Linear Low-Density Polyethylene and Zirconium Phosphate Nanocomposites: Evidence from Thermal, Thermo-Mechanical, Morphological and Low-Field Nuclear Magnetic Resonance Techniques

Lamellar α-zirconium phosphate was synthesized by direct precipitation and also directly expanded with octadecylamine, through alcoholic solution. To produce a nanocomposite, it was incorporated in linear low-density polyethylene in the molten state, using a counterrotating twin-screw extruder set at 170–190 °C and 100 rpm. The differential scanning calorimetry analysis revealed a decrease in the polyolefin melting temperature and crystallinity degree. The higher onset temperature of the zirconium phosphate modified with octadecylamine and linear low density polyethylene composite indicated an increasing of thermal stability and it suggests that some polyethylene chains entered into the filler's spacing. Dynamic-mechanical analysis evidenced an increase in both moduli (storage and loss). Wide-angle X-ray diffraction showed additional peaks—diffraction angles appeared in the region beneath 12°—which were attributed to partial intercalation of polyethylene chains between filler interlamellar spacing. By hydrogen low-field nuclear magnetic resonance, the two low intensity relaxation time peaks shifted to higher values, strongly suggesting interaction between the octadecylamine and polymer matrix into the filler galleries. From these results, it may be postulated that a partially intercalated and/or exfoliated nanostructure in the zirconium phosphate modified with octadecylamine and linear low density polyethylene composite was achieved.