TiO_2掺杂粒度对纤维素强度和热稳定性影响的分子模拟研究

变压器绝缘纸的主要成分为纤维素,为了提升绝缘纸的强度和热稳定性,利用纳米TiO_2掺杂纤维素,通过分子模拟方法研究不同纳米TiO_2粒度掺杂纤维素的强度和热稳定性.研究表明,纳米TiO_2使得纤维素强度提高,拉伸模量增大,抗形变能力增强,体积模量与剪切模量比值(K/G)增大,纤维素韧性增强;纳米TiO_2表面羟基与纤维素形成新的氢键网络使得径向分布函数峰值增大,复合体系更加稳定,其热稳定性增强.掺杂比例相同时,随着纳米TiO_2粒度减小,拉伸模量和柯西压增大,泊松比减小,纤维素的抗形变能力增强;纳米TiO_2表面羟基占有率越高,纳米TiO_2与纤维素越易形成氢键抑制纤维素链运动,纳米TiO_2也减小复合体系的自由体积,使得复合体系结构更加稳定,热稳定性更强.因此,掺杂小纳米TiO_2粒度是提升纤维素强度和热稳定性有效的方法.

Molecular simulation of the influence of TiO2 particle size on the strength and thermal stability of cellulose

The main component of transformer insulating paper is cellulose. In order to improve the strength and thermal stability of insulating paper, cellulose doped with Nano-TiO2 was used to study the strength and thermal stability of cellulose doped with different Nano-TiO2 particle sizes by molecular simulation. Studies have shown that Nano-TiO2 increases cellulose strength, tensile modulus, deformation resistance, ratio of volume modulus to shear modulus (K/G), and cellulose toughness. The formation of a new hydrogen bond network between hydroxyl and cellulose on the surface of Nano-TiO2 increases the peak value of radial distribution function, makes the composite system more stable and its thermal stability enhanced. With the same doping ratio, as the particle size of Nano- TiO2 decreases, the tensile modulus and Cauchy pressure increase, poisson''s ratio decreases, and the anti-deformation ability of cellulose increases. The higher the hydroxyl group share on the surface of Nano-TiO2, the easier it is for Nano-TiO2 to form hydrogen bonds with cellulose to inhibit the cellulose chain movement. Nano-TiO2 also reduces the free volume of the composite system, making the composite structure more stable and thermal stability stronger. Therefore, the particle size of doped TiO2 is an effective method to enhance the strength and thermal stability of cellulose.