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dc.contributor.advisorLuyt, A. S.
dc.contributor.advisorKrupa, I.
dc.contributor.authorMolefi, Jonathan Andrew
dc.date.accessioned2015-12-01T08:25:57Z
dc.date.available2015-12-01T08:25:57Z
dc.date.copyright2008-11
dc.date.issued2008-11
dc.date.submitted2008-11
dc.identifier.urihttp://hdl.handle.net/11660/1950
dc.description.abstractEnglish: Phase change materials based on polyethylene (LDPE, LLDPE and HDPE) and copper (micro and nano) blended with soft paraffin wax were studied in this work. The purpose of this study was to form composites that can store energy as well as conduct heat. The influence of wax content, as well as copper content and copper particle size, on the morphology and thermal, mechanical and conductivity properties was investigated. The scanning electron microscopy results show that both the Cu micro-and nano-particles were well dispersed in the matrix. The nano-particles, did, however, also form agglomerates. The results also show that the Cu micro-particles have a greater affinity for the wax than for the polyethylenes, giving rise to preferable crystallization of the wax around the Cu particles. The differential scanning calorimetry results show that the Cu micro- and nano-particles influence the crystallization behaviour of the polyethylenes in different ways. The extent to which the copper particles influence the crystallization behaviour of the polyethylenes also depends on the respective morphologies of the different polyethylenes. All the polyethylene/wax blends are immiscible or only partially miscible at wax contents of 30, 40 and 50%. The presence of wax in the polyethylene/wax blends reduces the melting temperatures of all three polyethylenes, indicating the plasticizing effect of the molten wax in the polyethylene matrix. The thermogravimetric analysis results show observable influence of both the presence of copper and the sizes of the copper particles, as well as the presence and amount of wax, on the thermal stabilities of the blends and composites. The thermal conductivities of the composites show a non-linear increase with an increase in Cu particle content. The presence of wax slightly decreases these values, confirming the preferable crystallization of wax around the Cu particles. The thermal conductivities of the Cu nano-particle containing composites, at the same copper contents, are almost the same as those of the micro-particle containing composites. Young’s moduli increased with an increase in copper content in both the polyethylene composites and the polyethylene/wax blend composites, except in the case of HDPE where a decrease was observed. The dynamic mechanical analysis storage moduli determined through dynamic mechanical analysis show the same trends as the Young’s moduli. The tensile strengths show variable behaviour, but mostly these values decrease with increasing Cu and wax contents. The energy storage results show that the heat transport is faster in the case of the blend composites compared to the polyethylene/wax blends, and the heat transport in the polyethylene/wax blends is also faster than in the neat polyethyleneen_ZA
dc.description.abstractAfrikaans: Faseveranderingsmateriale (PCMs), gebaseer op poliëtileen (LDPE, LLDPE en HDPE) en koper (mikro en nano) gemeng met sagte paraffienwas is in hierdie werk bestudeer. Die doel van hierdie studie was om komposiete te berei wat energie kan stoor en hitte kan gelei. Die invloed van washoeveelheid, sowel as die koperhoeveelheid en koper deeltjiegrootte, op die morfologie en termiese, meganiese en geleidingsvermoë eienskappe is ondersoek. Die skandeer elektronmikroskopie resultate wys dat beide die Cu mikro- en nanodeeltjies is goed versprei in die matriks. Die nanodeeltjies het egter ook agglomerate gevorm. Die resultate wys ook dat die Cu mikrodeeltjies ‘n groter affiniteit vir die was as vir die poliëtilene het, wat aanleiding gee tot verkieslike kristallisasie van die was om die Cu deeltjies. Die differensieel skandeer kalorimetrie resultate wys dat die Cu mikro- en nanodeeltjies die kristallisasiegedrag van die poliëtilene op verskillende maniere beïnvloed. Die mate waartoe die koperdeeltjies die kristallisasiegedrag van poliëtilene beïnvloed hang ook af van die onderskeidelike morfologieë van die verskillende poliëtilene. Al die poliëtileen/wasmengsels is nie- of slegs gedeeltelik mengbaar by washoeveelhede van 30, 40 en 50%. Die teenwoordigheid van was in die poliëtileen/wasmengsels verlaag die smelttemperature van al drie poliëtilene, wat dui op ‘n plastiseringseffek van die gesmelte was in die poliëtileenmatriks. Die termograwimetriese resultate wys opvallende invloed van beide die teenwoordigheid van koper en die grootte van die koperdeeltjies, sowel as die teenwoordigheid van en hoeveelheid was, op die termiese stabiliteite van die mengsels en komposiete. Die termiese geleidingsvermoë van die komposiete wys ‘n nie-liniêre toename met toenemende hoeveelhede Cu. Die teenwoordigheid van was verminder hierdie waardes effens, wat die verkieslike kristallisasie van was om die Cu deeltjies bevestig. Die termiese geleidingsvermoë van die nanodeeltjie bevattende komposiete is byna dieselfde as dié van die mikrodeeltjie bevattende komposiete. Young’s moduli het toegeneem met toenemende koper inhoud in beide die poliëtileen komposiete en die poliëtileen/wasmengsel komposiete, behalwe in die geval van HDPE waar ‘n afname opgemerk is. Die dinamies meganiese analise stoormoduli wys dieselfde neigings as die Young’s moduli. Die treksterktes wys veranderlike gedrag, maar meestal neem die waardes af met toenemende Cu en was inhoude. Die energie storingsresultate wys dat die hitte vervoer is vinniger in die geval van die mensel komposiete vergeleke met die poliëtileen/wasmengsel komposiete, en die hitte vervoer in die poliëtileen/wasmengsel komposiete is ook vinniger as in die suiwer poliëtileen.af
dc.language.isoenen_ZA
dc.publisherUniversity of the Free State (Qwaqwa Campus)en_ZA
dc.subjectThesis (Ph.D. (Chemistry))--University of the Free State (Qwaqwa Campus), 2008en_ZA
dc.subjectPolyethyleneen_ZA
dc.subjectWaxesen_ZA
dc.subjectParaffin waxen_ZA
dc.subjectCopperen_ZA
dc.subjectHeat -- Conductionen_ZA
dc.titleInvestigation of phase change conducting materials prepared from polyethylenes, paraffin waxes and copperen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free State (Qwaqwa Campus)en_ZA


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