Swell Ratio Parameter for Prediction of Chemically Crosslinked Low Density Polyethylene Foam Expansion Characteristics

Chemically crosslinked Low Density Polyethylene (LDPE) foam formation with traditional crosslinking system using Dicumyl Peroxide (DCP) alone and with the introduction of polyfunctional monomer, triallycynurate (TAC) is investigated. Samples were characterized as a function of relative concentration of DCP and DCP with TAC in solid and foamed states. It is shown that the introduction of TAC monomer in the crosslinking system provides higher crosslinking level than DCP alone. The addition of TAC monomer also showed significant reduction in DCP concentration to obtain similar crosslinking level. Foam density indicates that traditional parameter i.e. gel content to predict foam expansion is not suitable parameter when polyfunctional monomer is introduced into the system. Swell ratio which is crosslink density dependent is more suitable parameter to predict LDPE foam expansion characteristics. The results also showed that at a similar value of swell ratio either using DCP alone or with the addition of TAC into the system, give similar foam expansion characteristics i.e. similar foam density, cell size and foam mechanical properties.