Lubes em Foco Magazine – issue 96
Click on the magazine and read, download, or share the articles:
by: Ingrid Melchior
Application in Sugarcane Mills
The sugar and ethanol industry plays an important role in Brazil in several ways, whether in the production of alcohol, contributing to the reduction of fossil fuel use, in the food industry with the production of sugar, and in the energy sector through the valorization of milling byproducts. In addition, ethanol obtained from sugarcane also stands out as a valuable raw material for the production of renewable plastic resins, driving sustainable solutions in the chemical industry.
The milling of sugarcane is essential for obtaining all its derivatives, since it is through its juice that sugar and ethanol are extracted. After harvesting in the field, the cane goes through a cleaning stage and then goes through the stages of crushing and milling. The milling of cane involves the use of rollers, flywheels and bearings, which are responsible for compressing the vegetable fiber. In this process, the integrity of the aforementioned mechanical components is of utmost importance to guarantee not only the performance required for the milling stage, but also for the entire operation for the production of ethanol and sugar during the harvest.
The harvest in the central-south region – referring to the states of Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, and São Paulo – represents the largest volume of sugarcane milling in the country. In the 2023/2024 harvest, the region contributed approximately 640 million tons of sugarcane out of a total of 716 million tons of sugarcane milled during the period, as shown in Figure 1.
Figure 1: Distribution of sugarcane milling by state. Source: UNICAdata (Sugarcane and Bioenergy Observatory – 2023/2024 Crop Year).
Brazil is a benchmark in terms of sugarcane cultivation, development of technologies associated with the segment, and sustainable practices, with more than 50 years of experience in research and development. This is evidenced by analyzing the historical volume of sugarcane milling, shown in Figure 2. As can be observed, the sector has been growing consistently, with a record harvest in 2023/2024. Being a sector of great relevance to the agricultural market, the expectation is that it will continue to grow, supported by several factors such as policies to encourage the use of biofuels in Brazil, investments in mills, and logistical infrastructure for product distribution.
Figure 2: Historical monitoring of the sugarcane harvest in the central-south region. Source: UNICAdata (Sugarcane and Bioenergy Observatory)
This growth scenario requires that the other components of the chain also have appropriate performance, including the milling process. The efficiency of this process is strongly related to the lubrication of mechanical components, as it is a process that occurs under high pressure and with large loads. The composition of the lubricant used in this important stage of the process is crucial for its good performance, with the choice of base oil being a primary step. According to Carreteiro and Belmiro (2006), lubricating oils for mill bearings require high adhesion to metal, excellent film resistance, protection against oxidation, and the correct viscosity, especially under severe conditions such as contamination by sugarcane juice, rainwater, high loads, and subjection to high shear.
In this context, polyisobutene (PIB) stands out as a solution to be incorporated into this application. PIB is a synthetic product, belonging to Group V of the API – American Petroleum Institute, produced from the polymerization of isobutene molecules in the presence of a catalyst and temperature. This material is widely used in the lubricant segment, with proven performance both as an additive—acting as a Viscosity Index Modifier (VIM)—and as a base oil in formulations requiring high technical performance. Its application is especially advantageous in systems subjected to high shear conditions. The product is a colorless liquid at room temperature, hydrophobic, and clean-burning, meaning it does not generate deposits after the combustion process. Considering these characteristics and the requirements for lubricants used in sugarcane milling, PIB’s performance stands out: it has high adhesiveness, low interaction with water—given its hydrophobic characteristic—high viscosity, and shear resistance—an important characteristic that ensures the maintenance of the lubricating film without degrading its viscosity, despite mechanical stresses. The PIB32 grade exhibits excellent shear resistance even when subjected to different temperatures and increased shear rates, as shown in Figure 3.
Figure 3: Shear stability of PIB32 at 110°C, 120°C, 125°C and 135°C, showing the variation of viscosity (in Poises) as a function of shear rate. Data were obtained using a capillary viscometer (squares) and a high shear viscometer (circles). Data generated and provided by Braskem S.A.
The different types of polyisobutene (PIB) stand out as strategic solutions for lubricant applications, offering a wide range of viscosities that surpasses conventional mineral oils. Viscosities at 40°C range from 15 cSt to 22,000 cSt, while at 100°C they range from 210 cSt to 13,000 cSt, providing flexibility to meet requirements ranging from light formulations to systems with high viscosity requirements, according to the needs of each stage of the grinding process with different rotations, depending on the need for greater or lesser torque. In addition, PIBs have significantly higher viscosity indices than conventional mineral oils, which means less viscosity variation with increasing temperature. This combination of properties allows for optimizing lubricant performance, reducing wear and extending the service life of equipment, consolidating PIBs as essential components for applications that demand reliability and efficiency.
The different types of polyisobutene (PIB) stand out as strategic solutions for lubricant applications, offering a wide range of viscosities that surpass conventional mineral oils. Among the components available to meet these requirements and performance levels, materials that offer low interaction with water, thermal stability, and shear resistance, even under severe conditions, stand out. The combination of these characteristics allows the development of lubricants that maintain consistent performance, reducing failures and optimizing operational efficiency. Polyisobutene represents a highly efficient alternative for applications that require a balance between technical performance and cost-effectiveness, especially when compared to synthetic oils of groups IV and V. Grades with kinematic viscosities of approximately 680 cSt, 4350 cSt, and 12500 cSt – all measured at 100°C – are the most suitable for use as base oil in this application, as they provide an ideal balance between adhesiveness, viscosity, and water repellency, which are essential characteristics to ensure stability and protection in severe conditions, such as high-temperature environments, high mechanical load, and the presence of moisture, observed in sugarcane mills.
Ingrid Melchior Ferreira is part of the technical area of Braskem’s Chemical Specialties and Renewables business. She holds a degree in Chemistry and Science and Technology from the Federal University of ABC and is a postgraduate student in Polymer Engineering. Ingrid has worked at Braskem for 5 years.
