The influence of mold pressing parameters on PTC of HDPE/CB composites

Abstract

The influence of mold pressing parameters on the positive temperature coefficient of high-density polyethylenel carbon black composites was investigated. The composites with a low resistivity at room temperature and a high positive temperature coefficient can be obtainee with the mold pressing parameters as follows: mold pressing pressure 6–14MPa, mold pressing temperature 150–170°C, mold pressing time about 15 min, and room temperature of molded specimen after cooding for 20–60 minutes. The positive temperature coefficient effect of the composite is 7.7 when it is prepared under the mold pressing parameters, and the negative temperature coefficient effect is less than 0.8. Scanning electron microscopy (SEM) reveals some aggregations of carbon black particles with a size of 1 μm inside the composite, which was obtained at the mold pressing temperature of 180°C.

Keywords

composites / PTC / molding

References

[1] C P Wong, S Lou. Investigation on Effect of Carbon Black and Polymer Matrix on Conductive Polymer Composites with Positive Temperature Coefficient. In: 2000International Symposium on Advanced Packaging Materials, 2000: 343–348

[2] Omastova M, Chodak I, Pionteck J. Electrical and Mechanical Properties of Conducting Polymer Composites. Synthetic Metals, 1999, 102: 1251-1252.

[3] Feng J, Chan C M. Double Positive Temperature Coefficient Effects of Carbon Black-filled Polymer Blends Containing Two Semi-erystalline Polymers. Polymer, 2000, 41: 4559-4565.

[4] Premamoy G, Chakrabarti A. Conducting Carbon Black Filled EPDM Vulcanizates: Assessment of Dependence of Physical and Mechanical Properties and Conducting Character on Variation of Filler Loading. Journal of European Polymer, 2000, 36: 1043-1054.

[5] Chan C M, Cheng C L, Yuen M F. Electrical Properties of Polymer Composites Prepared by Sintering a Mixture of Carbon Black and Ultrahigh Molecular Weight Polyethylene Power. Polymer Engineering and Science, 1997, 37(7): 1127-1136.

[6] Nobuyuki A, Manabu T. Electrical Resistivity of the Polymer Layers with Polymer Grafted Carbon Blacks. Thin Solid Films, 1998, 334: 182-186.

[7] Xiong C X, Hu H R, Zhou Z Y, . Preparation of Polyacrylate-based Conductive Coatings and Its PTC Effect. Journal Wuhan University of Technology—Materials Science Edition, 2004, 19(1): 26-29.

[8] He X J, Chen F, Chen X F. PTC Effect of Carbon Black Filled Polypropylene. Journal of Materials Science Letters, 2001, 20: 589-590.

[9] Feng J, Chan C M. Positive and Negative Temperature Coefficient Effects of an Alternating Copolymer of Tetrafluoroethylene-ethylene Containing Carbon Black-filled HDPE Particles. Polymer, 2000, 41: 7279-7282.