Mechanical Properties Of Nano-CaCO₃Modified HDPE Sheath Of ADSS Optical Cable

High density polyethylene （HDPE） is suitable for10-35kV ADSS opticalcable sheath due to its excellent insulativity and environmental stress crackresistance, the tensile property of ADSS optical cable will be further improvedwith using HDPE which has excellent mechanical performance. For this, it willdecrease the usage amount of aramid yarn which is the main bearing element andthen reduce cost and expand applications.Nano-CaCO₃was filled in HDPE cable sheath in this paper aimed atimproving its mechanical properties. First, for improving the reunite and poorcompatibility questions, nano-CaCO₃was modified with aluminate couplingagent （ACA）, titanate coupling agent （TCA） and complex ester coupling agent（CECA）. Modification of modified CaCO₃（CA-CaCO₃） was characterized withactivation grade analysis and the optimal modification processes of each couplingagent were obtained. Coating effects of coupling agent on nano-CaCO₃werecharacterized with fourier transform infrared spectroscopy （FT-IR） analysis andthermogravimetric （TGA） analysis. Surface appearance and dispersibility werecharacterized with scanning electron microscope （SEM）, specific surface areaand sediment volume analysis. Second, CaCO₃/HDPE and other nanometerinorganic materials/HDPE optical cable sheath were prepared by melt blendingmethod and their mechanical properties were characterized and compared.Electrical and thermal aging properties of CA-CaCO₃/HDPE sheath have alsobeen studied.Experiment results showed that: CaCO₃which modified with CECA（CECA-CaCO₃） has the highest activation grade （approach to100%） and itsoptimal modification technological conditions are: concentration of CaCO₃is8.5%, modification time is70min, modification temperature is75℃and usage amount of CECA is greater than4wt.%. CaCO₃are covered by coupling agent,particle size change indistinctly, specific surface area is increased and thedispersibility is improved. CECA-CaCO₃shows the best dispersibility in matrixand its mechanical properties improving effect are better than ACA-CaCO₃andTCA-CaCO₃. Dosage of coupling agent should not be excessive or it will lowerthe mechanical properties slightly, otherwise the mechanical properties of opticalcable sheath decrease seriously with filling CaCO₃which are not modified （UM-CaCO₃）. Dispersiblility of modified CaCO₃in matrix can be influenced for itsexcessive dosage and the small dosage （less than10wt.%） can improve themechanical properties of HDPE cable sheath significantly. Tensile strength andelongation of HDPE cable sheath are separately increased16.8%and60.4%compared to the matrix when dosage of CECA-CaCO₃is7.5wt.%. CaCO₃filledsystem is better than SiO2, TiO2and ATH systems but little worse than Al₂O₃andZnO systems. Electrical properties of HDPE cable sheath are decreased for fillingof CaCO₃but it can also meet the requirements of national standard, thermalaging property is increased for filling of CaCO₃.