Biaxial orientation in LLDPE films: Comparison of infrared spectroscopy, X‐ray pole figures, and birefringence techniques

Abstract

In this study, linear low-density polyethylene films were produced using different processes (film blowing and biaxial orientation) and processing conditions. The orientation of the films was characterized in terms of their biaxial crystalline, amorphous, and global orientation factors using birefringence, tilted incidence polarized Fourier Transform Infrared Spectroscopy (FTIR), and Xray diffraction pole figures. Evaluation of a simplified FTIR procedure without the use of the tilted method for the determination of crystalline orientation factors proposed in the literature is also evaluated and assessed. The results indicate that FTIR overestimate the crystalline orientation factors, particularly for the crystalline a-axis. Significant discrepancies are also observed for the b-axis orientation, which may be due to an overlap of the amorphous phase contribution. Those differences are larger for films with low orientation, such as blown films. Amorphous phase orientation from FTIR depends on the band used and is not necessarily in agreement with that determined from the combination of X-ray and birefringence. The simplified FTIR procedure is proven to be inadequate in the case of linear low-density polyethylene blown films studied having a random lamellar crystalline morphology. POLYM. ENG. SCI., 46:1182-1189, 2006.

Orientation,Structure and Properties of Double-Bubble Oriented Lldpe Films

“…However, the numerical values are somewhat different. This type of result has already been reported in the literature [13,14]. The difference has been ascribed to the calculation procedure and/or the techniques themselves.…”

“…These results are contrary to those obtained with c-axis orientation and thus indicate clearly that a-and b-axes tend to orient away from MD and preferentially towards ND and TD respectively. This kind of behavior has already been observed with various PE films subjected to uniaxial stretching towards MD and restricted towards TD [13]. For the sake of comparison, the orientation functions assessed by means of FTIR and X-ray diffraction (XRD) techniques are both depicted in Figure 1.…”

Structure of blown films of polyethylene/polybutene‐1 blends

“…Reports about orientation of the a-axis or c-axis of the crystal lattice at an intermediate angle between MD and TD show that via the ratio k MD /k TD, the orientation can be tailored. This intermediate orientation was observed for high-density polyethylene (PE-HD) [5] in particular, and for linear lowdensity polyethylene (PE-LLD) [10,12,22].…”

“…The super-molecular structure, including the crystallinity, and the morphology and orientation of the crystals of blown films of polyethylene (PE) have been extensively studied [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Typically, blown films of PE are semicrystalline with a maximum degree of crystallinity, which depends on the molecular architecture/branching-characteristics.…”

Classification of polyethylene cling films by attenuated total reflectance-Fourier transform infrared spectroscopy and chemometrics

“…Furthermore, it has been shown that during the manufacturing process, the LDPE aligns to a degree, causing polarisation 7 . This factor needs to be considered when analysing the sample, as the polarisation of the film will cause variability in the intensity of the spectra acquired 24,25 . Spectra should thus be collected with the sample rotated 90° with respect to the original alignment.…”