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

• Published in: Journal of applied polymer science Vol. 118; no. 3; pp. 1541 - 1551
• Main Authors: Mngomezulu, M.E, Luyt, A.S, Krupa, I
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 05.11.2010; Wiley
• Subjects: Applied sciences; Blends; Composites; Dispersions; Exact sciences and technology; Flour; Forms of application and semi-finished materials; HDPE; Melts; morphology; Paraffin wax; Particulate composites; physical properties; Polyethylenes; Polymer industry, paints, wood; soft paraffin wax; Technology of polymers; Wood; wood flour; Viscoelasticity; physical properties; High density ethylene polymer; Dispersion reinforced material; Wood waste; Composite material; Thermal stability; HDPE; composites; soft paraffin wax; Olefin polymer; Water absorption; PCM material; blends; wood flour; Polymer blends; Mechanical properties; Cocrystallization; Tensile property; Experimental study; Thermal properties; Hot pressing; Chemical treatment; Morphology; Concentration effect; Paraffin wax; Rheological properties
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.32521

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, thermo-mechanical, 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 β-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.