Crystal structure and thermodynamic parameters of Nylon-1010

WAXD, SAXS, FTIR, DSC and density techniques have been used to investigate the crystal structure, crystal density ρ_c, amorphous density p_a equilibrium heat of fusion δH°_m and equilibrium melting temperature T°_m. By extrapolating the straight lines in the FTIR absorbance against density plot to zero intensity. ρ_c and ρ_a were estimated to be 1.098 and 1.003 g/cm³ respectively. The ρ_c obtained was too low in value. From X-ray diffraction patterns of uniaxially oriented fibres, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallized in the triclinic system, with lattice dimensions: a = 4.9 Å, b = 5.4 Å, c = 27.8 Å, α = 49°, β = 77°, γ = 63.5°. The unit cell contained one monomeric unit, the space group was P1 , and the correct value of ρ_c was 1.135 g/cm³. The degree of crystallinity of the polymer was determined as about 60% (at RT) using Ruland's method. SAXS has been used to investigate the crystalline lamellar thickness, long period, transition zone, the specific inner surface and the electron density difference between the crystalline and amorphous regions for Nylon-1010. The analysis of data was based upon a one-dimensional electron-density correlation function. δ H°_m was estimated to be 244.0 J/g by extrapolation of δH°_m in the plot of heat of fusion against specific volume of semicrystalline specimens to the completely crystalline condition (V = 1/ρ_c). Owing to the ease of recrystallization of melt-crystallized Nylon-1010 specimens, the well-known Hoffman's T_m-T_c method failed in determining T°_m and a Kamide double extrapolation method was adopted. The T°_m value so obtained was 487 K.