Effects of parameter changes on the structure and properties of low‐density polyethylene foam

Abstract

Several parameters, such as crosslinking agent concentration, blowing agent concentration, and temperature, were varied to evaluate their effects on the structure and mechanical properties of low‐density polyethylene (LDPE) foams. Dicumyl peroxide (DCP) was used as crosslinking agent, while azodicarbonamide (ADC) was utilized as the blowing agent at different levels. The formulations were prepared by using a thermostatically controlled heated two‐roll mill and foamed by using a compression molding technique via a single‐stage foaming process at three foaming temperatures (165, 175, and 185°C). The resultant LDPE foams were characterized and found to have a closed cell structure. The density and gel content increased proportionally with crosslinking level, whereas density decreased when ADC level and foaming temperature were increased. Another characteristic evaluated was the foam cell size decreased when the crosslinking level and foaming temperature were increased. In contrast, increasing the ADC concentration only gave a maximum cell size increase up to 6 phr that decreased when 8 phr of ADC was used. Results also indicated that compression stress increased proportionally with DCP level and decreased when ADC concentration and foaming temperature were increased. Impact studies on the prepared foams showed that their ability to absorb impact energy decreased with increasing crosslinking level, foaming temperature, and blowing agent concentration. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers

Deformation behavior of open-cell dry natural rubber foam: Effect of different concentration of blowing agent and compression strain rate

“…1. In general the compression stress-strain plots have similar characteristics to that of elastomeric foams studied by other researchers [5][6][7][8]. It was observed the compression stress of the foam decreased with increasing of BA concentration.…”

“…Bending of the cell edges and stretching of the cell faces are the primary mechanisms that control their structural response to mechanical deformation [1][2]. The mechanical behaviour of rubber foam has been discussed widely among the researchers [3][4][5][6][7][8]. Study performed by Sombatsompop [3] showed that the mechanical properties of cellular rubber were greatly affected by crosslink reaction which was affected by the curing process.…”

Preparation and characterization of multilayer foamed composite by rotational molding

“…This is due to the presence of voids in the polymer matrix which can be considered as defects in the tough polymer structure leading to lower impact resistance [41][42][43].…”

Influence of chemical nature, expansion ratio and cellular morphology on the fracture behaviour of flexible polyolefin-based foams assessed by the Essential Work of Fracture (EWF)

“…Although the mechanical response of these materials has been extensively studied under compression [1][2][3], there is still lack of knowledge about their fracture behaviour, with the scarce work focusing on rigid foams.…”