the low the method of determination by dsc is as follows dsc data may be obtained using a perkin elmer dsc 7 about 5 mg to about 10 mg of a sheet of the polymer to be tested should be pressed at approximately 200 u00b0 c to 230 u00b0 c then removed with a punch die and annealed at room temperature for 48 hours the samples should then be sealed in aluminum sample pans the dsc data should be recorded by first cooling the sample to u2212 50 u00b0 c and then gradually heating it to 230 u00b0 c at a rate of 10 u00b0 c minute keep the sample at 230 u00b0 c for 10 minutes before a second cooling heating cycle is applied both the first and second cycle thermal events should be recorded the melting temperature is measured and reported during the second heating cycle or second melt the dsc procedure may be continued to determine the heat of fusion and the degree of crystallinity of the polymer sample the percent crystallinity x should be calculated using the formula x area under the curve joules gram b joules gram 100 where b is the heat of fusion for the homopolymer of the major monomer component these values for b may be found from the polymer handbook fourth edition published by john wiley and sons new york 1999 a value of 189 j g b is used as the heat of fusion for 100 crystalline polypropylene the major component of the propylene ethylene copolymer of various embodiments described herein the propylene ethylene copolymer may have h f of about 17 5 to about 25 j g or about 18 to about 22 j g or about 19 to about 20 j g the.