Research On Improving The Dispersion And Performance Of CNTs/PC Composites By Ultrasound

Polycarbonate(PC)is one of the five major engineering plastics due to its excellent engineering properties,and its output ranks second among the five major engineering plastics.However,there are some unavoidable problems during its use:polycarbonate has poor fatigue resistance,resulting in short service life;polycarbonate has poor solubility resistance and is sensitive to notches;polycarbonate has high surface resistivity and its products will produce electrostatic effect,affect its use in the electronic and electrical industry.The modification of polycarbonate is particularly important.Carbon nanotubes(CNTs)have excellent mechanical and electrical properties.When they are added to polycarbonate materials as fillers,they can improve the above-mentioned defects of polycarbonate.The research direction of adding CNTs as fillers to the matrix of polymer materials has become a hot spot in the field of polymer research.This paper found through experiments that during the injection molding process of the PC/CNTs composite,the heating and melting will make the CNTs in the PC/CNTs composite reunite in the PC matrix.Secondary agglomeration is called the secondary agglomeration phenomenon of CNTs in this article.The secondary agglomeration of PC/CNTs composites is rarely reported in domestic and foreign research.In response to this problem,this article proposes the use of ultrasonic-assisted heating to introduce ultrasonic waves into the melting process of PC/CNTs composites,which can inhibit the secondary agglomeration of CNTs while making the dispersion of CNTs in the PC matrix more uniform.The industrial production of /CNTs composite materials has guiding significance.In this paper,the PC/CNTs composite materials prepared by melt blending are heated and ultrasonically assisted heating treatments respectively.Through environmental scanning electron microscope(SEM)tests on the cross-sections of the two sets of samples,the influence of heating and ultrasonic-assisted heating on the dispersion of CNTs was directly observed.Through the rheometer test and analysis of two sets of PC/CNTs composite samples.The rheological properties of the PC/CNTs composites were tested and analyzed,and the storage modulus,loss modulus,and complex viscosity of the PC/CNTs composite material in the low-frequency range under small amplitude shear oscillation were obtained,and the dispersion of CNTs in the PC matrix was analyzed.Finally,the differential scanning calorimeter(DSC)analysis showed that the thermal properties of the PC/CNTs composite material changed under different processing methods.The influence of heat treatment and ultrasonic-assisted treatment on the dispersion of CNTs is deduced from it.After deriving the influence of heating and ultrasonic than auxiliary heating on the dispersibility of CNTs in the PC matrix,the mechanical properties of PC/CNTs composites with two treatment methods were tested,such as tensile and nanoindentation,and the effect of ultrasonic-assisted heating treatment on the mechanical properties of the mechanical materials was tested.The results showed that:(1)The CNTs in the micro-topography of the PC/CNTs composite sample treated by ultrasonic-assisted heating were well dispersed,while in the sample treated only by heating,as the heating time and CNTs content increase,the number of CNTs not only increases.The more it comes,the larger its scale.(2)Ultrasonic heating treatment can make the storage modulus and complex viscosity of the PC/CNTs composite material in the small amplitude shear vibration test move to a higher direction,which means that the CNTs form a stronger network,that is,the CNTs in the PC Improvement of matrix dispersion.(3)Comparing the DSC curve of the sample loaded without ultrasound,only heating treatment will make the Tg of the PC/CNTs composite material increase,while the ultrasonic-assisted heating will make the Tg of the PC/CNTs composite material decrease,and the PC/CNTs composite The change of the material Tg is that heating will cause CNTs to agglomerate for the second time.More PC molecular chains will participate in the heat capacity process of glass transition,and ultrasound will break the agglomerates of CNTs,so that fewer PC molecular chains will participate in the heat capacity process.in.(4)PC/CNTs composite material after ultrasonic-assisted heating has better elastic modulus,elongation at break,tensile strength,yield stress,hardness,etc.are all increased by5 % to 15 %.