Preparation Of Paraffin Based Composites Containing Nano Cu₂O,Nanocopper/CNTs With Phase-Change Actuation And Study On The Thermal Properties

Paraffin with larger body expansion coefficient,stable chemical properties,rich source and low price,were focused on many fields,especially the micro-actuator.Paraffin has great potential in the high power micro-actuator,because paraffin as the power source of the micro-actuator can provide larger driving force and drive displacement.The low thermal conductivity of paraffin limits the further development of paraffin,because the low speed of thermal response of paraffin need to consume more energy to achieve a certain drive displacement.This paper tries to improve the thermal conductivity and the speed of thermal response of paraffin,with added the high thermal conductivity particles to the paraffin.In this thesis,cuprous oxide(Cu₂O)nanowires/particals and cuprous oxide/paraffin composites were synthesized by thermal decomposition using copper formate-octylamine as the precursors.The effects of different parameters parameters on phase structure,morphology,chemical state and phase transition behavior were investigated by means of X-ray diffraction,scanning electron microscopy,transmission electron microscopy,infrared spectroscopy,and differential scanning calorimetry.The thermal properties of composites were also studied by water bath device.The effects of surfactant concentration,precursor concentration and reaction temperature on morphology,size and distribution of cuprous oxide nanoparticles were investigated and the growth mechanism of cuprous oxide nanoparticles was also discussed.Main achievements and work are obtained as follows:Cuprous oxide(Cu₂O)/paraffin composites were synthesized by thermal decomposition using copper formate-octylamine as the precursors,oleic acid and oleylamine as the surfactant in the paraffin as solvent.A different form of cuprous oxide was obtained by changing the precursor concentration.The growth mechanism of cuprous oxide nanowiress was further investigated.Nanocopper decorated carbon nanotubes(Cu/MWCNTs)/paraffin composites was synthesized by thermal decomposition of Copper(II)formate-carbon nanotubes precursor in the paraffin using oleylamine as a surfactant,copper nanoparticles were attached to the carbon nanotubes surface.With the increase of oil amine and oleic acid mole ratio,cuprous oxide dispersion degree increase and composites thermal conductivity also gradually improve.With the increase of precursor concentration,cuprous oxide particle size decreased and then increased,composites thermal conductivity increased and then decreased.Nanocopper was more likely to deposit on carboxyl carbon nanotubes(COOH-CNTs)surface to form nano Cu/COOH-CNTs composites.And the thermal properties of nano Cu/COOH-CNTs/paraffin composites was better.