Ladderlike Polyphenylsesquioxane‐Doped Cellulose Insulation Paper with Upgraded Mechanical Strength

Ladderlike polyphenylsesquioxane (L‐PPSQ) with special planar ladder structure is significant to upgrade the mechanical strength of cellulose insulation paper. In this study, the effect of different content of L‐PPSQ on mechanical properties and dielectric properties of cellulose is first investigated by molecular simulation, and then insulation paper doped with L‐PPSQ is prepared for experimental verification. It is indicated in the simulation results that the elastic modulus, bulk modulus, and shear modulus of the cellulose are enhanced up to 36.82%, 27.96%, and 41.80%, respectively, when L‐PPSQ is added at 3 wt%, and the cellulose model with 3 wt% L‐PPSQ possesses the lowest dielectric constant. The reason is that L‐PPSQ can enhance the hydrogen bonding network of cellulose, weaken the degree of molecular chain motion, and strengthen the strength of molecular chains, which in turn manifests as the enhancement of mechanical strength. It is shown in the experimental results that the tensile strength and elongation at break of the composite insulation paper can be enhanced by 16.7% and 35.09% when the L‐PPSQ content is 3 wt%, which is consistent with the simulation results. The short‐term aging test shows that L‐PPSQ can also upgrade the mechanical strength of the insulation paper at high temperatures.