Effect of ultrasonic irradiation on low-density polyethylene molecular structure
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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.
KeywordsPolyethylene Ultrasonic irradiation CSDF Molecular weight
The authors gratefully acknowledge the financial support of CONACyT through projects Consolidación del Laboratorio Nacional de Materiales Grafenicos 299124 The authors also wish to thank Blanca Huerta, Guadalupe Mendez, Myriam Lozano, Jose Lopez, Ma Concepción González, Francisco Zendejo, Mario Palacios, Rodrigo Cedillo, Jesus Rodríguez, Sergio Zertuche, Adán Herrera, Luis Enrique Reyes, Alejandro Espinosa, Seyma de Leon, Josue Campos, Efraín Alvidrez, Marcelo Ulloa, Rosario Rangel, Anabel Ochoa and Daniel Alvarado, Guadalupe Tellez, Jorge Espinosa for their technical and informatics support.
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