Structure and properties of phase change materials based on HDPE, soft Fischer‐Tropsch paraffin wax, and wood flour

Abstract

Phase-change materials based on high density polyethylene (HDPE), soft Fischer-Tropsch paraffin wax (M3), and alkali-treated wood flour (WF) were investigated. The blend and composite samples were prepared by melt mixing using a Brabender Plastograph, followed by melt pressing. They were characterized in terms of their morphology, as well as thermal, mechanical, thermomechanical, and water absorption properties. Although SEM micrographs showed some evidence of intimate contact between the WF particles and the HDPE matrix as a result of alkali treatment, poor filler dispersion, and interfacial adhesion were also observed. Partial immiscibility of the HDPE and the M3 wax was noticed, with the WF particles covered by wax. There was plasticization of the HDPE matrix by the wax, as well as partial cocrystallization, inhomogeneity and uneven wax dispersion in the polymer matrix. The HDPE/WF/M3 wax composites were more homogeneous than the blends. The presence of wax reduced the thermal stability of the blends and composites. Both the presence of M3 wax and WF influenced the viscoelastic behavior of HDPE. The HDPE/M3 wax blends showed an increase in the interfacial amorphous content as the wax content increases, which resulted in the appearance of a b-relaxation peak. The presence of M3 wax in HDPE reduced the mechanical properties of the blends. For the composites these properties varied with WF content. An increase in wax content resulted to a decrease in water uptake by the composites, probably because the wax covered the WF particles and penetrated the pores in these particles. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: [1541][1542][1543][1544][1545][1546][1547][1548][1549][1550][1551] 2010

Structure and properties of phase‐change materials based on high‐density polyethylene, hard Fischer–Tropsch paraffin wax, and wood flour

“…The position of the observed additional peak at −14°C for the blend composites seems to depend on the H1 wax content. As in our previous work on soft wax‐based blend composites [31], we could not find an explanation for the origin of this transition.…”

“…The water uptake of these composites also decreases with an increase in wax content. As in the case of M3 wax‐containing composites [31], this is the result of the affinity between the wax and the WF, which shields the WF particles from the water and which reduces the number of voids in and around the WF particles. The water uptake of the 10% WF‐containing composites is clearly lower than that of the 20% WF‐containing composites.…”

“…At high WF content, the same amounts of wax did not effectively cover all the WF particles, which remained exposed to water. However, as the wax content increased, most of the filler particles were effectively covered by wax, which has also filled the pores and limited the water uptake by the composites [31].…”

Influence of the presence of medium-soft paraffin wax on the morphology and properties of iPP/silver nanocomposites

“…It was found that the presence, type and amount of the filler particles did not change the melting behaviour of PE or wax in the composites. A limited amount of research has been done on the dynamic mechanical properties of polymer/wax blend composites [11,13]. When expanded graphite was used as filler, an increase in storage modulus was observed with an increase in filler content, which was an indication that the filler reinforced the matrix and countered the softening effect of the wax [13].…”

“…No specific trends related to the amount of filler particles were observed. However, the presence of wood filler particles in the polymer/wax blends reduced the storage modulus [11]. The thermal conductivity of form-stable PCM composites was investigated in a number of studies [5,[12][13][14][15].…”