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The density

equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum

differential scanning calorimetry

wide angle X-ray diffraction and density measurement techniques. According to Starkweatber’ s method crystalline density ρ

c

and amorphous density ρ

a

were estimated to be 1.098 and 1.003 g/cm

3

respectively by extrapolating the straight lines of the IR absorbanee against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained ρ

c

was too low in value. Thereby the value of the ratio ρ

c

/ρ

a

is far less than generally accepted mean value for most crystalline polymers. Accordingly

traditional X-ray diffraction method was used through determining thc crystalline dimension（a=4.9

b=5.4

c=27.8

α=49°β=77.0°

γ=63.5°）

and a rather correct value of ρ

c

or the crystal density 1.13 g/cm

3

was obtained. The equilibrium heat of fusion △H

m

0

was estimated to be 244.0 J/g piotting △H

m

’s of specimens with different crystallinity against their corre sponding specific volumes 

sp

and extrapolating to completely crystalline condition (

sp

c

= 1/ρ

c

) As to the equilibrium melting temperature T

m

0

because of the easiness of recrystallization of melt crystallized Nylon 1010 specimen

the well-known Hoffman’s T

m

-T

c

method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted. The so obtained value of T

m

0

487 seems to be fairly reasonable.