Features of the change in the thermal coefficient of electrical resistance upon heating electrically conductive composites of crystallizable polyolefins with carbon black

Objectives. To investigate electrically conductive polymer composite materials (EPCMs) based on crystallizable polyolefins and electrically conductive carbon black for the production of self-regulating heaters; to study the mechanism of the occurrence of positive and negative temperature coefficients (PTC and NTC) upon heating such composites.
Methods. A comprehensive study of the structure and properties of crystallizable EPCMs with electrically conductive technical carbon was carried out. In order to measure the electrical characteristics of the composites, they were compacted into plates to model polymer heaters. Contact electrodes made of an ungreased brass mesh were embedded in their ends. The temperature dependencies of the electrical characteristics of the samples were investigated in a modified thermal chamber of an FWV 633.10 Vicat softening temperature meter. The change in the degree of crystallinity was analyzed by means of differential scanning calorimetry with a NETZSCH DSC 204 F1 Phoenix calorimeter. The dilatometric and rheological characteristics of the samples were studied using an IIRT-AM melt flow index tester.
Results. It was determined that the self-regulation ability (an abnormally high positive thermal coefficient of electrical resistance) of selfregulating heaters made of composites of crystallizable polyolefins with electrically conductive technical carbon cannot be explained by the thermal expansion of EPCMs alone. It was shown that in crystallizable polyolefin-based EPCMs, the inversion of the thermal coefficients of electrical resistance (transition from PTC to NTC) is associated with a change in the aggregate state of EPCMs and the beginning of its transition to a viscous-flow state. A mechanism involving a sharp increase in the electrical resistance of self-regulating crystallizable polyolefin-based composite with electrically conductive technical carbon was proposed and substantiated. This mechanism takes into account the additional shear deformation effect produced on the crystalline phase of the EPCM by numerous expanding melt microvolumes formed at the early stages of the melting process with a minimum change in the degree of crystallinity.

1. Ragushina M.D., Evseeva K.A., Kalugina E.V., Ushakova O.B. Polymer composite materials with electrically conductive antistatic properties. Plasticheskie Massy. 2021;(3-4):6-9 (in Russ.). https://doi.org/10.35164/0554-2901-2021-3-4-6-9

2. Bregman A., Taub A., Michielssen E. Computational design of composite EMI shields through the control of pore morphology. MRS Communications. 2018;8(3):1153-1157. https://doi.org/10.1557/mrc.2018.171

3. Chen J., Zhu Y., Huang J., Zhang J., Pan D., Zhou J., Ryu J., Umar A., Guo Z. Advances in Responsively Conductive Polymer Composites and Sensing Applications. Polym. Rev. 2021;61(1):157-193. https://doi.org/10.1080/15583724.2020.1734818

4. Chen L., Zhang J. Designs of conductive polymer composites with exceptional reproducibility of positive temperature coefficient effect: A review. J. Appl. Polym. Sci. 2021;138(3):49677. https://doi.org/10.1002/app.49677

5. Zhang P., Wang B. Positive temperature coefficient effect and mechanism of compatible LLDPE/HDPE composites doping conductive graphite powders. J. Appl. Polym. Sci. 2018;135(27):46453. https://doi.org/10.1002/app.46453

6. Zhang C., Ma C.A., Wang P., Sumita M. Temperature dependence of electrical resistivity for carbon black filled ultra-high molecular weight polyethylene composites prepared by hot compaction. Carbon. 2005;43(12):2544-2553. https://doi.org/10.1016/j.carbon.2005.05.006

7. Shen L., Wang F.Q., Yang H., Meng Q.R. The combined effects of carbon black and carbon fiber on the electrical properties of composites based on polyethylene or polyethylene/polypropylene blend. Polym. Test. 2011;30(4):442-448. https://doi.org/10.1016/j.polymertesting.2011.03.007

8. Markov V.A., Kandyrin L.B., Markov A.V. The effect of deformation on the electrical resistance of composites based on polyethylene and carbon black. Konstruktsii iz kompozitsionnykh materialov = Composite Materials Constructions. 2013;4:40-44 (in Russ.).

9. Markov A.V., Tarasova K.S., Markov V.A. Effect of relaxation processes during deformation on electrical resistivity of carbon black polypropylene composites. Tonk. Khim. Tekhnol. = Fine Chem. Technol. 2021;16(4):345-351. https://doi.org/10.32362/2410-6593-2021-16-4-345-351

10. Markov A.V., Gushchin V.A., Markov V.A. Thermoelectric characteristics of electrically conductive composites based on mixtures of crystallizing and amorphous polymers with technical carbon. Plasticheskie Massy. 2019;(1-2):44-47 (in Russ.).

11. Markov A.V., Markov V.A., Chizhov A.S. The influence of the characteristics of polyethylene on thermoelectric properties of their composites with black carbon. Plasticheskie Massy. 2021;(5-6):18-23 (in Russ.). https://doi.org/10.35164/0554-2901-2021-5-6-18-23

12. Zeng Y., Lu G., Wang H., Du J., Ying Z., Liu C. Positive temperature coefficient thermistors based on carbon nanotube/polymer composites. Sci. Rep. 2014;4(1):6684. https://doi.org/10.1038/srep06684

13. Luo S., Wong C.P. Study on effect of carbon black on behavior of conductive polymer composites with positive temperature coefficient. IEEE Trans. Compon. Packag. Technol. 2000;23(1):151-156. https://doi.org/10.1109/6144.833054

14. Vigueras-Santiago E., Hernnández-López S., Camacho-Lopez M., Lara-Sanjuan O. Electric anisotropy in high density polyethylene + carbon black composites induced by mechanical deformation. J. Phys.: Conf. Ser. 2009;167(1):012039. https://doi.org/10.1088/1742-6596/167/1/012039

15. Chen Y., Song Y., Zhou J., Zheng Q. Effect of uniaxial pressure on conduction behavior of carbon black filled poly(methyl vinyl siloxane) composites. Chinese Sci. Bull. 2005;50: 101-107. https://doi.org/10.1007/BF02897510

16. De Focatiis D.S.A., Hull D., Sánchez-Valencia A. Roles of prestrain and hysteresis on piezoresistance in conductive elastomers for strain sensor applications. Plastics, Rubber and Composites. 2012;41(7):301-309. https://doi.org/10.1179/1743289812Y.0000000022

17. Lee G.J., Suh K.D., Im S.S. Study of electrical phenomena in carbon black-filled HDPE composite. Polym. Eng. Sci. 1998;38(3):471-477. https://doi.org/10.1002/pen.10209

18. Choi H.J., Kim M.S., Ahn D., Yeo S.Y., Lee S. Electrical percolation threshold of carbon black in a polymer matrix and its application to antistatic fibre. Sci. Rep. 2019;9(1):6338. https://doi.org/10.1038/s41598-019-42495-1

19. Tang H., Chen X., Luo Y. Studies on the PTC/NTC effect of carbon black filled low density polyethylene composites. Eur. Polym. J. 1997;33(8):1383-1386. https://doi.org/10.1016/S0014-3057(96)00221-2

20. Brigandi P.J., Cogen J.M., Pearson R.A. Electrically conductive multiphase polymer blend carbon‐based composites. Polym. Eng. Sci. 2014;54(1):1-16. https://doi.org/10.1002/PEN.23530

21. Zaikin A.E., Bikmullin R.S., Zharinova E.A. Specifics of localization of carbon black at the interface between polymeric phases. Polym. Sci. Ser. A. 2007;49(3):328-336. https://doi.org/10.1134/S0965545X07030145 [Original Russian Text: Zaikin A.E., Zharinova E.A., Bikmullin R.S. Specifics of localization of carbon black at the interface between polymeric phases. Vysokomolekulyarnye Soedineniya. Ser. A. 2007;49(3):499-509 (in Russ.).]

22. Markov A.V., Chizhov A.S. Self-regulating electrically conductive materials based on polyethylene compositions with UHMWPE and carbon black. Tonk. Khim. Tekhnol. = Fine Chem. Technol. 2019;14(2):60-69. https://doi.org/10.32362/2410-6593-2019-14-2-60-69

23. Zhou P., Yu W., Zhou C., Liu F., Hou L., Wang J. Morphology and electrical properties of carbon black filled LLDPE/EMA composites. J. Appl. Polym. Sci. 2007;103(1):487-492. https://doi.org/10.1002/app.25020

24. Bao Y., Xu L., Pang H., Yan D.X., Chen C., Zhang W.Q., Tang J.H., Li Z.M. Preparation and properties of carbon black/ polymer composites with segregated and double-percolated network structures. J. Mater. Sci. 2013;48:4892-4898. https://doi.org/10.1007/s10853-013-7269-x

25. Yurkin A.A., Kharlamova K.I., Abramushkina O.I., Surikov P.V. Tekhnologiya pererabotki plasticheskikh mass ( Plastic Processing Technology: educational manual). Moscow: RTU MIREA; 2023. 95 p. (in Russ.). ISBN 978-5-7339-1995-9

26. Markov V.A., Kandyrin L.B., Markov A.V. The effect of polymer crystallization on the electrical resistance of their compositions with carbon black. Konstruktsii iz kompozitsionnykh materialov = Composite Materials Constructions. 2013;3:35-40 (in Russ.).

27. Knite M., Teteris V., Kiploka A., Kaupuzs J. Polyisoprenecarbon black nanocomposites as tensile strain and pressure sensor materials. Sens. Actuators A: Phys. 2004;110(1-3): 142-149. https://doi.org/10.1016/j.sna.2003.08.006

28. Starý Z., Krückel J., Schubert D., Münstedt H. Behavior of Conductive Particle Networks in Polymer Melts under Deformation. AIP Conf. Proc. 2011;1375:232-239. https://doi.org/10.1063/1.3604483

29. Xie H., Dong L., Sun J. Influence of radiation structures on positive-temperature-coefficient and negative-temperaturecoefficient effects of irradiated low-density polyethylene/ carbon black composites. J. Appl. Polym. Sci. 2005;95(3): 700-704. https://doi.org/10.1002/app.21220

30. Yi X.S., Zhang J.F., Zheng Q., Pan Y. Influence of irradiation conditions on the electrical behavior of polyethylene carbon black conductive composites. J. Appl. Polym. Sci. 2000;77(3):494-499. https://doi.org/10.1002/(SICI)1097-4628(20000718)77:3<494::AID-APP4>3.0.CO;2-K

31. Lee G.J., Han M.G., Chung S.Ch., Suh K.D., Im S.S. Effect of crosslinking on the positive temperature coefficient stability of carbon black-filled HDPE/ethylene-ethyalacrylate copolymer blend system. Polym. Eng. Sci. 2002;42(8):1740-1747. https://doi.org/10.1002/PEN.11067

32. Xie H., Deng P., Dong L., Sun J. LDPE/Carbon black conductive composites: Influence of radiation crosslinking on PTC and NTC properties. J. Appl. Polym. Sci. 2002;85(13):2742-2749. https://doi.org/10.1002/app.10720

33. Seo M.K., Rhee K.Y., Park S.J. Influence of electro-beam irradiation on PTC/NTC behaviors of carbon blacks/HDPE conducting polymer composites. Curr. Appl. Phys. 2011;11(3):428-433. https://doi.org/10.1016/j.cap.2010.08.013

34. Markov V.A., Kandyrin L.B., Markov A.V., Sorokina E.A. Effect of silane-crosslinking on electrical properties and heatresistance of carbon black-filled polyethylene composites. Plasticheskie Massy. 2013;(10):21-24 (in Russ.).