On the melting behaviour of linear polyethylene single crystals in mixtures with homogeneous short chain branched polyolefins

• Published in: Polymer (Guilford) 2022-09, Vol.256, p.125256, Article 125256
• Main Authors: Vega, Juan F., Ramos, J., Souza-Egipsy, V., Martínez-Salazar, J.
• Format: Article
• Language: English
• Subjects: Compatibility; Melting point depression; Polyethylene; Short chain branching; Single crystals
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2022.125256

The melting temperature depression of linear polyethylene lozenge single crystals is thoroughly examined in mixtures with a series of homogeneous high molecular weight branched polyethylene models, with special emphasis on the effect of short chain branching on the compatibility. The results indicate that the melting temperature of the lamellar single crystals is influenced both by the branching content of the surrounding matrix and by the relative volume concentration of the two polymers in the mixture. The discussion of the results is conducted around the compatibility of polymeric species as a function of the short chain branching content, invoking experimental and computational work performed by other authors. The observed depression indicates that the homogeneous mixing of the two polymers at the melting point may occur whenever the branching content is lower than 6–7 every 100 carbon atoms, a result that is reconciled with computer simulations and other experimental approaches. [Display omitted] •Melting point temperature of single crystals is reduced by the surrounding branched matrix.•The degree of depression depends on the branching content.•Critical branching content for immiscibility is around 6–7 branches every 100 carbon atoms.