THE RELATIONSHIP BETWEEN DP, FRACTURE DEGREE AND MECHANICAL STRENGTH OF CELLULOSE Iβ IN INSULATION PAPER BY MOLECULAR DYNAMIC SIMULATIONS.

The degree of polymerization (DP) has been regarded as an important symbol of mechanical strength, reflecting the aging condition of transformer insulation paper. In this article, a new concept called fracture degree is proposed on the basis of DP. First, nine cellulose Iβ crystal models with different fracture degrees were built. Then relevant mechanical parameters and hydrogen bond numbers were calculated by molecular dynamics (MD) simulation. Results showed that during the aging process of insulation paper with fracture of cellulose chain, the elastic constant C33 produces appreciable impact on the Young's modulus (E). With the decrease of DP and increase of fracture degree, the Young's modulus step decreases. To the 50% and 100% fracture degree models respectively, the relationship between their different degrees of polymerization and Young's modulus is subjected to similar exponential distributions. With the increase of the fracture degree, the average hydrogen bond number drops, and the change rules apply to the Young's modulus. Since hydrogen bond is the main factor of mechanical strength, it can be inferred that the fracture degree influences mechanical strength seriously. [ABSTRACT FROM AUTHOR]