Effect of ultrasonic irradiation on low-density polyethylene molecular structure
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Effect of ultrasonic irradiation on low‑density polyethylene molecular structure J. G. Martinez‑Colunga1 · S. Sanchez‑Valdes1 · L. F. Ramos‑deValle1 · E. Ramirez‑Vargas1 · C. Avila‑Orta1 · J. A. Rodriguez‑Gonzalez1 · C. J. Espinoza‑González1 · R. Benavides‑Cantú1 · T. Lozano‑Ramírez2 Received: 13 June 2019 / Revised: 3 October 2019 / Accepted: 23 October 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract The effect of ultrasonic (US) irradiation on solutions of low-density polyethylene (LDPE) was studied. Different irradiation times and intensities were examined. It was found that gel content increased very little as a result of US irradiation. However, this increase showed no variation with either the US irradiation time or intensity. The IR spectra of irradiated LDPE showed new absorption bands, indicating the presence of C–O groups, assumed to be the result of the US irradiation. GPC showed that the LDPE average molecular weight (Mw) decreases with an increase in either the US irradiation time or intensity. But these MWD curves, however, do not say if the “observed” modifications in Mw are due to chain scission or chain branching, which was inferred from the chain scission distribution function (CSDF) curves. From the GPC curves, it appears that chain scission is the dominant reaction at all US irradiation times and intensities. On the contrary, using the CSDF methodology, it appears that chain scission is the dominant reaction up to the intermediate irradiation times and intensities, but chain branching becomes dominant at the US higher times and intensities. On the contrary, using the proposed methodology, it appears that chain scission is the dominant reaction up to the intermediate irradiation times and power intensities, but chain branching becomes dominant at higher times and power intensities. Keywords Polyethylene · Ultrasonic irradiation · CSDF · Molecular weight
* J. G. Martinez‑Colunga [email protected] 1
Centro de Investigación En Química Aplicada, Blvd. Enrique Reyna 140, 25294 Saltillo, Coah, Mexico
2
Instituto Tecnológico de Cd. Madero, Juventino Rosas y Jesus Urueta, C.P. 89440 Cd. Madero, Tamaulipas, Mexico
13
Vol.:(0123456789)
Polymer Bulletin
Introduction Polyethylene is among the most widely used polymers because of its low cost, low weight, low temperature toughness, low density, low moisture absorption, good optical properties, and ease of processing and recycling. In recent years [1–13], interest in using high-intensity ultrasonic radiation, as an alternative method for the generation of free radicals in polymers, has arisen. Some studies [12–25] have reported on the effect of ultrasonic energy on polymer degradation in which temperature has a significant effect. The time and intensity of incidence of the ultrasonic energy play an important role in the formation and rate of formation of free radicals, which ultimately will be related to the degree of chain degradation and/ or cross-linking and therefore will have a direct influence on
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