Thermal fractionation and properties of different polyethylene/wax blends

Abstract

The influence of paraffin-wax type and content on the properties of its blends with HDPE, LDPE, and LLDPE was investigated. Melt-mixing of HDPE with wax gave rise to completely miscible blends for both 10 and 20% wax contents. A wax content of 30% gave rise to a partially miscible blend. These observations were supported by the thermal fractionation (stepwise cooling) results. Melt-mixing of LDPE with hard paraffin wax gave rise to a partially miscible blend for all wax contents investigated, while complete miscibility was observed for the 10% oxidized hard paraffin wax containing blend. Complete miscibility was observed for all the LLDPE/A1 wax blends, with A1 wax as an oxidized hard paraffin wax. This indicates possible cocrystalli-zation of this wax with LLDPE, which was also evident from the thermal fractionation curves. LLDPE blends with hard paraffin wax were, however, partially miscible for all wax contents. All the observations were supported by the surface free energy results. It is further clear from the thermal fractionation results that the presence of wax changed the crystallization behavior of LDPE and LLDPE. Changes in the tensile properties are explained in terms of the miscibility and proposed morphologies of the blends.

Plasticization and cocrystallization in LLDPE/wax blends

“…A number of studies have been conducted on the thermal properties of various paraffin waxes blended with polyethylenes . The used paraffin waxes were of different grades and melting temperatures.…”

“…Each preparation method gave different characteristics to the final materials. Some studies have demonstrated that an increase in wax content when blended with PEs resulted in a decrease in the melting and crystallization temperatures of the blends. This indicates that wax acts as a plasticizing agent for PE.…”

New Routes to Recycle Scrap Tyres

“…Tensile strength only increases with ester wax additive (Ceridust 5551) while it is lower with all the other additives. Hato and Luyt [Hato 2007] observed similar behaviour in terms of mechanical properties when they studied a blend of paraffin wax and HDPE. They explained the results in terms of morphology, suggesting a possible cocrystallization of the mixture HDPE/wax.…”

Shape stabilised phase change materials (SSPCMs): High density polyethylene and hydrocarbon waxes

“…However, in all instances at 70 °C, modulus and stress, irrespective of the mode of deformation, there was no significant difference between the two sets of blends. At 70 o C both waxes are in liquid state, since the movement of polymer chains mainly occurs in the amorphous part, shorter wax chains in the amorphous phase of polymer will promote chain mobility, which implies that the polymer chains are easier to draw from the lamellae [11]. On the other hand, the HDPE itself become more soften as some short chains start to become mobile at 70°C, which may induce a change in crystallinity compared with that at RT.…”