| Cellulosic paper, a network-constructed material, was mainly composed of naturallyoccurring fiber. Its thermo-mechanical strength is mainly controlled by the type of used fiberand fiber properties. Fiber properties mainly include fiber length, diameter, width, curl index,kink index, fines content, strength of fiber itself, inter-fiber bond strength and the relativebonded area. Based on above parameters, mathematical models regarding the paper tensilestrength was proposed and developed in recent years. Among these models, Page showed thatpaper tensile strength was largely governed by the strength of fiber itself and the inter-fiberbond strength. Page model was well-known and widely applied. However, some relatedparameters were not easily to obtain by common experimental methods. Furthermore, the effectof compliance ratio and water retention value on paper tensile strength was almost overlooked.Herein, regarding chemical and mechanical pulp as the research subject, we modified the Pagemodel using compliance ratio and water retention value to represent the relative bonded areabetween fibers. Moreover, Minitab soft was employed to fit the as-obtained experimental data.The modified model for paper tensile strength was developed for the purpose of providingfundamental instruction on practical production.Fiber length may be characterized by arithmetic av. fiber length, length weighted av. fiberlength and bass weighted av. fiber length. Based on the current literature, there has been limitedstudy regarding the influence of arithmetic av. fiber length and length weighted av. fiber lengthon paper tensile strength. For this reason, the effect of arithmetic av. fiber length and lengthweighted av. fiber length on paper tensile strength was highlighted in the present work. Resultsshowed that length weighted av. fiber length agree better with the paper tensile strength invariable trend. Hence, length weighted av. fiber length was defined as effective parameter inmodified Page model. In this study, zero span tensile strength was used to describe the strengthof fiber itself, and inter-fiber bond strength was represented by inter-paper bond strength. It wasfound that paper tensile strength is strongly dependent on the internal bond strength of papersheet, which supports that the break of paper sheet was remarkably affected by fiber pulled. In the modified page model, for chemical pulp, the correlation coefficient between the predictive value and experimental data of paper tensile strength was0.61,0.87, respectively, when using compliance ratio and water retention value to characterize the RBA. This result provided direct evidence that Page model was not a desired choice for predicting the paper tensile strength of chemical pulp. However, for thermo-mechanical pulp, the correlation coefficient between the predictive value and experimental data of paper tensile strength reached0.92, when using water retention value to characterize the RBA, and the ideal model for describing paper tensile strength was established and presented as follows:1/T=0.215-1.470(Cw+1)/lwWRVTo better understand the relationship between chemical pulp fiber properties and paper tensile strength, Shallhorn-Gurganal tensile energy absorption model was subsequently introduced in the present work. Modified model regarding paper tensile strength derived from chemical pulp was developed based on the hypothesis that tensile strength and elongation was almost affected by the same factor. Among those models, the model of T=m·sa·Cwb showed a desired coefficient between predictive value and experimental value, with a typical R2of0.91. This model was changed as T=m1·Cwa1·sb1lwc1when the parameter of length weighted was introduced, exhibiting a R2of0.90. Based on model T=m2·WRVa2·sb1·lwC2and T=m3·WRVa3·sb3·lwc3·kd, the correlate on coefficients between the predictive value and experimental data of paper tensile strength was0.95,0.96, respectively, showing no significant changes. In comparison with T=m3·WRVa3·sb3·lwc3·kd, T=m2·WRVa2·sb2·lwc1was more simple and explicit in the absence of kink index. The expression was presented as r=7.91×10-3·s0.76·WRV1.62·lw0.17. Herein, paper elongation (s) can be estimated from kink index (k) and RBA replacing model s=n·WRVα·kβ, the expression was defined as s=0.399·k-106·WRV1.84. |
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