To explore the tribological characteristics of cellulose nanocrystals derived through various preparation techniques when utilized as additives in water-based lubricants, two types of cellulose nanocrystals (S-CNC and C-CNC) were chosen. These were produced via sulfuric acid hydrolysis and oxidation methods. The morphology and structural features were assessed through techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), laser confocal Raman spectroscopy, elemental analysis, scanning electron microscopy (SEM), and laser particle size analysis. According to thermogravimetric analysis (TGA), the thermal stability of S-CNC is slightly superior to that of C-CNC. S-CNC exhibits liquid crystallinity when the concentration exceeds 0.5 %, whereas C-CNC does not display liquid crystallinity at any concentration tested. Further investigation was conducted on the frictional properties of the two types of CNCs using a UMT reciprocating friction tester. The results indicate that both types of CNC exhibit significant friction reduction properties at various additive concentrations, provided the addition does not exceed w=1 %. When below their respective liquid crystalline phase concentrations, the friction reduction performance of S-CNC is slightly inferior to that of C-CNC; however, when above the liquid crystalline phase concentration, the friction reduction performance of S-CNC surpasses that of C-CNC. The addition of w=0.5 % S-CNC leads to a relative reduction of 63.4 % in the friction coefficient compared to the base system. Analysis of the steel plate surface contact angle and post-wear surface suggests that the lubrication mechanism of CNC involves the adsorption of polar functional groups such as hydroxyl or carboxyl groups from the CNC structure onto the friction pair surface, forming a lubricating protective film to varying degrees. Additionally, the liquid crystalline structure of S-CNC facilitates the formation of an ordered lubricating film, further enhancing the frictional properties. These findings provide valuable insights into the application of nanocellulose crystals as lubricant additives.

中文翻译：

---

水基润滑油添加剂纤维素纳米晶制备技术与摩擦性能的相关性


为了探索通过各种制备技术获得的纤维素纳米晶体用作水基润滑剂添加剂时的摩擦学特性，选择了两种类型的纤维素纳米晶体（S-CNC 和 C-CNC）。这些是通过硫酸水解和氧化方法生产的。通过傅里叶变换红外光谱 (FT-IR)、X 射线粉末衍射 (XRD)、激光共焦拉曼光谱、元素分析、扫描电子显微镜 (SEM) 和激光粒度等技术评估形态和结构特征分析。根据热重分析（TGA），S-CNC的热稳定性略优于C-CNC。当浓度超过 0.5% 时，S-CNC 表现出液晶性，而 C-CNC 在任何测试浓度下都不表现出液晶性。使用 UMT 往复摩擦测试仪对两种 CNC 的摩擦性能进行了进一步研究。结果表明，只要添加量不超过 w=1%，两种类型的 CNC 在不同的添加剂浓度下均表现出显着的减摩性能。当低于各自的液晶相浓度时，S-CNC的减摩性能略逊于C-CNC；然而，当高于液晶相浓度时，S-CNC的减摩性能超过了C-CNC。添加 w=0.5% S-CNC 后，与基础系统相比，摩擦系数相对降低了 63.4%。 对钢板表面接触角和磨损后表面的分析表明，CNC的润滑机制涉及CNC结构中的羟基或羧基等极性官能团吸附到摩擦副表面，形成润滑保护膜以适应不同的磨损情况。度。此外，S-CNC的液晶结构有利于有序润滑膜的形成，进一步增强摩擦性能。这些发现为纳米纤维素晶体作为润滑油添加剂的应用提供了宝贵的见解。