforms from glassy and rigid to a rubbery state, over the glass transition region.…”

Glass‐transition temperature in the curing process of bismaleimide modified with diallylbisphenol A

“…The influence of this parameter on T g was previously reported by Boey and Qiang. 14 The low value of indicates that the increase in T g value lags significantly behind the increase in the degree of conversion. On the other hand a higher value of shows the T g following closely and consistently with the degree of conversion.…”

UV curing of a liquid based bismaleimide-containing polymer system

“…The use of radiation curing has been shown to give faster cure rates. This includes the use of microwave curing [19][20][21], UV [22][23] and ebeam [24][25][26] for curing of thin film thermosetting polymers have been shown to give practical and effective advantages [19][20][21]. N-acryloylmorpholine shows a capability to dissolve traditional BMI with high concentration.…”