The Adjustment And Control Of Conductive Network In Pmvs/tpu Polymer Blends And The Study Of Structure And Property

Improving the electrical conductivity and reducing the content of conductive fillers have becoming two main research targets on preparing conductive pofymer composites.It was found that the formation of double percolation conductive network structure of conductive filler loaded pofymer blends can not only improve the conductivity of eomposites but also reduce the content of filler.The double percolation conductive network structure has been widely used in the field of plastics but rarely in elastomer materials.In this subject,we prepared conductive composites using polymethylvinylsiloxane(PMVS)and polyurethane elastomer(TPU)as matrix at the same time filled with graphene(G)and carbon black(CB)as conductive fillers.We applied the double percolation theory in the field of elastomers to improve the electrical conductivity and decrease percolation threshold.Firstly,three key weight proportions of TPU:PMVS=30:70,TPU:PMVS=50:50 and TPU:PMVS=70:30 were designed to study the effect of the morphology on conductivity.As a result,for the PMVS/TPU composites at 30:70 and 70:30,we can observe typical sea-island structure.Instead,for the PMVS/TPU composites at 50:50,a cocontinuous structure is well developed.Under the same filler dosage,the conductivity of PMVS/TPU composite at 50:50 is higher than that at 30/70 and 70/30.It is indicated that the morphology of the matrix is one of the factors affecting the electrical conductivity of the composites.In addition,through the theoretical prediction and experiment,conductive filler was proved to selectively locate in the TPU phase.Then,G/TPU composite,G/PMVS composite and G/TPU/PMVS(TPU:PMVS=50:50)composite are prepared to research the conductivity and mechanical properties in different dosage of G.It came out that the conductivity of G/TPU/PMVS(TPU:PMVS=50:50)composite is higher than that of G/TPU and G/PMVS composite but elastic property is between G/TPU and G/PMVS composite,while mechanical property is worse than that of G/TPU and G/PMVS composite.When TPU:PMVS=50:50 was chosen,G/TPU/PMVS,CB/TPU/PMVS and G/CB/TPU/PMVS composite were prepared and the effect of the filler's amount on the conductivity was studied.It was found that the more filler use,the higher the conductivity is.When G was the conductive filler,percolation threshold of G/TPU/PMVS was finally obtained at 1.25 wt%.Simultaneously,its conductivity increased by 6 orders of magnitude and the conductive network begins to form.When CB as the conductive filler,percolation threshold of CB/TPU/PMVS was finally obtained at 2.23 wt%.Simultaneously,its conductivity increased by 5 orders of magnitude and the conductive network begins to form.Finally,G and CB were used together as conductive fillers(G:CB=1:1),percolation threshold of CB/GATPU/PMVS was obtained at 1.72 wt%,which indicate that the composite has better than the composite with the same amount of CB.