Heating Characteristics Of PANI Conductive Composites And Resistance Welding Of Polymer

Conductive polyaniline nanofibers were synthesized taking hydrochloric acid as the doping agent in this paper. The influence of pH value, ratio of aniline and ammonium persulfat and aniline concentration on the polymer structure and performance was examined.Then taking conductive polyaniline as conductive filler polyaniline conductive composite material was prepared. The effects of conductive filler ratio on the properties of conductive composite material were studied. The resistance heating rules of different ratio of the conductive composites were explored. Then, plastic welding experiments were conducted by using this conductive composite material as resistance. By monitoring the welding process,the influence of the welding voltage and welding time on welding strength was explored,further more, the optimal welding process conditions were achieved. Then, temperature field in welding process was simulated applying the finite element simulation software and the temperature field distribution in the process of welding was studied. Finally the simulation results were verified by the actual welding experimental results of producing heat.In this study, polyaniline was synthesised through Chemical oxidation polymerization and conductive composite materials was prepared by melt blending. The structure,properties and micro-morphologies of polyaniline and composite materials were investigated by FTIR,four-probe meter, SEM and DMA. The results showed that pH values, the ratio of polyaniline and ammonium persulfate and aniline concentrations are the main factors affecting the properties of polyaniline. The electrical properties of polyaniline are improved with the decrease of PH values, which also leads to significant differences in their structure and morphology. When the concentration of ammonium persulfate increases, the conductivity of the resulted polymer displays a nonlinear change. At the same time, their morphologies transform from platy aggregate to a fibrous structure. The conductivity of the resulted polymer decreases accompanying with the increase with the concentration of aniline, while the fiber diameter becomes thick. The conductivity of the composite materials increases with the increase of weight ratio of conductive filler. In addition, the sample using PP as matrix show better electrical properties compared with those filled with ABS when the weight ratio is the same. The heating curve indicates that the heat production of composite materials increases with the increase of weight ratio of conductive filler. What's more,the heat production of sample filled by PP is superior to those by ABS with same proportion. The dynamicmechanical analyze proves that mechanical properties of the composite materials are superior while adding both organic and inorganic fillers.In this paper,the change rules of the resistivity with temperature changed were discussed in welding process, founding that the electrical resistivity were declined as temperature increased which demonstrated it was NTC materials. What's more, the producing heat performance of resistance pellet was studied and the welding voltage was chosen according to the rule of producing heat. In addition, the influence of welding time on welding performance was analysed, concluding that increasing welding time appropriately can improve strength of the weldment, however, if welding time is too long could lead to welding zone temperature exorbitant, which made the welding parts damaged and influenced the quality of the welded joint. Then, applying finite element simulation software to simulate temperature field and the distribution of temperature field and its change rules in welding process were observed.Finally, the simulation results were verified according to regularity of actual welding experiments.