Journal of Electrostatics 120 (2022) 103755 0304-3886/© 2022 Elsevier B.V. All rights reserved. Investigation of electrical resistivity and electrostatic discharge sensitivity of Mg/ Ba(NO 3 ) 2 /novolac resin composite Mohammad Zhiani a, b, * , Akbar Zare a a Department of Chemistry, Isfahan University of Technology, Isfahan, 84156- 83111, Iran b Department of Physical Chemistry, Tarbiat Modares University, Tehran, 14115-175, Iran A R T I C L E INFO Keywords: Electrical resistivity ESD sensitivity Minimum ignition energy Mg/Ba(NO 3 ) 2 / novolac resin composite Response surface method Experimental design ABSTRACT Each composite energetic material (CEM) has specifc electrical resistivity (ER) and electrostatic discharge (ESD) sensitivity. These parameters depend on the concentration of composite ingredients. The effect of different mole ratios of ingredients on the ER and ESD sensitivity of Mg/Ba(NO 3 ) 2 /novolac resin composite was modeled by response surface methodology (RSM) and central composite design (CCD). Nonlinear regression analysis and analysis of variance (ANOVA) indicated that the predicted responses were in good agreement with the experi- mental results. The results showed an inversely proportional correlation between increasing the mole ratio of Mg with ER and the minimum ignition energy (MIE) of ESD ignition. Similarly, there is a directly proportional correlation between increasing the mole ratio of Ba(NO 3 ) 2 and the novolac resin with increasing ER and MIE. A composite with low ER will conduct electrical energy and accumulate joule heating to begin ESD ignition. Therefore, increasing the conductive Mg ratio in the composite decreases joule heating. Thus, the MIE decreases with an increase in the Mg concentration. Similarly, increasing the concentration of electrical insulated novolac resin or Ba(NO 3 ) 2 in the composite increases the joule heating and the MIE. Therefore, a correlation was made to predict the ESD sensitivity of composites with different mole ratios of ingredients according to the values ob- tained from their ER measurements. 1. Introduction Composite energetic materials are a mixture of fnely-powdered fuels and oxidants (and additives are sometimes included to promote specifc properties). They often include metallic or non-metallic fuels, inorganic or organic oxidants, and in some composites, they contain a binder [1]. Many factors such as preparation, grinding, formulation, oxygen bal- ance, compression, additives, and impurities affect inter-solid CEM re- actions [2–4]. The safety of mixing, transporting, storing, and loading into an end item and the proper functioning of the device are essential matters to producers. Several techniques can be applied to determine the sensi- tivity of CEM materials, including friction, impact, spark, and thermal sensitivity. It is increasingly important to understand the sensitivity of electrical discharge (ESD). The most typical ESD form is a spark. It oc- curs when the static electric feld strength is equal to or greater than the dielectric strength of air (i.e., 4–30 kV/cm) [5]. Each formulation of high energetic composites, depending on the concentration of its components, has specifc ER and ESD sensitivity. ER measurement is an easy, accurate, repeatable, non-destructive, and fast method to evaluate energetic materials. Weir et al. presented a link between electrical conductivity and ESD ignition sensitivity of Al/CuO composite. They expounded on the notion of multi-modal energy transfer as electrical and joule heating toward energetic material igni- tion. In addition, they found that by reducing the Al particle size in the mixture and increasing the surface-to-volume ratio of Al, the electrical resistance decreases, and the MIE for combustion decreases [5,6]. Poper et al. observed that adding CNT to a mixture of Al and CuO may increase the MIE by providing a conduit for electric energy to bypass the reactant powders [7]. Collins et al. showed that Al + MoO 3 composites were sensitive to spark, but their sensitivity is controlled by the Al 2 O 3 shell thickness around the Al particles. Increasing shell thickness leads to decreasing electrical conductivity and increasing ignition delay time of composite [8]. The stoichiometry of the fuels and oxidants ingredients is an important parameter infuencing the heat of combustion. A stoichio- metric composite is a balanced mixture of fuel and oxidant such that no excess of either remains after combustion. This balanced mixture is often * Corresponding author. Department of Chemistry, Isfahan University of Technology, Isfahan, 84156- 83111, Iran. E-mail addresses: m_zhiani@cc.iut.ac.ir (M. Zhiani), akbarzare777@gmail.com (A. Zare). Contents lists available at ScienceDirect Journal of Electrostatics journal homepage: www.elsevier.com/locate/elstat https://doi.org/10.1016/j.elstat.2022.103755 Received 18 February 2022; Received in revised form 17 June 2022; Accepted 1 September 2022