Study On The Flexible Polymer Composites With PTC Effect

Ever since the discovery of the polymer PTC composite materials,it has been constantly developing in the context of the close attention and hard work of researchers.Polymer PTC materials have a wide applictons due to its controllable resistivity at room temperature,wide range of PTC intensity and easy to adjust,easiness for processing,lower production cost and can suppress the NTC effect at high temperature after certain modification treatment.However,there are still some disadvantages in the existing research results.For example,how to make polymer PTC materials have lower room temperature resistivity and higher PTC strength under the premise of cost control,the stability of PTC effect is poor,and it is difficult to endow them with excellent mechanical properties and flexibility while maintaining good PTC properties.The percolation effect,PTC characteristics and mechanical properties of the polyethylene/carbon black composite are studied,and their characterization analysis is carried out by characterization test methods.A PTC composite material with a percolation threshold as low as 15% was prepared.When the content of CB is 30%,the room temperature resistivity can reach 10Ω·cm or less,and the PTC intensity can reach 6.5.Deeply studied the modification of POE in HDPE/POE/CB blend composite by controlling the variables separately.The flexibility of the composite is improved by adding POE,and the PTC stability of the composite has been improved.Prepared the HDPE/POE/CB composite PTC material with a percolation threshold of 10%-15%,and the PTC intensity can reach 6-8.When the CB content is 30% and the POE content is 18%,the composite material room temperature resistivity can be as low as 20Ω·cm,and the elongation at break can reach more than 1000%.The effect of PP on the properties of the composite when the PP which get a relatively high melting point added to the HDPE/POE/CB composite also has been studied.The addition of PP increases the mechanical strength of the composite to some extent,improves the PTC intensity and the stability of the PTC effect.The addition of PP increases the PTC strength of the composite to 7-9 and improve the stability of the PTC effect.Studied the percolation effect,PTC characteristics,stability and corresponding mechanical properties of HDPE/POE/CNTs composite.It is concluded that the percolation threshold of CNTs in the HDPE / POE / CNTs composite system is about 1%-2%,and the resistivity of the composite system decreases with increasing temperature.With the low dosage,the addition of CNTs will make the tensile strength of the composite increase first and then decrease,and the elongation at break will decrease.