Abstract

The volume electrical behavior of copy papers was influenced by several structural, compositional and mechanical properties that significantly affected charge transport mechanisms, through the fibrous network. In this work, the relationships between volume electrical resistivity (ρ_v) and physical and mechanical properties of commercial copy papers were systematically investigated using advanced statistical analysis in order to understand the factors controlling electrical performance, and their implications for paper quality and environmental stability. The examined parameters were moisture content, thickness, grammage, density, ash content on ignition at 900 °C, Bendtsen roughness, tensile strength in the machine direction (MD), cross direction (CD) and pick resistance in both MD and CD direction. Linear regression analysis indicated that volume resistivity decreased with increasing moisture content, density, ash content, grammage, roughness Bendtsen, and pick resistance, while it increased with increasing paper thickness, and tensile strength in the cross direction (CD). Moisture content, among the other parameters, exhibited the strongest influence on electrical behavior, and showed the role of moisture-assisted ionic conduction within the copy paper structure. However, the individual linear regressions generally showed low coefficients of determination, and suggested that the volume electrical resistivity was controlled by a combination of interacting structural factors, rather than a single variable. Descriptive statistical analysis revealed distinct distribution patterns among the investigated paper properties. Volume resistivity exhibited strong positive skewness and high kurtosis, indicating a highly asymmetric distribution, typical of moisture dependent electrical conduction in porous fibrous networks. Structural parameters such as grammage, density, thickness, roughness Bendtsen and ash content showed approximately symmetric distributions, with near normal kurtosis, indicating the controlled nature of the papermaking process. Pick resistance displayed moderate variability between the MD and CD, consistent with the anisotropic structure of paper. Distributional diagnostics using the Shapiro-Wilk test (n<50)revealed deviations from normality for volume resistivity, and moisture content, while the other properties followed approximately normal distributions. Levene’s test indicated heterogeneity of variances among groups with p<0.001. One-way analysis of variance (ANOVA) demonstrated significant differences among the examined property groups with F=10.245, p<0.001, and with a moderate effect size η2=0.304. This result was robust and was confirmed by Welch, and Brown-Forsythe tests, which also indicated significant differences (p<0.001). The statistical findings were supported by boxplots, histograms, and normal Q-Q plots, which illustrated the variability, and skewness of the volume electrical resistivity distributions. The results indicated that volume resistivity in copy paper was mainly controlled by moisture content, while structural parameters, such as thickness, and density, modulated conduction pathways within the fiber network. Mechanical surface properties, including roughness Bendtsen, and pick resistance, exerted secondary effects. The findings from this study may have contributed to a better understanding of the structural and electrical relationships in copy papers, and may have supported future research aiming at improving copy paper performance, its quality control, and also the environmental stability in printing, and electrostatic applications.

Keywords:Electric volume resistivity; Density; Paper moisture; Grammage; Paper thickness; Ash on ignition 900 °C; Tensile strength; Bendtsen roughness; Pick resistance; Fiber network; Ionic conduction; Multivariate analysis; Copy paper; Linear regression; One-way ANOVA; Descriptive statistical analysis; Normal Q-Q plots; Histogram; Boxplot; Machine direction (MD); Cross direction (CD); Electrostatic behavior