Forming The Structure And Properties Of The Carbon Black - High Density Polyethylene Conductive Composites

In this paper, CB-HDPE (high-density polyethyIene) composite was choosing,basing on industrialized equipments, technics and raw materials for processingcarbon(CB) black-polymers composites. Firstly from the vieWPoint of processing,the effects of industrialized processing conditions on conductive, mechanical andprocessible properties were studied systematically and deeply. By means of ESCA,IGC, WD, DSC ) SEM and computer aided image processing technique, therelations of composite's microsimcture and macroscopic properties were researchedand conclusions were listed as follows.l. StUdying effect of CB treatment with four types representative processingaids on conductivity, mechanical property and rheology, writer have discovered:ALL four kind of processing aids benefit the improvement of these three kind ofproperties, but reveals its own characteristic. Improvement of conductivity is moredistinct, fOr example, titanate coupling agent and stearic acid decrease itscomposite's room temperature resistivity 10l -- 102 times, as CB content is15%(w/w). The writer have given reasons for these phenomenon and put forwarthe own standpoints in the paper.2. Studied systematically the effect of two types of blending processes forCB-HDPE composite processing on the properties of the composite, the writerconsider that enhancement of blend is bad fOr conductivity; but blend in molten stateis good for impact strength and flowabiIity, and in solid state effect of blend isminate. Blend in molten state make HDPE crystals small, crystallinity large,quantity of CB particle benefit to conductivity decreasing; in solid state CBaggregate is sheltered with a insulate HDPE film, also CB structure will be brokendown during blend; all of these will make conductivity bad. But processing alds canlower this effect obviously.3.The effect of crosslink is restricting the movement of molten polymermolecules. As a result, increases composite's using temperature and stYengthens;stabilizes PTC intensity. But it hinders HDPE recrystallizability; raises heattreatment composite's room temperature resistivity, Weakens the heating agingproperty of the composite; Lowers the composite's hot decomposition temperature.4. Investigate relation of composite's resistivity and time at constanttemperature, firstly introducing principle of time temperature equivalent andrelaxation theory. On the basis of experimenta1 results put forward a new viewnointabout arising process and mechanism of H- PTC/ NTC, which can gives morecomplete and reasonable explains for the experimental phenomenon.5. Broke the limit of traditional heat tredrient method, temperature is belowmelting point of HDPE. Increasing temperature beyond the melting point,investigate the differences of composite's properties betWeen heat treatmeni and not.Discovered that heat treatment under high temperature can improve composite'sconductivity obviously; eliminate disadvantage effect of processing on conductivity;increase repeatable and stability of composite's resistivity in the processing, andheighten the quantity of qualified product. Give a reasonable explain for it, and bringforward optimization scheme for processing technics (the scheme have aPplied fOrthe patent).Doubtless, the results of this research pioneer an effective, economical, viableand new way, for lowering CB cofltent, increasing the material's usage period andprocessibIe property, in the research of the CB-polymer conductive composites.