are no particular limitations placed on these groups when the average molecular weight of r 2 as a poly ether or poly ester linking chain is less than 100 curing properties of the maleimide thereof are worse even if the compositions are cured the gel fraction of the energy cured composition tends to be lower the gel fraction is the percentage of material remaining after a cured film has been refluxed for example in methyl ethyl ketone for 3 hours at 80 u00b0 c then dried at 100 u00b0 c for one hour a cured maleimide derivative or composition which has a 99 8 gel fraction indicates that only 0 2 of the matrix was solubilized by the above reflux conditions i e a high degree of conversion the percentage conversion is defined as the ration of functional groups to a crosslinked matrix monitored by the disappearance of and ir absorption band during the course of 20 irradiation this real time ir measurement allows one to quantify percent conversion and provides insight into the reactivity the composition during irradiation 0025 fig1 and 2 show a plot of the percent conversion of maleimide to polymerized maleimide material over time as measured by real time infra red analysis as mentioned above as the molecular weight of r 2 decreases the curing properties of the maleimide became worse fig1 shows a plot of real time ir data for a bismaleimide derivative structure shown where r 2 is polytetramethyelene glycol as the molecular weight of the repeat unit n decreases i e 4000 curve 1 3000 curve 2 1000 curve 3 650 curve 4 and 250 curve 5 the conversion rate becomes lower however where the molecular weight of r 2 curve 6 is less than 100 the real time ir data shows the.