Low density polyethylene (LDPE) nano-polymers were subjected to a high power ultrasonic irradiation as a polymerization initiator, for different times (0, 5, 10 and 15 minutes). Characterization was performed on the non-irradiated and irradiated LDPE samples by measuring the low power ultrasonic wave velocities (Longitudinal and Shear) along with density measurements. X-ray diffraction (XRD) patterns revealed that the percentage crystallinity and crystalline size had changed significantly with
exposure to ultrasonic irradiation. The XRD patterns showed, the usual peaks relative to the planes (110) and (200). The XRD parameters indicated the formation of LDPE nano-polymer and the increase in the degree of crystallinity, lattice constants (a & b) and crystallite size for nano-LDPE samples with exposure time from 0 to 10 min, while with exposure time up to 15 min they decreased. However, the results obtained by the X-ray diffraction have been confirmed by the ultrasonic wave velocities
together with densities of the samples.
Key words: LDPE; Ultrasonic wave velocities; X-ray; Ultrasonic viscosity