Studies on blends of melt-processable liquid crystalline polymers and thermoplastics. I. Blend of polyesteramide with polyethylene

摘要

The processability characteristics, physicomechanical properties, and thermal decomposition characteristics of blends of low-density polyethylene (LDPE) and polyesteramide (PEA), a thermotropic liquid crystalline polymer, were studied using various analytical techniques. Studies on a Brabender Plasticorder at temperatures ranging from 170 to 230 degrees C showed good melt processability for the blends. The melt rheology of the blends containing 0-15% of PEA at 170 degrees C was studied using a capillary rheometer (Goettfert) fitted with a circular die (L/D = 30/1) at apparent shear rates ranging from 12 to 2300 s(-1). The samples containing PEA showed a comparatively lower die swell at high shear rates. X-ray diffraction measurements showed a reduction in crystallinity of LDPE in the presence of 2-4% of PEA. Scanning electron microscopic evaluation of the morphology of the fractured surface of the blend showed some degree of orientation, but not to the level typical of LCPs. However, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicated significant improvement in the resistance to thermooxidative decomposition of LDPE modified with PEA. (C) 2000 John Wiley & Sons, Inc. [References: 46]