Preparation And Property Research Of Nanocopper/paraffin Phase Change Composites For Actuation

Paraffin has become an ideal material for microactuator because of its low price and simple molding process,good stability and high volume phase transition expansion,paraffin microactuator has lots of advantages,including large driving force and driving displacement,simple manufacturing process,good environmental adaptability.It has been very potential in the future.The main drawback of paraffin is its low thermal conductivity,adding high thermal conductivity material to paraffin may increase its thermal conductivity,thus improving thermo-sensitivity.In this paper,we present a new method to prepare nanocopper/paraffin composite phase change materials-thermal decomposition of copper formate-amine precursors in one step.In this process,paraffin is used as both a reaction solvent and protective agent,thus eliminating the need for the collection and preservation of copper,since copper is tend to be oxided,the process is simple.This paper has studied the thermal decomposition process of four copper formate-amine complexes,choosing copper formate-octylamine complex as the optimal reaction precursor,then we explores the influence of the reaction temperature,the precursor concentration,stirring speed and surfactant types on particle size and morphology of nanocopper.The results show that nanocopper particle size is related to the reaction temperature,the optimum reaction temperature is 150?;precursor content has no effect on nano-particle size and morphology of nanocopper,with the increasing content of the precursor,nano-copper agglomeration phenomenon gradually increased;with stirring speed increases,the shape of a spherical copper nano gradual transition to the cube,and finally into a sphere;using oleylamine as the surfactant favors the dispersion of the nano copper,the average particle diameter is 10nm;using oleic acid as surfactant can prepare nano-copper with different morphology,like square,spherical,rod and triangles;using oleic acid and oleylamine as surfactant can prepare nano copper of flower-like morphology,which is composed by 5-6nm nano-copper particles.Finally,5wt%copper content of nano Cu/paraffin composite materials and oleylamine,oleic acid,oleylamine and oleic acid composite Modified Cu/paraffin composites are studied for its heat-sensitivity,thermal expansion and thermal stability.The results shows that the thermal response time of oleylamine and oleic acid-modified nano-Cu/paraffin composite is reduced by 55%,which proves to be best in heat-sensitivity.Expansion of all the composite were 7.72%,indicating that the surfactant has no effect on the volumn expansion.Oleylamine and oleic acid-modified nano-Cu/paraffin composite has the best thermal stability,which proves to be the ideal material for phase-change driven.