Enhancement and Prediction of Mechanical Properties of Microcellulose/ Nanocellulose-Modified Insulating Paper

The insulating paper in oil-paper insulated transformers is subjected to significant mechanical vibration and mechanical shock, putting considerable demands on the insulating paper’s strength and resistance to deformation. Therefore, effective enhancement and accurate prediction of mechanical properties are crucial in the application of cellulose-insulating paper. In this article, modified insulating paper with different mass fractions of cellulose nanowhiskers (CNWs), nanofibrillated cellulose (NFC), and microfibrillated cellulose (MFC) are prepared. The microscopic morphology, stress-strain curves, and Young’s modulus of the modified insulating paper are measured. The modification effects of microcellulose/nanocellulose with different aspect ratios on the mechanical properties of the insulating paper are compared. 10 wt% mass fraction of CNW-modified paper exhibits the highest Young’s modulus with an enhancement of 11.99%. The mechanism of microcellulose/nanocellulose modification on insulating paper is analyzed in terms of its strength, morphology, interface, and agglomeration. The prediction of Young’s modulus of modified insulating paper under different doping concentrations is realized based on the Halpin-Tsai model for filler modification under ideal conditions, considering the effects of agglomerated and interfacial phases, on the basis of detailed experimental results and comprehensive analysis. Experimental validation shows that the error of the proposed prediction model is less than 1.57%. This study is very beneficial for nano-modification and mechanical property enhancement of cellulose paper.