Hexagonal boron nitride (h-BN), an isoelectric analogous to graphene multilayer, can easily shear at the contact interfaces and exhibits excellent mechanical strength, higher thermal stability, and resistance toward oxidation, which makes it a promising material for potential lubricant applications. However, the poor dispersibility of h-BN in lube base oil has been a major obstacle. Herein, h-BN powder was exfoliated into h-BN nanoplatelets (h-BNNPs), and then long alkyl chains were chemically grafted, targeting the basal plane defect and edge sites of h-BNNPs. The chemical and structural features of octadecyltriethoxysilane-functionalized h-BNNPs (h-BNNPs-ODTES) were studied by FTIR, XPS, XRD, HRTEM, and TGA analyses. The h-BNNPs-ODTES exhibit long-term dispersion stability in synthetic polyol ester lube base oil because of van der Waals interaction between the octadecyl chains of h-BNNPs-ODTES and alkyl functionalities of polyol ester. Micro- and macrotribology results showed that h-BNNPs-ODTES, as an additive to synthetic polyol ester, significantly reduced both the friction and wear of steel disks. Elemental mapping of the worn area explicitly demonstrates the transfer of h-BNNPs-ODTES on the contact interfaces. Furthermore, insight into the lubrication mechanism for reduction in both friction and wear is deduced based on the experimental results.

Two acylated chitosan Schiff base samples ACSB-1 and -2 were synthesized via a two-step reaction pathway. First the chitosan Schiff base (CSB) was prepared utilizing 3,5-di-tert-butyl-4-hydroxybenzaldehyde. In the second step, esterification with lauroyl chloride catalyzed by 4-(dimethylamino)pyridine (DMAP) in N,N-dimethylacetamide (DMAc) solvent affords the final product acylated chitosan Schiff base (ACSB-1 and -2). The products were identified and characterized by Fourier transform infrared (FT-IR) spectroscopy, CHN analysis, thermogravimetry (TG), X-ray diffraction (XRD), etc. The synthesized compounds were evaluated as multifunctional additives for antioxidant and lubricity properties in N-butyl palmitate/stearate. A rotating pressure vessel oxidation test (ASTM D2272) was used for evaluating antioxidant property. The thermo-oxidative stability of the N-butyl palmitate/stearate oil was increased 1.5 times by using this additive in 3000 ppm concentration of ACSB-2 at 150 °C. Lubricity property was evaluated by using the four ball test (ASTM D4172A) which was performed at 75 °C temperature, frequency of 1200 rpm, and 198 N load for 60 min. The lubricating efficiency of the synthesized sample was estimated by measuring the average wear scar diameter (WSD) of the spherical specimen. The WSD is also found to be decreased significantly by adding these compounds as additives in N-butyl palmitate/stearate. Both samples passed the copper strip corrosion test (ASTM D130) too.

The present paper describes the first successful application of poultry waste chicken feathers in the development of green, biodegradable, and eco-friendly lubricant additives. The additive was synthesized through three step chemical functionalization of chicken feathers. The first step involves the reaction between chicken feather powder (CF) and (3-aminopropyl)trimethoxysilane (APTMS) to synthesis CF-APTMS, the second step involves the synthesis of CF-Schiff base by reacting CF-APTMS with 3,5-ditert-butyl-4-hydroxybenzaldehyde, and in the third step, esterification with lauroyl chloride catalyzed by 4-(dimethylamino)pyridine (DMAP) afforded the final product acylated chicken feather Schiff base. The applicability of this CF derived additive as a biodegradable and ecofriendly lubricating oil additive was investigated by testing the antioxidant, lubricity, and anticorrosion properties in polyol which was taken as a reference base fluid. A rotatary bomb oxidation test (RBOT) was used to evaluate the antioxidant characteristics while a four ball test was employed for the tribological properties. The additive is found to be very effective as an antioxidant and anticorrosive additive, but as an antiwear additive its potential is moderate.

No abstract

The concept of an “ecofriendly lubricant” has drawn much attention due to environmental issues related to conventional lubricants. Mere innovations in lube base oils are not enough. The introduction of new ecofriendly additives is also necessary to address such issues. Therefore, there is a need for the development of new multifunctional additives (MFA) that are environmentally benign. In view of this, the mixed esters of pentaerythritol monooleate with gallic acid (additive 1) and 3,5-di-tert-butyl-4-hydroxybenzoic acid (additive 2) have been synthesized. Both additives 1 and 2 were characterized by FT-IR, NMR, TG, and CHNS analyses. They were evaluated for antioxidant and detergent dispersant along with lubricity properties using the rotary bomb oxidation test, blotter spot test, and four ball test. The thermo-oxidative stability of the base oil was found to increase significantly in the presence of additives 1 and 2 at 3000 ppm concentration. The antioxidant, detergent dispersant, and lubricity properties of additive 1 have been found to be better than those of additive 2.