Compatibilization Of Liquid Sn/Melt PA6 Blends

Low-melting-point metals refer to simple metals or alloys with melting points below300°C.Common low-melting-point metals include Sn,Ga,In,and eutectic Sn-based alloys.Due to the characteristics of high conductivity,high fluidity and low toxicity of low melting point metals,it has been a hotspot for many scholars in recent years.Liquid metals at room temperature have been successfully used in microfluidic chips,software robots and flexible electronics.Although the research on low-melting-point metals has been continuous,its application has been greatly restricted.The main reason is the incompatibility of metal liquids and non-metallic materials.It is difficult to prepare uniformly dispersed liquid metal composites,or it is a big challenge to prepare liquid metal composites with nanometer scale.At present,the most commonly used is to compound liquid metal and polymer together to prepare functional composites.The dispersion size of the metal liquid is mostly above 20μm for liquid metal/polymer composites.At this time,the prepared composite is dielectric,and it does not have electrical conductivity.Until now,the difficult compounding of metal liquids and polymers has been a problem that plagued many researchers,so compatibilization of metal liquids/polymer systems has become necessary.Nanoparticles have been reported to compatibilize incompatible polymer blending systems.Inspired by this,we thought of using nanoparticles as compatibilizer to compatibilize low melting point metal liquid/polymer melt blends.In this paper,we studied the compatibilization of low melting point metal liquid/polymer melt blends by inorganic nanoparticles with Sn as the low melting point metal component and PA6 as the polymer component.First,we studied the influence and stability mechanism of inorganic nanoparticle types on the Sn liquid/PA6 melt blending behavior.We plan to use high-melting compounds with and without Sn metal elements and some carbon-based nanoparticles as investigation objects,and then determine nano-SnO₂ is the compatibilizer of Sn/PA6system.With the increase of nano-SnO₂ content,the arithmetic average particle size and volume average particle size of Sn particles in this system decrease,the smallest Sn particle size reaches the nanometer scale,and the interface debonding phenomenon of Sn particles and PA6 matrix also Obviously improved.And with the increase of nano-SnO₂ content,the interfacial tension of Sn liquid and polymer melt is also gradually reduced,again verifying the fact of compatibilization.It is reported that the conductivity of the low melting point metal/high melting point metal/polymer composite prepared by melt blending has an order of magnitude improve compared with that of the low melting point metal/polymer system because of the formation of a physically continuous metal network structure within the system.So we also studied the effect of nano-SnO₂ compatibilization on the microstructure of Sn/Cu/PA6composites.Composites with 40vol%total metal content and different compatibilizer content/remaining low melting point metal liquid ratio（V_N/V_L）were prepared.When V_N/V_L=0,except for the conductive metal phase formed in the composite,there are few or few free Sn particles in the polymer matrix.As the ratio of V_N/V_L increases,the continuity of the conductive metal network in the original system gradually deteriorates,and the number of free Sn particles in the polymer matrix gradually increases.When V_N/V_L=1.25,there are a large number of free Sn particles in the polymer matrix of the composite material.The metal liquid that originally constituted the conductive metal phase was"stripped",leaving only the solid intermetallic compound Cu₆Sn₅.The continuity of the conductive metal network in the system is destroyed,which also destroys the conductive network of the system.The research of low melting point metal/high melting point metal/polymer system shows that when the proportion of low melting point metal and high melting point metal is appropriate,the metal liquid will not be precipitated in the process of melting and mixing,but when the proportion is too high,the metal liquid will still be precipitated.In other words,in order to keep the metal liquid from separating out in the process of melting and mixing,there is a maximum ratio of low melting point metal to high melting point metal,which we call critical liquid-solid ratio.In this paper,we found that increasing the temperature is helpful to increase the critical liquid-solid ratio.In this chapter,we prepared Sn/Cu/PA6composite with 53.3vol%total metal content and different liquid-solid ratio at different processing temperature.The effect of processing temperature on the microstructure and liquid-solid ratio of Sn/Cu/PA6 composite was studied.The results show that under the same liquid-solid ratio,the higher the processing temperature,the less metal liquid is left in the composite material.For Sn/Cu/PA6 ternary composites with different processing temperatures,the higher the processing temperature,the higher the critical liquid-solid ratio of the composite.When the processing temperature is 300℃,the critical liquid-solid ratio of the Sn/Cu/PA6 composite can reach 5.And if the liquid-solid ratio is high enough,the more perfect the metal network structure inside the composite.For Sn/Cu/PA6 ternary composites with the same processing temperature and different liquid-solid ratio,the metal network structure of the composite with higher liquid-solid ratio is more continuous and the phase domain size is larger when Sn liquid does not separate out.According to the previous reports,the composite with this structure has more excellent comprehensive properties.