Effect of Nucleating Agent Characteristics on Cellular Structure and Mechanical Properties of Polyethylene Foams

Due to their unique properties such as proper strength to weight ratio, excellent thermal insulation, sound insulation and good mechanical properties polyethylene foams have received special attention from the scientific and industrial communities. One of the goals of modern research in the field of polyethylene foams is to increase the cell density and reduce the cell size of these materials to achieve the desired properties. Today, it is a well-known fact that the use of nucleating agents is absolutely necessary to control cell morphology (ie, cell density, cell size and distribution) in polyethylene foams. In the present study, first, two theories of nucleation and the characteristics of the nucleating agent have been fully discussed from the point of view of classical nucleation and self-consistent field theories, which are the most important and practical theories of nucleation in polymer foams. Then, the necessary characteristics for the selection of nucleating agent in polyethylene foams were introduced and examined. Based on the investigations carried out in this regard, it has been determined that the optimal concentration, volumetric free energy density, and especially surface tension of the nucleating agent, are the most important criteria and characteristics for the selection of a nucleating agent compared to other parameters such as geometry (F <1, the lowest effect compared to the other two factors) particle size, and dispersibility.