X-Ray and Infrared Studies on the Extent of Crystallization of Polymers

Abstract

The current x-ray and infrared techniques for estimation of the crystalline-amorphous ratio in polymers are surveyed. Representative data are assembled for some of the common crystallizing polymers. Advantages and limitations of the methods are pointed out.

Structure characterization of heat set and drawn polyamide 66 fibers by FTIR spectroscopy

“…Extrapolation of the plots in Fig. 2 confirms the assignment of the 1200 and 936 cm -1 bands to the crystalline phase and the 924 cm -1 band to the amorphous phase, providing a crystalline density of 1.26 g/cm 3 and a mean amorphous density of 1.08 g/cm 3 , which are close to the reported values [17] against density and obtained crystalline and amorphous densities of 1.22 and 1.06 g/ cm 3 , respectively [12], but these values were determined without taking into account the contribution of overlapping bands at 924 and 1136 cm -1 . Deconvolution of the bands at 1144 and 1136 cm -1 was carried out and the normalized absorbance of each band and the total absorbance were plotted against density, shown in Fig.…”

“…Samples were allowed approximately 24 hours for equilibration in the gradient column before the reading was taken. The volume fraction crystallinity was determined from (1) The density of crystalline phase ρ c and the amorphous phase ρ a of PA66 is taken as 1.24 and 1.09 g/cm 3 , respectively [17].…”

Polymorphism of Para-Dichlorobenzene

“…The Am+3 fluorescence spectrum shows somewhat different behavior in this respect from its analog Eu+'. In the former, we have observed fluorescence arising from four relatively low-lying excited electronic levels whereas in the latter fluorescence is observed only from the two lowest-lying electronic levels above the 7F ground-state multiplet: 3 …”

Effects of oxygen on the structural evolution of polyacrylonitrile fibers during rapid thermal treatment

“…where l is the X-ray wavelength with 0.1542 nm, q is the Bragg angle, b is full width at half maximum (FWHM) of the diffraction peak, and the k value is a constant of 0.89. 21 Differential scanning calorimetry (METTLER Toledo DSC-822, Mettler-Toledo, Switzerland) was used to perform exothermic reaction behavior analysis. About 5 mg for each sample was measured at temperature ranged from 50 to 440 C at the heating rate of 5 C min À1 under air ow.…”